Lori Bruhwiler: The CarbonTracker CH4 Assimilation System Top-down modeling approaches for estimating greenhouse gas fluxes combine observations, atmospheric transport models and best available estimates of sources/sinks to produce retrospective analyses of greenhouse gas budgets. Bottom-up, or process-based models, are often used as prior flux estimates. Revisions to these fluxes that arise from use of observational constraints can lead to model improvements and more accurate predictions of future emissions. CarbonTracker uses an ensemble Kalman smoother estimation technique and the TM5 atmospheric transport model to estimate surface fluxes that are in optimal agreement with global network observations and prior flux estimates. ~100 active sites are used by CarbonTracker; most are used in the assimilation, and the others are retained for evaluation. With so few network sites globally, many regions are not constrained by observations and the estimated fluxes in those regions are highly dependent on prior fluxes. Due to the distribution of Arctic network sites, characteristics of Arctic transport, and prior information about the spatial distribution of emissions, the Arctic is relatively well resolved. CarbonTracker-CH4 currently estimates fluxes for 4 source categories; fugitive emissions from fossil fuel extraction, emissions from agriculture and waste (including rice and ruminants), natural sources (wetlands and soil oxidation), and biomass burning emissions. Prior estimates for anthropogenic emissions are from the EDGAR 3 Data set (Olivier et al., 2005), wetland emissions based on Matthews et al. (1989, Fung et al.,1990), soil uptake estimates of Ridgwell et al. (1999), and biomass burning emissions from the GFED,v3 data product (Van Der Werf et al., 2004, 2004, 2006). Sources are estimated for 12 sub-continental scale land regions and 1 global ocean region. Photochemical loss rates vary over a fixed, repeating seasonal cycle, and have been optimized using observations of methyl chloroform.

Figure 2: Estimated CarbonTracker-CH4 methane emissions for Boreal North America and Boreal Eurasia. Note the large emissions during the exceptionally warm year 2007. Emissions remained high in Boreal Eurasia in 2008 as well. The CarbonTracker system is able to discriminate between these two Arctic source regions.

High emissions of carbon gases from a boreal headwater stream network of Interior Alaska

John T. Crawford1,2, Robert G. Striegl1, Kimberly P. Wickland1 & Emily H. Stanley2

1) U.S. Geological Survey, Boulder, CO

2) University of Wisconsin-Madison Center for Limnology, Madison, WI

Small boreal streams integrate the signals of terrestrial and aquatic carbon cycling in their catchments. Recent evidence suggests that despite their limited coverage on the landscape, small streams play a significant role in the downstream delivery of carbon and the emission of trace carbon gases (methane and carbon dioxide) to the atmosphere. However, aquatic gas emissions have not been well documented in many parts of the boreal forest including interior Alaska. We measured carbon gas emissions from a headwater stream network in the Beaver Creek watershed, Yukon River basin, during May (spring thaw) to September, 2011 using discrete measurements and continuous monitoring of stream pCO2. Carbon dioxide emissions from all sites averaged >4.5 gC m-2 day-1, with small streams exhibiting the highest and most variable emission rates. All sites were supersaturated with CO2 for the entire open-water season. Methane emissions averaged >9.1 mgC m-2 day-1 with a maximum of ~37 mgC m-2 day-1 in a mostly burned catchment. Low water temperatures and short water residence times probably limit in-stream respiration and support the hypothesis that high pCO2 in these streams is derived from terrestrial respiration and groundwater sources. Lower pCO2 of larger streams is likely controlled by rapid outgassing in upstream reaches and poor hydrologic connectivity with portions of the surrounding landscape. Overall, these small upland streams are a constant source of trace gases to the atmosphere during the ice free season and exhibit much higher emission rates than most previously studied boreal stream networks. This reinforces the need for more complete characterization of the spatial and temporal patterns of stream C-gas emissions when assessing whole watershed carbon budgets.

MDI BGCMDI-BGCMDI BGCMDI-BGC

Biogeochemical Model-Data Integration Group

Dr. Christian BeerMax Planck Institute for BiogeochemistryPostfach 10 01 64

D-07701 JenaTel. +49-(0)3641-576281 Fax +49-(0)3641-577200

E-Mail: cbeer@bgc-jena.mpg.de Web: http://www.bgc-jena.mpg.de/bgc-mdi/ Direktorium Martin Heimann Susan Trumbore

In the Max Planck Institute for Biogeochemistry we study the terrestrial component of the global carbon balance in the context of the whole Earth system from a theoretical point of view by applying the process-based ecosystem model JSBACH. This model serves as the land surface boundary for the Max Planck Earth System Model. It represents important ecosystem processes, such as photosynthesis, autotrophic and heterotrophic respiration, disturbances, dynamic vegetation, evapotranspiration and its compartments, runoff, etc. The dynamic state of the ecosystem is being represented by several vegetation and soil carbon pools, and the water and ice contents of five vertical soil layers and two snow layers. Our group has been developing this model further for representing specific processes occurring in permafrost-affected ecosystems, such as freezing and thawing. In doing so, we are deeply collaborating with the Max Planck Institute for Meteorology in Hamburg. The near-future development will focus on an improved representation of soil carbon dynamics of cryoturbated soils. The comparison of model results of recent carbon, water and energy fluxes and stocks with observations at several scales in concert with model projections until 2100 and 2300 will allow studying the vulnerability of permafrost soil carbon and its consequences within the Earth system.

Focus II: Process-based modelling of the soil in the Earth system

Effects of soil thermal dynamics on the carbon balance in high-latitude permafrost regions Altug Ekici[1,2]*, Christian Beer[1], Christian Hauck[2] ;

*aekici@bgc-jena.mpg.de

•  High amounts of carbon stocked in permafrost soils during glacial cycles

•  Changing climate and projected warming can thicken the active layer, thus increase the carbon flux to the atmosphere

•  Permafrost thawing requires a valid representation of physical and biogeochemical processes in the models

•  It is our aim to asses the carbon release due to active layer thickening and investigate the response of vegetation and atmosphere A

IMS &

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•  Jsbach-PF: new model version to simulate high latitude processes

•  Multi-layer hydrology scheme •  Freezing/thawing processes •  Modified soil thermal properties due to changing

amounts of soil water •  Multi layered snow scheme •  Organic layer insulation •  Results showed that accounting for these processes

improved simulations of soil thermal regime and hydrological dynamics C

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AFFILIATIONS:

[1] Max Planck Institute for Biogeochemistry, Jena, Germany [2] University of Fribourg, Fribourg, Switzerland ACKNOWLEDGEMENTS: Stefan Hagemann and Terrestrial Hydrology Group from Max Planck Institute

for Meteorology, Hamburg: for the multi layer hydrology scheme

REFERENCES: Johansen, O. (1975). Thermal conductivity of soils. PhD thesis,University of

Trondheim, Norway Niu G.Y.&Yang Z.L, 2006. Effects of Frozen Soil on Snowmelt Runoff and Soil

Water Storage at a Continental Scale. AMS Lunardini V.G., 1988. Heat conduction with freezing or thawing. Technical Report

88-1, US Army Corps of Engineers

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-Heat conduction using latent heat

-Supercooled water equation by Niu&Yang (2006)

-Heat conductivity by Johansen’s parameterization (1975)

-Heat capacity by Lunardini (1988)

Jsbach-PF Soil Thermal Module

Schilthorn site soil temperature and soil water water/ice concent comparison between observed and simulated data from two model versions: jsb-cnt (original), jsb-pf(modified)

Samoylov site soil temperature and soil water/ice content comparison between observed and simulated data from two model versions: jsb-cnt (original), jsb-pf(modified)

Schilthorn

Samoylov

Schilthorn mountain permafrost site: -3000m altitude -high snow cover -less organic material

Samoylov tundra site: -northern Siberia -arctic tundra region -organic material -ice-rich permafrost -polygonal structure

Heat conduction using latent heat g

-Supercooled water equation by Supercooled water equation byNiu&Yang (2006)u&Yang (2006)

-Heat conductivity by Johansen’sparameterization (1975)

Heat capacity by Lunardini (1988

bach-PFThermal Modul

jsb-cnt jsb-pf Rmse: 7.284 3.463 MeanAbsErr: 5.416 2.42 ModelEfficiency: -2.34 0.242

jsb-cnt jsb-pf Rmse: 11.30 8.56 MeanAbsErr: 8.49 6.74 ModelEfficiency: 0.02 0.44

Max. thaw depth from JSBACH simulated soil temperatures

Using remote sensing and GIS techniques to characterize permafrost landscapes and quantify landscape change

Benjamin Jones, U.S. Geological Survey – Alaska Science Center, bjones@usgs.gov, 907-786-7033

Main interests include: - Thermokarst lake dynamics - Characterization of permafrost landscape

features - Erosion of ice-rich permafrost coastlines - Spatial and temporal patterns of change and

associated processes

Recent Publications:

- Grosse, G, Jones B.M., Arp C. In Press. Thermokarst Lakes, Drainage, and Drained Basins. Elsevier Treatise in Geomorphology. 8 - Parsekian AD, Jones BM, Jones MC, Grosse G, Walter Anthony KM, Slater L (2011): Geometry of floating vegetation mats on the expanding margins of thermokarst lakes, northern Seward Peninsula, Alaska, USA. Earth Surface Processes and Landforms. doi:10.1002/esp.2210 - Grosse, G, Jones, B.M., Arp C. In Press. Thermokarst Lakes, Drainage, and Drained Basins. Treatise in Geomorphology. 8 - Jones, M.C., Grosse, G., Jones, B.M., Walter-Anthony, K.M. Accepted. Peat accumulation in a thermokarst-affected landscape in continuous ice-rich permafrost. JGR-Biogeosciences. - Arp, C.D., Whitman, M., Jones, B.M., Kemnitz, R., Urban, F., Grosse, G. In Review. Drainage Network Structure and Hydrologic Behavior of Three Lake-rich Watersheds on the Arctic Coastal Plain, Alaska. Arctic, Antarctic, and Alpine Research. - Jones BM, Grosse G, Hinkel KM, Arp CD, Walker S, Beck RA, Galloway JP (in press, 2011): Assessment of pingo distribution and morphometry using an IfSAR derived DSM, western Arctic Coastal Plain, northern Alaska. Geomorphology. doi:10.1016/j.geomorph.2011.08.007 - Daanen, R.P., Grosse, G., Darrow, M., Hamilton, T.D., Jones, B.M. In Review. Rapid frozen debris flow slide movement: implications for permafrost degradation and slope instability in the Brooks Range, Alaska. Natural Hazards and Earth System Science. - Jones, B. M., G. Grosse, C. D. Arp, M. C. Jones, K. M. Walter Anthony, and V. E. Romanovsky. 2011. Modern thermokarst lake dynamics in the continuous permafrost zone, northern Seward Peninsula, Alaska, J. Geophys. Res., 116:G00M03, DOI:10.1029/2011JG001666. - Arp, C. D., B. M. Jones, F. E. Urban, G. Grosse. 2011. Hydrogeomorphic processes of thermokarst lakes with grounded-ice and floating-ice regimes on the Arctic coastal plain, Alaska, Hydrological Processes, 25, 2422-2438, DOI: 10.1002/hyp.8019. - Jones, B. M., C. D. Arp, M. T. Jorgenson, K. M. Hinkel, J. A. Schmutz, and P. L. Flint. 2009. Increase in the rate and uniformity of coastline erosion in Arctic Alaska, Geophys. Res. Lett., 36, L03503, DOI:10.1029/2008GL036205. - Jones, B. M., C. D. Arp, R. A. Beck, G. Grosse, J., Webster, and F. E. Urban. 2009. Erosional history of Cape Halkett and contemporary monitoring of bluff retreat, Beaufort Sea coast, Alaska. Polar Geography 32:129-142. - Jones, B. M., C. A. Kolden, R. Jandt, J. Abatzoglou, F. Urban, and C. D. Arp. 2009. Fire behavior, weather, and burn severity of the 2007 Anaktuvuk River tundra fire, North Slope, Alaska. Arctic, Antarctic, and Alpine Research 41 (3):309-316, doi: 10.1657/1938-4246-41.3.309. - Hinkel, K. M., B. M. Jones, W. R. Eisner, C. J. Cuomo, R. A. Beck, and R. C. Frohn. 2007. Methods to assess natural and anthropogenic thaw lake drainage on the Western Arctic Coastal Plain of northern Alaska, J. Geophys. Res., 112, F02S16, DOI:10.1029/2006JF000584.

Background: - 2009 – Present: PhD Student, Permafrost Lab, UAF,

Advisor: Guido Grosse - 2005 – Present: Research Geographer, U.S. Geological

Survey – Alaska Science Center - 2003 – 2006: M.A. Geography, University of Cincinnati - 1997-2003: B.S. Environmental Studies, University of

Cincinnati

Examples from ongoing research efforts:

Pan-Arctic quantification and characterization of lakes and

drained lake basins

Pan-Arctic assessment of thermokarst lake expansion rates

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Towards a Circum-Arctic Lake Observation Network (CALON)

– recently funded NSF-AON project

- NSF-AON: ARC-1107481 - K. Hinkel, R. Beck, H. Liu, C. Kim, A.

Townsend-Small, and W. Eisner (Univ of Cincinnati), C. Arp and G. Grosse (Univ of Alaska-Fairbanks), J. Lenters (Univ of Nebraska-Lincoln), K. Frey (Clark Univ), and B. Jones (USGS)

- https://sites.google.com/a/giesn.com/nsf-calon/

- The objective is to develop a lake monitoring network across arctic Alaska to provide data for key indices using in situ measurements, field surveys, and remote sensing/GIS technologies

Hanna Lee Climate and Global Dynamics Division National Center for Atmospheric Research Boulder, CO, 80307 hannal@ucar.edu For my dissertation research, I investigated the effects of permafrost thaw on ecosystem carbon balance in arctic tundra. I evaluated how changes in landscape structure affect the carbon balance in a permafrost region, and its potential influence on future climate change. In collaboration with Dr. Ted Schuur (U. of Florida), we showed that land surface subsidence, kwnon as thermokarst, under permafrost thaw would shift permafrost zone from previously thought carbon sink to a large carbon source over decadal time scales at our Alaskan permafrost thaw gradient site. Permafrost thaw and thermokarst development stimulated permafrost carbon release (Lee et al. 2010, JGR-B). The degree of land surface subsidence can be used as a predictive variable for estimating variability in these emissions, and is closely tied to thermokarst development, which alters soil properties (Lee et al. 2011, GCB). Belowground hydrological changes created as a result of permafrost thaw and thermokarst affected carbon releases from the ecosystem in part by changing the partitioning of CO2 and CH4 released during thaw (Lee et al. in press, GCB). Currently, I am working with Dr. David Lawrence (National Center for Atmospheric Research, NCAR) to incorporate permafrost thawing and thermokarst in the CESM to improve the applicability of terrestrial C and N cycling within the CESM.

Permafrost RCN new participant introduction Hanna Lee (hannal@ucar.edu)

Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, CO 80307

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Microtopography

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The degree of land surface subsidence can be used as a predictive variable for estimating variability in these emissions, and is closely tied to thermokarst development, which alters soil properties (Lee et al. 2011, GCB).

Current work

Currently I am working with Dr. David Lawrence (National Center for Atmospheric Research, NCAR) to incorporate permafrost thawing and thermokarst in the CESM to improve the applicability of terrestrial C and N cycling within the CESM.

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Permafrost thaw and thermokarst development stimulated permafrost carbon release (Lee et al. 2010, JGR-B).

Previous work For my dissertation research, I investigated the effects of permafrost thaw on ecosystem carbon balance in arctic tundra. In collaboration with Dr. Ted Schuur (U. of Florida), we showed that land surface subsidence, known as thermokarst, under permafrost thaw would shift permafrost zone from previously thought carbon sink to a large carbon source over decadal time scales at an Alaskan permafrost gradient site.

Schematic showing how thermokarst can be parameterized

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Cold region hydrology

Model vs. obs hydrograph for Control and Improved Hydrology (ice impedance, prognostic wetland, perched water table, 2-way River / Soil interactions)

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Projection of surface warming due to thawing permafrost

Zhuxiao Li1, Kevin Schaefer1, Tom Chase2, Cameron Bracken3, Tingjun Zhang1, Andrew P.BARRETT1 and Lori Bruhwiler4

1National Snow and Ice Data Center, 449 UCB, University of Colorado, Boulder, CO 80309-0449; Phone: 303-492-4806, Fax: 303-492-2468, Email: zhuxiao.li@nsidc.org 2Cooperative Institute for Research In Environmental Sciences, University of Colorado 3 Center for Advanced Decision Support for Water and Environmental Systems, University of Colorado 4NOAA Earth System Research Laboratory

Thawing permafrost and the resulting microbial decomposition of previously frozen organic carbon is one of the most significant potential feedbacks from terrestrial ecosystems to the atmosphere in a changing climate. On the other hand, the additional of billions of tons of greenhouse gases in the atmosphere due to permafrost thawing will intensify the global warming. We investigate the interaction of permafrost thawing and global warming and estimate the surface warming due to permafrost carbon release during period of 1960-2200. We use SiBCASA (land surface model) projections based on A1B scenario to obtain the cumulative permafrost carbon flux to atmosphere, calculate the corresponding increase in atmospheric CO2 concentration and add it to the CO2 concentration of A1B scenario. We

will use the PLASIM (General Climate Model) to estimate the additional increase in surface air

temperature due to permafrost thawing in 21st and 22nd Century. Our SibCASA projections indicated a cumulative permafrost carbon release of 190±64 Gt by 2200, which is equivalent to an increase in atmospheric CO2 concentration of 87±29 ppm. Based on the Vostok record, an increase of ~80 ppm is

associated with 8-10 oC increase in global temperature after glacial termination, so strong surface warming due to permafrost thawing is expected.

Timing, Magnitude and Sources of Ecosystem Respiration in High Arctic Tundra of NW Greenland

1Lupascu, M., 1Stills A, 1Xu, X., 2Lett, C., 2Maseyk, K., 1Lindsey D. S., 1Thomas, J., 3Welker, J. M., 1Czimczik, C. I.

1Department of Earth System Science, University of California Irvine, Irvine, CA, USA

2Bioemco Campus AgroParisTech Grignon Université Pierre et Marie Curie Paris 6, France 3Environment and Natural Resources Institute, University of Alaska Anchorage, Anchorage, AK, USA

High arctic ecosystems with low vegetation density contain significant stocks of

organic carbon (C) in the form of soil organic matter that range in age from modern to ancient. How rapidly these C pools can be mineralized and lost to the atmosphere as CO2 (ecosystem respiration, ER) as a consequence of warming and, or changes in precipitation is a major uncertainty in our understanding of current and future arctic biogeochemistry and for predicting future levels of atmospheric CO2.

In a 2-year study (2010-2011), we monitored seasonal changes in the magnitude, timing and sources of ER and soil pore space CO2 in the High Arctic of NW Greenland under current and simulated, future climate conditions. Measurements were taken from May to August at a multi-factorial, long-term climate change experiment in prostrate dwarf-shrub tundra on patterned ground with 5 treatments: (T1) +2oC warming, (T2) +4oC warming, (W) +50% summer precipitation, (T2W) +4oC × +50% summer precipitation, and (C) control.

ER (using opaque chambers) and soil CO2 concentrations (wells) were monitored daily via infrared spectroscopy (LI-COR 800 & 840). The source of CO2 was inferred from its radiocarbon (14C) content analyzed at the AMS facility in UCI. CO2 was sampled monthly using molecular sieve traps (chambers) or evacuated canisters (wells).

Highest rates of ER are observed on vegetated ground with a maximum in mid summer – reflecting a peak in plant productivity and soil temperature. Respiration rates from bare ground remain similar throughout the summer. Additional soil moisture, administered or due to precipitation events, strongly enhances ER from both vegetated and bare ground. Cumulative ER for the sampling period was of 53.1 mmol C m-2 day-1 for the (C) vegetated areas compared to the 60.0 for the (T2), 68.1 for the (T2W) or the 79.9 for the (W) treatment. ER was highly correlated to temperature (eg. C = 0.8; T2W = 0.8) until middle of July, when heavy precipitation started to occur. In vegetated areas, ER is dominated by recently fixed C, but older C sources contribute during snow melt. Bare areas can be sources of old C throughout the summer. Under ambient climate conditions, pore space CO2 is produced from recently-fixed C near the surface and older C sources at depth. When summer rainfall is increased, recently fixed C is the dominant source of CO2 at all soil depths as recently fixed C is relocated deeper into the soil. Future conditions in NW Greenland will likely result in greater rates of ER, being especially dramatic if summer rainfall increases coincidently with warming. Our findings show that the sources of C efflux will still mostly being dominated by recently fixed C, due to the strong response of plants to water addition.

The field site is located near Thule Air Base in NW Greenland (76°31′52″N, 68°42′12″W). Mean annual air temperature is -11.6oC and has increased by 0.5oC per decade from 1971 to 2000 (Sullivan et al. 2008). Mean annual precipitation is 112 mm. The experiment is established in prostrate dwarf-shrub tundra on patterned ground. At the ecosystem-scale, vascular plants (Salix arctica, Carex rupestris, Dryas integrifolia) and bare soil/cryptogamic crust each cover 50% of the ground surface. Experimental set-up Five treatments (n=3) were assigned to 2.0×0.8 m2 plots within a 70×60 m2 area: (C) ambient temperatures, (T1) low warming (+2oC ~2030), (T2) high warming (+4oC ~2050), (W) added summer water (50% above the long-term average), (T2W) high warming plus summer watering. IR radiators (Kalglo Electronics Co. Inc., Bethlehem, PA) are suspended above the soil surface from rebar tripods (1 radiator/plot) (Sullivan et al. 2008).

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1Lupascu, M., 1Xu, X., 2Lett, C., 2Maseyk, K., 1Thomas, J., 1Lindsey, D. S., 3Welker, J. M. and 1Czimczik, C. I.

1Department of Earth System Science, University of California, Irvine, CA, U.S.A. 2Bioemco Campus AgroParisTech Grignon Université Pierre et Marie Curie Paris 6, France. 3Environment and Natural Resources Institute, University of Alaska, Anchorage, AK, U.S.A.

Ecosystem Respiration (R) Efflux of CO2 from the ecosystem to the atmosphere due to respiration by plants and soil microbes We measured CO2 emission rates using dynamic, opaque chambers with a portable infra-red analyzer (LiCor 840, 1400) in all treatments (C, T1, T2, W, T2W, n=2-3, rocky and vegetated) daily.

Soil pore space CO2 concentrations We manually monitored CO2 concentrations within the soil profile using wells placed at different depths (20, 30, 60, 90 cm) for each treatment with syringes and a LiCor 800 analyzer. Radiocarbon analysis (14C) The 14C content of CO2 is a measure of time since CO2 was fixed from the atmosphere by plants. Different sources of ecosystem respiration have distinct 14C contents and by measuring the 14C content of CO2, we can partition net ecosystem respiration into its main sources. While plants respire CO2 recently fixed from the atmosphere, microorganisms can decompose recent to fossil organic matter pools. We sampled ecosystem respiration by trapping CO2 on molecular sieve traps (Gaudinski et al. 2000). Soil CO2 from wells was sampled with evacuated canisters through a capillary system. Plant and microbial CO2 was sampled using in situ or laboratory incubations (Czimczik et al. 2006, Czimczik and Trumbore 2007). In the laboratory, CO2 was purified cryogenically on a vacuum line and converted to graphite targets using zinc reduction (Xu et al. 2007). The 14C content of graphite targets was measured using accelerator mass spectrometry at the W.M. Keck AMS laboratory of UC Irvine.

Arctic tundra soils store vast amounts of organic carbon (496 Pg in top 1 m, Tarnocai et al. 2009). Understanding how rapidly this pool can be mineralized as a consequence of warming and changes in precipitation is a major uncertainty in predicting future levels of CO2 in the atmosphere. With this study we want to address the following questions: 1. To what extent do long-term experimental increases in temperature and changes in precipitation alter the

magnitude and seasonal pattern of ecosystem-atmosphere CO2 fluxes? 2. How much do different sources of ecosystem CO2 emissions (plant respiration, microbial decomposition of

recently fixed C or old C pools) contribute to total ecosystem CO2 emissions under current and simulated, future climate conditions?

(1-2) Ecosystem Respiration (R):   CO2 emissions are higher from vegetated than rocky areas (Fig. 1).

On the landscape scale, vegetated areas emit 85 ±4.5 % of the total flux (Fig. 2).   Water addition (W) and the combination of water addition and warming (T2W)

increase CO2 emissions, especially in vegetated areas (Fig. 1).   In 2011, CO2 emissions were about 3 times higher than in 2010; due to higher

summer temperatures and lower precipitation (Fig. 2 & Tab. 1).

(3-4) Radiocarbon (14C) content of Ecosystem Respiration:   CO2 emitted from rocky areas is older than from vegetated areas (Fig. 3 & 4).   CO2 emissions display a large variability in ages (& sources) during the snowmelt and before

leaf-out, and become dominated by younger C as the summer progresses (Fig. 4).   There are no differences in the 14C content of CO2 emissions between treatments.   Sporadic emissions of old C (Fig. 4) seem to be correlated with rain events.   The overall sources of R in 2011 are older than in 2010 (seasonal mean, Fig. 3).

The summer of 2011 was warmer and drier than 2010 (Table 1).

(6-7) Radiocarbon content (14C-CO2) at different soil depths:   The age of [CO2] increases with depth.   [CO2] under vegetated areas is younger than under rocky areas.   Water addition (W, T2W) promotes the release of younger C in the top 60 cm,

while higher temperature (T2) stimulates the release of older C.   In 2010 (wetter) [CO2] at all depths is always younger than in 2011

(except at 20 cm; Fig. 6).

(a) Czimczik, C. I. and S. E. Trumbore (2007). Short-term controls on the age of microbial carbon sources in boreal forest soils. Journal of Geophysical Research 112:article G03001 (b) Czimczik, C. I., et al. (2006). Changing sources of soil respiration with time since fire in a boreal forest. Global Change Biology 12: 1–15. (c) Gaudinski, J.B., et al. (2000) Soil carbon cycling in a temperate forest: radiocarbon-based estimates of residence times, sequestration rates, and partitioning of fluxes. Biogeochemistry 51: 33–69 (d) Tarnocai, C.. et al. (2009). Soil organic carbon pools in the northern circumpolar permafrost region. Global Biogeochemical Cycles 23: 1-11. (e) Sullivan, P. F., et al. (2008). Energy and water additions give rise to simple responses in plant canopy and soil microclimates of a high arctic ecosystem. Journal of Geophysical Research 113: G03S08. (f) Xu, X., et al. (2007). Modifying a sealed tube zinc reduction method for preparation of AMS graphite targets: reducing background and attaining high precision. Nuclear Instruments and Methods in Physics Research B 259 (1):320–329

Acknowledgments: We thank the National Science Foundation (U.S.-NSF) for supporting this project (ARC-0909514). Furthermore we thank Cyril McCormick for his help in the autochamber development, and the staff at Thule and McGuire Air Base, Polar Field Services (K. Derry), and the Keck AMS lab for their support.

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(5) CO2 concentration at depth:   [CO2] increases with depth, during snowmelt and throughout the summer.   [CO2] is similar under rocky and vegetated areas.   In a given year, water addition (T2W and W) increases [CO2] at depth, especially under

vegetation. However, near the permafrost table (90 cm) higher precipitation in 2010 suppressed [CO2]. And, higher temperature (T1 and T2) reduces [CO2] at every depth.   Higher temperatures and lower precipitation in 2011 increased [CO2] at every depth.

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Exchanged variables related to permafrost/carbon

(11) Atmosphere)Land (MATSIRO) • Eastward Wind (lowest layer), Northward Wind (lowest layer), Air temperature (lowest layer),

Specific humidity (lowest layer), Air pressure (Lowest layer/Surface), Downward radiation fluxes (6 components: Visible/Near Infrared/Infrared, Direct/Diffuse), Solar Zenith Angle (for parameterization of radiation transfer in canopy), Mole Fraction of CO2 in Air (lowest layer), Henry constant (from CHASER), Precipitation (including snowfall, 2 types: cumulus/large-scale condensation), Surface deposition of soil dust (from SPRINTARS), Surface deposition of black carbon (from SPRINTARS)

(12) Land (MATSIRO) -> Atmosphere • Surface Upward Eastward Wind Stress, Surface Upward Northward Wind Stress, Surface Upward

Sensible heat flux, Surface Upward Latent heat flux, Upward radiation fluxes (Short wave/Long wave), Albedo (6 components: Visible/Near Infrared/Infrared, Direct/Diffuse), Surface temperature, Evapotranspiration (6 components: Transpiration/Interception/Ground, Evaporation/Sublimation), Snow sublimation, 10m Wind (to SPRINTARS, ,CHASER), 2m temperature (to SPRINTARS, CHASER), 2m Specific humidity (to SPRINTARS, CHASER), Surface wetness (to SPRINTARS), Snow water equivalent (to SPRINTARS), Bulk coefficient for eddy transfer (to SPRINTARS), Deposition fluxes of tracers (lowerst layer/surface) (to CHASER), Emission (to CHASER)

(13) MATSIRO)SEIB-DGVM • Precipitation, Downward short wave radiation, Mole fraction of CO2 in air, 2m temperature,

Eastward 10m wind speed, Northward 10m wind speed, 2m Specific humidity, Soil temperature (14) SEIB-DGVM)MATSIRO • Leaf Area Index, Atmosphere-Land carbon flux (Net carbon balance) (Through to Atmosphere)

Research Abstract

Working group “Permafrost Archives, Paleoclimate and Landscape Dynamics” (Head: Dr. Lutz Schirrmeister*), Alfred Wegener Institute for Polar and Marine Research, Periglacial Research Unit Potsdam

*contact: Lutz.Schirrmeister@awi.de, Jens.Strauss@awi.de

See also: http://www.awi.de/en/research/research_divisions/geosciences/periglacial_research/research_themes/permafrost_archives_palaeoclimate_and_landscape_dynamics/

Permafrost is a widespread distributed climate-driven phenomenon of arctic and subarctic regions. Due to long-term stable permafrost conditions frozen deposits preserves indicators of landscape evolution, which are considered as palaeo-environmental archives like sediment core sequences of limnic and deep marine deposits, and glacier ice cores. Numerous fossil bioindicators documenting climate and environmental variations are well-preserved in permanently frozen state. Sediment features reflect changes of accumulation and transport processes and finally periglacial landscape dynamics. Regarding organic matter, we apply a stratigraphic differentiated carbon balance and characteristic, relating the transformation of the organic substance with the permafrost dynamics during the last Late Quaternary climatic cycle. Thus we examine the “preserved” degradation of the organic matter fixed in permafrost. With a combination of modern methods of carbon analytics, sedimentology and detailed field work a comprehensive characteriza-tion, an estimate of the availability and a balance of fossil organic matter in ice-rich permafrost deposits is planned to be realized.

Fig.1: Methods of the applied multidisciplinary approach of

e.g. geocryological, geochronological, sedimentological, hydrochemical, isotope geochemical and remote sensing methods.

Lori Ziolkowski, Postdoctoral Fellow McMaster University, Hamilton, ON email: lorized@gmail.com

Microbial lipid membranes contain an isotopic fingerprint of the carbon sources and

subsequent metabolisms within the community. Since these lipid membranes are typically hydrolyzed quickly after cell death, characterizing the carbon isotopic composition of lipid membranes provides a snapshot of the microbial carbon cycling. When permafrost is warmed, the carbon respired by the soil become much more depleted in radiocarbon (Schuur et al. 2009). This research will exploit this change in the isotopic composition of the carbon to trace what microbes (bacterial, eukrarya and/or archaea) are utilizing the old carbon and provide an estimate of the microbial biomass. I will assess the quantity and isotopic composition of specific markers of bacteria (phospholipids fatty acids), eukarya (ergosterol) and archaea (ether-linked lipids), as well as other geochemical biomarkers, over the course of a controlled warming experiment using permafrost collected in May 2011 on Axel Heiberg Island, NU, Canada (79oN 90oW) by T.C. Onstott (Princeton) and others. This approach will highlight if the carbon source to the microbial community changes with warming. By tracing the fate and transformation of compounds entering the cell, we can further elucidate these reaction pathways and be more equipped to predict how these microbes will affect atmospheric CO2 and CH4.

IntroductionThe Arctic tundra contains more than 191.8 Pg C as soil organic matter. In order to predict with confidence future CO2 and CH4 releases to the atmosphere, it is necessary to understand the controls on these fluxes. The patterns and controls on net ecosystem CO2 and CH4 fluxes are complex and non-linear. Warming and drying of the tundra can result in increased net CO2 emissions from the Arctic to the atmosphere. However, areas that become warmer and remain wet, or become wetter, may be larger net emitters of CH4 to the atmosphere.

Materials and MethodsIn summer 2005 we initiated a large-scale, long-term manipulation in the Alaskan Arctic at the Barrow Experimental Observatory (BEO) as part of the NSF Biocomplexity Program (Fig. 1). This Biocomplexity experiment is the first large scale (1.2 km X 0.4 km) water table manipulation in the Arctic. The experiment was designed to investigate the link between methane and CO2 fluxes, measured by eddy covariance, and changes in soil water status, over complex terrain. In figure 2 are shown the Overarching BioComplexity Hypothesis: Changes in soil moisture will differentially affect the magnitude and even the sign of CO2 and CH4 flux.

Results and discussionIn the early season 2007, the South site shows a larger methane release than the North site (Fig. 4a). CO2 uptake during this period is pronounced for the South site, with substantial midday uptake. At the same time, the North site shows a small release, with very little evidence of midday CO2 uptake. The earlier snow melt at the South site is probably responsible for the earlier activation of the ecosystem for both CH4 and CO2 fluxes. Due to the earlier snow melt, the South site shows higher thaw depth (Fig. 3), higher soil temperature, higher soil moisture (Fig. 4a) in late June when compared to the North site. Later in the season the South site shows methane emission about 21% lower than the North site (Fig. 4b). A general linear model was used to estimate the differences in methane fluxes as a function of the differences in the environmental variables between North and South site.

Conclusion•Taken separately, thaw depth, soil moisture, and water table each explain more the 86% of the variability in the difference in the methane flux between the two sites.

• Because these variables have similar explanatory power, and because they are co-linear, it is very difficult to determine the most important variable driving the differences in methane fluxes.

The Biocomplexity Manipulation Experiment: Effect of Water Table Drop on CH4 and CO2 fluxes in the Alaskan Arctic at the Barrow Environmental

ObservatoryDonatella Zona and Walter C. Oechel

Global Change Research Group, San Diego State University, San Diego, CA, USA

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Fig. 2 BioComplexity Hypothesis: Changes in soil moisture will differentially affect the magnitude and even the sign of CO2 and CH4 flux

Fig. 3 Water table depths (a) and thaw depth (b) (cm from surface, positive above surface, negative below surface) during summer 2007 in the North and South site. Each point is the average of 12 points along the first 200 m downwind the towers; error bars represents standard errors of the mean.

Fig. 4 (a) Half-hour Methane fluxes and CO2 fluxes in the North and South site daily averaged volumetric water content in the first 10 cm depth and soil temperature at 10 cm depth in early season (June 18th to 22nd 2007). (b) Half-hour Methane fluxes and CO2 fluxes (b) in the North and South site), daily averaged volumetric water content in the first 10 cm depth and soil temperature at 10 cm depth in late season (July 16th to 23rd 2007).

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Aknowledgements

NSF, BASC, Hiroki Ikawa, John Kochendorfer, David Lipson, Anatoly N. Salyuk, Paulo C. Olivas and Steve F. Oberbauer

Fig. 2 Bio-complexity manipulation site (vegetated drained lake) in the Barrow Experimental Observatory (BEO), in Barrow, Alaska. On the right figure are shown the locations of the eddy covariance towers (in yellow) and of the additional infrastructures for the experiment. On the right is shown an aerial image of the site taken during summer 2006, before the initiation of the manipulation.

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Introduction•Vegetated drained lake basins are a major component (about 50–70% of the landscape) of the Arctic Coastal Plain (the northernmost part of Alaska). Greenhouse gas fluxes from lakes and vegetated drained lake basins have been largely unstudied. And the largest part of the research on the patterns and controls of CO2 flux in the Arctic excludes the land features that represent the majority of the landscape.

•The general assumption is that Young age drained lakes (i.e. that drained in the last 50*

years) have the highest net CO2 uptake due to the highest plants productivity, the maximum nutrient availability and the highest soil moisture.

•As available nutrients are immobilized in plant material and organic matter, plant productivity and net ecosystem exchange (NEE) should decline and we expect Medium (lakes that drained between 50-300 years ago) and Old age drained lakes (that drained between 300-2,000 years ago) to be progressively less productive than the Young age ones.

Materials and Methods•We used the age classification of the Barrow Peninsula by Hinkel et al. (2003) (see Fig. 1) to choose our sites (displayed in Fig. 2).

• Three portable towers were used to measure CO2, H2O and energy fluxes in these sites, with an open path infrared analyzer (Li-COR 7500, Li-COR, Lincoln, NE, USA) at a sampling rate of 10Hz. Wind speed, direction, and the energy fluxes were measured with a sonic anemometer (CSAT3, Campbell Sci., Logan, UT, USA) a recorded with a datalogger (CR 3000, Campbell).

•We measured at each site thaw depth, soil moisture (Fieldscout TDR 300 and ECH2O-5), net radiation (Net Radiometer, NR-Lite, Kipp and Zonen) incoming and reflected PAR, (PAR sensors, LI-190SB, LI-COR, Inc.), air T and RH (HMP45C-L, Vaisala Inc., Helsinki, Finland), soil T (type-T thermocouples) at surface, 5, and 10 cm below the ground and ground heat flux (G) (Model HFT3, REBS Inc., Seattle, WA, USA).

•Field spectra were collected using a full range spectrometer (350 - 2500 nm) (Analytical Spectral Devices, Boulder, CO) and standardized to Spectralon (Labsphere, North Sutton, NH, USA).

Characterization of carbon fluxes of a drained lake basin chronosequence, on the Alaskan Arctic Coastal Plain.

Zona D.1, W. C. Oechel2, K. M. Peterson3, R. Clements4, K. T. Paw U1, and S. L. Ustin1

1University of California, Davis, CA, USA 2San Diego State University, San Diego, CA, USA 3University of Alaska Anchorage, AK, USA, 4University of Edinburgh, Edinburgh, UK

Fig. 3 Oblique photographs and particular of the vegetation on the bottom right of basins divided by relative age: (a) young (Young 2, 31 July, particular from Footprint lake on 16 July) (b) medium, (Medium 2, 10 July, and particular from 8 Aug) (c) old (Old 2, 10 July), (d) is shows the vegetation inside a pond in an Old age drained lake (Old 1, 23 Aug 07) and the collection of spectral measurements. The figures show an increase in polygonization from Young to Old age drained lake and the establishment of more productive vegetation in the polygon centers (c).

Drained lake Age

Young Medium Old

GPP

gCO

2 m

-2 d

-1

0

4

8

12

16

Drained lake Age

Young Medium Old

gCO

2 m

-2d-

1

-8

-6

-4

-2

0

NEE

a)

b)

Week

0 2 4 6 8 10 12 14

FCO

2 (g

CO

2 m

-2d-

1 )

-12

-10

-8

-6

-4

-2

0

2

4

YoungMediumOld

a) b)

c)

Classified Landsat-7 image.Yellow: Young (0-50 years old)

Purple: Medium (50-300 years old)

Red: Old (300-2000 years old)

Green: Ancient (2000-5500 years old)

Hinkel et al., 2003

Fig. 2 Landsat-7 image from 30 Aug 2000 of the North Slope Alaska (displayed is Band 4). Indicated are the drained lakes measured during summer 2007 (Young age are in yellow, Medium age are in purple, Old age are in red).

Fig. 4 NDVI (Normalized Difference Vegetation Index), NDNI, (Normalized Difference Nitrogen Index), NDWI (Normalized Difference Water Index) and CAI (Cellulose Absorption Index) averaged per each drained lake over the summer period.

Fig. 5 Ecosystem respiration (ER) and gross primary production (GPP) (a) and net ecosystem exchange (NEE) (gCO2m-2d-1) (b) for different lake ages averaged over the whole period of measurements (12 June to 27 Aug 07).

Results and discussion•Young age drained lakes appeared to have the highest plant productivity, the maximum plant nitrogen and the highest plant water content (Fig. 4).The NDVI, much higher in Young age drained lakes than in the Medium and Old age, would suggest a higher productivity of these basins compared to the other ages, probably connected to the higher plant nitrogen content as show by the higher NDNI.

•The traditional view (Odum, 1969) that old-growth ecosystems are carbon neutral (i.e. when photosynthesis balances respiration) is not valid in our site: Medium and Old drained lakes showed similar average CO2 sink over the whole season (Fig. 5) and Young and Old similar sink activity at peak season (week 6-8) (Fig. 6). Probably the formations of ponds following polygonal expression, which increase in the Old basins (Fig. 3c) (Husseley and Michelson, 1966; Billings and Peterson, 1980), the consequent local mineralization in the ponds allows the growth of Arctophila, and increases the productivity of the Old basins at peak season (see Fig. 3c).

ConclusionThis is the first time, to our knowledge, in which CO2 fluxes from relatively young ecosystems (about 50 years old) were compared to ecosystems several thousands years old (Old age drained lakes). The ability of thousand years old ecosystems to maintain biomass accumulation is probably connected to the increase polygonization and re-establish of productive plants (Billings and Peterson, 1980; Bliss and Peterson, 1992).

Fig.1 Landsat-7 and classified Landsat-7 image for Barrow region; yellow areas represent young basins; purple areas represent medium basins; red areas represent old basins; and green areas represent ancient basins (from Hinkel et al., 2003).

*The classification initially made by Bliss and Peterson, 1992 and improved by Hinkel et al., 2003 grouped the lakes that drained during mmmm1950 as Young age lakes, making them about 58 years onld at the current time

Fig. 6 Fluxes of CO2 (gCO2m-2d-1) for different lake ages averaged over the different weeks of measurements. Positive values indicate carbon sources and negative values indicate carbon sinks.

Acknowledgements

Funding for this study was provided by the Department of Energy, USA. We would like to thank the SDSU field crew and all the BASC and UIC, Craig Tweedie and Adrian Aguirre for GP support and Kenneth Hinkel for proving the Landsat image.

d)

Bibliography

•Billings, W. D., and K. M. Peterson, 1980. Vegetational change and ice-wedge polygons through the thaw-lake cycle in arctic Alaska, Arctic and Alpine Research, 12, 413–432

•Bliss, L. C., and K. M. Peterson. 1992. Plant succession, competition, and the physiological constraints of species in the Arctic. pp. 111-133, In: F. S. Chapin III, R. L. Jefferies, J. F. Reynolds, G. R. Shaver, and J. Svoboda (eds.), Arctic E cosystems in a Changing Climate: An Ecophysiological Perspective. Academic Press, Orlando, Florida.

•Hinkel, KM, Eisner WR, Bockheim JG, Nelson FE, Peterson KM, Dai X. 2003. Spatial extent, age, and carbon stocks in drained thaw lake basins on the Barrow Peninsula, Alaska. Arctic, Antarctic, and Alpine Research 35: 291–300.

•Hussey KM, Michelson RW. 1966. Tundra relief features near Point Barrow, Alaska. Arctic 19: 162–184.

•Odum, E. P. The strategy of ecosystem development. Science 164, 262–270 (1969).