The historic drought affecting the Greater Horn of Africa (Ethiopia, Eritrea, Somalia, Djibouti, Kenya and Sudan) is the unprecedented combination of a lack of rain and high temperatures which could not have occurred without the consequences human emissions of greenhouse gases, shows a scientific study published Thursday, April 27.
"Climate change caused by human activities has made agricultural drought in the Horn of Africa about 100 times more likely" than in the past, said a report by the World Weather Attribution (WWA), a global network of scientists that assesses without the link between extreme weather events and climate change. Since the end of 2020, the countries of the Greater Horn of Africa, a large peninsula in the east of the continent, have been suffering their worst drought in forty years.
Five rainy seasons in a row have killed millions of cattle and destroyed crops. According to the UN, 22 million people are threatened by hunger in Ethiopia, Kenya and Somalia (where there is also an Islamist insurgency).
According to the nineteen scientists who contributed to the report, climate change has had "little effect on recent annual rainfall" in the region. But it strongly influenced the rise in temperatures, responsible for a sharp increase in evapotranspiration which led to record drying of soils and plants. “It is climate change that has made this drought so severe and exceptional,” Joyce Kimoutai, a Kenyan climatologist contributing to the report, summed up in a telephone briefing on Wednesday.
Both annual rainy seasons affected
The WWA network, founded by renowned climatologists, has established itself in recent years by its ability to assess the influence, more or less strong and unsystematic, between extreme weather events - heat waves, floods, drought, etc. – and human-caused climate change. Its results, produced on a rush, are published without going through the lengthy process of peer-reviewed journals, but combine peer-reviewed methods, first with historical weather data and climate models.
This time, the WWA has focused its study on three of the most affected countries (southern Ethiopia and Somalia and eastern Kenya). He found that climate change is altering the two rainy seasons in opposite ways: the heaviest, between March and May, "becomes drier and rainfall deficit is twice as likely" as in the past, while "the small season becomes more humid".
But in recent years, "this short-season wet pattern has been masked by the cyclical weather phenomenon of La Niña" which reduces tropical rainfall and which there is no evidence to date is influenced by the anthropogenic climate change. This rare conjunction, in a region that has had five consecutive rainy seasons since the end of 2020, then combined with the increase in temperatures to lead to record drying of soils and plants.
Had the planet not already warmed by 1.2 degrees from pre-industrial times, this rainfall would have left the region unusually dry at worst, below the first degree of drought severity. in the American classification, ensures the WWA. Clearly, "climate disruption was a necessary condition for such a severe drought to occur," the scientists conclude.
The current situation is described as "exceptional drought", the fourth and final level of alert on the American scale. Once unlikely, it now has a 5% chance of reoccurring each year.
