Tuesday, 15 December 2015


Senate Hearing: Data or Dogma

by Judith Curry
The Senate Commerce Committee Hearing ‘Data or Dogma? Promoting Open Inquiry in the Debate Over the Magnitude of the Human Impact on Earth’s Climate‘ is about to begin.

The website for the Hearing is at the Commerce web site [link].  Witnesses:
  • Dr. John Christy
  • Dr. Judith Curry
  • Dr. William Happer
  • Mr. Mark Steyn
  • Dr. David Titley
It is my understanding that there will be a podcast on the web site, and that the Hearing will be televised on CSPAN, and that links to the testimonies will be available on the web site.
John Christy’s testimony [ChristyJR]
Mark Steyn’s testimony is a MUST READ [Steyn testimony]
My testimony is here [Curry Senate testimony 2015].  Below is the text of my verbal remarks.
JC verbal remarks
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 2nd 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 21st 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.

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