Friday, February 13, 2009

Tenacious drought in Latin America

IPS, via Tierramérica: For months now, yellowed pastures, cracked soil and dead livestock have been the landscape of what otherwise are the most productive farming areas of Argentina, Brazil, Paraguay and Uruguay. Scientists say it is so far impossible to determine if the drought is a manifestation of climate change processes. "Climate change cannot be characterised by one single event, but rather by a series over the long term," University of Buenos Aires climatologist Vicente Barros, member of the Intergovernmental Panel on Climate Change (IPCC), told Tierramérica.

Some experts believe the lack of rain could be related to the influence of La Niña, the cool phase of the cyclical climate event known as El Niño/Southern Oscillation, which changes the surface temperature of equatorial Pacific Ocean currents and affects the region's climate. "La Niña is still very strong and the forecasting models aren't adjusted to reflect the disturbances it causes," agricultural engineer Eduardo Sierra, an Argentina climate expert, finds himself explaining to someone almost daily.

In 2007, the IPCC and former U.S. vice-president Al Gore won the Nobel Peace Prize for their contribution to building knowledge and raising awareness among the public about climate change over the past two decades.…Barros, along with experts José Marengo of Brazil and Madeleine Renom of Uruguay, told Tierramérica that it is impossible to assert that the current drought is an unequivocal manifestation of climate change, because the weather changes must be assessed over the long term.

The three agree that "what can be attributed to climate change is the greater climate variability, like fluctuations in the maximum and minimum rainfall, and the greater frequency, and in some cases the intensity, of extreme phenomena," summarised Renom, meteorologist and professor at the University of the Republic of Uruguay….

A cool-water anomaly known as La Niña occupied the tropical Pacific Ocean throughout 2007 and early 2008. In April 2008, scientists at NASA’s Jet Propulsion Laboratory announced that while the La Niña was weakening, the Pacific Decadal Oscillation—a larger-scale, slower-cycling ocean pattern—had shifted to its cool phase. This NASA image shows the sea surface temperature anomaly in the Pacific Ocean from April 14–21, 2008. The anomaly compares the recent temperatures measured by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on NASA’s Aqua satellite with an average of data collected by the NOAA Pathfinder satellites from 1985–1997. Places where the Pacific was cooler than normal are blue, places where temperatures were average are white, and places where the ocean was warmer than normal are red.

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