Ethiopian Droughts Linked To El Nino
By Paul Homewood
The Met Office have recently claimed that “Human influence on global climate contributed to the causes of the 2011 East Africa drought”. Their claims are based on the theory that higher sea temperatures are exacerbating drought. (I will leave aside the issue of whether sea temperatures have even been increasing in the last decade, or whether mankind would be responsible if they were).
However, a paper from 1997 has come to light, by Tsegay Wolde-Georgis, entitled “El Nino and Drought Early Warning in Ethiopia”, which totally undermines the Met paper. Wolde-Georgis, at the time, was working for NCAR at the University of Colorado, and his research draws on similar findings by several other scientists.
Essentially, he finds that Ethiopian droughts coincide with El Nino events, and that their severity also varies according to the strength of the El Nino events. It is not SST’s per se that cause droughts, but the interaction of wind direction, ocean currents and changes in atmospheric pressure. Furthermore, the effects are transmitted by “atmospheric teleconnections over great distances”.
Among the points he makes are :-
- ENSO is a coupled air and ocean phenomenon with global weather implications.
- It is believed that ENSO is often associated with devastating droughts in Northeast Brazil, Australia, parts of Africa, the failure of Indian monsoons, Atlantic hurricanes etc.
- Many researchers now believe that the occurrence of various droughts in Africa are caused by physical processes related to the occurrence of ENSO events thousands of miles away.
- There have been notable droughts in Ethiopia throughout human history.
- History suggests droughts occur about every 5-6 years in Northern Ethiopia.
- 1888 was a major ENSO year, that damaged the economies of Brazil and Australia, as well as Ethiopia. In 1888/89, about a third of the population in Ethiopia died because of famine.
- The 1982/83 ENSO was the most extreme event in at least a century, i.e since the 1888 event, and led to the 1983/84 drought.
- The association between ENSO and droughts in Ethiopia is due to an atmospheric teleconnection or “the linkages over great distance of seemingly disconnected weather anomalies”.
The paper includes a Chronology of Ethiopian droughts, which I reproduce below.
It is worth pointing out that the author of this paper wrote it in an attempt to discuss how “ENSO based drought early warning systems” could be used to plan in advance for droughts. As such, he relied on the work of others regarding the science behind ENSO and droughts, rather than presenting the findings as his own.
It is a pity that scientists at the Met are not building on this sort of work, rather than involving themselves in babyish attempts to blame droughts on mankind.
El Niño (EN) is the increase in the surface temperatures (SST) in the central and eastern equatorial Pacific Ocean. EN results from changes in the pattern and direction of winds and ocean currents in the region, which have potentially catastrophic effects. Many researchers now believe that the occurrence of various droughts in Africa, especially in Southern Africa and the Horn, are caused by physical processes related to the occurrence of ENSO events thousands of miles away. If valid and reliable information about the linkages between these occurrences becomes available, it could help to forecast Sub-Saharan African droughts. ENSO-based drought early warning could send a "wake-up call" to governments to prepare for national food shortages. With such information, policies that reduce the impact of drought could be introduced. An early warning with many months of lead time, such as could be provided by ENSO information, would eliminate the excuse of national governments who claim to be unaware of the advent of drought. When drought causes famine, and a reliable drought early warning was available, it becomes a man-made disaster.