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Facts and Myths about Global Warming. John R. Christy NWS Climate Services University of Alabama in Huntsville 20 June 2007. Consensus is not Science. Michael Crichton. Consensus is not Science. Michael Crichton. All Science is numbers. William Thompson (Lord Kelvin).
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Facts and Myths about Global Warming John R. Christy NWS Climate Services University of Alabama in Huntsville 20 June 2007
Consensus is not Science Michael Crichton
Consensus is not Science Michael Crichton All Science is numbers William Thompson (Lord Kelvin)
Some people will do anything to save the Earth ...except take a science course.
Some people will do anything to save the Earth ...except take a science course. Greenhouse “Affect”, Rolling Stone P.J. O’Rourke
Two Main observing systems for detecting Greenhouse Gas effects • Surface thermometers • Daily High Temperature • Daily Low Temperature • Daily Mean Temperature (popular) • Upper Air Temperatures • Balloon • Microwave emissions
Vertical Temperature Change due to Greenhouse Forcing in Models Model Simulations of Tropical Troposphere Warming: About 2X surface Lee et al. 2007
Is Mean Surface Temperature an Appropriate Index for the Greenhouse Effect? TMean = (TMax + TMin)/2
Day vs. Night Surface Temp Nighttime - disconnected shallow layer/inversion. Temperature affected by land-use changes, buildings, farming, etc. Daytime - deep layer mixing, connected with levels impacted by enhanced greenhouse effect
Night Surface Temp Warm air above inversion Warm air Cold air near surface Buildings, heat releasing surfaces, aerosols, greenhouse gases, etc. can disrupt the delicate inversion, mixing warm air downward - affecting TMin. Nighttime - disconnected shallow layer/inversion. But this situation can be sensitive to small changes such as roughness or heat sources.
The nighttime minimum is related to the delicate formation of the nocturnal boundary layer which can be easily disrupted, mixing warm air downward and sending temperatures up dramatically Walters et al. (in press)
No. Alabama Summer TMax Temperatures Christy 2002
Mean TemperatureSoutheast USA 1899-2003 Models Observation
MODIS 21 Jul 2002 Jacques Descloitres MODIS Land Rapid Response Team NASA GSFC
+ Valley Stations • ° Mountain Stns • Christy et al. 2006, J. Climate
Valley affected by irrigation and urbanization Christy et al. 2006
Christy et al. 2006 Consistent with irrigation and urbanization Consistent with irrigation
Sierras warm faster than Valley in model simulations Snyder et al. 2002
East Africa: 5°S-Eq, 35-40°E (Nairobi, Mt. Kilimanjaro, Mt. Kenya) Christy et al. (submitted) uses 10 times the amount of surface data Upper Air Daytime warming rate 20% of Mainline Datasets in E. Africa
Model vs. Observations TMin minus TMax Preliminary study
Is Mean Surface Temperature an Appropriate Index for the Greenhouse Effect? Evidence indicates TMaxis the better metric to serve as a proxy for monitoring deep atmospheric change Pielke et al. 2007, Walters et al. 2007, Christy et al. (submitted)
Upper Air Temperatures • Recent claims suggest the upper air temperature record is in agreement with the surface and with climate models, so global warming theory must be right • IPCC more or less supports this view • UAH satellite data reportedly “flawed”
Vertical Temperature Change due to Greenhouse Forcing in Models Model Simulations of Tropical Troposphere Warming: About 2X surface Lee et al. 2007
Christy and Spencer 2005 Christy and Norris 2006 Christy et al. 2007
Christy and Norris 2006 Christy et al. 2007
Global Bulk Atmospheric Temperatures UAH Satellite Data Warming rate 60% of model projections
Total Greenhouse Effect • Water vapor and Clouds Dominate • Total Greenhouse Effect is variable • Climate models show strong water-vapor/cloud positive feedback with increased CO2
Tropical Temp. and Cloud Forcing (major part of total greenhouse effect) based on latest satellite sensorsNegative feedback on monthly time scalesSpencer et al. (submitted)
What about Cold Places?
North Polar RegionsHadCRUT3 Period of most polar ice observations
Greenland Summer Temperatures1780-2005 Period of most polar ice observations
AlaskaHadley CRU 3 (°C)Shift in 1977, but high natural variability
When Hemingway writes “Snows of Kilimanjaro”—half of the “snows” are already gone X Mass Gain in 2006 Molg and Kaser 2007
Regional Snowpack, Central Andes, 1951-2005 Masiokas et al. 2006
Ice Cores Antarctica Schneider et al. 2006 Doran et al. 2002 Thermometers
Antarctica snow accumulation trends cm/yr 1992-2003 Davis et al. 2005 See also: Monoghan et al 2006 Van de Berg et a. 2006
Evidence Thus Far • Global surface temperature is rising, but in a way inconsistent with model projections of GHG forcing • Overall decline in ice mass, with sea level rise of about 1” per decade • Severe weather not becoming more frequent
Main Point: I don’t see a disaster developing But, suppose you do ….