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A Must Read: “Global Temperature Change,” by James Hansen et al.

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"A Must Read: “Global Temperature Change,” by James Hansen et al."

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When a major science journal publishes a major climate article led by our top climate scientist–and is wise enough to make it an open access article — you MUST read it. I reviewed an early draft of “Global Temperature Change,” by James Hansen et al in the current Proceedings of the National Academy of Sciences and consider it one of the most important articles published this year — or any year — worth reading a few times.

The article is already making headlines for showing that by 2050 the Earth will be warmer than it has been for a million years, thanks to human emissions of greenhouse gases. If we take strong actions to limit further emissions starting today — what the authors call the AS [alternative scenario] — we can limit total warming from preindustrial levels to about 2°C, but even that risks sea level rise of one meter per century.

Failing to act, the authors warn, ensures far higher temperature rise, “which could yield sea level rise of several meters per century with eventual rise of tens of meters, enough to transform global coastlines.” That is “the disastrous BAU [business as usual]” case.

Equally worrisome is that “species loss under BAU has the potential to be truly disastrous, conceivably with a majority of today’s plants and animals headed toward extermination.”

The paper notes that the alternative scenario limits the severe but difficult-to-quantify risks of melting tundra and other serious carbon cycle feedbacks that Climate Progress has discussed. Yet even one more decade of inaction is likely to render that scenario “infeasible.”

The time to act is now.

Two other highlights are worth noting. First, the article sets the record straight on recent warming trends and how climate models have accurately predicted them. NASA’s press release points out, “the Earth is now reaching and passing through the warmest levels seen in the last 12,000 years. And the warming is accelerating:

Global warming is now 0.6°C in the past three decades and 0.8°C in the past century. It is no longer correct to say ”most global warming occurred before 1940.” A better summary is: slow global warming, with large fluctuations, over the century up to 1975, followed by rapid warming at a rate 0.2°C per decade.

Second, the article utterly trashes the disinformation in Michael Crichton’s recent bestseller, State of Fear. Why take the time to do so?

… because the author’s views on global warming have been welcomed in testimony to the United States Senate and in a meeting with the President of the United States, at a time when the Earth may be nearing a point of dangerous human-made interference with climate.

This article is the strongest climate warning to date in a major peer-reviewed journal by leading climate scientists. Every political leader must take heed, and those that don’t must be replaced.

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9 Responses to A Must Read: “Global Temperature Change,” by James Hansen et al.

  1. Ben says:

    It would be good to read up on both sides of an argument before blindly following this junk.

    http://www.junkscience.com/news/robinson.htm

  2. Joe says:

    I confess that I am wedded to the scientific “side” of this “argument.” Climate Progress will address the anti-scientific side from time to time, but in this case some of the top climate scientist in the country have directly done so in the posted article.

    A 9-year old article posted on a web site whose origins lie in the tobacco industry disinformation campaign, hardly deserves much weight against a major article by leading climate scientists in a leading peer-reviewed journal.

  3. Fergus Brown says:

    On Climate Science, Roger Pielke Sr. asks why Prof. Hansen has chosen to use SAT as a metric rather than ocean heat content, a metric he seems to have found acceptable last year. I’d love to be able to answer him, but I don’t know; can you enlighten me?

  4. Joe says:

    I have put in a query to Hansen and will let you know of any reply.

  5. Fergus Brown says:

    Appreciated. As is your blog. I’m adding it to my favourites. One day, I may even say something interesting on it. Regards,

  6. Fergus Brown says:

    No answer from Hansen, then, Joe? Any guesses from you?
    Regards,

  7. Joe says:

    Just go back to the Climate Science web site and read the comments, especially from Gavin Schmidt of NASA and realclimate.org:

    “Roger, Whether you like it or not (and I guess you don’t), global mean surface temperature is the primary metric of climate change in both the scientific discussion and in public discourse…. Your insinuation that their revisiting of the 1989 paper is an attempt to avoid talking about ocean heat content is beneath you.”

  8. [...] I wish the audio of the panel was online. There is this brief article. Here’s a description of some new research that appeared just before the conference and drove some of the discussion. [...]

  9. online game says:

    I am wedded to the scientific “side” of this “argument.” Climate Progress will address the anti-scientific side from time to time, but in this case some of the top climate scientist in the country have directly done so in the posted article.