Study Projects Warmer, Drier Horn of Africa

Scientists generally agree climate change will impact the Horn of Africa in coming years. The question is - will the region become drier or wetter?

A new study says the frequent hot spells and droughts of recent years could grow even worse for Somalia, Djibouti and Ethiopia. The study warns that "progressively less rain during the long rains' season in March, April and May could exacerbate tensions in one of the world's most geopolitically unstable regions."

The findings, however, are at odds with older computer models that say long-term, the region will become wetter.

University of Arizona associate professor Jessica Tierney is lead author of the study, which appeared in the October 9 issue of the Journal for Science Advances.

She says researchers based their findings, in part, on an evaluation of ancient marine sediments in the Gulf of Aden, off the Somali coast. The sediments reveal what the regional climate was like over the last 2,000 years.

Tierney says the sediment indicates the rate of recent drying in the Horn is virtually unprecedented.

"We can calculate the rate of the changes that have happened before. About 300 years ago, it was quite a bit wetter than today. And then before that it was actually drier, sort of similar to today," she says. "But what's different about the 20th century is if you look at how fast the change from wet to dry has been occurring, we haven't seen such a fast transition like that in the last thousand years, at least."

Tierney says the rapid drying appears linked to the rise in greenhouse gases that scientists blame for global warming.

"As we increase greenhouse gases, we're potentially driving a very rapid change in the hydrological cycle in the Horn of Africa," she says. "And it's pushing the whole region toward a drier and drier state."

"What we don't know everything about is how that works on the ground. That's a question that now we're really looking into, as a follow-up on the study is really getting into the why."

One thing the scientists know is that prolonged drought can affect food supplies for millions of people. The 2011-2012 drought in the Horn killed an estimated 250,000 people in Somalia and forced more than 900,000 others to flee to neighboring countries.

Tierney says researchers expected their findings to confirm the computer model predictions. She thinks they didn't because the models may have difficulty simulating rainfall in the Horn of Africa.

Regardless of whether the Horn becomes much drier or wetter, the impact will be big.

"If it gets much wetter, like the models suggest, then we could see situations where we've got flooding," Tierney says. "And then if it gets much drier, of course, that has major implications for drought, famine, and food security."