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Four Things I Think I Know About Climate John R. Christy University of Alabama in Huntsville Alabama State Climatologist
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We should always begin our scientific assessments with the following statement: At our present level of ignorance, we think we know … Paraphrase of Richard Mallory Hoover High School Fresno CA Physics Teacher 1968
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Testing Hypothesis (assertions) about Climate UAHuntsville builds datasets from scratch 1.Popular surface temperature datasets are poor metrics for checking on the greenhouse effect - and they are poorly measured as well 2.Warming is occurring but at a rate and in a manner that is inconsistent with model projections of enhanced greenhouse warming 3.Sensitivity research suggests the climate system is less sensitive to CO2 increases as depicted in models due to unaccounted-for negative cloud feedbacks 4.Impacts on global emissions of current legislative actions are minuscule and will have no discernable impact on whatever the climate is going to do
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Testing Hypotheses on Global Warming 1. Testing Assertions based on Popular Surface Temperature Datasets Popular surface datasets tend to: (a) overstate the warming, and (b) serve as a poor greenhouse metric
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CO2 up 38% at current rate of 0.6% per year
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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 Warm air above inversion Cold air near surface Greenhouse signal
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Night Surface Temp Nighttime - disconnected shallow layer/inversion. But this situation can be sensitive to small changes such as roughness or heat sources. Buildings, heat releasing surfaces, aerosols, greenhouse gases, etc. can disrupt the delicate inversion, mixing warm air downward - affecting TMin. Warm air above inversion Cold air near surface Warm air
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MODIS 21 Jul 2002 Jacques Descloitres MODIS Land Rapid Response Team NASA GSFC
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Nighttime temperatures rising but not because of greenhouse gas warming, but nighttime readings are included in popular datasets Daytime temperatures tell more accurate story Christy 2002, Christy et al. 2006, 2007, 2009, Pielke et al 2008, Walters et al. 2007
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Nighttime temperatures rising but not because of greenhouse gas warming, but nighttime readings are included in popular datasets Daytime temperatures tell more accurate story Christy 2002, Christy et al. 2006, 2007, 2009, Pielke et al 2008, Walters et al. 2007
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1. (c) Some surface data sources are simply poor
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Kilimanjaro
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Testing Hypothesis (assertions) about Climate UAHuntsville builds datasets from scratch 1.Popular surface temperature datasets tend to be poor metrics for checking on the greenhouse effect - and they are often poorly measured as well 2.Warming is occurring but at a rate and in a manner that is inconsistent with model projections of enhanced greenhouse warming 3.Sensitivity research indicates the climate system is less sensitive to CO2 increases as depicted in models due to unaccounted-for negative cloud feedbacks 4.Impacts on global emissions of current legislative actions are minuscule and will have no discernable impact on whatever the climate is going to do
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Testing Hypotheses on Global Warming 2. (a) Testing Assertions based on Climate Models for global trend magnitude Climate models tend to overstate or misrepresent the warming
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Predictions
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Observations Predictions
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G. Schmidt NASA/GISS
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Individual Model Surface Trends 1979-2010
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Trends ending in 2008 with various start years IPCC AR4 Model Runs (22 models) vs. Obs. Start Year
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Trends ending in 2008 with various start years IPCC AR4 Model Runs (22 models) vs. Obs. Start Year
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Trends ending in 2010 (Jun) with various start years IPCC AR4 Model Runs (22 models) vs. Obs. Start Year
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Global Bulk Atmospheric Temperatures UAH Satellite Data Warming rate 50% of model projections Christy et al. 2007, 2009
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Testing Hypotheses on Global Warming Testing Assertions based on Climate Models - Sierra Nevada loses 80% of snow by 2100 Observations contradict this
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Snyder et al. 2002 Sierras warm faster than Valley in model simulations
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Christy and Hnilo 2010. Trend +1.1 cm/decade
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Testing Hypotheses on Global Warming 2. (b) Testing Assertions based on Climate Models concerning Tropical Upper Air Temperature trends Climate models tend to misrepresent the observed relationship
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A Climate Model Simulation is a Hypothesis How does one define a falsifiable test for a model hypothesis?
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Douglass, Christy, Pearson and Singer 2007 Select a prominent metric dependent on the main perturbation in forcing - a large signal - test against observations One such signal is the vertical structure of the tropical tropospheric temperature trend - i.e. how surface and upper air trends compare
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Vertical Temperature Change due to Greenhouse Forcing in Models Model Simulations of Tropical Troposphere Warming: About 2X surface Lee et al. 2007
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Best Estimate of Models - given surface trend close to observed °C/decade
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Upper air trends of four observed datasets are significantly cooler in this apples to apples comparison °C/decade
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Upper air trends of four observed datasets are significantly cooler in this apples to apples comparison (Douglass et al. 2007). °C/decade
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Putting the hot and cold extremes (thick red) of model trends tied to actual surface trend, models are still too hot which in this case all models have been tied to the actual observed surface trend. °C/decade
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A different test asks whether the models and observational upper air trends agree if NO restriction is placed on the model surface trends (i.e. apples to oranges.) Extremely weak hypothesis to test and does NOT address the sfc-to-upper air relationship (a key signature of greenhouse warming in models.)
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Putting the hot and cold extremes (thick red) of model trends tied to actual surface trend, models are still too hot which in this case all models have been tied to the actual observed surface trend. °C/decade
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Christy et al. 2007, 2010; Christy and Norris 2006, 2009; Randall and Herman 2008; Klotzbach et al. 2009, 2010; McKitrick et al. 2010 Ratio of Lower Tropospheric Trend to Surface Trend (Amplification Ratio) Model Median
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Land Surface Temperatures overstate warming Model Expectation (Surface less than upper air) Observations (Surface much more than upper air)
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McKitrick et al. 2010 Over the interval 1979-2009, model-projected temperature trends are two to four times larger than observed trends in both the lower and mid-troposphere and the differences are statistically significant at the 99% level. [Note: recalculated Santer et al. 2008 method, and even with surface trend variation found Santer et al.s result is not verified.] Klotzbach et al. 2010 [Our] result is inconsistent with model projections which show that significant amplification of the modeled surface trends occurs in the modeled tropospheric trends. Christy et al. 2010 Table 2 displays the new per decade linear trend calculations [of difference between global surface and troposphere using model amplification factor] … over land and ocean. All trends are significant at the 95% level.
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Testing Hypothesis (assertions) about Climate UAHuntsville builds datasets from scratch 1.Popular surface temperature datasets tend to be poor metrics for checking on the greenhouse effect - and they are often poorly measured as well 2.Warming is occurring but at a rate and in a manner that is inconsistent with model projections of enhanced greenhouse warming 1.Sensitivity research suggests the climate system is less sensitive to CO2 increases (as depicted in models) due to unaccounted-for negative cloud feedbacks 4.Impacts on global emissions of current legislative actions are minuscule and will have no discernable impact on whatever the climate is going to do
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Testing Hypotheses on Global Warming 3. Testing Assertions on the sensitivity of the climate to increases in greenhouse gas forcing Climate models tend to overstate the sensitivity due to missing negative cloud feedbacks
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Response of Clouds and Water Vapor (shortwave and longwave) to Increasing CO2 Negative Feedback? (mitigates CO2 impact) Positive Feedback? (enhances CO2 impact - models)
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A Climate Model Simulation is a Hypothesis How does one define a falsifiable test for a model hypothesis?
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Select a prominent metric dependent on the main perturbation in forcing - a large signal - test against observations One such test is to calculate the climate feedback parameter during monthly and annual scale variations
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Spencer and Braswell
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Global Warming in Models is Greatly Magnified by Positive Feedbacks Warming from CO 2 only Warming in models amplified by clouds & vapor (~3 deg. C by 2100) Satellite data suggests clouds reduce warming (~0.5°C by 2100) Spencer and Braswell.
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Testing Hypothesis (assertions) about Climate UAHuntsville builds datasets from scratch 1.Popular surface temperature datasets tend to be poor metrics for checking on the greenhouse effect - and they are often poorly measured as well 2.Warming is occurring but at a rate and in a manner that is inconsistent with model projections of enhanced greenhouse warming 3.Sensitivity research suggests the climate is less sensitive to CO2 increases than depicted in models due to unaccounted-for negative cloud feedbacks 4.Impacts on global emissions of current legislative actions are minuscule and will have no discernable impact on whatever the climate is going to do
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Testing Hypotheses on Global Warming 4. Testing Assertions the impact of regulations on climate Regulations will have a minuscule impact on whatever the climate is going to do
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What did California do? Force a limit on emissions of Light Duty Vehicles California AB 1493 seeks to reduce tail- pipe emissions of CO2 by 26% by 2016 11 NE States adopted AB 1493 Trial in Federal Court (Burlington VT) to address the engineering, legal and climate issues of AB 1493, April-May 2007
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What did California do? Force a limit on emissions of Light Duty Vehicles California AB 1493 seeks to reduce tail- pipe emissions of CO2 by 26% by 2016 11 NE States adopted AB 1493 Trial in Federal Court (Burlington VT) to address the engineering, legal and climate issues of AB 1493, April-May 2007
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What did California do? Force a limit on emissions of Light Duty Vehicles California AB 1493 seeks to reduce tail- pipe emissions of CO2 by 26% by 2016 11 NE States adopted AB 1493 Trial in Federal Court (Burlington VT) to address the engineering, legal and climate issues of AB 1493, April-May 2007
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What did California do? Force a limit on emissions of Light Duty Vehicles California AB 1493 seeks to reduce tail- pipe emissions of CO2 by 26% by 2016 11 NE States adopted AB 1493 Trial in Federal Court (Burlington VT) to address the engineering, legal and climate issues of AB 1493, April-May 2007
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IPCC Best Estimate
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California AB 1493 26% CO2 reduction LDV 2016
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The temperature impact on global temperatures if the entire world adopted AB 1493 is an undetectable 0.03°C. Latest sensitivity results suggest the impact is even smaller.
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Pg 46 Plaintiffs expert Dr. Christy estimated that implementing the regulations across the entire United States would reduce global temperature by about 1/100 th (.01) of a degree by 2100. Hansen did not contradict that testimony. Judge William Sessions III Ruling 12 Sept 2007 AB 1493 is legal
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Questions What could make a dent in forecasted global temperatures? What would be the impact of building 1000 nuclear power plants and putting them on-line by 2020? –(average 1.4 gigawatt output each)
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Questions What could make a dent in forecasted global temperatures? What would be the impact of building 1000 nuclear power plants and putting them on-line by 2020? –(average 1.4 gigawatt output each)
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IPCC Best Estimate
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Net Effect of 10% CO2 emission reduction to A1B Scenario (~1000 Nuclear Plants by 2020)
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Testing Hypothesis (assertions) about Climate UAHuntsville builds datasets from scratch 1.Popular surface temperature datasets tend to be poor metrics for checking on the greenhouse effect - and they are often poorly measured as well 2.Warming is occurring but at a rate and in a manner that is inconsistent with model projections of enhanced greenhouse warming 3.Sensitivity research suggests the climate is less sensitive to CO2 increases than depicted in models due to unaccounted-for negative cloud feedbacks Impacts on global emissions of current legislative actions are minuscule and will have no discernable impact on whatever the climate is going to do 4.Impacts on global emissions of current legislative actions are minuscule and will have no discernable impact on whatever the climate is going to do
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Kenya, East Africa
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Energy Transmission Energy System Energy Use Energy Source
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Consensus is not Science Michael Crichton
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Consensus is not Science William Thomson (Lord Kelvin) All Science is numbers Michael Crichton
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