Originally Posted by
dustrpilot
...crop yields are going up, and have been for the last 30 years that I've been involved in agriculture. So if your claiming a warmer earth is causing a decrease in crop yield I have to throw the BS flag on that play.
Notwithstanding you flag, that's exactly what I'm claiming. We are bumping up against the "crop yield" threshold, beyond which past experience becomes irrelevant. If you're
in your 20s, you will live to see food riots in this country.
...As plant scientists refine their understanding of climate change and the subtle ways in which plants respond, they are beginning to think that the most serious threats to agriculture will not be the most dramatic: the lethal heatwave or severe drought or endless deluge. Instead, for plants that humans have bred to thrive in specific climatic conditions, it is those subtle shifts in temperatures and rainfall during key periods in the crops' life cycles that will be most disruptive. Even today, crop losses associated with background climate variability are significantly higher than those caused by disasters such as hurricanes or flooding.
John Sheehy at the International Rice Research Institute in Manila has found that damage to the world's major grain crops begins when temperatures climb above 30 degrees C during flowering. At about 40 degrees C, yields are reduced to zero. "In rice, wheat, and maize, grain yields are likely to decline by 10 percent for every 1 degree C increase over 30 degrees. We are already at or close to this threshold," Sheehy says, noting regular heat damage in Cambodia, India, and his own center in the Philippines, where the average temperature is now 2.5 degrees C higher than 50 years ago...
The Irony of Climate | Worldwatch Institute
Originally Posted by Lester Brown
Above all, water shortages and climate change will constrain output. Every one-degree Centigrade increase in temperature will reduce grain yields by 10 percent, he said.
That will take some time, however. For the moment, analysts are looking more closely at seasonal factors.
Kudos to the Post for quoting Brown. But I think they missed his point.
Climate change is already contributing to the extreme weather (and local water shortages) that are helping to drive up food prices...
Washington Post, Lester Brown explain how extreme weather, climate change drive record food prices. | ThinkProgress