Climate change in tropics poses food threat to poor

Higher temperatures will reduce growing seasons critical for crops needed to
feed the world’s poor, a report says

3.6.2011 (Guardian)

by John Vidal

The shorter growing seasons expected with climate change over the next 40 years will imperil hundreds of millions of already impoverished
people in the global tropics, say researchers working with the world’s leading
agricultural organisations.

The effects of climate change are likely to be seen across the entire tropical
zone but many areas previously considered to be relatively food secure are likely
to become highly vulnerable to droughts, extreme weather and higher temperatures,
say the researchers with the
Consultative Group on International Agricultural Research (Cgiar).

Intensively farmed areas like north-east Brazil and Mexico are likely to see
their prime growing seasons fall below 120 days, which is critical for crops such
as maize to mature. Many other places in Latin America are likely to experience
temperatures that are too hot for bean production, a staple in the region, says
the report.

The impact could be felt most in India and south-east Asia. More than 300 million
people in south Asia are particularly prone to even a 5% decrease in the length
of the growing season, say the authors.

“Such a change over the next 40 years could significantly affect food yields
and food access for people already living on the edge,” says the report
Mapping Hotspots of Climate Change and Food Insecurity (pdf).

Higher peak temperatures are also expected to extract a heavy toll on food producers.
“Today there are 56 million food-insecure and crop-dependent people in parts of
west Africa, India and China who live in areas where, in 40 years time, maximum
daily temperatures could exceed 30C. This is close to the maximum temperature
that beans can tolerate, while maize and rice yields suffer when temperatures
exceed this level. Even with optimal amounts of rain, African maize can decline
by 1% for every day spent above 30C,” says the report.

“We are starting to see much more clearly where the effects of climate change
on agriculture could intensify hunger and poverty,” said Patti Kristjanson, research
leader at the the Cgiar research programme on
Climate Change, Agriculture, and Food Security. “Farmers already adapt to variable weather by changing their planting schedules.
What this study suggests is that the speed of climate shifts and the magnitude
of the changes required to adapt could be much greater. In some places, farmers
might need to consider entirely new crops or new
farming systems.”



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Global warming has already reduced the global yields of key crops, say scientists

June 3, 2011

Source: SciDev.Net

Maize and wheat production have been 3.8 and 5.5 per cent lower, respectively,
than they would have been without the temperature rises associated with climate
change since the 1980s, according to the statistical analysis.

Rice and soya yields have dropped in some parts of the world and risen in others,
so overall the warming has not changed their net global production.

Linking climate change to food prices for the first time, the scientists, led
by David Lobell of Stanford University, United States, have shown that these losses
have probably led to at least a six per cent rise in food prices between 1980
and 2008.

The news comes as the UN this week (3 May) revised upwards its population prediction
for the planet — to 10.1 billion by 2100.

“Without successful adaptation, and given the persistent rise in demand for maize
and wheat, the sizeable yield setback from climate change is likely incurring
large economic and health costs,” said the team, whose work was published in Science
yesterday (5 May).

The team developed two models of crop productivity using data from countries
around the world. Both models included complex factors such as the increases in
yield from technological advances in farming, but one included the actual increase
in global temperatures between 1980–2008, while the other kept the temperature
constant at 1980 levels.

For maize, warming was linked with a reduced yield of around eight per cent in
Brazil and seven per cent in China, but an increase of about one per cent in India.
In Africa, there were significant yield drops in Egypt, Mozambique and Uganda,
but substantial increases, linked to temperature drops, in Kenya, Tunisia and

Wheat productivity in the developing world was significantly reduced in Afghanistan,
Brazil, Iraq, Libya and Morocco.

And, although the global productivity of soya remained level, Brazil experienced
a drop of five per cent, and Paraguay 7.5 per cent, while Argentina showed a 2.5
per cent increase.

The study did not take into account the fertilising effect of extra carbon dioxide
in the atmosphere — thought to increase yields for rice and soy but have no effect
on maize and wheat.

“We are not saying climate change is the only or even a major cause of price
increases for major commodities,” Lobell told SciDev.Net. “Most people would say
biofuel and trade policies are probably more important for food price rises. But
what we are saying is that climate change is also a factor.”

Gerald Nelson, a senior research fellow at the International Food Policy Research
Institute in the United States said the results demonstrated that “the way climate
plays out in individual locations in the future is going to be very important
for global effects”.

For developing countries it underlined the urgency of adapting agriculture to
climate change — and building better infrastructure so that farmers can benefit
from higher prices for their crops, he said.

Link to full paper in Science


More news from: SciDev.Net



Published: June 4, 2011