Saturday, July 28, 2012

Is the US Drought Really That Extraordinary?

Despite all the headlines, I am not convinced the current U.S. drought is that exceptional, compared to history. I'm sure it's very tough for farmers, and will be for those who will be buying their food, but farming has always been a tough business.

Here is data on the U.S. Drought Monitor, which looks broadly at the U.S.

US Drought Monitor, July 24, 2012

The following are plots of the percent of the U.S. counties that is "moderately to extremely dry," going back over a century. Granted, this is a broader brush than the information above, since it puts an area in one of two bins instead of five.

So it definitely shows a serious drought today -- but it's akin to about a dozen that have occurred since 1895, and is not as severe as the 1934 or the mid-1950s (which was both broader and longer). Perhaps the spike are becoming a little more frequent in recent decades, but that's not obvious (unlike what Paul Krugman wrote).

Here's the 12-month moving average, which makes things a little clearer:

And here is the dry area 12-month percentage expressed as its standard deviation from the mean:

The current drought looks like a fairly normal drought, at least so far, with no evidence of "Dust Bowlification." (Notice how Romm sneaks in a plot of heat when writing about drought. They're not the same thing.)

I'm sure many farmers are being seriously affected. But farming has always been a tough business (which is why we have price supports). I just don't see an extraordinary drought in this data, but an ordinary drought.


Dano said...

The issue is that we are less resilient. The house of cards is getting yet another breeze. It is likely we will never be resilient again.



William Connolley said...

Are we less resilient? I see no evidence for that. But I'm not paying attention.

This is just a regional thing, and not my region, so I'm not that interested, but you've analysed "moderately to extremely dry". I did wonder if perhaps this drought was notable as extreme, so would show up if you looked just at "extremely dry", if those stats are available.

charlesH said...

What IS different this time is the ethanol mandate which consumes ~40% of the corn crop.

Crony capitalism at it's finest. People going hungry because they can't afford food while big agribusiness "pigs out".

Dano said...


Are we less resilient? I see no evidence for that. But I'm not paying attention.

Just wrt to this topic (and policies that exacerbate responses), the indicators that show our societies aren't adapting to this shock.



Joshua said...

Wouldn't the attribution of "extraordinary" necessarily require that you control for attribution?

Controlling for known variables that influence climate, if you're left only with CO2 emissions as attribution, then (assuming you haven't missed unknown variables) this is extraordinary.

Why should anyone formulate an opinion one way or the other without discussing the contributing variables?

That said, I think that your point of distinguishing between heat and drought is very much on point (although I think it is a bit misleading to single out Romm in that regard).

David Appell said...

Crony capitalism is essentially what we have everywhere -- why should agriculture be any different?

charlesH said...

From the NYT:

Corn for Food, Not Fuel

"An act of God, right? Well, the drought itself may be, but a human remedy for some of the fallout is at hand — if only the federal authorities would act. By suspending renewable-fuel standards that were unwise from the start, the Environmental Protection Agency could divert vast amounts of corn from inefficient ethanol production back into the food chain, where market forces and common sense dictate it should go."