Independent UK: Expanding tropics 'a threat to millions'

Expanding tropics 'a threat to millions'
By Steve Connor, Science Editor
Published: 03 December 2007


The tropical belt that girdles the Earth is expanding north and south, which could have dire consequences for large regions of the world where the climate is likely to become more arid or more stormy, scientists have warned in a seminal study published today.

Climate change is having a dramatic impact on the tropics by pushing their boundaries towards the poles at an unprecedented rate not foreseen by computer models, which had predicted this sort of poleward movement only by the end of the century.

The report comes as representatives from 191 countries around the world assemble on the island of Bali in Indonesia, to negotiate a new international treaty to cut down on greenhouse gas emissions. Scientists have found that, during the past 25 years the equatorial region classified as climatologically tropical has expanded polewards by about 172 miles which has meant that a further 8.5 million sq miles of the Earth are now experiencing a tropical climate, compared to 1980.

The scientists warned there are grave implications for the many millions of people living in dry, subtropical regions bordering the tropics, which are at risk of becoming even more arid because of changes to rainfall patterns and wind directions.

"Several lines of evidence show that, during the past few decades, the tropical belt has expanded. This expansion has potentially important implications for subtropical societies and may lead to profound changes to the global climate system," the scientists say in their study published online in the journal Nature Geoscience. ......(more)

The complete piece is at: http://environment.independent.co.uk/climate_change/article3218026.ece