International Journal of - WhatDoTheyKnow

!PCC WGI TAR Expert Review Comments 20-01-00 Chapter 2

I do not wish to take this statement out of context, but I would emphasis the "might" (WHAT WE SAY!).Further, it should be mentioned [it is, elsewhere in the text] that the records for the PDO, IPO, NP and theNAO are all bi-phasic and in coincidence with the global temperature record. Each cycle is in one phaseduring the 1900-1940 warming, shifts phase during the 1940-1970 cooling/stagnation, and reverts to thefirst phase during the current warming. ITS APROXIMATELY TRUE BASED ON A VERY SMALLSAMPLE. NO ACTION NEEDED.Steven Japar, Ford Motor Co., USA

Page 54, line 25Change "responsible for" to "connected with" (to avoid unproven imputation of causality) YESDavid E Parker, Hadley Centre, UNITED KINGDOM

Page 54, line 26Change "effects" to "features related to" (to avoid unproven imputation of causality) YESDavid E Parker, Hadley Centre, UNITED KINGDOM

Page 54, line 29:There is a link to the precipitation increase in south Scandinavia (see comment to p. 44).YESChristian-D. Schoenwiese, J.W. Goethe University, Germany

Page 54 line 30:Sigurdsson and Jonsson 1995 not in reference list ADDPovl Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Page 54, Line 33... (Kushnir et al. 1997) and is probably related to the rapid abatement of cold NE winds (bora) that hasbeen observed in the northern Adriatic area (Pirazzoli and Tomasin, 1999\ [Pirazzoli, P.A. and A.Tomasin, 1999: Recent abatement of easterly winds in the northern Adriatic, International Journal ofClimatology, 19, 1205-1219].GETTING LOCAL AGAIN-DISCUSSP.A. Pirazzoli, CNRS Laboratoire de Geographie Physique, France

Page 54, Lines 42-43."the regional manifestation" should read "a regional expression" OKDavid W. J. Thompson, Dept. of Atmospheric Sciences, University of Washington, USA.

Page 54, Line 42-45Thompson et al, 1999 show (Fig. 8) that the AO has been most prominent over the last decade. Its largestdepartures are mostly over this period, which is probably why it was not detected in earlier studies. It mayme more correct to describe it as the "Arctic Trend" rather than the AO.AO IS FIRMLY IN THE LITERATURE AND FIG 2.40 SHOWS THAT THIS IS ANOVERSIMPLIFICATION. SO I DON'T AGREEJohn Kidson, NIWA, New Zealand

Page 54, line 49-501) For climate change, much more relevant than the correlation of the monthly values are the correlation oflow-pass filtered values or of decadal-mean values. YES-WE SHOULD CALCULATE THESE-WHO?2) E.g. the recent rise in the AO looks more pronounced than the rise in the Hurrell NAO3) Why is not the Hurrell NAO compared to the Jones NAO? In the Jones NAO, the recent rise is even lesspronounced than in the Hurrell NAO. DISCUSS. THERE ARE ISSUES HERE OF EXACTLY WHICHSET OF WINTER HALF YEAR MONTHS ARE USED.Gerrit Burgers, KNMI, The Netherlands

Page 54, Lines 49-50."The time series of the North Atlantic Oscillation (NAO) and AO are nearly indistinguishable: thecorrelation coefficient is 0.95". This statement may be easily misinterpreted. Most in the climate dynamics

111


community associate the time series of the NAO with the difference in sea-level pressure between stationdata in Iceland and the Azores (or Portugal). Defined as such, the correlation between the NAO and the AOis only -r=0.7. Deser (1999) is referring to the leading EOF of the Atlantic half of the NH. The distinctionbetween station based indices of the NAO and the leading EOF of the Atlantic half of the hemisphere isextremely important and should be clearly articulated. YES INDEEDDavid W. J. Thompson, Dept. of Atmospheric Sciences, University of Washington, USA.

Page 54, line 54Plot Figs. 2.39 and 2.40 on same graph to aid comparison and save space. I AGREE, THEY SHOULD BEFOR THE SAME MONTHS AND DAYID PARKER SHOULD BE ASKED TO CREATE IT! ANDCORRELATION CALCULATED.David E Parker, Hadley Centre, UNITED KINGDOM

Page 55, lines 2-7: The discussion of North Atlantic Ocean SST variability should also reference Mestas-Nunez and Enfield (1999), whom have shown this multidecadal variability cleanly after first removing theENSO component from the data. YES

SECTION DELETEDChris Landsea's Comments

Page 55, lines 2-31The following article also discusses the dominant role of air-sea interaction in forming the tripole SSTpattern characterizing the Atlantic decadal oscillation, together with a discussion on the importance ofoceanic advection in bringing the phase reversal of the oscillation. Watanabe, M., M. Kimoto, M. Kachi,and T. Nitta, 1999: A comparison of decadal climate oscillations in the North Atlantic detected inobsertvations and a coupled GCM. J. Climate, 12,2920-2940. In addition, using subsurface observationsand a mixed-layer ocean model, the following upcoming article discusses persistence of the tripole SSTpattern from one winter to another via so-called "recurrence mechanism" in the ocean mixed layer.Watanabe, M., and M. Kimoto, 1999: On the persistence of decadal SST anomalies in the North Atlantic. J.Climate, in press. (Also please pay attention to: Alexander, M. A., and C. Deser, 1995: A mechanism forthe recurrence of wintertime midlatitude SST anomalies. J. Phys. Oceanogr., 25, 122-137.)TOO MANY REFS: DISCUSS WHICH. MORE APPROPRIATE FOR CHAPTER 7.M. Kimoto, CCSR, Univ. Tokyo, Japan

Section deleted

Page 55 line 3-4:please rephrase to: a cold subpolar anomaly region, relative warmth in the middle latitudes, and a coldanomaly region between ...TRUE- WILL READERS UNDERSTAND THIS?Povl Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Section deleted

Page 55, lines 23-31: Reference should also be given to Gray et al. (1997) for suggesting that themultidecadal North Atlantic Ocean SST variations are linked to the North Atlantic Deep Water Formation.YES?Chris Landsea's Comments

Section deleted

Page 55, Line 35Comment: The Cavalieri et aI., 1997 reference should be deleted here (it dealt with the north polar regionas a whole, not with individual regions), and the Parkinson et aI., 1998 reference should have the datechanged to 1999. OKClaire L. Parkinson, NASA Goddard Space Flight Center, USA.

112

IPCC WGI TAR Expert Review Comments 20-01-00 Chapter 2

Change Made

Page 55, Lines 37, 38, 39.In line 37, insert the references Mysak et al. 1996; Mysak and Venegas 1998; before the referencePrinsenberg et al. 1997.Rationale:These added references describe atmospherically forced sea ice motions over a larger spatial scale thanwhat is discussed in Prinsenberg et aI., and also they emphasize the decadal timescale of Arctic air-ice-seaclimate variability. OK BUT WE NEED MYSAK ET AL (1996) FROM LAURENCE.Lawrence A. Mysak, McGill University, USA

Page 55, lines 38 and 39I suggest the following revision:...to detect, although Mysak and Venegas (1998) have shown that when the ice cover is reduced east of

Greenland, the NAO changes from a negative to a positive phase, in response to enhanced ocean-to-atmosphere heat fluxes, a process that is part of a proposed decadal scale climate cycle.Rationale:The idea of the atmosphere responding significantly to changes of sea ice cover in the Greenland Sea goesback to earlier work at McGill (eg, Mysak et al. 1990, in Climate Dynamics), and therefore, for historicalaccuracy and fairness, the reference to the earlier paper of Mysak and Venegas (1998) is more appropriatethan the Deser et al. reference.BEST TO REFER TO BOTHLawrence A. Mysak, McGill University, USA

Page 55 line 46:Osborne et al. (1999) not in reference list. ADD .. DELETED LAST E OF OSBORN.Povl Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Page 55, lines 47-48.Suggested re-wording: ...Cook et al. (1998) reconstruction because it has little variance in common with the1824-1873 portion of the Jones et al. (1997) index .. YES. NO. THE CAVEAT IN THAT SENTENCEREGARDING THE EARLY JONES DATA MUST BE MAINTAINED!!!Dr. Timothy J. Osborn, Climatic Research Unit, UEA, UK

page 56, line 20:please explain the expression Trans Polar Index THIS CAN PROBABLY BE OMMITTEDHeinz-Jiirgen Ahlgrimm, FAL Braunschweig, Germany

Page 56, lines 23-27Notes the "out-of-phase relationship between the long-wave troughs in the Tasman Sea - New Zealand andsouthwest Australian regions during the austral winter on decadal time scales. Also notes the decrease inthe strength of the trough over the Tasman SealNew Zealand region during the austral winter over the1965-1980 epoch. However, while also observing this feature, Allan and Haylock (1993) notes a decreasein troughing southwest of Australia during the same period. They also note that there appears to be a multi-decadal signal superimposed on a longer term trend such that higher pressures are experienced over theentire region towards the end of the period. YES, BUT CAN WE GET RID OF MOST OF THIS?Neil Plummer, Bureau of Meteorology, Australia

Page 56, lines 33-35Are these changes consistent with the shifts in the L index noted in the previous para on page 56? GETRID?Neil Plummer, Bureau of Meteorology, Australia

Page 57, Lines 6-7; lines 18-19.The Antarctic Oscillation (the AAO) and the High Latitude Mode are different names for the same mode of

113

[PCC WG[ TAR Expert Review Comments 20-01-00 Chapter 2

variability - not "similar" modes of variability. I would suggest using the annular mode nomenclature inlieu of the AAO nomenclature. Both annular modes (the NH and SH annular modes) are evident year-round, but are only coupled with the stratosphere during certain times of year. The SH annular mode ismost active in the stratosphere during the SH spring; as of yet there is no evidence that it is most active inthe troposphere during this time.DISCUSSDavid W. J. Thompson, Dept. of Atmospheric Sciences, University of Washington, USA.

Page 57, lines 7-8How significant are the weakening in the westerlies? PROBABLY REMOVE?Neil Plummer, Bureau of Meteorology, Australia

Page 57, Lines 7-8.This sentence should end ", but this may result from changes in observational coverage" or similar text. It'snot possible to be sure of the reality of this trend, though it is consistent with changes in the HADCM2model driven by observed SST and sea ice. REMOVE?John Kidson, NIWA, New Zealand

Page 57. line 13What are the noticeable affects on climate? DO WE NEED THE ARCTIC CIRCUMPOLAR WAVE FORTHIS REPORT?Neil Plummer, Bureau of Meteorology, Australia

Page 57 line 18.ANO -> AAO YES. THIS IS REPETITIVE WITH SECTION ABOVE. COMBINEKevin E. Trenberth, NCAR, USA

Page 57, lines 32 - 36.The wording here is "leading" the reader and should be redone. The question is not whether globalwarming has caused a shift from La Nina's to more frequent EI Nino's since 1976, but rather ifanthropogenic trace gas forcing has caused such a shift. Further, it is of interest how much that shift itselfhas contributed to the global warming since 1976 - regardless if it can be ascribed to anthropogenic tracegases or not.DISCUSSGerd R Weber, Germany

Page 57, Lines 53-54.It is wrong to claim the "Antarctic Oscillation" is a new phenomenon. It has been known since the work ofvan Loon in the 1970s and is most commonly referred to as the High Latitude Mode (HLM) by SHclimatologists. For references see, for example, Kidson 1999, 1 Climate, p 2808, Kidson & Watterson 1999,lAS p3859. Thompson et al extended this earlier work by examining interactions with the lowerstratosphere. YES, SO KIDSON 1988 IS THE HISTORICAL REFERENCE WITH SELECTED RECENTREFS.John Kidson, NIWA, New Zealand

Page 58 and Page 132 (Figure 2.3)Emphasis must be done in different time scale trends: annual, seasonal, daily. In our opinion is one of themost relevant conclusion from that Report. OK BUT DON'T UNDERSTAND FIGURE 2.3 REFERENCECortina, J; De Luis, M.; Gonzalez-Hidalgo, J.C.; Sanchez, J.R.; Raventos, J.Department of Ecology. University of Alicante. Spain.

Page 58. Line 3.We are now reduced to trying to assess the variability of variability and the changes in changes. I find thisutterly confusing. Replace this heading by "Studies on Climate Variability."NO - NO ONE ELSE HAS APROBLEM.Vincent R. Gray, Climate Consultant, New Zealand

114

[PCC WGI TAR Expert Review Comments 20-01-00 Chapter 2

8. Line 5.Again,"Background" tries to force conclusions before the evidence is presented. Delete the heading andput most of the material at the end.DON'T AGREE THOUGH CAN WE SHORTEN?DISREGARDVincent R. Gray, Climate Consultant, New Zealand

Page 58, lines 16-17Should be" ... not well approximated by a normal distribution." YES.MAKE CHANGE FIXNeil Plummer, Bureau of Meteorology, Australia

Page 58, Line 22It should not be used personnel terms such as "us" and "we". US IS NOT GOOD. BUT WE IS NORMALUSE.IPCC LANGUAGE? DELETE "US"Carlos Borrego, Universidade de Aveiro, Portugal

Page 58 Line 27.Replace Heading with "Long-term Changes in Variability and Extremes" NO

DISREGARD, BUT HEADING DOES NEED A "?" YESVincent R. Gray, Climate Consultant, New Zealand

Page 58, line 27 (Section 2.7.2)I know of a comprehensive study by staffs of Japan Meteorological Agency on the long-term changes inextremes in Japan. Contact person: Dr. Masato Murakami <[email protected]>, Head, ClimateDiagnostics and Prediction Division, Japan Meteorological AgencyDISCUSSRESEARCH? ASK FOR MATERIALM. Kimoto, CCSR, Univ. Tokyo, Japan

Page 58, lines 33Large changes in extremes for modest changes in mean climate - suggest a reference to Katz and Brown(1992). YES. NEED FULL REFERENCE.REST OF REFERENCE? OKNeil Plummer, Bureau of Meteorology, Australia

Page 58, lines 45 - 54:Why not use station data for longer records? There are regional limitations, but that is outweighed by morecomprehensive information on the true range of variability within the instrumental period (see also page 59,lines 22 - 47).BOTH LONG HOMOGENISED STATION RECORDS AND GRID POINT DATA ARE USEFUL.NEED A SENTENCE OR TWO TO DISCUSS THIS. MORE OF THE LATTER WILL BECOMEAVAILABLE.!Gerd R Weber, Germany

Page 58. line 45 to page 59 line 16Some of these declines in varaince may be a result of increasing density of data. THIS IS AN ISSUETHAT IS CURRENTLY BEING TACKLED BUT EXISTING ANALYSES MAY BE CORRUPTEDTO SOME EXTENT.Reference in line 50 is Jones et al. 1999. YESSTATED LATER IN PARAGRAPH WHERE IS EVIDENCE? NOTE THIS FOR LONG-TERMSTUDIESDavid E Parker, Hadley Centre, UNITED KINGDOM

115

!PCC wor TAR Expert Review Comments 20-01-00 Chapter 2

Pages 58 and 59, lines 45-54{p58) and lines 1-16{p59)Discussion focuses on interannual variability then intra-annual variability then interannual variability again.Suggest including lines 7-10 (p59) in earlier discussion. NEED A LOGICAL SECTION STRUCTURERESTRUCTURE PARAGRAPH OK CHANGENeil Plummer, Bureau of Meteorology, Australia

Page 59, line 19Is there evidence to suggest that intra-annual temperature variability has decreased in the SouthernHemisphere? Decreases were not found for Australia (Karl et al. 1995, Plummer 1996). SHOULD REF

*** Note, however that preliminary results from longer records suggests that intra-annual variability mayalso be decreasing over much of Australia. These results will be confirmed prior to the second review. ASKFOR AN INPUT?DISCUSS CONTACT NEIL PLUMMERNeil Plummer, Bureau of Meteorology, Australia

Page 59, line 24"... also found in PARTS OF Australia." Also include reference to Stone et al. (1996) in line 25. NEED AFULL REFERENCE.ADD "PARTS" - NEED COMPLETE REFERENCE OKNeil Plummer, Bureau of Meteorology, Australia

Page 59, line 26Absolute daily extremes - is this the highest and lowest value each year? DEFINEBY MONTH AND YEAR (EXPLAINED IN TEXT) THIS NEED TO BE UPDAGED (ONLYTHROUGH 1989). TALK TO PETERSONNeil Plummer, Bureau of Meteorology, Australia

Page 59, Line 30'In China ..... , and a reduced number of very hot days (Zhai and Sun,1999), I think this statement ismisleading. In the cited reference, what it stated was:' Seasonal I-day extreme maximum temperaturesmainly reflect decreasing trends, while seasonal I-day extreme minimum temperature are increasing'. Infact, in Wang and Gaffen (2000a, 2000b) we have shown daily apparent temperature extremes (in terms ofboth number of days or number of 3-day heat wave events) are increasing in China (refer to the attachedfigure 2 and 3). IDENTIFY FIGS. DISCUSS.NEEDS RESEARCH AND DISCUSSION YES, BUT THIS INCLUDES MOISTURE SITEREFERENCES (NO CONSIDERATION OF URBANIZATION IN ANALYSIS. POINT OUT NOURBAN ASSESSMENTJulian Wang, NOAA, USA

Page 59, Lines 41-42This sentence misrepresents the reasons for the different findings of Gaffen and Ross (1998), comparedwith Karl and Knight, 1997, Kunkel et al. 1996, 1999a. It is not simply the influence of humidity thatyielded increases in extreme apparent temperature in the Gaffen and Ross study. Extreme temperatureevents also showed increases, both for daytime and for nighttime. The discrepancy is much more likelydue to the different periods of analysis, and, secondarily, to the use of first-order weather stations (byGaffen and Ross) vs cooperative observing stations (by the others). Overall, I think this paragraph sendsmixed messages, and needs to be re-crafted to indicate that, although the 1930's represented a period offrequent extreme heat events, trends in later decades are upward.A FEW SUBTLE ISSUES HERE THAT NEED TO GOT RIGHTHER CITATION IS NOT PRECISE - RECRAFT? URBANIZATION EFFECTS ARE INCLUDED INTHE GAFF EN RESULTS. SHOULD WE MENTION?Dian Gaffen, NOAA, USA

116

rpcc WGr TAR Expert Review Comments 20-01-00 Chapter 2

Page 59. Line 49"It is clear ... about 0.6C" It is extremely unclear!. Give a most probable figure and 95% confidencelimits. ITS UNNECESSARY IN THIS CONTEXT!SAME AS HIS FORMER COMMENTS AGREE WITH CHRIS!Vincent R. Gray, Climate Consultant, New Zealand

Page 59, Line 51.Add: (maximum), and that over two thirds of measured surface warming since 1950, at least in theNorthern Hemisphere, is in the winter half-year, with over three-quarters of that originating in the coldanticyclones of Siberia and northwestern North America (Michaels et al., 2000 in press)Reference:Michaels, P.J., Knappenberger, P.c., Balling, Robert C. Jr., and Robert E. Davis, 2000. Observed warmingin cold anticyclones. Climate Research in proof.#WE DON'T NEED ALL THIS AND CAN REFER TO FIGS 2.10-2.11 BUT REMIND PEOPLE THATWARMING IS NOT UNIFORMDISCUSS YES AND CAN REFERENCE MICHAEL'S (IF WE CAN READ IT!) NOT HERE!Patrick J. Michaels, Department of Environmental Sciences, USA

Page 60Supervise the references. There exist some mistake. Haylock and Nichols, 2000, Yamamoto and Sakurai(1999), Lai (1999) Gorland et al. (1998) are not listed. MORE MISSING REFS. I SUSPECT WE HAVEMOSTNEED TO BE ADDED FIX REFERENCESCortina, J; De Luis, M.; Gonzalez-Hidalgo, J.C.; Sanchez, J.R.; Raventos, J.Department of Ecology. University of Alicante. Spain.

Page 60, section 2.7.2.2 PrecipitationFor those comfortable with probability distributions this is a useful way to think of the observed changes inprecipitation. It may not be as useful for the intended audience for the IPCC Report.FIG 2.42 NEEDS DISCUSSION. THERE MAY BE A BETTER WAY AND THE TEXT ABOVE LINE21 ASSUMES TOO MUCHDISCUSS YES, EXPLAIN FIG. WOULD HELP! FIX CAPTION. DELETE.W.D. Hogg, Atmospheric Environment Service, Canada

Page 60, Line 3It may be advisable to add some description concerning the detection problem of extreme rainfallintensity, such as difficulties in extreme event detection and confirmation of statistical significant of theresults.A SENTENCE OR TWOGOOD POINT, BUT ISN'T THIS FROM SOMEWHERE IN THE CHAPTER? WE EXPLAIN THIS INTHE 1sTPARAGRAPH! MEASUREMENT ISSUE!R.Yamamoto, Geophysical Institute,Kyoto University, Kyoto, Japan

Page 60. Line 7.Studies on regional patterns of rainfall concentration may be very sensitive to the meteorological stationsselected. As rainfall patterns can be highly variable at small spatial scales, the use of an homogeneous, welldistributed regional data base may give misleading results unless each particular station is chosen as a goodrepresentative of a given area (De Luis, M; Raventos, J; Gonzalez-Hidalgo, J.C; Sanchez, J.R. and Cortina,J. Spatial Analysis of Rainfall Trends in the Region of Valencia (E Spain) Submitted to Int. J. Climatol.).HAS THIS BEEN DONE IN EXISTING ANALYSES?ADD? SEE KARL ET AL., 1998 WHICH SHOW LITTLE CHANGE IN CONTINENTAL SCALEPRECIP CHANGES 200 VS.I0,000 STATIONS.Cortina, J; De Luis, M.; Gonzalez-Hidalgo, J.C.; Sanchez, J.R.; Raventos, J.Department of Ecology. University of Alicante. Spain.

Page 60, line 9Insert after "greatest precipitation": (however, for a number of stations across the USA the gamma

117


distribution underestimates the probability of extremes such as the maximum daily precipitation amount;Wilks, 1999).Wilks, D.S., 1999: Interannual variability and extreme-value characteristics of several stochastic dailyprecipitation models. Agricultural and Forest Meteorology, V. 93, pp. 153-169YES, MAY NEED TO CONSULT GROISMANO.K. ~ ADD. TOO MUCH TEXT? BUT GROISMAN FOCUSES ON UPPER TAIL 5% NOT ONABSOLUTE EXTREME. NOT USING TO E-------- EXTREMES, BUT THE CHARACTER OFTHE CHANGES IN THE TAILS.Rick Katz, NCAR, USA

Page 60, line 18Insert after "precipitation rates": Making use of the statistical theory of extremes, Katz (1999) obtainedresults consistent with Groisman et al. (1999).Katz, R.W., 1999: Extreme value theory for precipitation: Sensitivity analysis for climate change.Advances in Water Resources, V. 23, pp. 133-139 OKO.K. ADD. ADDRick Katz, NCAR, USA

Page 60, line 30"... for those areas with increased mean total precipitation the increase in heavy precipitation rates shouldbe significantly larger." Reference to eastern and northeastern Australia. I don't believe that this has beenobserved in those regions during the twentieth century (e.g. Hennessy et al. 1999). Remove reference toPlummer et al. Also, strictly, "eastern" encompasses the northeastern region. OKREMOVE PLUMMER REF. ~ RESEARCH HENNESSY ET AL. 1999 CHECK, ADD HENNESSYREF.Neil Plummer, Bureau of Meteorology, Australia

Page 60, Line 33Misspelling: Forland ==> Forland OKCORRECT OKE.Forland, Norwegian Met.Inst., Norway

Page 60, Line 33:Missing in reference list: Forland et al (1998). (Added below)Forland, E.l., H.Alexandersson, A.Drebs, I.Hanssen-Bauer, H.Vedin & O.E.Tveito, 1998: Trends inmaximum I-day precipitation in the Nordic region. DNMI-KLIMA 14/98, 55pp, Norwegian Met. Inst.,Box 43 Blindern, N-0313 Oslo, Norway OKADD REFERENCE OKE.Forland, Norwegian Met.Inst., Norway

Page 60 line 33-35:The Forland et al. (1998) reference is missing and the essence of the report is, that no change is observed inmaximum one-day precipitation in the Nordic countries. Please rephrase accordinglyEXISTING SENTENCE IS AMBIGUOUS. FRICHS SUGGESTION IS DIFFERENT IN MEANINGREF. ADDED ABOVE ~ CHANGE TEXT REPHRASE ~ NO CHANGE. SEE NEW MAP OFFRICH. DO WE WANT TO INCLIDE? TIME SERIES OF TREND WOULD BE HELPFUL.Povl Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Page 60, lines 34-35"... the tendency for increases may not be continuous, ... " - not clear what this means. AS ABOVEWILL BE HANDLED IN REPHASING ABOVE AS ABOVENeil Plummer, Bureau of Meteorology, Australia

Page 60, lines 37-46Suggest shortening this para. IT RAMBLES A BITAGREE ~ ALL THE EXPLANATION NOT NECESSARY SHORTEN PARAGRAPH

118


Neil Plummer, Bureau of Meteorology, Australia

Page 60 line 37-46.This example is not as clear as it could be. Direct reference to Fig. 2.42 (which should be labelled "Changein Prob P>O" along the X-axis) should be used and mention made of the fact that the location parameter hasto change if the total accumulation stays constant and the number of days (hence probability of precip)decreases. By the way, in Canada we find that both the accumulation and number of precip days haveincreased so that heavy and extreme events have not increased significantlyFIG 2.42 COULD BE MADE CLEARER? DISCUSS.MAYBE SO, DISCUSS EXPLAIN FIGUREW.D. Hogg, Atmospheric Environment Service, Canada

Page 60, lines 48-52Strong decrease since 1910 in the intensity of rain falling on very wet days and in the number of very wetdays. Remove reference to Plummer et al. Include reference to Hennessy et al. (1999) for the decrease invery wet days (in winter).OKREMOVE AND ADD REFS - CHANGE TEXT OKNeil Plummer, Bureau of Meteorology, Australia

Page 61 -Supervise the references. There exist some mistake. Groisman et a12000, Zhang et al (2000) are not listed.Cortina, J; De Luis, M.; Gonzalez-Hidalgo, .r.c., Sanchez, J.R.; Raventos, J. ADDADD REFERENCESDepartment of Ecology. University of Alicante. Spain.

LANDSEA COMMENTSSection 2.7.3.1: This section overall is in very good shape(it had better be since this reviewer wrote a good portion ofit). Just a few minor points of clarification and to makethe writeup fit in better with other sections (BELOW).

Page 61, section 2.7.3.1last paragraph, together with figs. 2.47/48: It seems to me that the information expected to occur in fig.2.48 is already present in fig. 2.47. However, that figure would require some additional explanation.NEED TO REDUCE NUMBER OF ATLANTIC HURRICANE DIAGRAMS BY CONSOLIDATIONOR EVEN REMOVING SOME INFORMATIONIS FIGURE 2.48 NEEDED, MAYBE NOT NO 2.48? INSERT FIG 2.45 AND 2.46. DELETE FIG2.44. EXPLAIN IN 2 SENTENCES.Dr. Andreas Sterl, (KNMI), The Netherlands

Page 61, line 3.Remove "extreme", it is an undefined and therefore editorial. SHOULD BE DEFINED EARLIERAGREE DEFINE HEAVY AND EXTREME GLOSSARY EXTREME EVENTS.Patrick J. Michaels, Department of Environmental Sciences, USA

Page 61, Line 4Between the brackets the word "which" is repeated. YESCORRECT THE TEXT OKCarlos Borrego, Universidade de Aveiro, Portugal

Page 61. Line 15Replace Heading by "Extreme Weather and Climate Events" NONO, BUT PUT "?" IN HEADING OKVincent R. Gray, Climate Consultant, New Zealand

Page 61: Line 15.

119

rpcc war TAR Expert Review Comments 20-01-00 Chapter 2

One comment on the interannual variability of tropical cyclones, it has been suggested that the PacificDecadal Oscillation (PDO) may have an influence on Atlantic Ocean hurricane basin activity. Thisinfluence may be similar to ENSO related influence, but playing out over longer time scales. Lupo andJohnston (2000) (The Interannual Variability of Atlantic Ocean Basin Hurricane Occurrence and Intensity.Submitted to National Weather Digest, November 1999) demonstrate that the PDO does influence AtlanticOcean basinwide hurricane activity and intensity. In short, they demonstrate that during the low (negative)phase of the PDO, the Atlantic Ocean basin tends to be more active. They also demonstrate that during thenegative (positive) phase of the PDO, there is little (significant) ENSO related variation in hurricaneactivity. Additionally, they demonstrate that hurricane intensity varies with ENSO phase in that there arefewer intense storms during El Nino years. Finally, it is shown that ENSO and PDO related variability maybe different for sub-basins (Caribbean, Gulf of Mexico, etc.) within the AtlanticYOU MAY WANT LUPO TO INPUT. NOT CLEAR WHETHER THIS INVOLVES A MODULATIONOF ENSO EFFECTS BY PDO (LIKE MODULATION OF ENSO EFFECTS ON AUSTRALIA BY THEHIGHLY CORRELATED IPO).Anthony R. Lupo, University of Missouri - Columbia, USA

Page 61, Line 17In this section the focus is on hurricane number and windspeed. However, the newest GFDL modelindicates that the largest change that may result is an intensified peak rainfall rate. Are there any studies ofthis? In any case, one should be mentioning that this is a variable that is very important for society, but isvery hard to record. Also, thought should be given to recording the areas that hurricanes occur andexamining ifthere are trends or changes in extent. Also, it is seeming that powerful hurricanes areoccurring later and later in the year. Is this being looked at?FAIR POINTS, ISSUES FOR CHAPTER 14?Michael C. MacCracken, U. S. Global Change Research Program National Assessment CoordinationOffice, USA

LAND SEA COMMENTPage 62, line 24 and Figure 2.46: For some reason, the wrongfigure was inserted here. The correct figure 2.45 is attachedas a .gif file. REPLACE

Page 62, line 24... numbers of intense hurricanes ... DIAGRAM SAYS "MAJOR" SHOULD USE SAME WORDFIG. 2.46 DOES NOT CORRESPOND EXACTLYTO TEXT OKDavid E Parker, Hadley Centre, UNITED KINGDOM

Page 61 line 30Nino should be written as Nino YESCHANGE (SAME AS BELOW) OKAlicia M. Lavin, Instituto Espaftol de Oceanografia. Spain

Page 61 Line 31Nino should be written as Nino YESCHANGE OKAlicia M. Lavin, Instituto Espaftol de Oceanografia. Spain

Page 61 Line 36Nino should be written as Nino YESCHANGE OKAlicia M. Lavin, Instituto Espaftol de Oceanografia. Spain

Page 61, line 42Include reference to Nicholls et al. (1998) here as well as line 47. OKADD REF IN TEXT? REF. IS ON LINE 47 CIPCCALREADY REFERENCED)Neil Plummer, Bureau of Meteorology, Australia

120


LANDSEA COMMENTSPage 61, lines 44-45: This decrease in the Australian moderateand strong tropical cyclones IS statistically significant atthe 5% level, but this should be recomputed with the additionaldata point of the 1998-99 season. (I will provide the updatedfigures this week.) ADD AND CALCULATE

Page 61 Line 48Nino should be written as Nino YESCHANGE (SAME) OKAlicia M. Lavin, Instituto Espaiiol de Oceanografia. Spain YES

Page 61 Line 54Nino should be written as Nino YESCHANGE (SAME) OKAlicia M. Lavin, Instituto Espaiiol de Oceanografia. Spain

LANDSEA COMMENTSPage 62, Figure 2.45: For 1999 (to complete the 1990s), thecontinental U.S. was hit by one major hurricane (Bret) andtwo weaker hurricanes (Floyd and Irene) for a total ofthree hurricanes. ADD ADD

Page 62, line 25What about a significant decreasing trend from the late 1940s to the early 1990s? PROBABLY.CALCULATE?IS IT SIGNIFICANT OR NOT? WHY CALCULATE SUB-INTERVALS? 20 YR. SMOOTHINGNeil Plummer, Bureau of Meteorology, Australia

Page 62, lines 25-26Suggest including the definition for major hurricanes. YES, POSSIBLY ON DIAGRAM CAPTIONSHOULD BE DONE SOMEWHERE CAT 3, 4, 5 WIND SPEED;::::. DEFINE FIG.Neil Plummer, Bureau of Meteorology, Australia

LANDSEA COMMENTPage 62, lines 28-29: Switch "1998" to "1999" on both lines.(The Atlantic hurricanes continue to be quite active from1995-1999.) YES OK

Page 62, line 36Is the Fig. shown Fig 2.47 or 2.48? SHOULD BE COMBINED IF POSSIBLESIMILAR TO COMMENT ABOVE FIG 2.47 AND 2.46 COULD BE COMBINED, BUT CHANGEEOF TO INDEX OF N.A. TEMP.David E Parker, Hadley Centre, UNITED KINGDOM

LAND SEA COMMENTSPage 62, Figure 2.47: The correct figure to use here waswrongly placed as Figure 2.46. OK DELETE 2.48? LAND SEA SUGGESTION.

Page 62, page 45: Add Landsea et al, (1999) as a referencelinking North Atlantic SST variations to major hurricaneactivity. YES OK

Page 62, line 46: Clarify here that the SST region of interest

121


is specifically that of 10-20N latitude from North Africato Central America. YES OK

Page 62, lines 45-47: These North Atlantic SST variations arepart of the NAO-associated multidecadal SST changes describedin section 2.6.6.2. CHECK WEAK CORRESPONDENCE WITH NAO

Page 63, Figure 2.48: The correct figure to use here waswrongly placed as Figure 2.47. OK NO FIG 2.48

Page 63, line 1: Remove "and the Northwest Pacific" YES? DELETE LAST SENTENCE OFPARAGRAPH.

Page 63: Line 7.Should include studies, which have shown the variation of extratropical cyclones over the North Americancontinent could be included in section 2.7.3.2. These include, but are not limited to, Agee (1991, Journal ofClimate, p 263), or Zishka and Smith (1980, Monthly Weather Review, p 387).IF RELEVANT TO IPCCDISCUSS NOT DIRECTLY RELEV ANTAnthony R. Lupo, University of Missouri - Columbia, USA

Page 63, Lines 19-21This statement does not convey quite the right impression, as there have been some Southern Hemispherestudies carried out, and these are not mentioned below.Sinclair et ai, MWR, 125, 2531-2543 tried to look at secular changes over a 14-year period and foundchanges in the variance structure over data-sparse regions, suggesting that it is either very difficult orimpossible to determine these changes over a long period. Simmonds and Keay 2000, J Climate, in press,have a paper entitled "Variability ofSH extratropical cyclone behavior 1958-1997". From NCEPreanalyses they showed a reduction in seasonal mean cyclone densities at most locations south of 40S,especially near 60S and increases to the north. Again it is difficult to separate real trends from those due tochanging data distribution. A modelling study by Sinclair & Watterson 1999, J Climate 12, 3467-3485showed decreases of 10-15% in both cyclone and anticyclone frequency in the CSIR09 GCM with adoubling in C02. These matched the decreases in baroclinicity and weakening of the westerlies. Cycloneintensity also decreased. The only exception was over northern Europe where there was evidence ofincreased storm track activity in agreement with other studies.NOT MUCH HETE BASED ON DATA TO QUOTE. REANALYSES ARE DANGEROUS TO USE ASHINTED. DISCUSSSTATEMENT IS O.K. DISCUSS WHETHER TO INCLUDE NEW STUDIES TOO SHORT, NOTEXTREME. CITE THE TWO STUDIES IN LINES 19-21, BUT INDICATE THAT, "SOMESYSTEMATIC CHANGES OBSERVED, SUCH AS A REDISTRIBUTION OF CYCLONEFREQUENCY IN THE S.H. MID AND HIGH LAT. BUT DATA ARE NOT VERY RELIABLE.John Kidson, NIWA, New Zealand

page 63 line 23-24:please remove findings of Schmidt & von Storch, as these were reported in SAR.FAIR POINT. YOU COULD MOVE THE WAVAS TEXT ON p54 (2.6.6.2) TO THIS POINT. ITSBASICALLY THE SAME TEAM.REMOVE KEEP FOR COMPLETENESS, SHORTEN SENTENCE. OK, LEQVE OUT.Povl Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Page 63, Line 23-24Alexandersson et al. (1998 and 1999) should be referenced. There is a need to co-ordinate writing betweenchapters 2.6.6.2 and 2.7.3.2 because strong winds associated with cyclones are discussed in both.ANOTHER EXAMPLE OF NEEDING TO LOOK AT THE TWO SECTIONS TO TRY TO SAVESPACE YET BE COMPLETE

122

[PCC WGr TAR Expert Review Comments 20-01-00 Chapter 2

PROBABLY SO ~ REFERENCE THE STUDIES MOVE LINE 30-40 FROM SECTION 2.6.6.2 TO2.7.3.2 AND SHORTENHeikki Tuomenvirta, Finnish Meteorological Institute, Finland

Page 63, line 24:Last word 'trend' (instead of'trends').YESCHANGE TEXT OKChristian-D. Schoenwiese, J.W. Goethe University, Germany

Page 63, line 32Suggest adding that Allan and Haylock (1993) have found increases in high pressure southwest of theAustralian continent, which are linked to decreases in precipitation in that area.DANGER OF REPETITION WITH EARLIER SECTIONSMAYBE 1993 PAPER IS A BIT OLD IGNORENeil Plummer, Bureau of Meteorology, Australia

Page 63, lines 34-43Too much emphasis here given that the trends are unlikely to be significant in the longer term.BUT IT'S A "HOT" TOPIC IN THE ATLANTIC. LINES 24-40 on p54 HAVE SOME GOOD TEXT ONTHIS POINT. THERE MAY BE A WAY OF REDUCING THIS A BIT AND CROSS REFERRING TOTHIS SECTION OF 2.6.6.2DEBATABLE ~ DISCUSS KEEP ~ AGREE WITH CHRIS. LAST SENTENCE LINKS TO NAO X-REF. WASA-BAMS (1998)Neil Plummer, Bureau of Meteorology, Australia

Page 63, lines 34 ~ 46It is interesting and can be expected to hear that wave heights have increased over the North Atlanticbetween the 1960s and the 1990s. In view of what has been said in the preceding paragraph (Lines 19 ~ 32)and on pages 53 ~ 54, that increase coincides with a recovery of the NAO from its lowest values on record.That should be pointed out in order not lead the reader to draw incorrect conclusions. YES:CATEREDFOR BY MY SUGGESTIONS ABOVEO.K. ADD TEXT MORE DISCUSSION FROM CIRCULATION SECTIONGerd R Weber, Germany

Page 63, lines 34 - 46 < ocean waves>This paragraph deserves a separate subsection heading: "Ocean waves" and perhaps, even better "Oceanwaves and storm surges", with an expanded text. COULD HAVE A SUBSECTION. WE HAVENOTHING ON TRENDS IN STORM SURGESMAYBE SO, DISCUSS OK. 2.7.3.3 NEW "OCEAN WAVES". IGNOREGerbrand Komen, KNMI and University of Utrecht, USA

Page 63, lines 45 - 46 < ocean waves>Add: "In the WASA project (WASA, 1998) decadal variability of the wave climate of the North Atlanticwas studied. The assessment about changes in the wave climate was achieved by a two-step procedure; firsta state-of-the-art wave model was integrated with 40 years of winds obtained from an atmospheric analysis;then a regression was built which related monthly mean air-pressure distributions to intra-monthlypercentiles of wave heights at selected locations with the help of the 40 year simulated data; finallyobserved monthly mean air pressure fields from the beginning of this century were fed into the regressionmodel derive best guesses of wave statistics throughout the century. The conclusion is significant decadalvariability but no century time scale trend. TOO LONG BUT EXACTLY MY POINT. I THINK MY P 54CONCLUSION IS BETTER THAN THE LAST SENTENCEAnother study of variations in the global wave climate was based on the atmospheric 15-year reanalysis ofECMWF (Ster! et al, 1998). This study detected trends in significant wave height of more than 12 ern/yearin the North Atlantic in January, but also a large month-to-month variability. On a seasonal basis trendswere only significant in small areas." TOO SHORT A PERIOD?SOME OF THIS SHOULD BE INCLUDED TEXT SIZE!

123


• WASA, 1998: Changing waves and storms in the Northeast Atlantic? Bull. Amer. Met. Soc. 79,741-760. GOT MISSED FROM REFERENCE LIST

• Sterl, A., GJ. Komen and P.D. Cotton, 1998. Fifteen years of global wave hindcasts using ERA winds:Validating the reanalysed winds and assessing the wave climate. J. Geophys. Research, 103, No. C3,5477-5492.

ADD REF. IS NECESSARY MOVE P. 54 TEXT AND REVISE AS APPROPRIATE.Gerbrand Komen, KNMI and University of Utrecht, USA

Page 63, lines 45 - 46 < change in Atlantic wave climate>The meaning of this sentence is not clear. What is meant? That natural variability in the wave climate iswidespread? THE SENTENCE SHOULD BE REWRITTEN TO REFLECT THE INFORMATION ONp54PLUMMER (ABOVE) SUGGESTED DOWNPLA YING THIS (REMOVE ONE OF THE "CLIMATESYSTEM" REFS. OKGerbrand Komen, KNMI and University of Utrecht, USA

Page 64, lines 1-15:There are some published studies indicating that the PDSI has not changed significantly over thecontiguous US this century, or if anything, points to slightly moister conditions in the summer. Someappropriate sentences and references would be helpful here.KEEP ANY ADDITION VERY SHORTNEEDS SPECIFICITY AND REFERENCES - DISCUSS TOO DETAILED! COULD DISCUSSMANY AREASGerd R Weber, Germany

Page 64, Lines 34-43The US has seemed to experience some unusual tornadic situations recently (e.g., a tornado in Salt LakeCity, tornadoes in mid-winter, etc.). Is any analysis being done of what is happening out at the wings of thedistribution about tornadic conditions?CHAPTER 14 ISSUES HERE?DISCUSS NOT RELEVANT HERE, WE PRESENT TRENDSMichael C. MacCracken, U. S. Global Change Research Program National Assessment CoordinationOffice, USA

Page 64, lines 52-54The last sentence is superflouous: delete it. YES?AGREE DISAGREE. KEEP IT, SUMMARIZE PARAGRAPH. SHORTEN 1ST AND LASTSENTENCE. P. 65 LINES 2-4 SHORTEN!David E Parker, Hadley Centre, UNITED KINGDOM

Page 65 section 2.8:This is a very compact and concise summary - very good.Dr. Andreas Sterl, (KNMI), The Netherlands

Page 65. Line 9."it is likely" How likely. Put a figure on it. LIKELY HAS A QUANTIATIVE FIGURE ON IT ON PAGE8.THIS IS A SUMMARY HE DIDN'T READ THE CHART OR FORGOT.Vincent R. Gray, Climate Consultant, New Zealand

Page 65, line 13"temperature variability has decreased ... " - is there enough evidence to conclude that this is the case for theinterannual time-scale? What about the Southern Hemisphere for both interannual and intra-annual?DISCUSS

124


*** Note, however that preliminary results from longer records suggests that intra-annual variability mayalso be decreasing over much of Australia. These results will be confirmed prior to the second review.DISCUSS IN LIGHT OF NEW RESULTS: STATEMENT STANDSNeil Plummer, Bureau of Meteorology, Australia

Page 65 lines 14-17The sentence beginning "The Increase of global temperatures .... " is convoluted and hard to follow and maybe misleading. It seems to say that the temperature increases resulted in increases in the minimumtemperature but not the maximum. Actually, the rise in the minimum leads to an increase in averagetemperature unless the maximum falls by an equivalent amount. Furthermore, the sentence implies thatthere was an increase in the frequency of much above normal but it couldn't be found. (Actually, it hasbeen found in some regions; see comment about page 59.) I would suggest something along the lines of"Occurrences of much-below-average temperatures have diminished while there has not been a largeincrease in much-above-average temperatures." THE SENTENCE IS TOO LONG-SOMETHING LIKETHISFIRST PART ~ DON'T THINK IT SAYS THIS BUT, REMOVE "LESS APPARENT" FROM TEXTJUST ADD "NOT" AFTER THE BUT OR USE ELLIOTT'S. OMIT LESS "APPARENT" USE "ISLESS"W.P. Elliott. NOAA, USA

Page 65-line 17:The rest of this paragraph is difficult to read. Please clarify the wording.CANNOT SEE A PROBLEM. DISCUSSDON'T AGREE IGNORES. Fred Singer, Science & Environmental Policy Project, USA

Page 65. Line 24"Is the Climate Really Changing?" Another foolish heading. Of course the climate is really changing.What we are trying to find out is whether it matters. Replace Heading with "Significance of CurrentClimate Changes" HAS SOMETHING OF A POINT. KEEP THE QUESTION BUT WE MIGHT FIND ASTRONGER PHRASEDISCUSS SUGGEST "DETECTION OF CLIMATE CHANGE"? OR "OBSERVED CLIMATECHANGE"Vincent R. Gray, Climate Consultant, New Zealand

Page 65, lines 24 ff-rnuch of this section is rather repetitive of the summaries at the end of sections or of the ExecutiveSummary. I can see the need for a concluding section but it can be dangerous to say the same thing (oralmost the same thing) too many times -it can make absolute consistency difficult!AN EXCELLENT CHANCE TO REDUCE LENGTH. I SUGGEST WE SEE WHAT THE BESTPRACTICE IS IN OTHER CHAPTERS AND WHAT WE HAVE DONE IN THE PASTDISCUSSMAKE THIS OUR EXRC SUM? ADDRESSES GRAY'S GENERAL COMMENT "JUST KEEPTHE OBSERVED CHANGES INTERNALLY CONSISTENT?John Houghton, IPCC WGI Co-chair, UK

Page 65 Line 26."What are the Clearest Changes? This whole paragraph is an attempt to force conclusions on the reader. Itshould be relegated to the end of the section. NODON'T AGREE IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 65. Line 28."Our confidence in the changes and variations of climate vary from variable to variable" Variations varyfrom variable to variable. Yes, I think I understand. How do you measure your "confidence"?

125


WE STATE HOW. THE RESULTS ARE JUDGEMENTAL AND STAND OR FALL BY THECOMBINED RESPONSES OF ALL REVIEWERS. THEIR REASONED RESPONSES WOULDAFFECT THE LIKELIHOOD USING THE WORDS ON PAGE 8CHANGE "VARY" TO "CHANGE WE SHOULD STATE THIS!Vincent R. Gray, Climate Consultant, New Zealand

Page 65. Line 38"The clearest signal" of what?• The period from 1910 to 1945 was presumably a "signal" of recovery from the very cold natural climate

fluctuation of the 19th century.• The period from 1945 to 1976, when the temperature fell was a "signal" of what?• The temperature rise from 1976 to 1998 was a "signal" of increased solar activity, combined with local

heating around urban and cold rural measurement stations.• ITS NOT OUR JOB TO GIVE REASONS. THIS IS PROVIDED IN CHAPTER 12Vincent R. Gray, Climate Consultant, New Zealand

Page 65. Line 40"We are virtually certain" What probability figure would you put on that?ITS ON PAGE 8IT IS DEFINED IN TEXT IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 65. Lines 40,41"Best Estimate" Not that, again!. Give a most probable figure plus 95% confidence limits.WE COULD USE THE WORDS "MOST PROBABLE." WE GIVE THE 95% CONFIDENCE LIMITS.USE "LIKELY" LANGUAGE IN TEXT USE LEXICONVincent R. Gray, Climate Consultant, New Zealand

Page 65. Line 41"about" Give 95% confidence limits.THIS MOST PROBABLE VALUE IS O.lC .... CONFIDENCE LIMITS ARE NOT NEEDEDNOT NECESSARY AGREE WITH CHRISVincent R. Gray, Climate Consultant, New Zealand

Page 65 Line 43.The evidence for the absence of urban heat islands is fallacious, since it fails to allow the possibility ofrural heat islands in remote cold climates. IGNORE .SHOULD HIS WORK BE ACKNOWLEDGED SOMEWHERE? IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 65, line 46It is important to note that the three different research teams referred to did not use the identical data set. Infact, there was minimal overlap between the data sets used by Mann et al and those variously used byBriffa et al. The latter's data sets were entirely made up or were dominated by tree-ring density data,whereas only 22 of the several hundred records that were condensed to the 112 records used by Mann et alwere of this type. Moreover, at least the Mann et al data set includes marine records such as coral data forrecent centuries. Therefore the sentence might be modified to read 'Three different research teams haveanalyzed sets of paleoclimatic data for the Northern Hemisphere for the past 1000 years.'FAIR POINT? SECTION DROPPED OKMalcolm K. Hughes, University of Arizona, USA

Page 65 line 46-48:"very likely" should be changed to "likely" or "possible" based on the above discussion ( see page 43, line26-32 comment).PROBABLY DO SOMETHING HERE. SECTION DROPPED.

126


Dr. Guoyu Ren, National Climate Center, Beijing, China

Page 65 Line 47"indicted that". To what level of certainty? "very likely" How much is that? "unprecedented" how much is

that? PROBABLY CHANGE UNPRECEDENTED. WE DEFINE VERY LIKELY ON P8. SECTIONDROPPED. USE LEXICONVincent R. Gray, Climate Consultant, New Zealand

Page 65 Line 48."likely to have been" How likely? WE DEFINE LIKELY ON P8DEFINED IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 65 Line 49"as much as twice as large" How large is that? REPHRASE SLIGHTLYVincent R. Gray, Climate Consultant, New Zealand

Page 65. Line 51.Separate out troposphere and stratosphere changes, instead of trying to incorporate them in the samesentence. There needs to be a sentence which states that satellite measurements over the past twenty yearsin the lower troposphere, where it assumed greenhouse warning is concentrated, show only a fraction (figure updated to recent records) of the warming that was indicated by surface measurements and this waslargely atfribiifable to an unusually large El Nino event in 1998.USE BETTER WORDING HERE GUIDED BY NRC REPORT CONCLUSIONSDISCUSS RE-WORD LINES 50-54 IN LIGHT OF NEW ANALYSESVincent R. Gray, Climate Consultant, New Zealand

Page 65-line 51:The prior discussion does not support the claim that increases in lower tropospheric temperature of satelliteand balloon measurements "have been confirmed by a variety of different analyses."THIS NEEDS REWORDING AS ABOVETRUE ~REWORK SEE ABOVES. Fred Singer, Science & Environmental Policy Project, USA

Page 65. Line 51Increases/decreases should be most probable figures plus 95% confidence limits.WANTS QUANTITATIVE DISCUSSIONQUANTIFY? ADD NUMBERS IN REVISED TEXTVincent R. Gray, Climate Consultant, New Zealand

Page 65. Line 52."Usable balloon measurements have been confirmed" What does that mean? Surely the balloonmeasurements confirm the lower warming shown by the satellitesAS ABOVE.SENTENCE IS CORRECT AS STANDS SEE ABOVEVincent R. Gray, Climate Consultant, New Zealand

Page 65. Line 52."Useable balloon measurements have been confirmed" What does that mean?AS ABOVEDISCUSSED IN CHAPTERC R de Freitas, University of Auckland,New Zealand

Page 65 Line 53."quantitative conclusions" That would be a change! IGNOREDISREGARD IGNORE

127


Vincent R. Gray, Climate Consultant, New Zealand

Page 65, line 53:Delete 'about' (appears twice). YESCHANGE TEXT OKChristian-D. Schoenwiese, J.W. Goethe University, Germany

Page 66, line 1New analyses of historical variability in NA and Eurasian spring cover extent reveal that there has been asignificant reduction in NH spring snow cover this Century. [Brown 1997, 2000]THIS WOULD ALSO GO INTO EXECUTIVE SUMMARYINCLUDE? DISUSS NEED SPEC. REFERENCE OK, BUT NEED TO MENTION INCREASES INAUTUMNRoss D. Brown, Environment Canada

Page 66, Line 2."very likely" How much is that?QUANTIFIED ON P8DEFINED IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 66, Line 2."very likely" Be specific use statistical terms. AS ABOVEDEFINED IGNOREC R de Freitas, University of Auckland,New Zealand

Page 66 Line 4.What is "virtually certain"?QUANTIFIED ON P8DEFINED IGNOREC R de Freitas, University of Auckland,New Zealand

Page 66 Line 4."virtually certain" How much is that? AS ABOVEDEFINED IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 66. Line 12." Most reliable and clearest" By how much?A MEANINGLESS REMARKREWORK TEXT IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 66. Lines 19, 22, 29."It is likely that" How likely is it?QUANTIFIED ON PAGE8DEFINED IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 66, Line 20Change "because of" to ", determined through". OKCHANGE TO "IT IS UNLIKELY THAT THERE HAS BEEN" OR "AS DETERMINED BY" OKClaire L. Parkinson, NASA Goddard Space Flight Center, USA.

Page 66 Line 23.A little more confidence" How much is that?

128

rpcc WGr TAR Expert Review Comments 20-01-00 Chapter 2

MEANINGLESS COMMENT IN THE CONTEXTCHANGE "CONFIDENCE" TO "KNOWLEDGE" IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 66, Line 27.Slightly more confidence" How much more?

MEANINGLESS COMMENT IN THE CONTEXTCHANGE "CONFIDENCE" TO "KNOWLEDGE" IGNOREVincent R. Gray, Climate Consultant, New Zealand

Page 66, Line 27.Slightly more confidence" ???SEE ABOVE IGNOREC R de Freitas, University of Auckiand,New Zealand

Page 66 lines 27-28."we still think it is likely that cloud amount over the oceans and land as a whole has increased over the pastcentury by 1 to 2%." I would limit the statement to the second half of the century. Cloud changes prior to1950 are unreliable because of changes in observing procedures and archiving procedures; Joel Norris andPeter Wright have both written about this. OK? CONSISTENT WITH TEXT?DISCUSS OKStephen G. Warren, University of Washington, USA

Page 66. Line 281 to 2%. Give most probable and 95% confidence limits. REFER BACK TO TEXT. BE HELPFUL TO

HAVE THESE THEIR GIVEN THE SMALL NUMBERSVincent R. Gray, Climate Consultant, New Zealand

Page 66. Line 32.How low is "any confidence" PERHAPS WE DO NEED CONFIDENCE STATEMENT EQUIVALENTSOF THE LIKELIHOOD STATEMENTS. NOT SURE ABOUT THISREPHRASE "CONFIDENCES" WITH "LIKIHOODS" DISCUSSVincent R. Gray, Climate Consultant, New Zealand

Page 66. Line 35.Replace Heading with "Consistency between different climate parameters" NODISREGARD IGNORE IS EVIDENCE CONSISTETN WITH A WARMING WORLD?"Vincent R. Gray, Climate Consultant, New Zealand

Page 66.Line 37.This paragraph is biased, as it confines itself entirely to consistencies and ignores the inconsistencies. Themost important inconsistency is between the surface temperature record and that of the satellitemeasurements of the past twenty years .. The possibility that the satellites might be right and the surfacerecord biased upwards is never discussed. Yet there is ample evidence that this is so.• "urbanisation" studies have failed to recognise the possibility that rural sites in severe climates might be

subject to as much or even more temperature drift upwards than are urban sites. The evidence for this isthat the rural sites show the greatest temperature increases and reductions in diurnal range.

• Surface temperature measurements continue to miss out important regions. They have important gaps,notably during the world wars, and they include data which may not be of the highest quality.

• BULLET LINE 48-49 NEEDS REPHRASING IN LIGHT OF NRC REPORT WORDSDISCUSSED IN TEXT FIX LINE 48-49. GIVE TIME FRAME. ADD SURFACE VS.TROPOSPHERE. MAY BE -----? -- ?????- ----- DATA PROBLEMS AND/OR PHYSICALEFFECTSVincent R. Gray, Climate Consultant, New Zealand

129


Page 66. Line 37."Compare trends" This should be done using proper mathematics.THIS IS NOT AN APPROPRIATE REMARK IN THIS CONTEXT. THE QUANTIATIVECOMPARISON OF TRENDS WITH WHAT WE EXPECT PHYSICALLY IS THE JOB OF CLIMATECHANGE DETECTION AND ATTRIBUTION IN CHAPTER 12DISREGARD AGREEVincent R. Gray, Climate Consultant, New Zealand

Page 66. Line 38"qualitative consistencies" Purely subjective and unworthy of consideration in a supposedly scientificReport. There should be proper quantitative studies.THAT IS CHAPTER 12DISCUSS AGREE, BUT NOT CHAP 12 WORK, OUR WORK E.G. IF TEMP AND SNOWCOVER - THIS INCREASES CONFIDENCEVincent R. Gray, Climate Consultant, New Zealand

Page 66, lines 41 - 42:This is not the case for 1976 - 1998, see Table 2-1WE NEED TO DRAW ATTENTION TO THIS.DISCUSS - CHANGE "SIMILAR" TO "INCREASING" I DON'T SEE THE POINT? ALLPOSITIVE! AND WHEN NECESSARY ADJ-----.Gerd R Weber, Germany

Page 66. Line 42.How similar is "quite similar?IN MAIN TEXT TO WHICH THESE REMARKS REFER. COULD ADD OVER THE LAST 140YEARS.SEE ABOVE OK, BUT SINCE 1976 ALL STRONGLY POSITIVE AND WITHIN ±2a. GIVENUMBERS!Vincent R. Gray, Climate Consultant, New Zealand

Page 66 Line 44.Highly consistent with" How much is that? ITS QUALITATIVELY HIGHLY CONSISTENT. AQUANTITATIVE MEASURE REQUIRES EXTENSIVE PHYSICAL MODELLING WHICH HAS JUSTSTARTEDREWORD ADD "QUALITIVELY" ADD REGIONAL BEFORE ----??? ????Vincent R. Gray, Climate Consultant, New Zealand

Page 66- line 44:Decreases in mountain glaciers are consistent with the earlier warming, before 1940, taking account of thedelays of decades required to make an impact. NOT FOR MOST MOUNTAIN GLACIERS. THIS NEEDSTO BE CLEARER IN GLACIER SECTIONDISCUSS IYES --- BRING THIS POINT UP IN MOUNTAIN GLACIER SECTIONS. ADD "OVERTHE LAST CENTURY"S. Fred Singer, Science & Environmental Policy Project, USA

Page 66. Line 48.Fails to state that the increase in tropospheric temperatures is much less than that found with the surfacetemperatures, that it is not evident for the Southern Hemisphere, and that it disappears if allowance is madefor the large El Nino event of 1998 REMARKS ABOVE. 1998 PROBLEM DIAPPEARS WHENADDING 1999WHERE IS THE CITED REFERENCE? ADD 1999 DATAVincent R. Gray, Climate Consultant, New Zealand

Page 66, line 48.There is no statistically significant increase in annual MSU temperatures, and only a significant increase in

130

lPCC WGl TAR Expert Review Comments 20-01-00 Chapter 2

the monthly readings if the 1998 spike is included. Change the text to reflect this reality.AS ABOVEDISCUSS - REFERENCE? AS DISCUSSED EARLIERPatrick J. Michaels, Department of Environmental Sciences, USA

Page 66- line 48:Satellite and balloon measurements do agree, but they do not show an increase in tropospheric

temperatures AS ABOVE.SEE ABOVE NOT TRUE, BALLOONS SHOW AN INCREASE SINCE 1960S. Fred Singer, Science & Environmental Policy Project, USA

Page 66, Line 53The word "about" is repeated. NO LINE 53O.K. - ADJUST TEXT ??Carlos Borrego, Universidade de Aveiro, Portugal

Page 67, line 1[ This figure shows the consistent relationship between NH seE and air temp over a much longer periodthan the NOAA satellite record ... ]

NH SeE v's Air Temp Anomalies, 1922-1997

48,------------------.------------------.

•• I March r=-O.68 II46

52'1 44 •E.x: • •c~ 42 .. •'Ew ..,...U 40 •C/)

•• ,.38 • •36

-40 -20 0 20 40AirTempAnomaly(deg. C*10)

Scatterplot of reconstructed (1922-1971) and satellite-observed (1972-1997) NH snow cover extent fromBrown (2000) versus NH mid-latitudinal (40-600N) land surface temperature anomalies for March. Airtemperature anomalies were computed from the Jones (1994) gridded land temperature dataset. Source: R.Brown, AES/CCRP.CONSIDER THIS FOR MAIN TEXTDOES NOT BELONG IN THIS OVERVIEWRoss D. Brown, Environment Canada

Page 67, Line 13Change "Where available" to "Where data are available". YESO.K. OKClaire L. Parkinson, NASA Goddard Space Flight Center, USA.

Page 67 Line 15.Replace "all" with "many". ITS PROBABLY "MOST"MAYBE SO, DISCUSS USE MOST

131

tree wor TAR Expert Review Comments 20-01-00 Chapter 2

Vincent R. Gray, Climate Consultant, New Zealand

Page 67. Line 15."interrelate" when did you even try to do it properly?TO GET RID OF THESE REMARKS WE SHOULD POINT OUT UP FRONT OF THIS CHAPTERWHAT IS BEYOND ITS SCOPE.Vincent R. Gray, Climate Consultant, New Zealand

Page 67. Line 15"consistent with" How consistent?THE MEASUREMENT OF CONSISTENCY IS A MULTIVARIATE PROBLEM FOR CLIMATECHANGE DETECTION AND ATTRIBUTION USING MODELSDISCUSS REWORDING OF PARAGRAPH DEVELOP LEXICON?Vincent R. Gray, Climate Consultant, New Zealand

Page 67, lines 15 -17:Yes, but it appears as if at least the last 25 years (the period of a rapid temperature increase) thosecirculation anomalies and temperatures are closely related. What has caused what?THIS POINT NEEDS TO COME OUT IN THE MAIN TEXT MORE AND BE REFLECTED HEREDISCUSS BE CAREFUL => TENDENCY TO ATTRIBUTE CIRCULATION CHANGES TOWARMING, BUT WARMING MAY CAUSE FORMER!Gerd R Weber, Germany

Page 67, line 15 to 17Comment :The chapter conclude that all indicators are consistant with with a globally warming climatechange over the last century. With sperinposed, mostly shorter time scale,regional variations in atmosphericcirculation, the conclusion must be uncertain for the regional variation, because the Chapter 10 concerningThe Evaluation and Projections of regional Climate Information, the report suggest more coordination ofthe efforts thus necessary to evaluate the different methodologies, inter-compare methods and models andapply these methods to climate change research in a comprehensive strategy YES, CLARIFY WHAT WEMEAN FOR DIFFERENT SCALES.DISCUSS REWORDING OF PARAGRAPH WORK ON THE REGIONAL PART OF THISSENTENCEAllali Abdelkader, DPV, Morocco

Page 68, line 24 (NO SUCH LINE ON MY COPY)An introduction should be included here that mentions Chapter 12, and discusses a little the difference inemphasis of Chapter 2 and Chapter 12 (e.g. Chapter 2 is explorative and centers on "changes in 30 yearmeans" and Chapter 12 tries to test "can part of recent changes be attributed to human influences?").POINT I MADE ABOVEGerrit Burgers, KNMI, The Netherlands

I HAVE rusr ACCEPTED THE REFERENCE CHANGES:Page 70:Missing reference (cited on P. 33, line 19, and perhaps elsewhere): Briffa KR, Schweingruber FH, JonesPD, Osborn TJ, Shiyatov SG and Vaganov EA (1998a) Reduced sensitivity of recent tree growth totemperature at high northern latitudes. Nature 391, 678-682.(NOTE THAT THIS IS 1998a)Dr. Timothy J. Osborn, Climatic Research Unit, UEA, UK

Page. 70, line 49:The "Briffa, Jones, Schweingruber and Osborn" reference should be 1998b (NOTE THE 'b')Dr. Timothy J. Osborn, Climatic Research Unit, UEA, UK

Page 71, line 9Brown, R.D., 2000: (in press).

132


Ross D. Brown, Environment Canada

Page 71. line 14,15Brown et al. reference should read:Brown, S. J., D. E. Parker, C. K. Folland and 1. Macadam, 1999: Decadal variability in the lower-tropospheric lapse rate. Submitted to Geophysical Research Letters.Simon J. Brown, Meteorological Office, UK

Page 76 line 43:please move Frich before RaynerPo vi Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Page 77, before line 12 insert:Ferland, EJ. & I.Hanssen-Bauer, 1998, Operational correction of measured precipitation in Norway. In:Goodison,B.E., P.Y.T.Louie & D.Yang: WMO Solid Precipitation Measurement Intercomparison, Finalreport, WMO/TD-No.872, WMO, Geneve, p.70-73Forland, E.J., H.Alexandersson, A.Drebs, 1.Hanssen-Bauer, H.Vedin & O.E.Tveito, 1998: Trends inmaximum l-day precipitation in the Nordic region. DNMI-KLIMA 14/98, 55pp, Norwegian Met. Inst.,Box 43 Blindern, N-0313 Oslo, NorwayForland, E.]. & 1.Hanssen-Bauer, 1999, Increased Precipitation in the Norwegian Arctic: True or False?(Accepted in Climatic Change)E.Foriand, Norwegian Met.Inst., Norway

Page 79, before line 53 insertHanssen-Bauer, 1.& EJ.Forland, 1998, Long-term trends in precipitation and temperature in the NorwegianArctic: can they be explained by changes in atmospheric circulation patterns? Climate Research, 10, 143-153Hanssen-Bauer, I. & E.J.Forland, 2000, Temperature and precipitation variations in Norway 1900-1994 andtheir links to atmospheric circulation. (Accepted in Int. J. Climatol)E.Forland, Norwegian Met.Inst., Norway

Page 84, Line 39Reference is Vol 12, pp 2808-2830.John Kidson, NIW A, New Zealand

Page 85 Line 21New ref.: Koslowski, G. and R.Glaser, 1998: Variarions in Reconstructed Ice Winter Severity in theWestern Galtic from 1501 to 1995, and their Implications for the North Atlantic Oscillation, ClimaticChange 41,175-191.C. Pfister, Unitobler, Switzerland

Page 86, Line 8correct date for Lamoureux and Bradley reference is 1996 (not 1995), but see my comment on Page 27, line13D. Hardy, Univ. of Massachusetts, USA

Page 87 line 33EI Nino should be written as El Nino

Alicia M. Lavin, Instituto Espafiol de Oceanografia. Spain

Page 87 Line 34El Nino should be written as El NinoAlicia M. Lavin, Instituto Espaftol de Oceanografia. Spain

Page 88 Line 1

133


New ref. Martin Vide, J. and M. Barriendos, 1995: The Use of Rogation Ceremony Records in ClimaticReconstruction: A case study from Catalonia (Spain), Climatic Change 30, 201-221.C. Pfister, Unitobler, Switzerland

Page 89, between Lines 21 and 22,Insert the following reference:Mysak, L.A., R.G. Ingram, J. Wang, and A. van der Baaren, 1996, The anomalous sea-ice extent inHudson Bay, Baffin Bay and the Labrador Sea during three simultaneous ENSO and NAO episodes.Atmosphere-Ocean, 34, 313-343.Lawrence A. Mysak, McGill University, USA

Page 90Missing reference (cited on P. 55, line 46, and perhaps elsewhere):Osborn TJ, Briffa KR, Tett SFB, Jones PD and Trigo RM (1999) Evaluation of the North AtlanticOscillation as simulated by a coupled climate model. Clim. Dyn. 15,685-702.Dr. Timothy J. Osborn, Climatic Research Unit, UEA, UK

Page 91In the references, reference to Parilla (page 17, line 32) is missing. It is as follows: (be carefull with two rin Parrilla)Parrilla G., A. Lavin, H. L. Bryden, M. J. Garcia and R. Millard, 1994. Rising temperatures in thesubtropical North Atlantic Ocean over the past 35 years. Nature 369, 48-51.Alicia M. Lavin, Instituto Espaiiol de Oceanografia. Spain

Page 91, Lines 3-6Delete the Parkinson et al. 1998 reference on lines 3-4; update "in press" on line 6 to "104,20,837-20,856";and add the following reference (for p.24 revision): Parkinson, C. L., 1999: Variability of Arctic sea ice:The view from space, an 18-year record, Arctic, in press. Yes, AllynClaire L. Parkinson, NASA Goddard Space Flight Center, USA.

Page 99, lines 38-40:Please update the reference:Vinnikov, Konstantin Y., Alan Robock, Ronald J. Stouffer, John E. Walsh, Claire L. Parkinson, Donald J.Cavalieri, John F. B. Mitchell, Donald Garrett, and Victor F. Zakharov, 1999: Global warming andNorthern Hemisphere sea ice extent. Science, 286,1934-1937. Yes, AllynAlan Robock, Rutgers University, USA

Page 99, Lines 39-40This Vinnikov et al. article is now in press, scheduled to be published in Science on December 3,1999,with the revised title "Global warming and Northern Hemisphere sea ice extent".Claire L. Parkinson, NASA Goddard Space Flight Center, USA. see above

Page 91, Line 47, 48Omit reference Pfister, 1998C. Pfister, Unitobler, Switzerland

Page 91, Line 49 and 52The both papers are already published.Rudolf Brazdil, Masaryk University, Czech Republic

Page 91 , Line 51Instead of Special Issue etc.: Climatic Change 43, 5-53.C. Pfister, Unitobler, Switzerland

Page 92, Line 2Instead of Special Issue etc.: Climatic Change 43,55-110.

134


C. Pfister, Unitobler, Switzerland

Page 92, Line 3,4Omit reference Pfister, .....C. Pfister, Unitobler, Switzerland

Page 94, lines 1-4:Robock and Mao (1992) and Robock and Free (1995) are not referenced in chapter.Alan Robock, Rutgers University, USA

Page 99, Line 3Add: "Tuomenvirta, H, H Alexandersson, A. Drebs, P Frich and PO. Nordli, 2000: Trends in Nordicand Arctic temperature extremes and ranges. J.CUm. (in print)"Heikki Tuomenvirta, Finnish Meteorological Institute, Finland

Page 99 line 3:please insert in References:Tuomenvirta, H., H. Alexandersson, A. Drebs, P. Frich, & P.O. Nordli, 2000: Trends in Nordic and Arctictemperature extremes and ranges. Journal of Climate (in press).Povl Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Page 99, lines 38-40:Please update the reference:Vinnikov, Konstantin Y., Alan Robock, Ronald J. Stouffer, John E. Walsh, Claire L. Parkinson, Donald J.Cavalieri, John F. B. Mitchell, Donald Garrett, and Victor F. Zakharov, 1999: Global warming andNorthern Hemisphere sea ice extent. Science, 286, 1934-1937.Alan Robock, Rutgers University, USA

Page 99, Lines 39-40This Vinnikov et al. article is now in press, scheduled to be published in Science on December 3,1999,with the revised title "Global warming and Northern Hemisphere sea ice extent".Claire L. Parkinson, NASA Goddard Space Flight Center, USA.

Page 99, lines 43-44:Please update the reference:Vinnikov, Konstantin Y., Alan Robock, Shuang Qiu, and Jared K. Entin, 1999: Optimal design of surfacenetworks for observation of soil moisture. J. Geophys. Res., 104, 19,743-19,749.Alan Robock, Rutgers University, USA

Page 100, Line 29Reference is made to an abstract of an AGU meeting presentation. Are these appropriate references for thiswork?Melissa Free, NOAA ARL, USA

Page 101, Line 44Please insert the following to the list of the References:Yamamoto,R. and Y.Sakurai,1999: Long-term intensification of extremely heavy rainfall intensity in recent100 years. World Resource Review, 11,271-281R.Yamamoto, Geophysical Institute, Kyoto University, Kyoto, Japan.

Page 103, Fig 2.1Are the standard error limits point wise or simultaneous? Do they take into account temporal dependence?TAKE DETAILS FROM JONES PAPERPeter Guttorp, National Research Center for Statistics and the Environment, USA

Page 104, Fig. 2.2

135


Why are the urban stations confined to a grid?BETTER CAPTION NEEDEDPeter Guttorp, National Research Center for Statistics and the Environment, USA

Page 104, Figure 2.2Derived from Easterling et al. - possible problems (refer comments on Page 11 line 22, above).MAY REPLACE ANYHOW?Page 105, Figure 2.3The Australian cloud cover anomalies have been extended to 1998 (Plummer et al. 1997, Collins and Della-Marta 1999). However, the Bureau's National Climate Centre provided Jim Salinger (Lead Author, Ch 2TAR) with unadjusted data several months ago. It is not clear whether these data are being used in anupdated analysis but, if they are (perhaps in Dai et al. 1999?), they will need to be adjusted. I intend todiscuss this issue further with Dr Salinger.DISCUSSNeil Plummer, Bureau of Meteorology, Australia

Page 105, Figure 2.3Pearson's correlation coefficients in the Fig.2.3 need to be indicated with the statistical significance levels.YES, IF WE KEEP THE FIGUREMurat Turkes, Turkish State Meteorological Service, Turkey

Page 105 Figure 2.3 caption.I think the reference is 1999 not 1997. I don't have Dai's paper here with me, but I think cloud cover is thesolid line, not dashed as stated.TOM-PLEASE ADVISEStephen G. Warren, University of Washington, USA

Page 107, Figure 2.5Please, correct (b) and (c) to (a) and (b) YESHeikki Tuomenvirta, Finnish Meteorological Institute, Finland

Page 108 Fig. 2.6These curves need some uncertainty measures to be comparable. SHOULD BE POSSIBLE BUT NOTTILL THIRD DRAFT POSSIBLYPeter Guttorp, National Research Center for Statistics and the Environment, USA

Page 109 Fig. 2.7These curves need some uncertainty measures to be comparable.POSSIBLE FOR THIRD DRAFT BUT COULD BE DIFFICULT TO SHOW CLEARLYPeter Guttorp, National Research Center for Statistics and the Environment, USA

Page 109, Figure 2.7Methods and point numbers of the filters used for smoothing need to be explained for each smoothed areaweighted global annual land surface air temperature series: for example, 9-point Gaussian filter or 21-pointbinomial filter. YESMurat Tiirkes, Turkish State Meteorological Service, Turkey

Page 109-111, Figures 2.7-2.9Some of the lines are repeated. Is three separate figures really needed?WILL CONSIDER THIS BUT PROBABLY FOR THIRD DRAFTHeikki Tuomenvirta, Finnish Meteorological Institute, Finland

Page 110, Figure 2.8Figure captions of the sub-figures in Fig.2.8 should be corrected as: (a) Northern hemisphere; (b)Southern Hemisphere; and (c) Globe. YES

136


Method and point number of filter used to smooth combined annual land-surface air and seatemperature anomalies should be given in the figure caption. YES

Murat Tiirkes, Turkish State Meteorological Service, Turkey

Page 111, Fig 2.9Are the standard error limits point wise or simultaneous? Do they take into account temporal dependence?SAY HOW CALCULATEDPeter Guttorp, National Research Center for Statistics and the Environment, USA

Page 114 Figure 2.12has an insufficient captionYES.David E Parker, Hadley Centre, UNITED KINGDOM

Page 114, Figure 2.12:further explanation in the text below of the Figure is missing AS ABOVEHeinz-Jiirgen Ahlgrimm, FAL Braunschweig, Germany

Page 114 fig. 2.12:The captions needs completion. AS ABOVEDr. Andreas Sterl, (KNMI), The Netherlands

Page 116.figureThe MSU time series should be continued through to the end of 1999. YESHaroon Kheshgi, ExxonMobll, USA

Page 116, Figure 2.14:Which version ofMSU is used here? Is it MSU version B? ADD VERSIONS. Fred Singer, Science & Environmental Policy Project, USA

Page 117, Figure 2.15:By taking the endpoint in 1998, a bias is introduced. Please show also the data for 1979-1997. FIXED BYADDING 1999S. Fred Singer, Science & Environmental Policy Project, USA

Page 117, Fig. 15Since NCEP does not fit into the trend estimate by Santer et al. (1996), while ERA does, this discrepancyshould at least be noted for the period 1979-1993, which is common to both reanalyses. Of course, as inNCEP, there are time-dependent errors in ERA, see e.g. Stendel et al. (accepted) (already referenced as"submitted" on page 96, lines 42/43). ADD SOMETHING IN MAIN TEXTMartin Stendel, Danish Meteorological Institute, Denmark

Page 118, Figure 2.16The apparent discrepancies between temperature and snow cover in the latter period warrants discussion.Note also that the caption should note that temperature anomalies increase downward.I THINK THESE DIAGRAMS SHOULD BE MUCH SIMPLER.- DISCUSSNeil Plummer, Bureau of Meteorology, Australia

Page 118, Figure 2.16:Very complex and difficult to understand, may be missingYES!Heinz-Jiirgen Ahlgrimm, FAL Braunschweig, Germany

Page 119, Figure 2.17:Description of the Yvaxis is missing YES

137


Heinz-Jiirgen Ahlgrimm, FAL Braunschweig, Germany

Page 119, Figure 2.17Method of filter with the point number is missing in the caption of the Fig.2.17.NEEDED IN REVISEDDIAGRAMMurat Tiirkes, Turkish State Meteorological Service, Turkey

Page 120, Figure 2.18Method of filter with the point number is missing in the caption of the Fig.2.18. YESMurat Turkes, Turkish State Meteorological Service, Turkey

Page 121, Figure 2.19Have gaps in the series been filled in here (e.g. winter and autumn from 1941-44 )? WALSH TO ANSWERAND ADD TO WALSHES NEW CAPTIONNeil Plummer, Bureau of Meteorology, Australia

Page 121, Figure 2.19:It is strange that the large warming between 1900-1940 showed no effect on NH sea ice. Shrinkingoccurred in summer; little trend in winter. No trend I Antarctic (Fig 2.18, p. 120). Please explain --- or atleast, comment.ASK WALSH TO COMMENTS. Fred Singer, Science & Environmental Policy Project, USA

Pages 123 and 124 Figs. 2.21 and 2.22Comment: the two graphs give different information. Fig. 2.22 concerns a longer time interval and uses allavailable annual data, including uncalibrated ones and measurements over short periods. The use of such anapproach is questionable. Fig. 2.21 gives a mean as an index. The cumulative plotting enhances the "signalto noise ratio" and makes trhings much more clear. A discussion of various approaches is given byHaeberli, W., Frauenfelder, R. and Hoelzle, M. (1999): On rates and acceleration trends of global glaciermass changes. Geografiska Annaler. (To appear in December, cf. attachmenmt tarfala).Wilfried Haeberli, Geography Department, University of Zurich, SwitzerlandTHIS WILL BE REPLACED BY A SINGLE GLACIER RECESSION DIAGRAM

Page 125, fig. 2.23:What is the "Null Hypothesis" that is tested? THESE WORDS NEEDED CHANGINGOR EXPLAINING FIGURE HAS BEEN APPROPRIATELY MODIFIEDDr. Andreas Sterl, (KNMI), The Netherlands

Page 125, Figure 2.23To be consistent with earlier figures, the ±2 standard error region should be shown.CAN WE GET THIS? AGREEDNeil Plummer, Bureau of Meteorology, Australia

Page 126, Figure 2.24What does the record suggest about changes in decadal and interannual variability over the millennial andhow is this consistent with later discussions on variability in the instrumental record (e.g. apparentdecreases in interannual temperature variability during the 20th Century).DISCUSS THIS POINT I THINK THIS IS BETTER ADDRESSED IN FIGURE 2.34 FROMPERSPECTIVE OF ENSONeil Plummer, Bureau of Meteorology, Australia

Page 126, Figure 2.24:This graph essentially denies the existence of the Little Ice Age and Medieval Climate Optimum. Thiscontradicts other proxy data we know of. [Jacoby, Dahl-Jensen, Keigwin] These other data show nowarming since 1940.THIS REMARK SHOULD BE ADDRESSED IN MAIN TEXT. THE REVIEWER ONCE AGAIN HAS

138

rpcc wet TAR Expert Review Comments 20-01-00 Chapter 2

CONFUSED REGIONAL AND LARGE-SCALE TRENDS, AND THESE ISSUES AREDISCUSSED IN DEPTH IN THE TEXT.S. Fred Singer, Science & Environmental Policy Project, USA

Page 126/127, figs. 2.24/25:These figures give more or less the same information, and only one of them should be retained. If thedecision is made to retain them both, the following two problems should be resolved:1. Due to the usage of different base periods the two figs. Are hard to compare.

3. According to fig. 2.24, the temperature of 1998 exceeded that of any other year, even taking a 2-sigmauncertainty into account. From figure 2.25 there are at least two periods (around 1175 and 1350) wereT+2-sigma exceeds the 1998 temperature.

THERE IS SOME CONFUSION HERE. DISCUSS THERE IS NO INCONSISTENCY BETWEEN 2SIGMA LIMITS FOR THE TWO FIGURES. 1998 IS A PARTICULARLY ANOMALOUSSINGLE YEAR (>2.3 SIGMA EVENT) WHILE THE DECADAL-SCALE TREND OF THE LATE90s ISN'T AS ANOMALOUS. MANN ET AL (1999) MAKE THIS EXPLICIT DISTINCTION.Dr. Andreas Sterl, (KNMI), The Netherlands

Page 128, Figure 2.26:Give reference. YESS. Fred Singer, Science & Environmental Policy Project, USA

Page 128, Figure 2.26Do the dashed lines represent interpolations to missing data?NEED TO STATENeil Plummer, Bureau of Meteorology, Australia


Page 129/130/131, figs. 2.27-29:The captions need completion YES.Dr. Andreas Sterl, (KNMI), The Netherlands

Pages 130/131, Figures 2.28/2.29:Description of Y-axes seems not to be correctBETTER DESCRIPTIONS NEEDED. DO WE NEED ALL THESE PALEO DIAGRAMS?Heinz-Jiirgen Ahlgrimm, FAL Braunschweig, Germany

Page 132, Figure 2.30:Is this the same figure as Figure 3.11 on page 155 of IPCC-SAR?CAN WE REMOVE THIS?S. Fred Singer, Science & Environmental Policy Project, USA

Page.132 Figure 2.3With respect to such problems, methodologically there is a lack of studies about variability trends, thatussually are presented as anomalies over the mean value, is that: positives and negatives values. Wesuggest that the absolute value could be a possibility worthy to explore as a data to analyzed understatistical techniques.NOT SURE WHAT THIS MEANSCortina, J; De Luis, M.; Gonzalez-Hidalgo, J.C.; Sanchez, J.R.; Raventos, J. Department of Ecology.University of Alicante. Spain.

Page 132, Fig. 2.30:Please revise diagram as and if better data become available. Otherwise remove diagram, as it isinconsistent with trends quoted in the text, e.g. ~ 10 % increase over extratropical landmasses and ~

139

[PCC WGI TAR Expert Review Comments 20-0[-00 Chapter 2

30 % increase in precipitation over Svalbard. AGREES WITH ME!Povl Frich, Hadley Centre for Climate Prediction and Research, United Kingdom

Page 133, Figure 2.31Is there a problem with these plots? For example, the grid-point over the eastern interior of Australia showsdecreases in all three sub-periods but increases over 1900-1998. This may be possible because, in severalregions, precipitation series will contain large discontinuities between the sub-periods.CHECKNeil Plummer, Bureau of Meteorology, Australia

Page 133 and 134, Figure 2.31Comment: the presented trends of annual precipitation totals - up to 200%ICentury and up to 40%lDecadeare probably incorrect (possible incorrect precipitation normals, or incorrect precipitation time series; thetrends are very great even at low annual precipitation totals)CHECKAss. Prof., Dr. Milan LAPIN, Comenius University, Slovak Republic


Page 136, Figure 2.33This figure can be replaced with a single-panel figure based on Figure 2 of the Ross and Elliott manuscriptsubmitted to 1. Climate in November, 1999. I will send a copy of this manuscript to Chris Folland (Chapter2 author). I HAVE THIS AND ITS BETTERRebecca J. Ross, NOAA, USA

Page 137, Figure 2.34[see also comments to Ch2, page 6, line 49-50, and to page 50]Take the Kaplan or GISST3.0 reconstruction from 1876 onwards instead of the 1902-1998 series, becauseit includes the large 1877178 event. Extend the Mann and Stahle estimates to the present, in order to showhow well they capture the magnitude of the 1982/83 and 1997/98 events.DISCUSS- POSSIBLY COMBINE 2.34 AND 2.35 THE GISST3.0 DATA HAS NOW BEEN USEDFOR COMPARISON. THE LATTER SUGGESTION (UPDATING THE PROXY SERIESBEYOND 1980) IS NOT POSSIBLE. THIS IS FUNDAMENTALL LIMITED BY THE LENGTHOF THE PROXY DATA SERIES.Gerrit Burgers, KNMI, The Netherlands

Page 137, fig 2.34Nino in the title, picture and 5 times in the text YES AGREED; TYPESETTER CAN HANDLE THISAlicia M. Lavin, Instituto Espaiiol de Oceanografia. Spain

Page 138 fig 2.35Nino in the title, picture and text YESAlicia M. Lavin, Instituto Espaiiol de Oceanografia. Spain

Page 141, Figure 2.38- Method of filter, whether it is Gaussian or binomial, is missing with in the figure caption.

There is also missing in the right side of the smoothed line of sea level pressure anomalies, withrespect to padding for the last years of the seriesYES- NOT SURE WHAT LAST REMARK MEANS.

Murat Tiirkes, Turkish State Meteorological Service, Turkey

Page 142, Figure 2.39Method of filter with the point number is missing within the caption ofFig.2.39. YES

140


Murat Turkes, Turkish State Meteorological Service, Turkey

Pages 142/143; Figures 2.39 and 2.40:Missing descriptions of the Y-axes YESHeinz-Jiirgen Ahlgrimm, FAL Braunschweig, Germany

Page 143, Figure 2.40Method of filter with the point number and explanation for the Y axis title (Y values) of the Fig.2AO aremissing. YESMurat Turkes, Turkish State Meteorological Service, Turkey

Page 143, Figure 2.40Comment: missing AO index scale YESAss. Prof., Dr. Milan LAPIN, Comenius University, Slovak Republic

Page 145, Figure 2.42Not easy to interpret this figure. Suggest label Y-axis "Changes in the probability of a day with intenseprecipitation" and the X-axis "Changes in the probability of a day with precipitation".PROBABLY REVISENeil Plummer, Bureau of Meteorology, Australia

Page 147, Figure 2.44'Dotted line' in the figure caption needs to be corrected as 'thin red line.' YES?Murat Tiirkes, Turkish State Meteorological Service, Turkey

Page 149, Figure 2.46Method of filter with the point number is missing within the caption of the Fig.2A6. YESMurat Tiirkes, Turkish State Meteorological Service, Turkey

Page 150, Figure 2.47Links with SSTs not mentioned in text (p62) but are shown in the Figure.NEED TO ADD IN TEXTNeil Plummer, Bureau of Meteorology, Australia

Page 150, Figure 2.47:The abbreviation EOF should be explained IN FULL IN MY VERSIONHeinz-Jiirgen Ahlgrimm, FAL Braunschweig, Germany

Page 152, Figure 2.49:Shows decreasing trend of strongest tornadoes since about 1970.

DO WE REALLY NEED THIS?S. Fred Singer, Science & Environmental Policy Project, USA

Page 153. Fig. 2.50aI would ascribe ** to the observation about declining diurnal temperature range. It can hardly be lesscertain than the statement that the 1990s were the warmest decade of the millennium. The latter statementdepends on interpretation of a scattering of proxy data, and I would accord it with a probability of between80% and 90% so that ** is marginally generous. DISCUSS NOT SURE WHERE DAVID COMES UPWI THIS ESTIMATE. WE WORKED OUT THE STATISTICS QUITE CAREFULLY IN OUR '99ARTICLE. HAS HE IDENTIFIED A MISTAKE IN OUR STATISTICS?? WE WOULD NEEDMORE INFORMATION FROM HIM TO ACT ON THIS COMMENT.David E Parker, Hadley Centre, UNITED KINGDOM

Page 154, Figure 2.50bThis figure might be misleading. It says no change in extratropical storm frequency. I suggest to replacethis by "remarkable decadal variability in the North Atlantic Index, but no centennial trend."

141

[PCC WGf TAR Expert Review Comments 20-01-00 Chapter 2

DISCUSSGerbrand Komen, KNMI and University of Utrecht, USA

ReferencesBlake, W., Jr.1964:Preliminary account of the glacial hisory of Bathurst Island, Arctic Archipelago.

Geological Survey of Canada, Paper 64-30,8 p.Blake,W., 1974: Periglacial features and landscape evolution, central Bathurst Island, District of Franklin.

Geological Survey of Canada, Paper, 74-1, Part B, p. 235-244.Dowdeswell and 10 others (1997): The Mass Balance of Circum-Arcic Glaciers and Recent Climate

Change. Quaternary Research 48, pp 1-14.Dyke, A.S.,& T.E.Morris, 1990; Postglacial history of the Bowhead whale and of driftwood penetrations;

implications for paleoclimate, in the central Canadian Arctic. Geological Survey of Canada Paper,89-24, p.17.

Dyke,A.S., J.E.Hooper & J.M.Savelle, 1996: A history of sea ice in the Canadian Arctic Archipelago basedon post-glacial remains of the Bowhead Whale (Balaena mysticetus).Arctic, 49, pp.235-255.

Jania & Hagen (1996): Mass Balance of Arctic Glaciers. Eds J.Jania & J.O.Hagen. Faulty of EarthSciences, University of Silesia, Poland, & International Science Committee Report #5.

Koerner,R.M. 1989: Ice Core Evidence for Extensive Melting of the Greenland Ice Sheet in the LastInterglacial. Science, 44, pp. 964-968.

Koerner, RM. & D.A.Fisher (1990): A record of Holocene summer climate from a Canadian high-Arcticice core. Nature, 343(6259), pp. 630-631.

Koerner, RM. & L.Lundgaard (1995): Glaciers and Global Warming. Geographie physique et Quaternaire,49 (3), pp. 429-434.

Koerner, RM. 1997: Some comments on climatic reconstructions from ice cores drilled in areas of highmelt. Journal of Glaciology, 43(143), pp.90-97.

Koerner,R.M., 1999: Climate and the ice core record. In Poles Apart: A Study in Contrasts. Ed.A.G.Lewkowicz. P.237.

Werner,A., 1988. Holocene glaciation and climate change, Spitsbergen. (Ph.D. thesis, University ofColorado, U.S.A)

Roy M Koerner, Geological Survey of Canada

P. Alpert and M. Mandel, "Wind variability - An indicator for a mesoclimatic change in Israel", J. ofClimate and Appl. Met., 25, 1568-1576, 1986.T. Ben-Gai, A. Bitan, A. Manes and P. Alpert, "Long-term change in October rainfall patterns in southernIsrael" Theoretical and Applied Climatology, 46, 209-217, 1993.T. Ben-Gai, A. Bitan, A. Manes and P. Alpert, "Long-term changes in annual rainfall patterns in southernIsrael" Theoretical and Applied Climatology, 49, 59-67, 1994.T. Ben-Gai, A. Bitan, A. Manes, P. Alpert and S. Rubin, "Spatial and temporal changes in annual rainfallfrequency distribution patterns in Israel", Theoretical and Appl. Climatology, 61,177-190, 1998.J. Otterman, A. Manes, S. Rubin, P. Alpert and D. O'c. Starr, "An increase of early rains in southern Israelfollowing land-use change?" Bound. Lay. Meteor., 53, 333-351,1990.S. Paz, E. H. Steinberger, H. Kutiel. Extended abstract in: Proc. ECAC Conference, Vienna, 1999.E. Piervitali, M. Colacino and M. Conte, "Rainfall over the central-Western Mediterranean basin in theperiod 1951-1995. Part I: precipitation trends", Nuovo Cimento C, 21, 331-344,1998.R Romero, J. A. Goijarro, C. Ramis and S. Alonso, " A 30-year (1964-1993) daily rainfall data base for theSpanish Mediterranean regions: first exploratory study". Intern. 1. of Climatology, 18, 541-560, 1998.E. H. Steinberger and N. Gazit-Yaari, "Recent changes in spatial distribution on annual precipitation inIsrael", J. Climate, 9, 3328-3336,1996.E. H. Steinberger, Proceedings of the 7th International Conference on Water and EnvironmentalCooperation for the next Millennium, June, Jerusalem, pA5, 1999.Prof. Zev Levin, Dr. Colin Price, Dr. Shimon Krichak, Tel-Aviv University, ISRAEL

REFERENCES that need to be added ifmy recommendations are accepted:

142


Levitus, S., R. Gelfeld, T. Boyer, and D. Johnson, 1994: Results of the NODC and IOC Data Archaeologyand Rescue projects. Key to Oceanographic Records Documentation No. 19, National OceanographicData Center, Wash., D.C., 67 pp.Levitus, S. and J. Antonov, 1997: Variability of Heat Storage of and the Rate of Heat Storage of theWorld Ocean, NOAA NESDIS Atlas 16. U.S. Gov. Printing Office, Wash., D.C., 6 pp., 186 figs.Levitus, S., and J. Antonov, X. Zhou, H. Dooley, K. Selemenov, V. Tereschenkov, 1995: Decadal-scalevariability of the North Atlantic Ocean. Natural Climate Variability on Decade-to-Century Time Scales.National Academy of Sciences Press, 318-324.Levitus, S., R. Gelfeld, T. Boyer, D. Johnson, M.E. Conkright, C. Stephens, T. O'Brien, 2000: Results ofthe NODC and IOC Data Archaeology and Rescue projects. Key to Oceanographic RecordsDocumentation No. XX, National Oceanographic Data Center, Wash., D.C., YY pp.Levitus, S., J.Antonov. T.P. Boyer, and C. Stephens, 2000: Warming of the World Ocean. Submitted forpublication.Dr Sydney Levitus, NODC, USA

References:Hahn, C.l, and S.G. Warren, 1999: Extended Edited Cloud Reports from Ships and Land Stations over theGlobe, 1952-1996. Numerical Data Package NDP-026C, Carbon Dioxide Information Analysis Center(CDIAC), Department of Energy, Oak Ridge, Tennessee (Documentation, 79 pages).Warren, S.G., I.G. Rigor, N. Untersteiner, V.F. Radionov, N.N. Bryazgin, Ye.I. Aleksandrov, and R.Colony,1999: Snow depth on Arctic sea ice. J. Climate, 12, 1814-1829.Stephen G. Warren, University of Washington, USA

ReferencesEllsaesser et aI., 1986, "Global Climatic Trends as Revealed by the Recorded Data, Reviews of Geophysics24(4),745-792.H Ellsaesser, Livermore, USA

ReferencesAllan, R.l and Haylock, M.R. 1993. Circulation features associated with the winter rainfall decrease insouthwestern Australia. Journal of Climate, 6, 1356-1367.Collins, D.A. and Della-Marta, P.M. 1999. Annual climate summary 1998: Australia's warmest year onrecord. Australian Meteorological Magazine, 48, 273-283.Hennessy, K.J., Suppiah, R. and Page, C.M. 1995. Australian rainfall changes, 1910-1995. AustralianMeteorological Magazine, 48,1-13.Karl, T.R., Knight, R.W. and Plummer, N. 1995. Trends in high-frequency climate variability in thetwentieth century. Nature, 377, 217-20.Katz, R.W. and Brown, B.G. 1992. Extreme events in a changing climate: Variability is more importantthan averages. Climatic Change, 21, 289-302.Lavery, B. M., Joung, G. and Nicholls, N. 1997. An extended high-quality historical rainfall dataset forAustralia. Australian Meteorological Magazine, 46, 27-38.Nicholls, N., Landsea, C. and Gill, J. 1998. Recent trends in Australian region tropical cyclone activity.Meteorology and Atmospheric Physics, 65, 197-205.Plummer, N. 1996. Temperature variability and extremes over Australia: part 1 - recent observed changes.Australian Meteorological Magazine, 45, 233-250.Plummer, N., Nicholls, N., Lavery, B. M., Leighton, R. M. and Trewin, B. C. 1997. Twentieth centurytrends in Australian Climate Extremes Indices. In: CLIVARlGCOSIWMO Workshop on indices andindicators for climate extremes, Asheville, NC, USA, 3-7 June 1997.Stone, R., Nicholls, N., and Hammer, G. 1996. Frost in northeast Australia: trends and influences of phasesof the Southern Oscillation. Journal of Climate, 9,1896-1909.Neil Plummer, Bureau of Meteorology, Australia

References:Angelakis A. & Issar A. eds (1996): Diachronic Climatic Impacts on Water Resources withEmphasis on Mediterranean Region. NATO - ASI Series, vol.1, 36, 193-229, ISBN-3-540-60561-4,Springer Verlag.

143

!PCC war TAR Expert Review Comments 20-01-00 Chapter 2

Brown N., Issar A. eds, (1998): Water, Environment and Society in Times of Climatic Change.Kluwer, pp. 241 - 271.Monterin, U. (1937) II clima sulle Alpi ha mutato in epoca storica?, in Ricerche sulle variazionistoriche del clima italiano, II, 2, CNR ~ Comitato Nazionale per la Geografia, Bologna.Pinna, M. (1996) Le Variazioni del Clima: dall' Ultima Grande Glaciazione alle prospettive per if XXIsecolo, Franco Angeli, Milano.Prof. Walter Dragoni, Dipartimento Scienze Terrapiazza dell'Universita 1, ITALIA

GALLO REFSGallo, K.P., D.E. Easterling and T.C. Peterson, 1996: The influence of landuse/land cover on climatological values of the diurnal temperature range,J. Climate, 9:2941-2944.

Gallo, K.P. and TW. Owen, 1999: Satellite-based adjustments for the urbanheat island temperature bias, J. Appl. Meteorol., 38, 806-813.

Gallo et al. 1999 currently cited in TAR references.

Pielke Sr., RA, R.L. Walko, L.T Steyaert, P.L. Vidale, G.E. Liston, WALyons, and TN. Chase, 1999: The influence of anthropogenic landscapechanges on weather in South Florida, Mon. Wea. Rev. 127, 1663-1673.

Stohlgren, T.J., TN. Chase, R. A Pielke, Sr., TG.F. Kittel and J.S.Baron, 1998: Evidence that local land use practices influence regionalclimate, vegetation, and stream flow patterns in ajacent natural areas,Global Change BioI., 4, 495-504.

LANDSEA REFERENCES AND FIGURE:

Gray, W. M., J. D. Sheaffer, and C. W. Landsea, 1997: Climatetrends associated with multidecadal variability of Atlantic hurricaneactivity. ~Hurricanes, Climate and Socioeconomic lrnpacts ,Edited by H. F. Diaz and R. S. Pulwarty, Springer, Berlin, 15-53.

Landsea, C. W., R. A Pielke, Jr., A M. Mestas-Nunez, and J. A Knaff,1999: Atlantic basin hurricanes: Indices of climatic changes._Climatic Chanqes, 42,89-129.

Mestas-Nunez, AM., and D.B. Enfield, 1999: Rotated global modes ofnon-ENSO sea surface temperature variability. _J. Climate_, 12,2734-2746.

144


Atlantic Named & Subtropical Storms1944-1998

(/)

EL-

.8(f)

o 10 ~~~"~HH~~'_~~~~~'_~~~~~~~~~~~

15

L-a).cE::::lZ

5

o ~~~~~~~~~~~~~~~~~~~~~~~~~1~1~1~1~1~1~1m1~1~1~1~

Year

FIGURES

Levitus's figures

Captions for figures submitted with this review:

Fig. XXITime series of upper ocean heat storage (0-300 m) for the world ocean and individual hemispheres fromLevitus et al. (2000) WHERE ARE THE FIGURES?

Fig. XX2Time series (five year running mean) of heat storage for the world ocean integrated through 3000 m depth

EXTRA COMMENTSExcerpts on ENSO observed and paleo.AN INPUT FROM TIMMERMAN AND CANEFrom Axel Timmermann and Mark Cane

The EI Ni\-no/Southern Oscillation (EN SO) phenomenon originates in the tropical Pacific, butaffects climate conditions globally. ENSO is an irregular low-frequency oscillation between awarm (EI Niv-no) and a cold state (La Niv-na) with a preferred timescale of 2-8 years. ENSOextremes have a strong impact on the societies of many countries as well as on sensitiveecological systems. It is estimated that the 1982-3 EI Niv-no caused US$13 billion (US usage) indamage worldwide and was responsible for 2000 deaths. The impacts of the even stronger1997-8 EI Niv-no were somewhat mitigated By prediction and monitoring based on the markedincrease in our knowledge in the intervening 15 years. There is a vast literature on ENSO related

145


climate variability and its impacts (see Glantz, 1996 for a popular account) which holds usefullessons for anthropogenic climate change. Here we address only the direct connections betweenENSO and greenhouse warming.

\subsection{ ENSO: past and present}

A variety of paleo proxies and archeological investigations (e.g Sandweiss Et al. 1996, 1997;Rodbell et al. 1999; Zhang et al. 1989; Quinn 1992; Villalba 1990; Thompson and MosleyThompson 1989; K\"onnen et al. 1998; references In Fagan, 1999) provide considerableevidence for past variations in the strength and frequency of ENSO extremes. A number of thesestudies focus on the Mid-Holocene (10000 BP - 5000 BP) and offer conflicting interpretationsof the data (Sandweiss et al. 1996, 1997; letters to Science 276 p996-7; DeVries, et al 1997;Rodbell et al 1999.) Based on results of a modeling study, Clement et al (1999) suggest that theENSO cycle does not cease, but the frequency of strong events is sharply reduced, resumingrather abruptly at about 5000 BP. This interpretation reconciles the available data, as it impliesgenerally dryer conditions in Peru and Ecuador, but an absence of extreme cold events (LaNiv-nas), In the modeling study the changes in the character of ENSO are a response to thesmoothly varying, small amplitude insolation change imposed by the earth's varying orbit.

Figure 1 indicates that there is considerable irregularity in the ENSO Cycle in the modern record.There is an apparent climate "shift" in the Tropical and North Pacific at around 1976 (Trenberth1990, Trenberth and Hurrell 1994, Graham 1994). The last 20 years are characterized byrelatively high ENSO variability, including the two strongest EI Niv-no events (1982/83,1997198) in the 130+ years of instrumental records and an unusual long-lasting warmspell in the early 1990s.

WHERE IS FIG 1?

146

International Journal of - WhatDoTheyKnow

Documents

Transcript of International Journal of - WhatDoTheyKnow