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Arctic Sea Ice decline in the 21st Century

Filed under: — group @ 12 January 2007 - (Français)

Guest Commentary by Cecilia Bitz, University of Washington

Last month a paper I co-authored received considerable media attention. Headlines read “Experts warn North Pole will be ‘ice free’ by 2040″, “The Big Melt: Loss of Sea Ice Snowballs“, and “Arctic Clear for Summer Sailing by 2040: Models Predict Rapid Decline of Sea Ice”. The story also reached NPR, BBC, CBC, the Discovery channel, and Fox News, among others. Dr. Marika Holland, the first author of the paper, was inundated with media attention. About a dozen journalists contacted me too. I was impressed by the questions they posed — questions that probably reflect what the public most wants to know. However, after giving lengthy interviews, I would read the resulting article and see my explanations boiled down to a few lines. In this essay, I’d like to explain the science in the paper and give my answers to the most often asked questions.

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El Nino, Global Warming, and Anomalous U.S. Winter Warmth

Filed under: — mike @ 8 January 2007 - (Slovenčina) (Svenska)

It has now become all too common. Peculiar weather precipitates immediate blame on global warming by some, and equally immediate pronouncements by others (curiously, quite often the National Oceanic and Atmospheric Administration in recent years) that global warming can’t possibly be to blame. The reality, as we’ve often remarked here before, is that absolute statements of neither sort are scientifically defensible. Meteorological anomalies cannot be purely attributed to deterministic factors, let alone any one specific such factor (e.g. either global warming or a hypothetical long-term climate oscillation).

Lets consider the latest such example. In an odd repeat of last year (the ‘groundhog day’ analogy growing ever more appropriate), we find ourselves well into the meteorological Northern Hemisphere winter (Dec-Feb) with little evidence over large parts of the country (most noteably the eastern and central U.S.) that it ever really began. Unsurprisingly, numerous news stories have popped up asking whether global warming might be to blame. Almost as if on cue, representatives from NOAA’s National Weather Service have been dispatched to tell us that the event e.g. “has absolutely nothing to do with global warming”, but instead is entirely due to the impact of the current El Nino event.

[Update 1/9/07: NOAA coincidentally has announced today that 2006 was officially the warmest year on record for the U.S.]
[Update 2/11/08: It got bumped to second place. ]
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Consensus as the New Heresy

Filed under: — group @ 3 January 2007

Gavin Schmidt, Michael Mann, David Archer, Stefan Rahmstorf, William Connolley, and Raymond Bradley

Andy Revkin, who’s one of the best journalists on the climate beat, wrote a curious piece in the NY Times discussing the ‘middle stance’ of the climate debate. It’s nice to see news pieces on climate that aren’t breathless accounts of a new breakthough and that take the time to point out that the vast majority of relevant scientists take climate change extremely seriously. To that extent, the message of this piece was a welcome one. The curious part, however, was the thread running through the piece that this middle ground is only now emerging, and even curiouser, that this middle ground can be characterized as representing some sort of ‘heresy’.

Heresy, is commonly defined as ‘an opinion or doctrine at variance with the official or orthodox position’. So where does this idea come from, and why is it now ‘emerging’?
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The Physics of Climate Modelling

Filed under: — gavin @ 3 January 2007 - (Français) (Português)

This is just a pointer to a ‘Quick Study’ guide on The physics of climate modelling that appears in Physics Today this month, and to welcome anyone following through from that magazine. Feel free to post comments or questions about the article here and I’ll try and answer as many as I can.

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