A sign on a California farmhouse fence reads, 'Pray for rain - 1 Thess. 5:17'. Photo: Justin Sullivan / Getty Images

By Michael Mann
8 December 2014

(Huffington Post) – Just a couple months ago, I critiqued a pair of studies that disputed any linkage between human-caused climate change and the exceptional 2014 California drought. Now comes yet another study ("Causes and Predictability of the 2011-14 California Drought") with the imprimatur of the National Oceanic and Atmospheric Administration (NOAA), announced with great fanfare (a NOAA press conference), drawing yet again the same conclusion. My criticisms of the latest study are yet again basically the same, but for reasons I explain below, that conclusion is even more implausible now than it was just two months ago.

Let me start by noting that this latest report (unless I've missed something?) doesn't appear to be an actual peer-reviewed scientific article, but rather, an internal NOAA report. That causes me some concern, as the claims have not yet been submitted to the independent scrutiny of the larger scientific community in the manner it would have if it were published in a peer-reviewed scientific journal.

That having been said, my main concerns are far more fundamental. The methodology used in the current article, in my view, is deeply flawed because it doesn't properly account for a number of potentially important factors behind the record California drought. […]

Most inexplicable of all, though, is the fact that the authors pay only the slightest lip service to the role of surface temperature in drought, focusing almost entirely on precipitation alone. That neglects the fact that California experienced record heat over the past year, and this anomalous heat certainly contributed to the unprecedented nature of the current drought. Another article published just a week ago in one of the premier peer-reviewed journals in the field, Geophysical Research Letters (GRL), preemptively critiqued the present study, by stressing the importance of looking at the role of extremely high surface temperatures as well as precipitation in assessing the factors behind, e.g., the 2014 California drought:

And most ironic of all, just days ago, another article in GRL concluded that the record heat played a role in making the current California drought the worst such drought in at least 1200 years! (see also this discussion by Peter Gleick). [more]

Climate Change and the Record 2014 California Drought


  1. Anonymous said...

    It often seems as if the scientific community does not talk to each other. The right hand doesn't know what the left hand is doing.

    It would be hard to even imagine that the record drought in California is not tied to climate change, because this simply makes no sense whatsoever.

    A dramatically warmer ocean has been scientifically recorded. So has a severely disrupted jet stream.

    I've seen utterly useless connedspiracy articles that claim H.A.A.R.P. has been used to "prevent rain storms" and "bust up clouds" over California. This makes a much sense as claiming that climate change is not contributing to the drought for the reasons cited above.

    No precipitation (or next to none) means no snowpack and reservoirs being depleted. I was in California very recently and saw how low Shasta Dam really was. It was the worst I'd ever seen - and I used to live only 3 miles away and I've seen the effects of drought in this lake before.

    I also wrote the software that manages the water measurements flowing through this dam (and Keswick, Whiskeytown, Trinity, etc.) dams.

    There's been nothing like this anywhere in the entire history of Reclamation (they're the federal agency that manages the dams).

    The scientific community would do well to check their results among other scientists, even if this isn't a peer-reviewed paper.

    It's pretty obvious that the catastrophe in California isn't imaginary like other connedspiracies.  


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