Copenhagen, Denmark
March 11, 2009
Source:
Bioversity
International
Scientists and policymakers at the
Climate Change Conference in Copenhagen today heard from CGIAR
scientists about research that can help poor farmers to adapt
to, and possibly even profit from, climate change. Andy Jarvis,
senior scientist at Bioversity International and the
International Centre for Tropical Agriculture, showed how
geographical information systems can pinpoint opportunities.
Jarvis, an expert on the use of geographical information systems
to interrogate large datasets, asked three related questions.
What, broadly, is going to happen to agriculture? How can we
best help in the search for sustainable solutions? And how will
climate change affect the wild relatives on which many crops
depend for their future?
A lot is known about how changing climate will affect the
productivity of the main staple crops, precisely because they
are the main staples. There are detailed models about how the
physiology of those species responds to changes in temperature,
water, seasonality and so on.
“The top ten crops account for a lot of calories,” Jarvis said,
“But real food and nutrition security depends on far more
species.”
Jarvis and his colleagues used a simpler model, Ecocrop, to ask
what climate change will do to the 50 most important food crops,
from alfalfa to yams, defined by total area planted.
While it does not capture detailed yield forecasts, Ecocrop does
reveal a broad picture of the suitability for different crops
under different climatic conditions. Overall, global suitability
for the top 50 crops rises: the area suitable for growing them
increases.
“But agricultural geography changes,” Jarvis said. Latin America
will see a drop of 2.5% while Europe's suitable area expands by
almost 18%.
Looking in more detail at the number of species, the overall
diversity, that will be suitable in each area, there are, Jarvis
says, “clear areas of concern”.
Eastern Brazil, the Sahel, south Asia and the Mediterranean
could lose up to half of their crop species.
“The challenge will be greatest where a major staple becomes
unsuitable, but alternatives exist and we need policies to
change now in order to capitalise on the opportunities and
minimize the negatives,” Jarvis said.
This is the core of another CGIAR scientist's conference paper
on Thursday, which will ask how farmers can be helped to adapt
their farming systems.
Homing in on just one species, the common bean (Phaseolous
vulgaris) all analyses show clearly that most areas of
Africa will experience a severe drop in the area suitable for
the crop, largely as a result of lower rainfall. But the climate
models also indicate that if farmers in Malawi, Mozambique and
the Sahel had access to varieties with a little more drought
resistance, their future would be much more secure.
There are about 268,000 accessions of common beans in genebanks.
Many don't have data about their drought resistance. Where are
breeders or farmers supposed to start looking? Jarvis and his
colleagues believe they have an answer.
About one third of all the beans in genebanks can also be found
in the datasets made available by the Global Biodiversity
Information Facility (GBIF). These records reveal where the
samples were collected. “The geographic information gives us the
climate,” Jarvis explained.
The researchers looked specifically for varieties that had been
collected in places where the rainfall over the three month
growing season was less than 300 millimetres, well below the
average needed for a good bean crop. There were 3608 accessions
that had been collected in drier areas, mostly in Central Europe
but with some representatives from the Sahel and dry parts of
the southern Andes.
“Those are the best candidates for a breeding programme,” said
Jarvis, “and our models also show that drought resistant beans
would have a huge impact in parts of Africa.”
Quite apart from direct effects of climate change, shifting
patterns of pests and diseases also threaten future agriculture.
Already the world is seeing new disease patterns, for example
UG99 rust disease of wheat and Asian soybean rust in North
America. An invaluable source of solutions in the past has
always been wild relatives, which have supplied plant breeders
with resistance to various challenges. But the crop wild
relatives are themselves threatened by climate change. Jarvis
and his colleagues have previously looked at the potential
impact on target species such as peanut, potato and cowpea. In
the latest study they have used information gathered through
GBIF to paint a broad-brush picture of the impact on a pool of
343 species relevant to 11 different crops.
Knowing where the specimens were collected makes it possible to
calculate all the places that share a similar climate, and that
therefore could host those species. The climate change models
then show how the areas with those specific climates shrink or
grow, which in turn shows which areas are at greatest risk of
losing crop wild relatives, and therefore where efforts to save
them should be concentrated.
“Sub-Saharan Africa, eastern Turkey, the Mediterranean and parts
of Mexico,” summarised Jarvis. “Those are the priority places to
collect crop wild relatives.”
New datasets and new computing methods, along with more widely
available data, have enabled scientists like Jarvis to be a lot
more precise about their predictions for the impact of climate
change on agriculture. And that, in turn, has enabled them to
identify the places and actions that are most likely to have a
positive impact, which should be good news for policy-makers
struggling to make the most of limited resources. |
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