Some Things I Think I Know About the Climate

Transcription

1 Some Things I Think I Know About the Climate John R. Christy University of Alabama in Huntsville Alabama State Climatologist

2 We at UAHuntsville build climate datasets from scratch to test assertions (hypotheses) being made about the climate system

3 "Global" Surface Temperature Tmean is Average of Day and Night 0.6 HadCRUT3 (2011 Jan-May only) CO2 up 38% at current rate of 0.6% per year

4 East Africa TMax (Christy et al. 2 Obs: (HadCRUT3) C/de Kilimanjaro

5 East Africa TMax (Christy et al. 2 Obs: (HadCRUT3) C/de Kilimanjaro Obs: (UAH) C/dec

6 16 14 CA Valley and Sierra (Jun-Nov) Valley TMin Sierra TMin C C CA Valley and Sierra Annual Avg TMax 1910 Valley TMa Sierra TMa 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

7 Sierras warm faster than Valley in model simulations Snyder et al. 2002

8 Western Slope Sierra Nevada Snowfall 133 Years: to Average = W Slope 9-Point avg Prelim

9 Fundamental issue is to discover how sensitive the climate system is to rising concentrations of CO2 and other greenhouse gases Zero Feedback Stefan-Boltzmann Warming for doubled CO2 C.

10 Fundamental issue is to discover how sensitive the climate system is to rising concentrations of CO2 and other greenhouse gases Zero Feedback Stefan-Boltzmann. Model Projections (Positive feedback) Warming for doubled CO2 C.

11 Fundamental issue is to discover how sensitive the climate system is to rising concentrations of CO2 and other greenhouse gases Zero Feedback Stefan-Boltzmann. Analysis (~zero to negative feedback). Model Projections (Positive feedback) Warming for doubled CO2 C.

12 History Lesson GISS-A(88) GISS-B(88) GISS-C(88) Predictions

13 History Lesson GISS-A(88) GISS-B(88) GISS-C(88) UAH-LT (SfcAdj) RSS-LT (SfcAdj) Predictions Observations Jan-Jun

14 Trends ending in 2011 with various start years IPCC AR4 Model Runs (22 models) vs. Obs Median of Model trends Mean of Model Trends HadCRUT3v UAHLTsfc RSSLTsfc Start Year

15 Vertical Temperature Change due to Greenhouse Forcing in Models Model Simulations of Tropical Troposphere Warming: About 2X surface Lee et al. 2007

16 Models: Mean and Standard Error Model -2SE Model +2SE Model Best Guess C/decade Best Estimate of Models - given surface trend close to observed

17 100 Observations: Four "corrected" Datasets HadAT IGRA RATPAC RICH C/decade Upper air trends of four observed datasets are significantly cooler in this apples to apples comparison

18 Models vs. Obs Model -2SE Model +2SE Model Best Guess HadAT IGRA RATPAC RICH C/decade Upper air trends of four observed datasets are significantly cooler in this apples to apples comparison (Douglass et al. 2007).

19 RSS Tropical Lower Tropospheric data have spurious warming in the 1990s. Below is warming in RSS relative to all other datasets ( minus ) Christy and Norris 2006, 2009; Christy et al. 2007, 2010, 2011; Klotzbach et al. 2008; Randal and Herman UAH5.4 LT RSS3.3 LT HadAT LT RATPAC LT RC1.4 LT RICH LT ERA-I U-Air Mean ERSST3b HadCRUT3v GISS LOI

20 Ratio Trop/Tsfc Christy et al Christy et al Thorne et al Christy et al Models UAH RSS HadAT RATPAC RAOBCORE RICH Trend K/decade

21 Klotzbach et al 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. Christy et al [Our observational] result is inconsistent with model projections which show that significant amplification of the modeled surface trends occurs in the modeled tropospheric trends. McKitrick et al Over the interval , 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 method, and even with surface trend variation found Santer et al. s result is not verified.]

22 Response of Clouds and Water Vapor (shortwave and longwave) to Increasing CO2 Negative Feedback? (mitigates CO2 impact) Positive Feedback? (enhances CO2 impact - models) Water Vapor and Clouds CO2 Other 20 0 Relative Temperature Effect

23 The Real Climate System Behaves Very Differently from IPCC Climate Models Anaylses derived from Spencer and Braswell Less Sensitive Cum. Average Regression Slope (W m-2 K-1) INM CM30 Terra CERES LW+SW vs UAH MT, global (10 years) CGCM31 ECHAM5 CNRM CM3 GFDL CM20 CSIRO MK30 More Sensitive to forcing Fraction of Record

24 Spencer and Braswell 2011

25 Net Radiative Flux. Time of Temperature Peak. Spencer and Braswell 2011 Interannual climate sensitivity.

26 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

27 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

28 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

29 Scenario 50% and 80% reduction in US CO2 emissions by 2050 Climate Sensitivity of 1.5 C C P50 Mid-Range Scenario 80% Reduction 50% Reduction Net Impact if all US adheres to 50% reduction by 2050 is 0.07 C

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