• 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.