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<DIV class=article_view><FONT size=4>Study links African drought to Pacific sea
temperature</FONT></DIV>
<DIV class=author>Gilbert Nakweya. Additional reporting by Mićo Tatalović </DIV>
<DIV class=source>16 March 2012</DIV>
<DIV class=date><A
href="http://www.scidev.net/en/agriculture-and-environment/natural-disasters/news/study-links-african-drought-to-pacific-sea-temperature.html">http://www.scidev.net/en/agriculture-and-environment/natural-disasters/news/study-links-african-drought-to-pacific-sea-temperature.html</A></DIV>
<DIV class="article_content cf">
<P><SPAN>[NAIROBI] Researchers in the United States have found a link between
low <A href="http://www.scidev.net/en/agriculture-and-environment/water/"><FONT
color=#336699>rainfall</FONT></A> in East Africa during the March-May rainy
season, and changes in sea surface temperature in the tropical Pacific Ocean.
</SPAN></P>
<P><SPAN>The region endured a catastrophic <A
href="http://www.scidev.net/en/agriculture-and-environment/natural-disasters/"><FONT
color=#336699>drought</FONT></A> last year. The lack of rain in 2010 during the
October-December rain season </SPAN>— known as the 'short rains' — <SPAN><A
href="http://www.scidev.net/En/news/forecasters-warned-of-horn-of-africa-drought-last-year.html"><FONT
color=#336699>was widely anticipated</FONT></A> due to an established link
between these rains and El Niño and La Niña events. </SPAN></P>
<P><SPAN>But researchers say last year's failure of the region's other key
rains </SPAN>— the <SPAN>so-called 'long rains', which tend to fall between
March and May </SPAN>– was much harder to anticipate.</P>
<P><SPAN>"Historically, the long rains have not shown a strong relationship to
El Niño and La Niña the way the short rains do," Bradfield Lyon, a co-author of
the study and climate scientist at Columbia University's International Research
Institute for Climate and Society, told <EM>SciDev.Net</EM>. </SPAN></P>
<P><SPAN>Lyon and colleague David DeWitt have now identified a link between the
'long rains' and ocean temperatures in the Pacific. </SPAN></P>
<P><SPAN>They noted that in 1999, there was an abrupt change in Pacific ocean
surface temperatures. The western Pacific surface became warmer, while surface
temperatures in the eastern Pacific became cooler. Historical climate
observations were combined with climate model experiments, and the authors
concluded that these changes were strongly linked to "a similarly abrupt decline
in East African long rains that occurred around that time". </SPAN></P>
<DIV>Their findings were published in <EM>Geophysical Research Letters</EM> in
January.</DIV>
<P><SPAN>The researchers did not find an explanation for the change in ocean
temperatures. And long-term <A
href="http://www.scidev.net/en/climate-change-and-energy/"><FONT
color=#336699>climate change</FONT></A>, which their study did not address, "may
further complicate the picture", Lyon said. </SPAN></P>
<P><SPAN>They also warn that the disruption to the 'long rains' may continue for
a few more years. </SPAN></P>
<P><SPAN>"The slowly varying nature of these ocean conditions suggests that the
current pattern may persist for several years to come," Lyon said, although he
added there may be variations from one year to the next. </SPAN></P>
<P><SPAN>Chris Funk, a climatologist with the Famine Early Warning Systems
Network (FEWS NET), told <EM>SciDev.Net</EM> this was "an excellent study".
</SPAN></P>
<P><SPAN>The paper "makes an eloquent case that it has really been changes in
the central–western Pacific that have been most important" in affecting the long
rains, he said, adding "it will likely lead to improved forecasts". </SPAN></P>
<P><SPAN>Funk said his own research, motivated by the study, had shown that
seven of the past eight failed 'long rains' were linked to Pacific sea
temperatures. </SPAN></P>
<P><SPAN>"This research is already influencing climate forecasting and <A
href="http://www.scidev.net/en/agriculture-and-environment/food-security/"><FONT
color=#336699>food security</FONT></A> preparedness in a positive way," he
added. </SPAN></P>
<P><SPAN><A href="http://www.agu.org/pubs/crossref/2012/2011GL050337.shtml"
target=_blank><FONT color=#336699>Link to abstract in <EM>Geophysical Research
Letters</EM></FONT></A> </SPAN></P>
<P><EM></EM> </P></DIV></FONT><BR>
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