— Satellite data shows the potential for drought-induced famine in eastern
is worse than originally estimated by a panel of global experts, according to a study commissioned by NASA and the U.S. Geological Survey.
Using a combination of data from environmental satellites, sensors and weather gauges, researchers linked declining rain over the eastern and southern regions of
with warmer temperatures in the
. The data showed a pattern of warmer sea surface drawing rain over the ocean, pushing dry air over land during traditional rainy seasons that stimulate local agriculture.
If this trend continues without measures to address a drop in crop growth, the region will experience a 50 percent rise in undernourishment, said Molly Brown, one of the study’s authors and research scientist with Science Systems and Applications Inc. near NASA’s
“This is not a theoretical problem,” she said. “There has been a 30 percent decrease in rainfall since
The study, which merges global warming’s environmental effects on
with a projected human toll, agrees with predictions by the United Nations’ Intergovernmental Panel on Climate Change (IPCC) that rainfall on the southern end of
will decrease. However, the study contradicts IPCC predictions that rainfall on the eastern side of the continent will increase. The disparity between the new findings and the widely accepted IPCC climate change predictions proved an obstacle to getting the study published, said Brown.
Chris Funk, lead author of the study and a research scientist at the
, said the difference is in the model used by the IPCC compared with his team’s use of satellite data and historic observations.
“We focused on conditions over the
and used historic relationships to connect the rainfall conditions over the ocean with the rainfall conditions we would expect over land,” he said. “IPCC projections use a number of different global climate models, which must estimate sea surface temperatures and precipitation. The models estimate temperatures well but not precipitation.”
The IPCC acknowledges in its 2007 annual report that precipitation data is limited in some regions. It notes, however, improvement in understanding projected patterns of precipitation since 2006.
In the future, scientists will have a more reliable tool for measuring precipitation: NASA’s Global Precipitation Measurement (GPM) mission. The next-generation Earth science mission includes a core spacecraft scheduled for launch in July 2013 and a low-inclination satellite scheduled for launch in November 2014. The mission is to ensure that 90 percent of the globe is covered during a three-hour period, said Art Azarbarzin, GPM program manager.
“The scientists are really waiting for this,” Azarbarzin said. “[Current] sampling is not as frequent as they would like it. At any given time there will be a lot more data for them to work with and more samples give them a better data base.”
Funk, who is working with NASA on GPM, said the instrument will lead to a more accurate and complete understanding of global precipitation patterns for research. For the
study, Funk relied upon the Global Precipitation Climatology Project, which combines rainfall data from multiple satellites and instruments including the Special Sensor Microwave/Imager, or SSM/I, used by the Defense Meteorological Satellite Program, NASA’s Aqua Earth observing satellite and the National Oceanic and Atmospheric Administration’s polar orbiting series of satellites.
For now, the
study is a good example of data that is needed as policymakers attempt to prepare for the potential negative effects of global warming, said Sharon Burke, senior fellow with Center for a New American Security. National security officials, top retired military officers and organizations such as the Center for a New American Security and Center for Strategic and International Studies all have warned over the past year that global warming could trigger mass migration, famine and political unrest in developed and developing nations.
Burke, who coordinates “war game” exercises designed to help policymakers understand and prepare for global warming’s possible impact, said her searches for detailed information often reveal gaps in information. The study’s combination of climate predictions and social impacts makes it unique, she said.
“That kind of information is in short supply,” Burke said. “There are so many aspects, especially adapting to climate change where we just don’t have enough research. … It’s important to know what the application for this kind of study is and how to put that scientific knowledge into policy terms.”