Global Warming: we’re on thin ice! Evidence of global warming Denial of global warming Convergence...
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Transcript of Global Warming: we’re on thin ice! Evidence of global warming Denial of global warming Convergence...
Global Warming: we’re on thin ice!Global Warming: we’re on thin ice!
• Evidence of global warming
• Denial of global warming
• Convergence of evidence
Compton Tucker
NASA/Goddard Space Flight Center &
Climate Change Science Program Office
Measured Surface Temperature Measured Surface Temperature the past 150 yearsthe past 150 years
5 warmest years: 1998, 2002, 2003, 2004, 5 warmest years: 1998, 2002, 2003, 2004, 20052005
Warming Warming greatest at greatest at
high high latitudeslatitudes
Amplification of Amplification of warming due to warming due to
decrease of decrease of albedo (melting of albedo (melting of
snow and ice)snow and ice)
Mann, Bradley, & Hughes (1998):Mann, Bradley, & Hughes (1998):The “hockey stick” surface temperatureThe “hockey stick” surface temperature
Proxy data used by Mann et al. 1998Proxy data used by Mann et al. 1998
Tree Ring DendrochronologyTree Ring Dendrochronology
Tree Ring DendrochronologyTree Ring Dendrochronology
Tree Ring Temperature ReconstructionsTree Ring Temperature Reconstructions~40% tree ring variation is due to temperature~40% tree ring variation is due to temperature
Best tree ring chronology is bristlecone pine series from Best tree ring chronology is bristlecone pine series from US west that grows >3,000 m & extends >4,000 yearsUS west that grows >3,000 m & extends >4,000 years
Much of the Much of the controversy over controversy over
surface surface temperature temperature
reconstructions has reconstructions has been associated been associated with tree ring with tree ring
proxy temperatureproxy temperature
Some ring-width seriesSome ring-width series
Cook, 1989
Four red spruce ring-width series from the same stand – different Four red spruce ring-width series from the same stand – different trends related to competition and disturbance.trends related to competition and disturbance.
Coral 18O/16O TemperatureReconstruction
Proxy Surface Temperaturesfrom corals, sediments, and
ice cores using 18O/16O18O = (18O/16O)sample - (18O/16O)SMOW x 103 ‰ (18O/16O)SMOW
SMOW = Standard Mean Ocean Water
1818O: O: 0.20%0.20%
1717O: O: 0.04%0.04%
1616O: O: 99.76%99.76%
The vapor pressure of HH221616O is > than that of O is > than that of
HH221818O; converselyO; conversely HH22
1818OO passes into the liquid state more readily. Because condensation is the result of cooling, the greater the fall in
temperature the lower the 1818O concentration O concentration in Hin H22O will be. Isotope concentration can thus O will be. Isotope concentration can thus
be considered a function of temperature.be considered a function of temperature.
Greenland ice core: high resolution/distinct layers
Greenland ice core--yearly layers
McIntyre and McKitrick 2003McIntyre and McKitrick 2003a reanalysis with a subset of Mann et al. a reanalysis with a subset of Mann et al.
1998’s data1998’s data
15th century the warmest time 15th century the warmest time in the past 1000 to 2000 years?in the past 1000 to 2000 years?
Same result as Mann et al. 1998 when Same result as Mann et al. 1998 when 5 PCs are used for 15th century5 PCs are used for 15th century
Same result as Mann et al. 1998Same result as Mann et al. 1998
Proxy data used by Mann et al. 1998Proxy data used by Mann et al. 1998
Total Solar Irradiance
Arctic Sea Ice Trends
2005 summer minima
1979 summer minima
Warmer Earth Warmer Earth Greener NorthGreener North
Arctic Sea Ice Extent 1979 to 1999Arctic Sea Ice Extent 1979 to 1999
Claire Parkinson et al. 2002
Majority of Glaciers are recedingMajority of Glaciers are receding
Receding GlaciersReceding Glaciers
Holgate Glacier July 24, 1909Holgate Glacier July 24, 1909
Holgate Glacier August 13, 2004Holgate Glacier August 13, 2004
Sea Level Rise from thermal expansion Sea Level Rise from thermal expansion & input of water from melting glaciers& input of water from melting glaciers
20 cm (7 inches) in a century20 cm (7 inches) in a century
Bore Hole Temperature Reconstructions
Bore Hole LocationsBore Hole Locationsdifferent physics (different physics (thermal diffusivity) thermal diffusivity)
& 10s of years time steps& 10s of years time steps
Bore Hole Temp. ReconstructionsBore Hole Temp. Reconstructions
~500 years
Subsurface Annual TemperatureSubsurface Annual Temperature12.8 m depth @ North Dakota12.8 m depth @ North Dakota
Bore Hole Data for Eastern & Bore Hole Data for Eastern & Western North America Western North America
((Huang & Pollack)Huang & Pollack)
Pollack & Huang Pollack & Huang Bore Hole DataBore Hole Data
Bore Hole Cumulative Temperature
Figure 6 from pollack and huang p. 365
National Research Council’s National Research Council’s June 2006 ReportJune 2006 Report
Data density circa 1000 ADData density circa 1000 AD
Data density circa 1500 ADData density circa 1500 AD
Equilibrium Climate from Ice Core DataEquilibrium Climate from Ice Core Data
J. HansenJ. Hansen
• Estimate Estimate climate climate
forcing (W/mforcing (W/m22) ) from from
atmospheric atmospheric composition composition
changeschanges
• Regress Regress Temperature Temperature
anomalies anomalies against against climate climate forcing forcing
Data
c8 = ~ 10k year periodicity
c12 = ~ 400,000 year periodicity
modes 10 to 13 : 20k, 40k, 100k, & 400k yearsmodes 10 to 13 : 20k, 40k, 100k, & 400k years
Equilibrium Climate from Ice Core DataEquilibrium Climate from Ice Core Data
J. HansenJ. Hansen
• Estimate Estimate climate climate
forcing (W/mforcing (W/m22) ) from from
atmospheric atmospheric composition composition
changeschanges
• Regress Regress Temperature Temperature
anomalies anomalies against against climate climate forcing forcing
Atmospheric CO2 measurements
Atmospheric CO2 since 1740
Different dCO2/dtime slopes reflect
techno-economic conditions
Climate Forcing: expressed as a change in Climate Forcing: expressed as a change in radiative heating (W/mradiative heating (W/m22) at surface for a given ) at surface for a given
change in trace gas composition or other change change in trace gas composition or other change external to the climate systemexternal to the climate system
Where the Where the rubber hits the rubber hits the
roadroad
Surface melt on Greenland ice sheet
descending into moulin, a vertical shaft carrying the water to base of ice sheet.
Source: Roger Braithwaite
January 31, 2002
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Gravity Recovery & Gravity Recovery & Climate ExperimentClimate Experiment
500 km orbit500 km orbit
220 km separation220 km separation
Distance accuracy Distance accuracy 0.001 mm0.001 mm
Greenland Mass Loss from GRACEGreenland Mass Loss from GRACE
Satellite record melt of 2002 was exceeded in 2005
Surging Surging glaciers & glaciers &
meltingmelting
Greenland Ice: Greenland Ice: 70 m thinning in 5 years70 m thinning in 5 years
> Streaming, >Earthquakes> Streaming, >Earthquakes
It’s only a matter of time…
400 km3 ice = 1 mm sea level
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1900 1950 2000 2050 2100 2150
Atm
osph
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Oil
Gas
Coal
Biosphere
Business-as-Usual(2% annual growth until 50% depletion, then 2% annual decline)
What, me worry?
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Atm
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Oil
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Coal
Biosphere
Alternative Case: Coal Phaseout(+2%/yr to 2012; +1%/yr to 2022; linear shutdown between 2025-2050)
J. Hansen