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By Megan Rowling
BARCELONA, Jan 7 (Thomson Reuters Foundation) - Droughts and
extreme heat have cut national cereal production by 9 to 10
percent on average around the world in the last half-century,
and the impact has worsened since the mid-1980s, researchers
Cereal production losses averaged 13.7 percent in drought
years from 1985, compared with 6.7 percent during earlier
droughts, a new study published in the journal Nature found.
It examined the effects of some 2,800 weather disasters on
16 cereals in 177 countries from 1964 to 2007.
The trend could be due to any combination of rising drought
severity - although whether droughts have got worse is still
under debate - increasing vulnerability and exposure to drought,
and greater reporting of drought events, the researchers said.
The study highlights the urgency for the global cereal
production system to adapt to extremes in a changing climate,
"Our findings may help guide agricultural priorities and
adaptation efforts, to better protect farming systems and the
populations that depend on them," said senior author Navin
Ramankutty, professor of global food security and sustainability
at the University of British Columbia.
The analysis did not identify any impact on crop production
from floods and extreme cold in national data, they noted.
While the damage to cereal production from droughts and
extreme heat was considerable, the effect was short-term, as
agricultural output rebounded and continued to grow after the
disasters, the study said.
Droughts - which can last for several years - appear to be
more harmful, reducing cereal yield and causing complete crop
failure in some areas, whereas extreme heat only affected yield,
RICH COUNTRIES SUFFER
The study showed production took a bigger hit from extreme
weather in technically advanced agricultural systems in North
America, Europe and Australasia than in developing countries.
In wealthy nations, production dropped by nearly 20 percent
due to droughts, double the global average.
In comparison, the average production deficit was around 12
percent in Asia and just over 9 percent in Africa, while extreme
weather had no significant effect in Latin America and the
Caribbean, the study said.
This could be explained by the differing approaches of large
and small-scale farming, the authors said.
"Across the breadbaskets of North America, for example, the
crops and methods of farming are very uniform across huge areas,
so if a drought hits in a way that is damaging to those crops,
they will all suffer," said Corey Lesk, a recent graduate of
"By contrast, in much of the developing world, the cropping
systems are a patchwork of small fields with diverse crops. If a
drought hits, some of those crops may be damaged, but others may
survive," Lesk added.
As farmers in wealthier countries rarely depend on harvests
for food and can usually insure crops against bad weather, the
best strategy for them may be to maximise yields rather than
minimise the risk of weather-related crop damage, as subsistence
farmers would seek to do, the researchers said.
(Reporting by Megan Rowling, editing by Tim Pearce. Please
credit the Thomson Reuters Foundation, the charitable arm of
Thomson Reuters, that covers humanitarian news, women's rights,
trafficking, corruption and climate change. Visit www.trust.org)