Weatherdem's Weblog

Bridging climate science, citizens, and policy

2012 U.S. Drought: Impacts & Historical Context


The National Climate Data Center, in its summary of drought conditions as of the end of June 2012, reported that 55% of the contiguous U.S. was experiencing moderate to extreme drought, as the graphic below shows.  This is the largest percentage since December 1956 when 58% of the U.S. experienced similar conditions.  The Palmer Drought Index, whose data base goes back 112 years, is relied upon for drought comparisons before 2000.


Figure 1. Drought conditions across the United States as of early July 2012 from the Drought Monitor.

In my last post on drought, I stated, “There’s no widespread crisis to speak of yet, but inhabitants as well as policymakers should monitor conditions as the year progresses.”  Well, the NCDC established the case for a widespread crisis with their latest summary, which was not issued until after my post.  Crops and livestock are now being negatively affected.  The following two charts show corn and soybean prices.  The recent peaks are due to worsening conditions across the breadbasket and the USDA’s recent crop downgrade.



Figure 2. Corn (top) and soy (bottom) prices and volume charts for the past 12 months.

[h/t Bonddad]

1988 was also a very bad year for corn in the U.S.  Here is a chart from the USDA comparing 1988 and 2012 corn ratings:


Figure 3.  Comparison of corn ratings (good + excellent) as determined by the USDA as of early July 2012.

You can see that conditions in 1988 worsened earlier in the year (solid blue line @30% ~3 weeks before the solid yellow line).  It remains to be seen how bad conditions eventually get in 202.

So conditions are the worst since Dec. 1956.  How else do today’s conditions compare to earlier droughts?  The following graphic from USA Today helps put them in context:


Figure 4. Comparison of extensive drought in U.S. history.

The percentage of the country in moderate to severe drought in June 2012 is the sixth highest since 1900.  The 1930s are well known as Dust Bowl years.  Conditions aren’t expected to get that bad, even if drought were to dominate the area for the next few years, primarily because of changes in farming practices.  Topsoil was easily scoured from the earth in the 1930s and was moved around by winds, sometimes for dozens or hundreds of miles, hence the name ‘Dust Bowl’.  The droughts of the mid-1950s were also quite extensive.  The U.S. is fortunate that the return period of these conditions was ~55 years.

I’ve also written in my drought posts that the current drought, extensive and intense as it is, is not without historical precedent and that a clear climate change linkage is not available at this time.  With generally warmer temperatures and more variable precipitation patterns, one might conclude that drought would be more likely to occur in recent years than in the 1900s.  As the USA Today chart shows, that clearly hasn’t happened.  The conditions in 2012 are more closely related to the double-dip La Niña that just ended:


Figure 5. Time series of temperature anomalies in the NINO3.4 region.  Positive values for 5 consecutive 3-month periods correspond to El Niño events while similar periods with negative values correspond to La Niña events.

This drought is very serious and everybody should treat it as such  Part of that statement is acknowledging the lack of a clear anthropogenic climate change signal at this point in time.  Conditions aren’t expected to significantly improve in the next couple of weeks.  The extent and intensity of drought can expand and worsen within that time.  We can also expect higher prices for food starting next year and into 2014 – additional economic headwinds that the U.S. can ill-afford at this time.


5 thoughts on “2012 U.S. Drought: Impacts & Historical Context

  1. Thanks Weatherdem. This year’s drought in the US may not be the worst on record but the consequences may prove to be so because of everything else that is going on… Stuff like (1) the late frosts that have also decimated a wide range of soft fruit crops and (2) floods elsewhere in the World that have damaged root crops such as potatoes… As I have pointed out on my blog, it was the failure of harvests and subsequent spikes in food prices in late 2010 that triggered the Arab Spring uprisings in early 2011.

    Even though we cannot know whether there were just as many simultaneous problems in earlier times (i.e. before the globalised telecommunication age in which we live) the fact remains that the Massachusetts Institute of Technology team headed by Dennis and Donella Meadows (that produced The Limits to Growth reports in 1972, 1992 and 2005) told us a very long time ago that the longer we failed to address the unsustainable nature of perpetual growth, the more likely we were to face multiple problems at once… They also predicted that the Earth would run out of the ability to cope with these problems long before humans ran out of space to live or farm.

    The former World Bank economist looked at the same problem from a slightly different perspective and concluded that perpetual quantitative economic growth would eventually morph into uneconomic growth – when the cost of controlling and/or rectifying the environmental damage done by that growth is greater than the value of all the goods and services (i.e. benefits) of that growth.

    Whichever way you care to look at the problem; it would appear that we have arrived at this long-predicted destination. It would therefore be very useful if people would stop dismissing climate change as a politically-motivated scam and just accept that it is simply the consequence of burning fossil fuels faster than the Earth is capable of dealing with the pollution caused. We can but hope.

    • Martin-
      Your point regarding harvest failure and subsequent uprisings is duly noted. Indeed, such events are likely to continue in places with lower food security and simultaneous weak central forms of government – i.e., too much of the developing world. In places like the U.S. and U.K., the situation is quite different as we can both attest. I may not like seeing higher food prices for a year, but I’m much more resilient to them than others.

      I can’t say one way or the other whether we’ve arrived at the inflection point between economic growth to uneconomic growth, although I will agree that such a point probably exists. Predictions have been made for quite some time as to where such a point lies. I guess I’m not convinced we’re quite there yet. That said, folks in developing nations are once again more likely to feel the effects of such a transition first. I am cautiously optimistic that we as a species are close to the point at which our technological innovation can insulate us to some degree from such a point.

      • I hope you are right but am inclined to think it wise to “hope for the best but plan for the worst”…!

  2. This is so interesting. Not in an entirely good way, though! I’m in one of the countries (UK) that is getting far more rain than usual and it’s frightening for our agriculture and horticulture.

    • Thanks for stopping by & commenting, argyle!

      Yes, the UK has had multiple years in a row of rather unusual weather phenomena one behind the other. Agricultural pressures aren’t limited to drought, obviously.

      Hope to see you around.

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