March 21, 2014

 

 

Decline in predicted crop yields is larger than first thought and could endanger food security, unless carbon dioxide emissions are cut, according to research conducted by Australian, British and American scientists.

 

The study found that the situation will worsen in the second half of the century, with tropical areas worse hit than temperate regions.

 

An analysis of more than 1,700 simulations found that across all regions and all crops, including wheat, corn and rice, yields will drop by 2% each decade, based on a two centigrade rise by 2050.

 

For some crops, the situation will be much worse, with wheat and corn in tropical areas experiencing a 40% decline if temperatures reach five centigrade warmer than pre-industrial levels.

 

Governments have agreed a target of limiting temperature rise to two centigrade above pre-industrial levels, although scientists warn the planet could experience a four centigrade or even five centigrade rise if carbon dioxide emissions are not drastically cut.

 

The report's co-author Mark Howden, of the Commonwealth Scientific and Industrial Research Organisation (CSIRO), said the situation was worse than previously thought.

 

"We looked at a whole range of temperature and rainfall scenarios and found results that were distinctly far more negative than the previous Intergovernmental Panel on Climate Change (IPCC) report," he said.

 

Howden said countries already expected to suffer food insecurity due to climate change will be the worst hit by yield declines, with rising temperatures causing more damage than changes to rainfall patterns.

 

A lack of rainfall will be the biggest issue for many farming areas in Australia, with a hotter, drier climate causing more variable, lower yields.

 

Howden said adaption to these trends, such as changing planting times and irrigation, could produce a 10-15% increase in global yields compared to no action, providing food to 500 million to one billion people around the world.

 

However, with increased consumption and population growth will require a 14% increase in yields per decade, a target Howden said would be "far more difficult" with climate change.