At the Royal Society discussion meeting, Food Crops in a Changing Climate, scientists from around the world discussed the impacts of a changing climate on the productivity of staple food crops, as well as how best to forecast these impacts.

The focus remained largely on the production of crops such as maize, rice, soybeans and wheat in tropical countries, where most of the world’s food is grown, but where people are the most vulnerable to global warming.

Investigations were conducted to predict how increasing temperatures, drought and ground-level ozone concentrations would result in a substantial reduction in crop yields, outweighing the beneficial fertilisation effects currently predicted from rising levels of atmospheric carbon dioxide.

Other studies by scientists from the UK and Denmark also showed that just a few days of hot temperatures could severely reduce the yield of major food crops such as wheat, soybean, rice and groundnuts if they coincided with the flowering of these crops.

These results also suggested that there were particular thresholds above which crops become very vulnerable to climate change.

“Growing crops much closer to real conditions has shown that increased levels of CO2 in the atmosphere will have roughly half the beneficial effects that were previously hoped for in the event of climate change,” explained Professor Steve Long of Illinois University. “In addition, ground-level ozone, which is also predicted to rise but has not been extensively studied before, has been shown to result in a loss of photosynthesis and 20% yield loss.”

“Both these results show that we need to seriously re-examine our predictions for future global food production as they are likely to be far lower than previously estimated.”

By Jane Kettle

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