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Carbon Brief Staff

Carbon Brief Staff

21.08.2013 | 12:50pm
ScienceClimate models predict hard times ahead for global food production
SCIENCE | August 21. 2013. 12:50
Climate models predict hard times ahead for global food production

Global food production is set to take a hit in the coming decades, new research predicts.

As rising greenhouse gas emissions drive changes in rainfall patterns, river flows and temperatures, the availability of food may decline, it says.

What’s more, with less to go around, food prices look set to rise while welfare standards fall.

Less food, more expensive

The research, published in the journal Climatic Change, shows that under both optimistic and pessimistic scenarios of future emissions, the many effects of climate change could together cause food production to fall 0.5 per cent by the end of this decade, and 2.3 per cent by the 2050s.

As a result of the decrease in food production, the price of food is set to rise, the paper says. By midcentury, staple foods like cereal grains, sugar cane and wheat are predicted to be roughly 40 per cent more expensive than they would be in a world without climate change.

Fruit and vegetable prices are similarly effected, costing 30 per cent more in a climate changed world in 2050: 

Food Prices

Winners and losers

The research suggests that welfare standards and economic growth could suffer as a direct result of shrinking food resources and rising prices. Worldwide, global welfare losses could exceed $280 billion by 2050, it predicts. For developing economies where agriculture is the main driver of the economy, it could be a particular problem.

Climate change could also indirectly affect regional economies by changing the big players in global food markets. Areas worst affected by climate change will have less food to trade, and will instead rely more on imports, which in turn means taking the biggest welfare hits. On the other hand, regions where climate change makes conditions more hospitable for growing crops, welfare levels might get a boost.

Individual impacts can be misleading

To predict these changes in food production and prices, the research looked at all the main ways climate change could affect agriculture – simulating the combined effect of rising temperatures, changing rainfall patterns, altered river flows, and the growth-boosting effects of having more carbon dioxide in the atmosphere.

The authors warn that looking at individual impacts of climate change can lead to a “false appreciation” of how agriculture is likely to be affected in the future. The carbon dioxide fertilisation effect is a good example of this.

The idea is that plants grow bigger when atmospheric levels of carbon dioxide rise, because plants use carbon dioxide as one of their main building blocks. At the same time the plants become more efficient at using water, meaning they need to take up less to survive.

This seems like good news, and if it was the only factor at play, this study suggests more carbon dioxide would indeed push up global food production and improve welfare standards. But as the chart below shows, it would be misleading to conclude on this basis alone that climate change will be good news for agriculture.


Change in global welfare by the 2050s as a result of changes in agriculture. All factors of climate change shown top, carbon dioxide fertilisation effect only shown fourth down. Adapted from Calzadilla et al. (2013).

This graph shows that when all aspects of climate change are considered, global food production is set to suffer, in turn leading to big welfare losses.

Conclusive findings?

The modelling used here is quite special, because as part of looking at how climate change could affect food production, it also looks at how climate change will affect water availability.

Dr Andy Wiltshire, a Met Office scientist who co-authored the paper, explained to Carbon Brief:

“Often the impacts of climate on food and water are treated separately, but really the interaction is very important as agriculture is one of the dominant consumers of freshwater”.

It’s also important to look at water availability and crop growth together, because irrigation is one way farmers can adapt to climate change in areas which are predicted to become drier in the future. Indeed, the modelling showed that crops grown using irrigation were less vulnerable to climate change than crops reliant on rainfall.

The study has its limitations, however. These are the results of just one model, and there are many studies which suggest food availability could increase in certain regions. It also doesn’t consider how extreme weather events could change in the future, and what effect that might have on crop yields.

Nevertheless, the new study highlights how complicated the picture is for food production under climate change. And according to this model, the outlook looks pretty gloomy – it could well be that the world is a hungrier place in the future.

Calzadilla et al. (2013) Climate change impacts on global agriculture. Climatic Change. DOI: 10.1007/s10584-013-0822-4


Update - 22/8/13 - The graph on food prices and the preceeding text was adjusted to reflect that the percentage calculations, provided by the paper's author, were changes relative to a world in 2050 without climate change. Previously this article stated the change was relative to 2001 prices.

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