Speaking of ominous

Another find in the April 30 New Scientist is the news that

climate change is set to do much worse damage to global food production than even the gloomiest forecasts have so far predicted, according to studies presented on Tuesday and Wednesday at the Royal Society in London.

Until now, the idea was that the higher temperatures and more frequent droughts caused by global warming would be offset by faster photosynthesis from the increased levels of CO₂. Labs tests had suggested the latter effect might often outweigh the first.

No such luck, says Stephen Long, a crop scientist at the University of Illinois at Urbana-Champaign. In open-field experiments with maize, rice, soybean and wheat he found that adding extra CO2 led to a beneficial effect only half as great as indicated by the lab experiments. Worse, when he added doses of ozone to the fields, to simulate the expected rise in ozone smogs due to higher temperatures, yields fell further.

So even one of the few claimed benefits of global warming - that it might increase crop yields in some regions - has probably fallen by the wayside.