For the last three years or so, we have observed (and in the case of many, lived through) the California drought. During the last week, we waited for news about the mud slide in Washington State with 25 confirmed dead (some identified and some –as of yet –not) and a score still missing. Spring is just beginning, bringing with it the expectations of heavy floods after a winter with record snow. Yet, for many, the central question is – climate change or not climate change? The appropriate Shakespearian continuation seems to be “Whether ‘tis nobler in the mind to suffer the slings and arrows of outrageous fortune, or to take arms against a sea of troubles, and by opposing end them.”
Let’s go into some more detail:
In mid-February President Obama visited California to offer some help in the non-ending drought that they are facing.
Here is a local glimpse of that visit:
President Obama toured the parched fields of the Central Valley on Friday, assuring ranchers and farmers that he was committed to addressing the effects of California’s drought because ‘what happens here matters to every working American – right down to the food that you put on your table.’
Obama’s administration announced $170 million worth of initiatives to help the valley’s ranchers and people struggling to make ends meet because of the drought…
During a roundtable discussion with ranchers and community leaders in Firebaugh (Fresno County), Obama joked about the lengthy and incendiary history of water politics in California, saying, ‘I’m not going to wade into this. I want to get out alive on Valentine’s Day.’
The bulk of the aid package that the White House unveiled Friday consists of $100 million for ranchers facing livestock losses and $60 million to help food banks in the hardest-hit areas.
From there the President went to Palm Springs to play a few well-deserved rounds of golf on beautifully watered green lawns.
The worsening drought in California will force a first-ever complete cutoff of federally supplied irrigation water to most farm districts throughout the state’s Central Valley heartland this year, the U.S. Bureau of Reclamation said on Friday.
The projected 2014 zero allocation to all but a handful of agricultural districts supplied by the federally run Central Valley Project comes three weeks after forecasts of similarly drastic cuts were announced by managers of a separate water-delivery system operated by the state. California grows roughly half of all U.S. fruits and vegetables, most of that in the Central Valley, and ranks as the No. 1 farm state by value of agricultural products produced each year.
On February 25, during a Senate Hearing, John Holdren, the White House Science Adviser, was challenged by Senator Jeff Sessions (R-AL) for misleading the public in claiming that the drought is a consequence of anthropogenic (human caused) climate change. The reprimand was partially based on Roger Pielke’s testimony (July 18, 2013). Who is Roger Pielke? As he says in his self-written bio before the testimony, his degrees were in mathematics, public policy and political science and he was a professor of environmental science at the University of Colorado.
His “take home points” in his testimony include the following:
- It is misleading, and just plain incorrect, to claim that disasters associated with hurricanes, tornadoes, floods or droughts have increased on climate timescales either in the United States or globally. It is further incorrect to associate the increasing costs of disasters with the emission of greenhouse gases.
- Globally, weather-related losses ($) have not increased since 1990 as a proportion of GDP (they have actually decreased by about 25%) and insured catastrophe losses have not increased as a proportion of GDP since 1960.
- Hurricanes have not increased in the US in frequency, intensity or normalized damage since at least 1900. The same holds for tropical cyclones globally since at least 1970 (when data allows for a global perspective).
- Floods have not increased in the US in frequency or intensity since at least 1950. Flood losses as a percentage of US GDP have dropped by about 75% since 1940.
- Tornadoes have not increased in frequency, intensity or normalized damage since 1950, and there is some evidence to suggest that they have actually declined.
- Drought has “for the most part, become shorter, less frequent, and cover a smaller portion of the U. S. over the last century.” Globally, “there has been little change in drought over the past 60 years.”
- The absolute costs of disasters will increase significantly in coming years due to greater wealth and populations in locations exposed to extremes. Consequent, disasters will continue to be an important focus of policy, irrespective of the exact future course of climate change.
John Holdren is generally too busy to respond immediately to any climate change deniers, but in this case he was directly challenged by a United States senator, so he chose to respond in detail a few days after his testimony. His detailed response was posted on the White House blog post (the battle of the bloggers). Here are some highlights:
Linking Drought to Climate Change
In my recent comments about observed and projected increases in drought in the American West, I mentioned four relatively well understood mechanisms by which climate change can play a role in drought. (I have always been careful to note that, scientifically, we cannot say that climate change caused a particular drought, but only that it is expected to increase the frequency, intensity, and duration of drought in some regions, and that such changes are being observed.)
The four mechanisms are:
- In a warming world, a larger fraction of total precipitation falls in downpours, which means a larger fraction is lost to storm runoff (as opposed to being absorbed in soil).
- In mountain regions that are warming, as most are, a larger fraction of precipitation falls as rain rather than as snow, which means lower stream flows in spring and summer.
- What snowpack there is melts earlier in a warming world, further reducing flows later in the year.
- Where temperatures are higher, losses of water from soil and reservoirs due to evaporation are likewise higher than they would otherwise be.
These lines were the milder parts of the response. The most pointed parts were focused on nailing Pielke for picking and choosing almost all of his quotes, and disengaging them from their original context (go to my last week blog, March 25, 2014 to read more about the role of original documents in argumentations.)
On March 9, an OP-ED in the New York Times, written by Martin P. Hoerlig, a Research Meteorologist at NOAA (National Oceanic and Research Administration) touched on the same topic:
CALIFORNIA is now in the midst of the third year of one of its worst droughts on record. As our planet gradually warms from our rampant burning of fossil fuels, it’s only natural to wonder what role climate change has played in California’s troubles.
The answer is this: At present, the scientific evidence does not support an argument that the drought there is appreciably linked to human-induced climate change…
It resembles the droughts that afflicted the state in 1976 and 1977. Those years were at least as dry as the last two years have been for the state as a whole…
One way of accounting for the combined effects of rainfall and temperature on drought is to examine soil moisture. Long-term soil moisture observations are not readily available, but have been estimated using sophisticated models. The 2012 report on extreme events by the Intergovernmental Panel on Climate Change examined the evidence for regional changes in soil moisture since 1950, and made the following assessment for western North America…
The new IPCC report is a long document. It comes as a report of three working groups, with each presenting its own section of more than 1000 pages. Only the first of these working groups reports has been released (it came out late last year), while the second working group’s report is expected any day. Given the sheer volume of the full document, everybody will have plenty of opportunity to fish for whatever sentence fits their unchanging world view. One such relevant quote, taken from the summary of the first working group report, is given below:
Changes in the global water cycle in response to the warming over the 21st century will not be uniform. The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase, although there may be regional exceptions (see Figure SPM.8). {12.4, 14.3}
Climate scientists have a common understanding (as explicitly stated by John Holdren in his aforementioned response to Pielke’s testimony) that specific, localized, events can never be claimed to be caused by climate change; one can never claim that such events could not take place in the absence of human contributions. However, a statement that disconnects severe droughts from climate change must therefore by design disconnect climate change from any changes in the water cycle – including floods and other severe weather events. Since most of the serious impacts of climate change manifest themselves through changes in the water cycle, such disconnections, in my mind, are not much different from denying anthropogenic climate change in the first place, no matter the credentials of the deniers.
