Warming oceans set the stage for dangerous but predictable droughts in East Africa

Frequent droughts – interspersed with floods – have become the new normal in eastern East Africa in recent years, causing a massive food security crisis. In 2020, the Horn of Africa entered its longest and most severe drought in more than 70 years, and 2022 marked the driest spring drought on record. More than 20 million people experienced extreme hunger due to poor harvests and more than 9 million livestock died.

In what has been described as the East African climate paradox, climate change models have failed to anticipate these droughts, instead predicting increased spring rains. However, researchers at the Famine Early Warning Systems Network (FEWS NET) were able to predict these droughts using tailored forecasts based on sea surface temperatures.

Although identifying the link to Pacific Ocean temperatures improved forecasts, giving aid agencies the opportunity to reduce loss of life and livelihoods, scientists did not yet fully understand why this link existed. In a recent study published in The future of the EarthChris Funk and his colleagues examine the cause of this link.

La Niña events have become more strongly linked to droughts since the dramatic warming of the western Pacific Ocean in 1998. Researchers delved into data on sea surface temperatures and precipitation observations and noted that rising temperatures in the western Pacific cause the eastern ocean to warm in The western sea surface temperature gradient will become more extreme.

In spring, when East Africa usually experiences a rainy season, La Niña phenomena accentuated by climate change amplify this phenomenon. These gradients intensify an airflow pattern known as the Walker circulation, which tends to generate high heat and humidity near Indonesia but reduces humidity over East Africa.

The researchers showed that climate models predict that the east-west Pacific sea surface temperature gradient will continue to strengthen in coming decades, making it likely that droughts will continue to be common in East Africa. But identifying the link between sea surface temperature and precipitation has already allowed FEWS NET scientists to predict many of the worst drought periods, as well as anticipate extreme rainfall and flooding in 2023. This study further improves scientists’ understanding of how climate change is leading to more extreme, but predictable, fluctuations in the Walker circulation.

This story is republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here.