The drought in the US west/midwest is starting to have severe effects on the US corn crop. For example, Sober Look posts this chart of corn prices:
and Reuters reports that:
The worst drought in the Midwest since 1988 has done considerable damage to this year's corn crop. The USDA slashed its corn yield estimate for the world's top grower and exporter by an unprecedented 20 bushels, to 146 bushels per acre.Against this background, I was interested to see what the PDSI data are telling us. It turns out that NOAA maintains a PDSI for the "Corn Belt" of the US, and I plotted the June value for it here:
Half of the U.S. corn crop began pollinating in late June under triple-digit temperatures and severe rain deficits, conditions which damaged yield potential beyond repair.
Drought conditions in the Midwest worsened over the past week. A weekly U.S. drought monitor showed about a third of the nine-state region in severe to exceptional drought in the week ended July 10, up from about a quarter of the region a week ago.
The last data point is for June 2012 and you can see that indeed it's at -2: a significant drought, though nowhere near dustbowl levels yet. However, the situation has continued into July and may yet become apocalyptic.
The relationship to climate change is clearly complicated by the fact that the data show a generally upward trend (ie wetter): that linear trend is 1.1/century, with a standard error of 0.4 - a statistically significant result. This is consistent with the fact that the US midwest is generally trending wet in the global PDSI trend map, despite the fact that most of the planet is drying: