An unsettled climate

Dr. Judith CurryBy Judith A. Curry
School of Earth and Atmospheric Sciences
Georgia Institute of Technology
September 21, 2014

I’ve been invited by several venues to write an op-ed related to my recent presentation at the National Press Club.

Versions of the op-ed are starting to appear, below is the full text with my title.
An unsettled climate

In a press conference last week, UN Secretary-General Ban-Ki Moon stated: “Action on climate change is urgent.  The more we delay, the more we will pay in lives and in money.” The recently appointed UN Messenger of Peace Leonardo DiCaprio stated “The debate is over. Climate change is happening now.”

These statements reflect a misunderstanding of the state of climate science and the extent to which we can blame adverse consequences such as extreme weather events on human caused climate change. The climate has always changed and will continue to change. Humans are adding carbon dioxide to the atmosphere, and carbon dioxide and other greenhouse gases have a warming effect on the climate. However, there is enduring uncertainty beyond these basic issues, and the most consequential aspects of climate science are the subject of vigorous scientific debate: whether the warming since 1950 has been dominated by human causes, and how the climate will evolve in the 21st century due to both natural and human causes. Societal uncertainties further cloud the issues as to whether warming is ‘dangerous’ and whether we can afford to radically reduce carbon dioxide emissions.

At the heart of the recent scientific debate on climate change is the ‘pause’ or ‘hiatus’ in global warming – the period since 1998 during which global average surface temperatures have not increased. This observed warming hiatus contrasts with the expectation from the 2007 IPCC Fourth Assessment Report that warming would proceed at a rate of 0.2°C/per decade in the early decades of the 21st century. The warming hiatus raises serious questions as to whether the climate model projections of 21st century have much utility for decision making, given uncertainties in climate sensitivity to carbon dioxide, future volcanic eruptions and solar activity, and the multidecadal and century scale oscillations in ocean circulation patterns.

A key argument in favor of emission reductions is concern over the accelerating cost of weather disasters. The accelerating cost is associated with increasing population and wealth in vulnerable regions, and not with any increase in extreme weather events, let alone any increase that can be attributed to human caused climate change. The IPCC Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation found little evidence that supports an increase in extreme weather events that can be attributed to humans. There seems to be a collective ‘weather amnesia’, where the more extreme weather of the 1930’s and 1950’s seems to have been forgotten.

Climate science is no more ‘settled’ than anthropogenic global warming is a ‘hoax’. I am concerned that the climate change problem and its solution have been vastly oversimplified. Deep uncertainty beyond the basics is endemic to the climate change problem, which is arguably characterized as a ‘wicked mess.’ A ‘wicked’ problem is complex with dimensions that are difficult to define and changing with time. A ‘mess’ is characterized by the complexity of interrelated issues, with suboptimal solutions that create additional problems.

Nevertheless, the premise of dangerous anthropogenic climate change is the foundation for a far-reaching plan to reduce greenhouse gas emissions. Elements of this plan may be argued as important for associated energy policy reasons, economics, and/or public health and safety. However, claiming an overwhelming scientific justification for the plan based upon anthropogenic global warming does a disservice both to climate science and to the policy process. Science doesn’t dictate to society what choices to make, but science can assess which policies won’t work and can provide information about uncertainty that is critical for the decision making process.

Can we make good decisions under conditions of deep uncertainty about climate change? Uncertainty in itself is not a reason for inaction. Research to develop low-emission energy technologies and energy efficiency measures are examples of ‘robust’ policies that have little downside, while at the same time have ancillary benefits beyond reducing greenhouse gas emissions. However, attempts to modify the climate through reducing CO2 emissions may turn out to be futile. The hiatus in warming observed over the past 16 years demonstrates that CO2 is not a control knob on climate variability on decadal time scales. Even if CO2 mitigation strategies are successful and climate model projections are correct, an impact on the climate would not be expected until the latter part of the 21st century. Solar variability, volcanic eruptions and long-term ocean oscillations will continue to be sources of unpredictable climate surprises.

Whether or not anthropogenic climate change is exacerbating extreme weather events, vulnerability to extreme weather events will continue owing to increasing population and wealth in vulnerable regions. Climate change (regardless of whether the primary cause is natural or anthropogenic) may be less important in driving vulnerability in most regions than increasing population, land use practices, and ecosystem degradation. Regions that find solutions to current problems of climate variability and extreme weather events and address challenges associated with an increasing population are likely to be well prepared to cope with any additional stresses from climate change.

Oversimplification, claiming ‘settled science’ and ignoring uncertainties not only undercuts the political process and dialogue necessary for real solutions in a highly complex world, but acts to retards scientific progress. It’s time to recognize the complexity and wicked nature of the climate problem, so that we can have a more meaningful dialogue on how to address the complex challenges of climate variability and change.

Related essays

In the midst of preparing my essay, Steve Koonin’s WSJ op-ed was published Climate Science is Not Settled.  Most of Koonin’s points are very similar to what I have been saying, I would say the main difference is related to decision making under deep uncertainty.  Koonin states “We are very far from the knowledge needed to make good climate policy.”  I argue that there are strategies for decision making under deep uncertainty that can be useful for the climate change problem, particularly if you are not trying to solve the problem of extreme weather events by reducing carbon dioxide emissions.  But overall I am thrilled by Koonin’s op-ed — since he operates higher in the scientific and policy food chain than I do, his voice adds much gravitas to the message that I think needs to get out regarding climate science and policy.  I would also like to add that Koonin chairs the APS Subcommittee that is reviewing the APS climate change policy statement (see my previous post on the APS Workshop, where I met Koonin).

In the midst of the ‘mad crowd’ in New York City attending the People’s Climate March, sober people are trying to figure out ways to broaden the policy debate on climate change and do a better job of characterizing the uncertainty of climate change (both the science itself and the media portrayal of the science).  There is concern that the institutions of science are so mired in advocacy on the topic of dangerous anthropogenic climate change that the checks and balances in science, particularly with regard to minority perspectives, are broken.

Richard Lindzen’s CATO essay Reflections on Rapid Response to Unjustified Climate Alarm discusses the kickoff of CATO’s new center on rapid response to climate alarmism.  Anthony Watts has announced the formation of a new professional society The Open Atmospheric Society for meteorologists and climatologists, with a new open access journal.  Both of these efforts emphasize public communication.  I’m not sure what kind of impact either of these efforts will have, but I wish them well.

My thinking is that we need more voices from influential scientists like Steve Koonin, along with a more mature framing of the climate science problem and decision making framework that allows for dissent and examines a broader spectrum of solutions and approaches.


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