Climate precipitation

Does Northern Hemisphere volcanic eruptions influence Sahelian rainfall?

In a recent study in Nature Climate Change Haywood and colleagues demonstrate how volcanic eruptions can influence Sahelian precipitation. Sadly the article is not open access, but from the abstract it seems like they are providing further evidence that aerosols are important for rainfall in the Sahel. In this context I also recommend the study by Huang which shows how black carbon also is a player in this game.

Haywood and colleagues suggest that sporadic volcanic eruptions in the Northern Hemisphere cause Sahelian drought. Using de-trended observations from 1900 to 2010, they show that three of the four driest Sahelian summers were preceded by substantial Northern Hemisphere volcanic eruptions. They used a state-of-the-art coupled global atmosphere–ocean model to simulate both episodic volcanic eruptions and geoengineering by continuous deliberate injection into the stratosphere. In either case, large asymmetric stratospheric aerosol loadings concentrated in the Northern Hemisphere were a harbinger of Sahelian drought whereas those concentrated in the Southern Hemisphere induce a greening of the Sahel.

Africa cattle Climate livestock

Cattle and Climate in Africa

Map of cattle in Africa in the 1960s and 2000s
Estimated cattle (heads per square kilometre) density around 1960 (upper left), 2000 (upper right) and difference (2000–1960, bottom) relative to the mean.

The role of cattle in developing countries is as a source of high-quality food, as draft animals, and as a source of manure and fuel. Cattle represent important contribution to household incomes, and in drought prone areas they can act as an insurance against weather risk. So far, no studies have addressed how historical variations in temperature and rainfall have influenced cattle populations in Africa. The focus of this study is to assess the historical impact of climate variability on national cattle holdings. We reconstruct the cattle density and distribution for two time periods; 1955–1960 and 2000–2005. Based on estimates from FAO and official numbers, we generated a time series of cattle densities from 1961–2008, and compared these data with precipitation and temperature anomalies for the same period. We show that from 1961–2008 rainfall and temperature have been modulating, and occasionally controlling, the number of cattle in Africa.

Lunde and Lindtjørn (2013) Cattle and climate in Africa: How climate variability has influenced national cattle holdings from 1961–2008. PeerJ 1:e55