People who Changed Their Mind about Global Warming

Skeptic to Believer, or Believer to Skeptic


I’m building a list of…

  1. (a) climate scientists and (b) other prominent scientists
  2. (a) prominent conservatives, and (b) other public figures, journalists or professors

…who decided they were wrong about human-caused global warming (a.k.a. AGW or anthropomorphic/anthropogenic” global warming), after publicly stating a different opinion:

  1. People who decided that humans cause global warming after all (or that global warming is real after all, or that it’s a serious problem that warrants major public policy changes)
  2. People who decided that humans don’t cause global warming after all (or that it’s not serious enough to worry about, or that it’s a hoax)

If you’d like to add an item to this list, please leave a comment that includes

  1. Their name and category (climate scientist, prominent scientist, prominent conservative or public figure).
  2. Evidence that they changed their mind.
  3. Approximately what year they changed their mind (or two years: one before, one after)

I have seeded the list with a few names that I am aware of, but I’ll need help from readers to find more, particularly on the “don’t cause global warming after all” side. Acknowledgement: several names and quotes were taken from TheWeek.

Climate Scientists

Decided human activity causes global warming after all

  • Stephen Schneider, ~1981. Evidence: 1971 global cooling paper, 1981 NYT article (“conclusions about the extent of warming and how quickly it will occur would be reasonable if the assumptions on which they are based prove valid, but many can be challenged”). It is common knowledge that in the 1980s until his death in 2010, Schneider became a leading public advocate of sharp reductions of greenhouse gas emissions to combat global warming.

Decided humans don’t cause global warming after all

  • No names have been confirmed.

(Conservative climatologist Judith Curry was submitted, but she didn’t change her mind much; see footnote [1].)

Other Prominent Scientists

Decided human activity causes global warming after all

  • Richard Muller, of a team of skeptics that received a $150,000 Charles G. Koch grant to study the temperature record. Before: “Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics.” (2004) After: “Last year, following an intensive research effort involving a dozen scientists, I concluded that global warming was real and that the prior estimates of the rate of warming were correct. I’m now going a step further: Humans are almost entirely the cause” (2012)
  • Stu Ostro, Weather Channel senior meteorologist. Surveys (like those reviewed in this article) have shown that meteorologists tend to be the type of scientists that are most likely to be skeptical about climate science. Before: Large swings in temperature “happened long before humans had a chance to influence the environment, [and] typically occurred within a 10-year period, indicating that drastic climate change can occur through natural means, and quickly.” (1999) After: “When it comes to skepticism about AGW, you could say I have street cred,” but “it could be said that I ‘converted’ and became a ‘believer.’” (2010)

Decided humans don’t cause global warming after all

  • No names have been submitted

Prominent conservatives

Decided human activity causes global warming after all

  • Jerry Taylor, former staff director for the energy and environment task force at the American Legislative Exchange Council (ALEC) and former vice president of the Cato Institute. He changed his mind “gradually”… “early 2000s”. Before: “While Babbitt, Gelbspan and their sympathizers were huffing and puffing about greenhouse skepticism, the scientific community was, to a large degree, embracing it.” (1997), “The case for a global warming treaty […] is shockingly weak” (1998). After: “The risks imposed by climate change are real […] Conservatives should embrace a carbon tax […] in return for elimination of EPA regulatory authority over greenhouse gas emissions […]” (2015 PDF)
  • Bob Inglis, former Republican congressman, lost his seat in the House of Representatives in 2010 after changing his mind on global warming. In 2013 he started republicEn, a nonprofit that strives to introduce conservative voices and solutions into the national discourse on climate change.

Note: A group of prominent conservatives have put together a Republican plan for climate change action.

Decided humans don’t cause global warming after all

  • No names have been submitted

Other public figures, journalists & professors

Decided human activity causes global warming after all

  • Dmitri Medvedev, Russian president. Before: Climate change is ‘some kind of tricky campaign made up by some commercial structures to promote their business projects.” (2009). After: “Unfortunately, what is happening now in our central regions is evidence of this global climate change, because we have never in our history faced such weather conditions in the past.” (2010)
  • Bjorn Lomborg, Danish academic. Published a book arguing global warming was no big deal and not worth fighting; now argues for carbon taxes. Before: “In 20 years’ time, we’ll look back and wonder why we worried so much.” (2002) After: “We actually have only one option: we all need to start seriously focusing, right now, on the most effective ways to fix global warming.” (2010)
  • Michael Hanlon, science editor for The Daily Mail and former self-professed skeptic. Before: “Global warming, indeed much of environmentalism, has become a new religion…” (2000). After: “My views in recent years have shifted. For me, the most convincing evidence that something worrying is going on lies right here in the Arctic.” (2010)
  • Michael Shermer, publisher of Skeptic Magazine, reached a “flipping point” in 2006, acknowledging “overwhelming evidence for anthropogenic global warming.” Before: “Scientists like Bjorn Lomborg in The Skeptical Environmentalist have, in my opinion, properly nailed environmental extremists for these exaggerated scenarios.” (2008, referring to 2001)
    After: “Because of the complexity of the problem, environmental skepticism was once tenable. No longer. It is time to flip from skepticism to activism.” (2006)
  • Gregg Easterbrook, American journalist and author of A Moment on the Earth (1995) which was dismissive of mankind’s role in climate change. In 2006 he wrote an essay called “Case Closed: The Debate About Global Warming is Over.” Before: “Instant-doomsday hyperbole caused the world’s attention to focus on the hypothetical threat of global warming to the exclusion of environmental menaces that are real, palpable, and awful right now.” (1995, PDF) After: “Based on the data I’m now switching sides regarding global warming, from skeptic to convert.” (2006)

Decided humans don’t cause global warming after all

  • No names have been submitted


[1] Judith Curry said that in 2003 she wrote concerns “about the way climate research was treating uncertainty”. Then in 2005 she “decided that the responsible thing to do in making public statements on the subject of global warming was to adopt the position of the IPCC,” in part because “the subject was very complex and I had personally investigated a relatively small subset of the topic,” but by 2009 she was very critical of the IPCC and her entire field.

Even so, her most recent published research result (Lewis & Curry 2018) is clearly compatible with the consensus as it is typically defined in surveys: that “most” warming in the last 50 to 70 years was caused by humans. You see, Curry’s estimate of TCR is 1.20°C or 1.33°C (the latter for “infilled, globally-complete temperature data”). This is compatible with the IPCC’s most recent consensus range of 1–2.5°C. Mainstream TCR estimates of around 1.7°C are sufficient to attribute 100% of recent warming to humans, and 1.33°C isn’t that far off.

See also

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