By Joe Romm on Jun 30, 2013 at 12:36 pm
Scientists predicted a decade ago that Arctic ice loss would bring on worse western droughts. Arctic ice loss has been much faster than the researchers — and indeed all climate modelers — expected (see “CryoSat-2 Confirms Sea Ice Volume Has Collapsed“).
It just so happens that the western U.S. is in the grip of a brutal, record-breaking drought. Is this just an amazing coincidence — or were the scientists right and what would that mean for the future? I ask the authors.
Here is the latest drought monitor:
And that drought monitor predates the record-smashing heat wave now gripping the West.
Back in 2004, Lisa Sloan, professor of Earth sciences at UC Santa Cruz, and her graduate student Jacob Sewall published an article in Geophysical Research Letters, “Disappearing Arctic sea ice reduces available water in the American west” (subs. req’d).
As the news release at the time explained, they “used powerful computers running a global climate model developed by the National Center for Atmospheric Research (NCAR) to simulate the effects of reduced Arctic sea ice.” And “their most striking finding was a significant reduction in rain and snowfall in the American West”:
Where the sea ice is reduced, heat transfer from the ocean warms the atmosphere, resulting in a rising column of relatively warm air. The shift in storm tracks over North America was linked to the formation of these columns of warmer air over areas of reduced sea ice in the Greenland Sea and a few other locations, Sewall said.
I contacted Sloan to ask her if she thought there was a connection between the staggering loss of Arctic sea ice and the brutal drought gripping the West, as her research predicted. She wrote (back in late March):
Yes, sadly, I think we were correct in our findings, and it will only be worse with Arctic sea ice diminishing quickly. California is currently in a drought (as I watch every day — our reservoirs are at about 50% capacity right now, and I fear for the coming fire season, owning a house that backs up to greenspace and forest).
She directed me to her ex-student, now Assistant Professor of Geology at Kutztown University of Pennsylvania because he had done some additional work.
Sewall wrote me:
I am attaching a more definitive study (multiple fully dynamic models with greenhouse gas forcing) on the topic from 2005. The end result is about the same as the original 2004 study, just nailed down better.
Comparing current changes (2011 summer ice and 2011/2012 winter precipitation season) to the 2004 paper:
(1) Ice concentrations in August 2011 weren’t too far off from the ‘future’ in the 2004 paper. The “future” in the 2004 paper was 2050, so it seems we are moving faster than predictions (which has been seen in multiple studies of Arctic sea ice). That is likely due to the relatively conservative greenhouse gas scenarios that were used for the earlier IPCC assessments and associated simulations. Potentially the forthcoming AR5 will have more accurate/realistic/extreme responses in Arctic ice.
(2) Observed precipitation seems to be lower than in the 2004 simulations (50 – 70% of ‘normal’ in the Sierras vs ~85 – 90% of normal in the simulations) based on snowfall data from 2011/2012.
(3) The pattern of wetter conditions to the north of California is as predicted in the 2004 paper, Washington State reporting 107 – 126% of ‘normal’ precipitation, Southern Alaska reporting 106 – 148% of ‘normal’ precipitation for 2011/2012.
I think the hypothesis from 2004 and 2005 is being borne out by current changes. The only real difference is that reality is moving faster then we though/hoped it would almost a decade ago.