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State of the U.S. Climate Debate
Judith Curry
Georgia Institute of Technology
Climate Forecast Applications Network
science
President Obama’s
statements
“We will respond to the threat of
climate change, knowing that failure
to do so would betray our children
and future generations.”
"No challenge--no challenge--poses
a greater threat to future generations
than climate change."
“There’s one issue that will define the contours of this
century more dramatically than any other, and that is
the urgent and growing threat of a changing climate.”
UNFCCC Treaty (1992):
The UNFCCC established a goal of stabilization
of atmospheric greenhouse gases to prevent
dangerous climate change
IPCC:
1. Human-caused climate change is real
2. Human-caused climate change is dangerous
3. Action is needed to prevent dangerous human
caused climate change
Intended Nationally Determined Contributions (INDCs)
U.S. INDC:
• Reduce emissions by 26-28% below
2005 levels by 2025
• Economy-wide emission reductions of
80% by 2050
Environmental Protection Agency
(EPA): Clean Power Plan
By 2030, these steps will:
• Cut carbon power sector emission
by 30% nationwide below 2005 levels
• Cut particle pollution, nitrogen oxides, and
sulfur dioxide by more than 25%
• Avoid up to 6,600 premature deaths, up to
150,000 asthma attacks in children;
• Shrink electricity bills 8% by increasing energy
efficiency and reducing demand.
EPA Endangerment Finding
• In Massachusetts v. EPA (2007), the
Supreme Court held that greenhouse gases
are pollutants under the Clean Air Act.
• In 2009, the EPA determined that
Greenhouse gas pollution will endanger
public health.
State Governors’ perspectives on
climate change
Source: ClimateProgress
Selling the President’s Plan (I)
Social Cost of Carbon
Rationale: Assess cost-benefit of regulatory actions
that impact CO2 emissions
Challenge:
• Costs and benefits, estimated over 300 years, are
highly uncertain and contested
• High costs now will damage the economy and
development
• Social discount rate: how much should
we value potential damages to future
people?
Selling the President’s Plan (II)
Extreme weather
President Obama: "The best climate scientists in the
world are telling us that extreme weather events like
hurricanes are likely to become more powerful. Climate
change didn't cause Hurricane Sandy, but it might have
made it stronger.”
Chris Landsea, NHC: “How is it that the
White House links changes in hurricanes
today to global warming when WMO,
NOAA, and IPCC cannot?”
Are hurricanes made worse by climate change?
Source: Ryan Maue
Global tropical cyclone ACE
US landfalling hurricanes
Source: Roger Pielke Jr
Selling the President’s Plan (III)
Public health benefits
President Obama: “Carbon pollution causing climate
change is contributing to health risks for many children.
Over the past 3 decades, the % of Americans with
asthma has more than doubled and climate change is
putting those Americans at greater risk of landing in the
hospital”.
Challenge: CO2 does not impact air
quality and breathing. U.S. air quality
(ozone and particulates) has improved
substantially in past 3 decades.
Selling the President’s Plan (IV)
National Security
President Obama: ”Climate change constitutes a
serious threat to global security, an immediate risk to
our national security, and, make no mistake, it will
impact how our military defends our country,”.
Challenge: The main security issue is the impact
of extreme weather events,
which is better addressed by
adaptation. CO2 mitigation is
an ineffective national security
tool.
As ISIS marches . . .
Selling the President’s Plan (V)
Reduces global warming
The U.S. INDC of 28% reduction of emissions below
2005 levels by 2025 will prevent 0.03oC in warming by
2100.
Reducing U.S. total emissions by 80% by 2050 will
prevent 0.11oC in warming by 2100
Source: CATO
Senator James Inhofe (R)
Chair, Env. & Public Works Comm
Rep. Lamar Smith (R)
Chair, Science, Space & Tech Comm.
Wall Street Journal op-ed 4/23/15
The Climate-Change Religion
Earth Day provided a fresh opening for Obama to raise
alarms about global warming based on beliefs, not science.
Washington Post op-ed 5/19/13
Overheated rhetoric on climate change
hurts the economy
Climate change is an issue that needs to be discussed
thoughtfully and objectively. Unfortunately, claims that
distort the facts hinder the legitimate evaluation of policy
options.
The ‘treaty’ problem
Article II, Section 2, Clause 2 of the U.S.
Constitution includes the Treaty Clause:
“ [The President] shall have Power, by and with
the Advice and Consent of the Senate, to make
Treaties, provided two thirds of the
Senators present concur . . . “
Sense of the Senate Resolution 1/20/15
“Climate change is real and not a hoax” (98-1)
“Climate change is real; and human activity significantly
contributes to climate change.” (50-49)
___________________
Confusion between the scientific and political definition:
•Scientific defn: Climate change may be due to natural
processes, or to persistent anthropogenic changes.
•Political defn equates ‘climate change’ with
caused climate change (UNFCCC)
Natural climate variability versus humancaused climate change is at the heart of
scientific and policy debate
human-
Impact on the UNFCCC
President Obama intends to sign a UN climate
agreement without Congressional approval
French Foreign Minister Laurent Fabius in Bonn:
“We must find a formula which is valuable for
everybody and valuable for the U.S. without going
to the Congress”
To what extent is President Obama’s
Climate Commitment enforceable?
In the absence of state and Congressional support, the
Plan is being enforced through the Executive Branch via
the Environmental Protection Agency (EPA).
Challenges:
• Ongoing legal challenges, but so far the Supreme
Court has supported Obama
• The next President may choose not to
enforce, or even to abolish the EPA.
Republican Presidential Candidates (I)
Jeb Bush: “I don’t think the science is clear of
what % is man-made and what % is natural. It’s
convoluted. For the people to say the science is
decided on this is really arrogant. The climate
is changing. We need to adapt to that reality.”
Ted Cruz: “Specifically, satellite data
demonstrate there has been no warming over
the past 17 years. And I would note whenever
anyone makes that point, you immediately get
vilified as a ‘denier’ without anyone actually
refuting the facts.”
Republican Presidential Candidates (II)
Marco Rubio: “The question is, what
percentage of that is due to human activity? If
we do the things they want us to do, cap-andtrade, you name it, how much will that change
the pace of climate change versus how much
will that cost to our economy? “
Carly Fiorina: “The only answer to this is
innovation, and in that America could be the
best in the world.”
Republican Presidential Candidates (III)
Chris Christie: “when you have over 90% of
the world’s scientists who have studied this
stating that climate change is occurring and
that humans play a contributing role, it’s time
to defer to the experts.”
John Kasich: “I am just saying that I am
concerned about it, but I am not laying awake
at night worrying the sky is falling.”
Rick Santorum: “I for one never bought the
hoax. To suggest that man’s contribution is the
determining ingredient in the sauce that affects
the entire global warming and cooling is just
absurd on its face.”
Agreement:
•Surface temperatures have increased since 1880
•Humans are adding carbon dioxide to the atmosphere
•Carbon dioxide and other greenhouse gases have a warming
effect on the planet
Disagreement:
•Whether the warming since 1950 has
dominated by human causes
•How much the planet will warm in the
21st century
•Whether warming is ‘dangerous’
•Whether we can afford to radically
reduce CO2 emissions, and whether
reduction will improve the climate
been
21st
Science in the cross-fire
• President Obama: “We don’t have time for a
meeting of the flat earth society.”
• Congressional Republicans: Working on
substantial reductions to funding for climate
research
Ideologically-fueled research
Many scientists have become advocates for the
UNFCCC/IPCC ideology, which is leading scientists into
overconfidence in their assessments and public
statements and into failures to respond to genuine
criticisms of the scientific consensus.
The climate science establishment has become
intolerant to disagreement and debate,
and is attempting to marginalize and
de-legitimize dissent as corrupt
or ignorant.
Wall Street Journal
February 2, 2006
Cold Front
Debate Shatters Civility of Weather Science
Hurricanes Worsened by Global Warming?
Spats are so tempestuous,
sides are barely talking
Charge of “brain fossilization”
Mixing Politics and Science in Testing the
Hypothesis That Greenhouse Warming Is
Causing a Global Increase in Hurricane Intensity
BY J. A. CURRY, P. J. WEBSTER, AND G. J. HOLLAND
UN IPCC
JC’s concerns: Our core scientific research values
became compromised in the “war against the skeptics”:
•the rigors of the scientific method (incl reproducibility),
•research integrity and ethics
•open minds and critical thinking.
Climate Heretic: Judith Curry
Turns on Her Colleagues
Why can't we have a civil conversation about climate?
October 25, 2010
Hiatus (slow down) in global warming
El nino
Source: Robert Rohde
Source: UK Climatic Research Unit
Significance of the ‘hiatus’ since 1998
Source: Ed Hawkins
Growing divergence between models & observations:
• Are climate models too sensitive to greenhouse forcing?
• Is modeled treatment of natural climate variability inadequate?
• Are model projections of 21st century warming too high?
6/4/15
NOAA finds global
warming pause
didn’t happen;
hiatus disappears
with new analysis
Source: Ed Hawkins
Tom Karl, Director
NOAA NCDC
Implications for the future:
I. Consensus IPCC view
• The ‘pause’ is an artifact; or it will end soon,
with the next El Nino
IPCC AR5 Ch 11
Implications for the future:
II. View emphasizing natural variability
• The ‘pause’ will continue at least another decade
(into the 2030’s?)
• Climate models are too sensitive to human forcing;
21st century warming will be on the low end of IPCC
projections (or even below)
• Solar variations & volcanoes: wild card. Some
are predicting solar cooling in the near term
• Can’t rule out unforeseen surprises
Why do scientists disagree?
• Insufficient & inadequate observational evidence
• Disagreement about the value of different classes
of evidence (e.g. global climate models)
• Disagreement about the appropriate logical
framework for linking and assessing the evidence
• Assessments of areas of ambiguity & ignorance
• Belief polarization as a result of politicization
of the science
Uncertainty • Doubt • Ignorance
Is climate change ‘dangerous’?
UNFCCC: “stabilization of greenhouse gas
concentrations in the atmosphere to prevent
dangerous anthropogenic interference with the
climate system.”
What is ‘dangerous’ climate change?
•Extreme weather events
•Climate ‘tipping points’
•2oC (or 1.5oC) warming
•“fat tail” arguments
IPCC AR4
(2007)
IPCC AR5
(2013)
Nic Lewis
(2015)
Climate Sensitivity:
lopping off the
fat tail
How should we respond,
given the uncertainty?
• There is increasing evidence that the threat
from global warming is overstated
• However, if the threat is not overstated, there
are major shortfalls in current and proposed
solutions.
We’ve oversimplified both the climate change problem
and its solutions:
•undercuts the political process and dialog necessary
for real solutions in a highly complex world
•torques scientific research through politicization and
funding priorities
Wicked mess
http://judithcurry.com
Twitter: @curryja
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