One of thousands of dead cattle in the southern Somali Region of Ethiopia five years ago, in an earlier drought in the same region of the Horn of Africa (photo on Flickr by Andrew Heavens).

Scientists at the International Livestock Research Institute (ILRI), headquartered in Nairobi, Kenya, are saying that the current drought cycle in East Africa’s Horn, which has already led to famine in southern Somalia, cannot be ascribed to climate change, although there is evidence that La Niña is a probable cause.

Interviews by IRIN of ILRI scientists Phil Thornton, a systems analyst specializing in climate change in developing countries, and Jan de Leeuw, an environmental scientist leading ILRI’s rangelands research, were published in the Guardian‘s Development Network Blog.

‘. . . Philip Thornton, a senior scientist who works part-time with the Nairobi-based International Livestock Research Institute (ILRI) and the University of Edinburgh-based Institute of Atmospheric and Environmental Sciences, has done some pioneering work on projections of climate-change impact in eastern and southern Africa.

‘He told IRIN via email that projections of the climate change impact in east Africa were “a problem” as the authoritative inter-governmental panel on climate change’s (the IPCC) fourth assessment report “indicated that there was good consensus among the climate models that rainfall was likely to increase during the current century.

‘”But work by other climate scientists since then suggests that . . . certain Indian Ocean effects in east Africa may not actually occur.

‘”Some people think that east Africa is drying, and has dried over recent years; currently there is no hard, general evidence of this, and it is very difficult as yet to see where the statistical trends of rainfall in the region are heading, but these will of course become apparent in time.”

‘The IPCC’s fifth assessment report will be released in 2014.

‘Jan de Leeuw is the operating project leader in the vulnerability and sustainability in pastoral and agro-pastoral systems within ILRI’s people, livestock and environment theme. He points out that this La Niña event is one of the strongest since the 1970s. But he says La Niña, along with El Niño, appear in cycles that “we don’t understand”.

‘What we do know is that La Niña started to develop in August 2010. It cools surface waters in the central and eastern Pacific Ocean, while allowing warmer water to build in the eastern Pacific. “The pool of warm water in the east intensifies rains in Australia, the Philippines, and Indonesia. Domino-style, this pattern also increases the intensity of westerly winds over the Indian Ocean, pulling moisture away from east Africa toward Indonesia and Australia. The result? Drought over most of east Africa and floods and lush vegetation in Australia and other parts of Southeast Asia,” according to the US government’s National Aeronautics and Space Administration.

‘De Leeuw writes: “La Niña events were common from 1950 till 1976. Since then we had two decades [until about 1996] with fewer events of lesser depth. This has changed since then and over the last 15 years or so we have had more frequent La Niña events.”

‘Events as deep as the current La Niña occur once in 20 or 30 years, writes De Leeuw. “We are in a period now of more frequent La Niña events, but such a situation was there from 1950 till 1976 also.”

‘Thornton has the last word when he says research attention must focus on developing effective early warning systems and ways to help people affected by these events, who have no use for “academic” consideration of the linkages with climate change to cope better with the current levels of weather variability, “whatever happens in the future”.’

Read the whole article by IRIN on the Guardian‘s Development Network Blog: La Niña blamed for east African drought: Environmentalists call for the development of early warning systems to help countries prepare for adverse weather, 14 Jul 2011.