Surface Ozone May Pose Problems For Food Crops As Warming Grows

[hatrack]

"If farmers don't adapt, changing environmental conditions could damage food production. That's the disturbing message from the first open-air simulations of Earth's climate in 2050, which suggest that negative effects of increasing surface ozone will outweigh any benefits triggered by warming. Rising carbon-dioxide levels had previously led researchers to make rosy predictions about crop yields in coming decades — the gas promotes growth by increasing rates of photosynthesis, among other effects. But much of the work has been based on greenhouse trials and has ignored the impact of ozone concentrations near the ground. When researchers from the University of Illinois at Urbana−Champaign addressed this shortcoming in field trials of soya plants, they saw yields dive.

The result is a concern because the world's two largest soybean growers may face significant ozone increases, says crop scientist and study author Stephen Long. Urban air pollutants are expected to push up levels of near-surface ozone by at least 25% by the middle of this century, but rises in China — and in the US Midwest, where almost 300,000 square kilometres of soybeans are harvested annually — could be two to three times as great.

Ozone creates reactive molecules that destroy rubisco, an enzyme crucial for photosynthesis. It is also known to make leaves age faster. To investigate its effects, the Illinois team developed open-air experiments in which carbon dioxide and ozone were released from pipes that surrounded 16 plots of 200 square metres. By using wind sensors to control gas release, concentrations in the air over the plot were held close to the predicted 2050 levels over the three-year study.

The preliminary data, presented at a Royal Society conference held over 26−27 April in London, suggests that yields will be cut by up to 10%. Previous forecasts of crop yields made by the Intergovernmental Panel on Climate Change (IPCC) should now be revised, warns Long. "No agrochemical company would use to forecast how their chemical will affect crops, yet we use them to predict global food security," he complains. The open-air studies revealed further threats that greenhouse work had not spotted, including delayed maturation, which puts crops at risk of frost late in the season. And pests prospered. "The IPCC predicts that chewing insects will do worse in higher carbon dioxide," notes Long. "Unfortunately Japanese beetles like the environment. They live longer and produce more eggs."

EDIT

http://forests.org/articles/reader.asp?linkid=41687

[LaurenG]

1. I don't understand why so many

won't do a thing to change this. We have been receiving warnings for all these years. Too many times I've heard the dis-informed/misinformed state that this isn't really happening. Heart breaking.

Here's an excellent link for cyber protesting everything from clean water to the filibuster.

http://www.nrdc.org/action/