Global warming of only 2 degrees Celsius will be detrimental to crops in temperate and tropical regions, with reduced yields from the 2030s onwards, experts report.
“Our research shows that crop yields will be negatively affected by climate change much earlier than expected,” says Andy Challinor, a professor at the School of Earth and Environment at the University of Leeds and the study’s lead author.
“Furthermore, the impact of climate change on crops will vary both from year-to-year and from place-to-place–with the variability becoming greater as the weather becomes increasingly erratic.”
The study, published by the journal Nature Climate Change, feeds directly into the Working Group II report of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report, which is due to be published at the end of March 2014.
Rice, corn, and wheat
In the study, the researchers created a new data set by combining and comparing results from 1,700 published assessments of the response that climate change will have on the yields of rice, maize, and wheat.
The study offers the largest dataset to date on crop responses, with more than double the number of studies that were available for researchers to analyze for the IPCC Fourth Assessment Report in 2007.
In the Fourth Assessment Report, scientists had reported that regions of the world with temperate climates, such as Europe and most of North America, could withstand a couple of degrees of warming without a noticeable effect on harvests, or possibly even benefit from a bumper crop.
“As more data have become available, we’ve seen a shift in consensus, telling us that the impacts of climate change in temperate regions will happen sooner rather than later,” says Challinor.
Farmers will need to adapt
We could see, on average, an increasingly negative effect on crop yields from the 2030s onwards, the researchers say. The impact will be greatest in the second half of the century, when decreases of over 25 percent may become increasingly common.
These statistics already account for minor adaptation techniques employed by farmers to mitigate the effects of climate change, such as small adjustments in the crop variety and planting date. Later in the century, greater agricultural transformations and innovations will be needed in order to safeguard crop yields for future generations.
“Climate change means a less predictable harvest, with different countries winning and losing in different years. The overall picture remains negative, and we are now starting to see how research can support adaptation by avoiding the worse impacts,” says Challinor.
The NERC EQUIP programme, the CGIAR Research Program on Climate Change, Agriculture and Food Security, the European Union, Canadian International Development Agency, World Bank, New Zealand Ministry of Foreign Affairs and Trade, and Danida supported the research.
Source: University of Leeds