Greed, Green & Grains

In my last post I suggested we've been lucky so far when in comes to weather in the crucial corn belt region.  Although temperatures have been rising, at least in the corn belt during the key summer months, it's been relatively temperate. I've just gained new appreciation for how lucky we've been. I found these charts in a draft paper (PDF) by Jim Hansen and coauthors.  They show a remarkable shift in recent decades in the incidence of extreme temperatures, especially over land in the northern hemisphere (the bottom three charts in the first panel of six). The shift in summer temperatures in just the last two decades is tremendous.  The frequency of "very hot" temperatures has more than tripled (bottom-right chart, in the second panel of six).  I can see 1983 and 1988, the most recent two hot years that killed crop production in the crucial corn belt region. And while the whole northern hemisphere has seen a lot more very hot tem

Well, at long last I venture another blog post.  We'll see if I can keep this going... I think most people noticed the warm winter and spring.  Now we have official statistics:  via Climate Progress and WunderBlog , we've just experience the warmest 12 consecutive months on record in the United States, and by far the warmest January through April temperature anomaly on record.  This kind of warming in Spring will probably turn out to be good for agriculture.  It lengthens the growing season, allowing farmers to plant earlier. The bad side of warming comes in summer months.  Interestingly, we *still* haven't had especially warm weather during the critical summer months in the key crop-growing regions.  The last two summers were warm, but just a little warmer than average, according to our own extreme-heat degree-day calculations.  Here are some figures my colleague Wolfram Schlenker recently put together for degree days above 29C, our measure of extreme h