From this IRIN story that we found at the Guardian, we find the opinions of two scientists who have worked in the Horn of Africa.
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.