Quantcast

NOAA Report Misses Link Between California Drought and Human-Caused Climate Change

Climate

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.

I fear that the dubious claims by this latest report simply complicate prospects for having the very important and necessary conversation about what measures California will need to take to deal with what is likely to be a steadily worsening water crisis. Photo credit: Shutterstock

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.

First of all, there is the role of Pacific sea surface temperature (SST). Despite what the authors claim, the Pacific SST patterns underlying the ongoing drought-favorable conditions may be partly forced, and not simply a result of natural climate variability. The IPCC "CMIP5" climate models which the authors quote in their defense may not be getting these patterns right because of flaws that persist even in many state-of-the-art climate models involving the physics underlying El Nino and decadal tropical Pacific climate variability. One recent study suggests that climate change does in fact favor an SST pattern in the North Pacific that increases the incidence of the atmospheric circulation pattern responsible for the current rainfall deficit.

Secondly, the approach taken in this latest study doesn't account for  the potential influence of decreasing Arctic Sea Ice. Studies going back more than a decade show that reduced Arctic sea ice may also favor the atmospheric circulation pattern underlying the current pattern of California drought. More recent work by Jennifer Francis of Rutgers provides independent support for that mechanism.

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).

The authors of the new report would really have us believe that is merely a coincidence and has nothing to do with the impact of human-caused climate change? Frankly, I don't find that even remotely plausible.

I'm sure this latest study was done in good faith, and I don't question the intentions of the authors. But I'm troubled by the fact that the findings were announced with such fanfare (how many studies, let alone non peer-reviewed ones, get the benefit of a NOAA press conference?), when the conclusions are so flimsy, are contradicted by so much other peer-reviewed scientific work and involve a matter of tremendous societal importance. I fear that the dubious claims by this latest report simply complicate prospects for having the very important and necessary conversation about what measures California will need to take to deal with what is likely to be a steadily worsening water crisis. That is no small matter.

YOU MIGHT ALSO LIKE

California Experiences Worst Drought in 1,200 Years

Scientists Warn Leaders at Lima Climate Talks: Ocean Warming Drives Record Temperatures

ALEC Gives Congressional Climate Deniers Their 2015 Marching Orders

EcoWatch Daily Newsletter

A new study shows that half of all Arctic warming and corresponding sea-loss during the late 20th century was caused by ozone-depleting substances. Here, icebergs discharged from Greenland's Jakobshavn Glacier. Kevin Krajick / Earth Institute / EurekAlert!

The world awakened to the hole in the ozone layer in 1985, which scientists attributed it to ozone depleting substances. Two years later, in Montreal, the world agreed to ban the halogen compounds causing the massive hole over Antarctica. Research now shows that those chemicals didn't just cut a hole in the ozone layer, they also warmed up the Arctic.

Read More
Diane Wilson holds up a bag full of nurdles she collected from one of Formosa's outfall areas on Jan. 15. Julie Dermansky / DeSmogBlog

By Julie Dermansky

On the afternoon of Jan. 15, activist Diane Wilson kicked off a San Antonio Estuary Waterkeeper meeting on the side of the road across from a Formosa plastics manufacturing plant in Point Comfort, Texas.

After Wilson and the waterkeeper successfully sued Formosa, the company agreed to no longer release even one of the tiny plastic pellets known as nurdles into the region's waterways. The group of volunteers had assembled that day to check whether the plant was still discharging these raw materials of plastics manufacturing.

Read More
Sponsored

By Simon Coghlan and Kobi Leins

A remarkable combination of artificial intelligence (AI) and biology has produced the world's first "living robots."

Read More
Malaysian Environment Minister Yeo Bee Yin (front 2nd L) and officials inspect a container containing plastic waste shipment on Jan. 20, 2020 before sending back to the countries of origin. AFP via Getty Images

The Southeast Asian country Malaysia has sent 150 shipping containers packed with plastic waste back to 13 wealthy countries, putting the world on notice that it will not be the world's garbage dump, as CNN reported. The countries receiving their trash back include the United States, the United Kingdom, France and Canada.

Read More
Trump leaves after delivering a speech at the Congress Centre during the World Economic Forum annual meeting in Davos on Jan. 21, 2020. JIM WATSON / AFP via Getty Images

U.S. President Donald Trump dismissed the concerns of environmental activists as "pessimism" in a speech to political and business leaders at the start of the World Economic Forum (WEF) in Davos on Tuesday.

Read More