More intense heat waves due to global warming could diminish wheat crop yields around the world through premature ageing, according to a study published today in Nature Climate Change.
Current projections based on computer models underestimate the extent to which hotter weather in the future will accelerate this process, the researchers warned.
Wheat is harvested in temperate zones on more than 220 million hectares, making it the most widely grown crop on Earth.
Greenhouse experiments have shown that unseasonably warm temperatures -- especially at the end of the growing season -- can cause senescence, the scientific term for accelerated ageing.
Excess heat beyond the plant's tolerance zone damages photosynthetic cells.
Fluctuations in wheat yields in India have also been attributed by farmers to temperature, most recently a heat wave in 2010 blamed for stunting plant productivity.
To further test these experiments and first-hand observations, a trio of researchers led by David Lobell of Stanford University sifted through nine years of satellite data for the Indo-Ganges Plains in northern India and then used statistical methods to isolate the effects of extreme heat on wheat.
They found that a 2.0 Celsius increase above long-term averages shortened the growing season by a critical nine days, reducing total yield by up to 20 per cent.
