A new study using a sediment core extracted from the Gulf of Aden found the East African region covering Somalia, Djibouti and Ethiopia has dried at an unusually fast rate over the past century.
The Horn of Africa is becoming
drier in step with global warming, researchers said on Friday,
contradicting some climate models predicting rainier weather patterns in
a region that has suffered frequent food crises linked to drought.
A
new study using a sediment core extracted from the Gulf of Aden found
the East African region covering Somalia, Djibouti and Ethiopia has
dried at an unusually fast rate over the past century.
Lead
author Jessica Tierney, an associate professor at the University of
Arizona, told the Thomson Reuters Foundation the research team was
confident the drying was linked to rising emissions of climate-changing
greenhouse gases, and was expected to continue as the region heats up
further.
"If the region becomes dry, like we think
it might get, that completely changes your models for food security and
agriculture," she said.
Study co-author Peter
deMenocal of Columbia University's Lamont-Doherty Earth Observatory
warned that many aid groups are expecting "a wetter, greener future for
the Horn of Africa". But the new findings show "the exact opposite is
occurring".
The study could have important
implications for a region that has suffered political instability and
violence alongside regular droughts and hunger in recent decades,
forcing people from their homes and fuelling piracy on the seas off
Somalia.
The scientists used isotopes from leaf
waxes found in the 1-metre sediment sample from the ocean bed -
extracted while dodging Somali pirates in 2001 - to compare rates of
drying over the past 2,000 years.
When the climate
is drier, leaf waxes are more enriched with heavy hydrogen isotopes.
The scientists detected an increasing shift towards heavy hydrogen in
the last century as the climate dried out after a wet period during the
Little Ice Age from 1450-1850.
"What we see in the
paleoclimate record from the last 2,000 years is evidence that the Horn
of Africa is drier when there are warm conditions on Earth, and wetter
when it is colder," Tierney said.
Global-scale
models used to predict future changes have suggested the region would
become wetter due to higher rainfall in the "short rains" season from
September to November.
But the new study,
published in Science Advances, said those gains may be offset by
declining rainfall during the "long rains" season from March to May, on
which local rain-fed agriculture relies.
Tierney
said the findings would increase uncertainty around climate predictions
now, but should help build a more accurate picture in the longer run.
More
work is needed to develop finer-resolution regional models that can
more accurately predict precipitation shifts in both rainy seasons, as
well as to clarify the link between greenhouse gas emissions and drying,
she said.
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