Some ThingsI Think I KnowAbout the Climate

John R. ChristyUniversity of Alabama in Huntsville

Alabama State Climatologist

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

"Global" Surface Temperature

Tmean is Average of Day and Night

HadCRUT3 (2011 Jan-May only)

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-0.6

-0.4

-0.2

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0.6

1850 1870 1890 1910 1930 1950 1970 1990 2010

CO2 up 38% at current rate of 0.6% per year

East Africa TMax (Christy et al. 2009).

-1.5

-1.0

-0.5

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1.0

1.5

1900 1920 1940 1960 1980 2000

Obs: (HadCRUT3) +0.14 °C/decade

Kilimanjaro

East Africa TMax (Christy et al. 2009).

-1.5

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1.0

1.5

1900 1920 1940 1960 1980 2000

Obs: (UAH) +0.02 °C/decade

Obs: (HadCRUT3) +0.14 °C/decade

Kilimanjaro

CA Valley and Sierra Annual Avg TMax 1910-2003 .

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1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

°C

Valley TMax

Sierra TMax

CA Valley and Sierra (Jun-Nov) 1910-2003

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1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

°C

Valley TMin

Sierra TMin

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

Snyder et al. 2002

Sierras warm faster than Valley in model simulations

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1875 1890 1905 1920 1935 1950 1965 1980 1995 2010

W Slope

9-Point avg

Western Slope Sierra Nevada Snowfall133 Years: 1878-79 to 2010-11

Average = 1.0

2010-11 Prelim

Fundamental issue is to discover how sensitive the climate system is to rising concentrations of CO2 and other

greenhouse gases

0.0 . 1.0 . 2.0 . 3.0 . 4.0 .

Zero FeedbackStefan-Boltzmann .

Warming for doubled CO2 °C .

Fundamental issue is to discover how sensitive the climate system is to rising concentrations of CO2 and other

greenhouse gases

0.0 . 1.0 . 2.0 . 3.0 . 4.0 .

Zero FeedbackStefan-Boltzmann .

Warming for doubled CO2 °C .

Model Projections(Positive feedback) .

Fundamental issue is to discover how sensitive the climate system is to rising concentrations of CO2 and other

greenhouse gases

0.0 . 1.0 . 2.0 . 3.0 . 4.0 .

Zero FeedbackStefan-Boltzmann .

Warming for doubled CO2 °C .

Model Projections(Positive feedback) .

Analysis(~zero to negative feedback) .

History Lesson 1988

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1.0

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1960 1970 1980 1990 2000 2010 2020

GISS-A(88)

GISS-B(88)

GISS-C(88)Predictions

History Lesson 1988

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1.0

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1960 1970 1980 1990 2000 2010 2020

GISS-A(88)

GISS-B(88)

GISS-C(88)

UAH-LT (SfcAdj)

RSS-LT (SfcAdj)

ObservationsJan-Jun 2011

Predictions

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0.00

0.05

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0.15

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0.25

0.30

1979 1985 1990 1995 2000

Median of Modeltrends

Mean of Model Trends

HadCRUT3v

UAHLTsfc

RSSLTsfc

Trends ending in 2011 with various start yearsIPCC AR4 Model Runs (22 models) vs. Obs.

Start Year

Vertical Temperature Change due to Greenhouse Forcing in Models

Model Simulations of Tropical Troposphere Warming:About 2X surfaceLee et al. 2007

Models: Mean and Standard Error

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1000

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Model -2SEModel +2SEModel Best Guess

Best Estimate of Models - given surface trend close to observed

°C/decade

Observations: Four "corrected" Datasets

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900

1000

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

HadATIGRARATPACRICH

Upper air trends of four observed datasets are significantly cooler in this apples to apples comparison

°C/decade

Models vs. Obs

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800

900

1000

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

Model -2SEModel +2SEModel Best GuessHadATIGRARATPACRICH

Upper air trends of four observed datasets are significantly cooler in this apples to apples comparison (Douglass et al. 2007).

°C/decade

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

UAH5.4 LT

RSS3.3 LT

HadAT LT

RATPAC LT

RC1.4 LT

RICH LT

ERA-I

U-Air Mean

ERSST3b

HadCRUT3v

GISS LOI

RSS Tropical Lower Tropospheric data have spurious warming in the 1990s. Below is warming in RSS relative to

all other datasets (1996-7 minus 1991-1989)

Christy and Norris 2006, 2009; Christy et al. 2007, 2010, 2011; Klotzbach et al. 2008; Randal and Herman 2008.

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0.0 0.1 0.2 0.3 0.4Trend K/decade

Models

UAH

RSS

HadATRATPAC

RAOBCORE

RICH

Ratio Trop/Tsfc Christy et al. 2010 .

Christy et al. 2010 .

Christy et al. 2007

Thorne et al. 2007 .

McKitrick et al. 2010

Over the interval 1979-2009, model-projected temperature trends are two to four times larger than observed trends in boththe 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 observational] result is inconsistent with model projectionswhich show that significant amplification of the modeled surfacetrends 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.

Response of Clouds and Water Vapor (shortwave and longwave) to Increasing CO2

0

20

40

60

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100

Relative Temperature Effect

Water Vapor and Clouds

CO2

Other

Negative Feedback?(mitigates CO2 impact)

Positive Feedback?(enhances CO2 impact - models)

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Fraction of Record

Cu

m.

Av

era

ge

Re

gre

ss

ion

Slo

pe

(W

m-2

K-1

)

Terra CERES LW+SW vs UAH MT,

global (10 years)

CNRM CM3

CGCM31GFDL CM20

INM CM30ECHAM5

CSIRO MK30

The Real Climate System Behaves Very Differently from IPCC Climate Models

Less Sensitive

More Sensitive to forcing

Anaylses derived from Spencer and Braswell 2010 .

Spencer and Braswell 2011

Spencer and Braswell 2011Interannual climate sensitivity .

Time of Temperature Peak .

Net Radiative Flux .

Testing Hypothesis (assertions) about ClimateUAHuntsville 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 ofenhanced 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

Testing Hypothesis (assertions) about ClimateUAHuntsville 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 ofenhanced 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

Testing Hypothesis (assertions) about ClimateUAHuntsville 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 ofenhanced 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

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1.0

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199020002010202020302040205020602070208020902100

�C

P50 Mid-Range Scenario80% Reduction

50% Reduction

Net Impact if all US

adheres to 50%

reduction by 2050 is

0.07°C 2100

Scenario 50% and 80% reduction in US CO2 emissions by 2050 Climate Sensitivity of 1.5°C