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The Shape Of Droughts To Come: 2012 Versus The 1930s Dust Bowl

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"The Shape Of Droughts To Come: 2012 Versus The 1930s Dust Bowl"

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JR: Last month I had a piece, “We’re Already Topping Dust Bowl Temperatures — Imagine What’ll Happen If We Fail To Stop 10°F Warming.” The WashPost reported this week:

The United States will suffer a series of severe droughts in the next two decades, according to a new study published in the journal Nature Climate Change. Moreover, global warming will play an increasingly important role in their abundance and severity, claims Aiguo Dai, the study’s author.

His findings bolster conclusions from climate models used by researchers around the globe that have predicted severe and widespread droughts in coming decades over many land areas…

“We can now be more confident that the models are correct,” Dai said, “but unfortunately, their predictions are dire.”

For more on what the models have been saying, go here.

What follows is an update on the Dust Bowl of 2012 from Meteorologist Dr. Jeff Masters.

August 14, 2012 drought conditions showed historic levels of drought across the U.S., with 62% of the contiguous U.S. experiencing moderate or greater drought, and 46% of the county experiencing severe or greater drought. Image credit: U.S. Drought Monitor.

by Jeff Masters, via the WunderBlog

The great U.S. drought of 2012 remained about the same size and intensity over the past week, said NOAA in their weekly U.S. Drought Monitor report issued Thursday, August 16. The area of the contiguous U.S. covered by drought remained constant at 62%, and the area covered by severe or greater drought also remained constant at 46%. However, the area covered by the highest level of drought–exceptional–increased by 50%, from 4% to 6%.
Large expansions of exceptional drought occurred over the heart of America’s grain producing areas, in Kansas, Nebraska, Oklahoma, and Missouri. The new NOAA State of the Climate Drought report for July 2012 shows that the 2012 drought is 5th greatest in U.S. history, and the worst in 56 years. The top five years for area of the contiguous U.S. covered by moderate or greater drought:
  1. Jul 1934, 80%
  2. Dec 1939, 60%
  3. Jul 1954, 60%
  4. Dec 1956, 58%
  5. Jul 2012, 57%

The top five years for the area of the contiguous U.S. covered by severe or greater drought:

  1. Jul 1934, 63%
  2. Sep 1954, 50%
  3. Dec 1956, 46%
  4. Aug 1936, 43%
  5. Jul 2012, 38%

Comparison with the great Dust Bowl droughts of the 1930s

An important fact to remember is that the 2012 drought is–so far–only a one-year drought. Recall that 2011 saw record rains that led to unprecedented flooding on the Mississippi, Ohio, and Missouri Rivers. In contrast, the great droughts of the 1950s and 1930s were multi-year droughts. The Dust Bowl drought of the 1930s lasted up to eight years in some places, with the peak years being 1934, 1936, and 1939 – 1940. Once the deep soil dries out, it maintains a memory of past drought years. This makes is easier to have a string of severe drought years. Since the deep soil this summer still maintains the memory of the very wet year of 2011, the 2012 drought will be easier to break than the Dust Bowl droughts of the 1930s were.

In addition, a repeat of the dust storms of the 1930s Dust Bowl is much less likely now, due to improved farming practices. In a 2009 paper titled, Amplification of the North American “Dust Bowl” drought through human-induced land degradation, a team of scientists led by Benjamin Cook of the Lamont-Doherty Earth Observatory explained the situation:

During the 1920s, agriculture in the United States expanded into the central Great Plains. Much of the original, drought-resistant prairie grass was replaced with drought-sensitive wheat. With no drought plan and few erosion-control measures in place, this led to large-scale crop failures at the initiation of the drought, leaving fields devegetated and barren, exposing easily eroded soil to the winds. This was the source of the major dust storms and atmospheric dust loading of the period on a level unprecedented in the historical record.


Figure 2. Black Sunday: On April 14, 1935 a “Black Blizzard” hit Oklahoma and Texas with 60 mph winds, sweeping up topsoil loosened by the great Dust Bowl drought that began in 1934.

The Dust Bowl drought and heat of the 1930s: partially human-caused

Using computer models of the climate, the scientists found that the Dust Bowl drought was primarily caused by below-average ocean temperatures in the tropical Pacific and warmer than average ocean temperatures in the Atlantic, which acted together to alter the path of the jet stream and bring fewer precipitation-bearing storms to the Central U.S. However, the full intensity of the drought and its spatial extent could not be explained by ocean temperature patterns alone.

Only when their model included the impact of losing huge amounts of vegetation in the Plains due to poor farming practices could the full warmth of the 1930s be simulated. In addition, only by including the impact of the dust kicked up by the great dust storms of the Dust Bowl, which blocked sunlight and created high pressure zones of sinking air that discouraged precipitation, could the very low levels of precipitation be explained. The Dust Bowl drought had natural roots, but human-caused effects made the drought worse and longer-lasting.

The fact that we are experiencing a drought in 2012 comparable to the great Dust Bowl drought of the 1930s–without poor farming practices being partially to blame–bodes ill for the future of drought in the U.S. With human-caused global warming expected to greatly increase the intensity and frequency of great droughts like the 2012 drought in coming decades, we can expect drought to cause an increasing amount of damage and economic hardship for the U.S. Since the U.S. is the world’s largest food exporter, this will also create an increasing amount of hardship and unrest in developing countries that rely on food imports.

– Jeff Masters is the founder of the Weather Underground. This piece was originally published at the WunderBlog and was reprinted with permission.

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12 Responses to The Shape Of Droughts To Come: 2012 Versus The 1930s Dust Bowl

  1. John Mason says:

    Interesting piece – it is important to note, as Dr Masters has – that land management practices were an important factor in the ‘dustbowl’ of the 1930s. However, another factor today, compared to the 1930s, is that there are very many more mouths to feed, which translates as high demand for food globally, and in any bottleneck in supply this translates in turn to increased prices in our wonderful ‘free’ market system…. that ought to have the caveat, ‘free as long as you can afford it’!

    • Mulga Mumblebrain says:

      Don’t forget the role of the Holy, Infallible, Market, in asset price speculation, through commodities markets and financial derivatives, the mutant, proliferating, offspring of insurance. The Market, having the intrinsic amorality and indifference to the fate of others of the pluto-kleptocrats who comprise it, simply does not care if its speculative wagers lead to hunger and famine amongst the ‘useless eaters’, who, because of their poverty, are of no use to neo-liberal capitalism.

  2. prokaryotes says:

    The lack of political action to combat climate change, is probably the biggest threat to the United States of America.

  3. Peter Carter says:

    Joe Romm is doing the world a tremendous service by being a lone voice crying in the climate drought wilderness.

    An increasingly disastrous Northern hemisphere (particularly US grain belt)drought situation is unavoidable without drastic emergency intervention right now, while we may still have a chance of mitigating it.

    The all important factors in the Northern hemisphere drought today are the existing trend and (unlike 2030s)today’s global warming commitment.

    Another important factor to consider is the loss of Arctic spring snow and summer sea ice albedo cooling, which is the air-conditioner for the entire Northern hemisphere and is projected to increase Northern hemisphere drought as well as climate variability (Francis).

    An increase in drought with global warming has been long established in the assessments-kind of obvious really.

    There is a well-established trend of increasing global and Northern hemisphere drought.

    Today we are absolutely committed to a warming of double today’s warming that we are now experiencing, due to the ocean heat lag alone, as was established in the very first IPCC 1990 assessment.

    A summation of the unavoidable sources of additional warming indicates we are committed to 3° C by 2100- certainly this is the case without drastic emergency intervention.

    Presumably in part because there is so little alarm at today’s rapidly deteriorating climate situation re food security, combined national emissions policy pledges filed with the UN commit us to a warming of 4.4° C by 2100 (Climate Interactive)

    Today’s trend in Arctic sea ice extent and volume indicates a virtual ice free Arctic in a matter of years and not decades has most of the climate models have it.

  4. Richard Miller says:

    Joe,

    Aiguo Dai revised his 2010 paper with this new study that is referred to in the Washington Post. He suggested that he made an error and revised his maps from 2010 so the drought situation projections are not as rapid and as bad, although still dire, as his earlier work.

    It would be helpful if you would blog on his latest findings and the reason for his revisions.

    • Greatgrandma Kat says:

      not as dire? Not true as far as supply to the global food market. Look what happened when it was only the Russian wheat crop, this year its corn, soy, rice and wheat. We are already so low on emergence stockpiles there will be thousands more people starving, on top of the millions already there. With population increases we have no wiggle room for any cropfailures anywhere for any reason so even slightly worse growing conditions like even moderate droughts translate into people dead of stravation.

    • Joe Romm says:

      I have reprinted his revised charts a number of times, but can take another look.

  5. Brad Bergstrom says:

    It’s not just “improved farming practices” that make a major dust bowl less likely today (minor ones are happening right now though). A lot of land is now irrigated by sucking fossil water out of the Oglala Aquifer. Once the largest single source of water on the planet, it is now half depleted. Once it’s gone, when another severe drought hits, you will see another dustbowl, if any “farming practices” persist after irrigation is exhausted.