During our joint appearance on the Jeremy Vine show, George Monbiot said something that intrigued me, namely that there had been a decades long trend towards drought in the Horn of Africa.
This was interesting to me, as I'd heard this suggested before and had actually spent a short time trying to verify the claim about six months ago. However, I had been distracted by other things and had never bottomed it out.
After hearing George make the claim again, I decided it was worth digging a bit further and this post is the result. Although I can't say I have checked every available source, my researches have turned up very little to support the idea.
An IPCC report on the Regional Impacts of Climate Change produced this map of precipitation trends. It's rather old - dating from 1997 - but does seem to suggest a trend towards increasing rainfall in the area:
I wonder what George's source is?
From the African Journal of Agricultural Research:
Different researches had been conducted to assess the spatial and temporal patterns of rainfall in different parts of the country. Wing et al. (2008) in studied the trends and spatial distribution of annual and seasonal rainfall in different parts of Ethiopia using data from 134 stations in 13 watersheds between 1960 and 2002, and showed no significant changes in annual watershed rainfall for any of the watersheds examined, rather a significant decline in June to September rainfall (that is, Kiremt) were recorded in watersheds located in the southwestern and central parts of Ethiopia. Similarly, Osman and Sauerborn (2002) noted that summer rainfall in the central highlands of Ethiopia declined in the second half of the 20th century. On the other hand Seleshi and Zanke (2004) failed to find such a trend over central, northern, and northwestern Ethiopia. Instead, similar to Verdin et al. (2005) they found a decline of annual and Kiremt rainfall in eastern, southern, and southwestern Ethiopia. Woldeamlak and Conway (2007) argued declining of annual rainfall in the northwestern part rather there were no clear trend of annual rainfall during their observation time. Generally, Wing et al. (2008) in many parts of Ethiopia, Woldeamlak and Conway (2007) in drought prone areas of Amhara region (Northwestern Ethiopia), Seleshi and Zanke (2004) in central, northern, and north-western Ethiopia and Conway et al. (2004) in the central Ethiopian highlands and Conway (2000) in northeastern Ethiopian highlands agreed that there is no significant and clear trend in the annual rainfall pattern.