The historic drought affecting the Greater Horn of Africa is the unprecedented conjunction of a lack of rain and high temperatures that could not have occurred without the consequences of human emissions of greenhouse gases, shows a study science released Thursday.
“Climate change caused by human activities has made agricultural drought in the Horn of Africa about 100 times more likely” than before, says in 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 (Ethiopia, Eritrea, Somalia, Djibouti, Kenya and Sudan), a large peninsula in the east of the continent, have been suffering their worst drought for 40 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 insurrection).
According to the 19 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,” said Joyce Kimoutai, a Kenyan climatologist contributing to the report, in a telephone briefing on Wednesday.
Five rainy seasons with deficits
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 non-systematic, 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 low-season wet trend has been masked by the cyclical climate phenomenon of La Niña” which reduces tropical rains 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 rainy seasons since the end of 2020, then combined with the increase in temperatures to cause record drying of soils and plants.
If the planet had not already warmed by 1.2 degrees compared to the pre-industrial era, this rainfall would have subjected the region to conditions, at worst, “abnormally dry”, i.e. a level below the first degree of severity of drought in the American classification, assures the WWA.
Clearly, “climate change was a necessary condition for such a severe drought to occur”, conclude the scientists.
The current situation is described as an “exceptional drought”, the fourth and last level of alert on the American scale. Unlikely before, it now has a 5% chance of reproducing each year.