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.
Topics
Species
