Climatologist Breaks The Silence On Global Warming Groupthink

Dr. Judith Curry: I thank the Chairman and the Committee for the opportunity to offer testimony today. Prior to 2009, I felt that supporting the IPCC consensus on climate change was the responsible thing to do. I bought into the argument: “Don’t trust what one scientist says, trust what an international team of a thousand scientists has said, after years of careful deliberation.” That all changed for me in November 2009, following the leaked Climategate emails, that illustrated the sausage making and even bullying that went into building the consensus.

I starting speaking out, saying that scientists needed to do better at making the data and supporting information publicly available, being more transparent about how they reached conclusions, doing a better job of assessing uncertainties, and actively engaging with scientists having minority perspectives. The response of my colleagues to this is summed up by the title of a 2010 article in the Scientific American: Climate Heretic Judith Curry Turns on Her Colleagues.
I came to the growing realization that I had fallen into the trap of groupthink. I had accepted the consensus based on 2^nd order evidence: the assertion that a consensus existed. I began making an independent assessment of topics in climate science that had the most relevance to policy.
What have I concluded from this assessment?
Human caused climate change is a theory in which the basic mechanism is well understood, but whose magnitude is highly uncertain. No one questions that surface temperatures have increased overall since 1880, or that humans are adding carbon dioxide to the atmosphere, or that carbon dioxide and other greenhouse gases have a warming effect on the planet. However there is considerable uncertainty and disagreement about the most consequential issues: whether the warming has been dominated by human causes versus natural variability, how much the planet will warm in the 21^st century, and whether warming is ‘dangerous’.
The central issue in the scientific debate on climate change is the extent to which the recent (and future) warming is caused by humans versus natural climate variability. Research effort and funding has focused on understanding human causes of climate change. However we have been misled in our quest to understand climate change, by not paying sufficient attention to natural causes of climate change, in particular from the sun and from the long-term oscillations in ocean circulations.
Why do scientists disagree about climate change? The historical data is sparse and inadequate. There is disagreement about the value of different classes of evidence, notably the value of global climate models. There is disagreement about the appropriate logical framework for linking and assessing the evidence. And scientists disagree over assessments of areas of ambiguity and ignorance.
How then, and why, have climate scientists come to a consensus about a very complex scientific problem that the scientists themselves acknowledge has substantial and fundamental uncertainties?
Climate scientists have become entangled in an acrimonious political debate that has polarized the scientific community. As a result of my analyses that challenge IPCC conclusions, I have been called a denier by other climate scientists, and most recently by Senator Sheldon Whitehouse. My motives have been questioned by Representative Grijalva, in a recent letter sent to the President of Georgia Tech.
There is enormous pressure for climate scientists to conform to the so-called consensus. This pressure comes not only from politicians, but from federal funding agencies, universities and professional societies, and scientists themselves who are green activists. Reinforcing this consensus are strong monetary, reputational, and authority interests.
In this politicized environment, advocating for CO₂ emissions reductions is becoming the default, expected position for climate scientists. This advocacy extends to the professional societies that publish journals and organize conferences. Policy advocacy, combined with understating the uncertainties, risks destroying science’s reputation for honesty and objectivity – without which scientists become regarded as merely another lobbyist group.
I would like to thank the committee for raising the issue of data versus dogma in support of improving the integrity of climate science.
This concludes my testimony.


Dr. Judith Curry is Professor and former Chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology. Following is her verbal remarks as delivered to last week’s US Senate Commerce Committee Hearing on “Data or Dogma? Promoting Open Inquiry in the Debate Over the Magnitude of the Human Impact on Earth’s Climate.”

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