LONDON, July 19 (Xinhua) -- Persistent droughts in North America and around the Mediterranean could be partly due to changing sea surface temperature, according to a study published online Wednesday in the journal Scientific Reports.
To investigate the correlation between sea and land temperatures, researchers from the University of Exeter, University of Montpellier and Wageningen University analysed data from 1957 to 2002.
They found that sea surface temperatures in the North Pacific and North Atlantic became increasingly variable, and extremes lasted for longer.
The changes correlated with increases in land temperature variability, and persistence of extreme temperatures,as ocean temperatures are a major driver of conditions on land, according to the study.
"Our evidence shows that larger and more persistent variations in sea surface temperature have occurred in the North Atlantic and North Pacific and these contributed to more extreme and persistent temperature anomalies on parts of the world's land surface," said Professor Tim Lenton, from the University of Exeter and one of the authors of the study.
The researchers, who systematically scanned monthly temperature data to look for trends, note that such extended periods of high or low temperatures can have an effect "greater than the sum of their parts".
"For instance, a long heatwave can have greater impacts on human mortality than the sum of individual hot days, and multi-year droughts can have greater agricultural economic impacts than the sum of individual dry years," Professor Lenton said.
