Global warming could dry Caribbean, Central America
Rhett A. Butler, mongabay.com
April 14, 2006
Parts of the Caribbean and Central America are likely to experience drier summers by 2050 according to research presented by UCLA atmospheric scientists in the April 18 issue of Proceedings of the National Academy of Sciences (PNAS).
Analyzing 10 global climate computer simulations from various agencies, the researchers found that the majority of the computer models predict a substantial decrease in tropical rainfall to occur by mid-century. By the end of this century, the models show that summer rainfall could decline by 20 percent or more in parts of the Caribbean and Central America. However, the models project little change in winter rainfall in the region said J. David Neelin, UCLA professor of atmospheric and oceanic sciences and lead author of the study. By the end of this century, the models call for a decrease in summer rainfall of 20 percent or more in parts of the Caribbean and Central America.
“The regions in the tropics that get a lot of summer precipitation are going to get more, and the regions that get very little precipitation will get even less, if the models are correct,” Neelin said. “Certain regions in between will get shifted from a moderate amount of precipitation to a low amount. The bigger the temperature rise, the larger the change in precipitation.”
Roatan, Honduras. Photo by R. Butler
While climate change is the likely culprit fueling the projected decline in rainfall, Neelin cautioned that precipitation changes resulting global warming are more difficult to tie to global climate than changes in temperature, which can be easily measured.
“Precipitation change is much more difficult than temperature change to detect, and requires great precision; the models do not all agree, but the majority of them do,” Neelin said. “A slight error — for example, whether the wind is flowing from a dry region into the convection zone, or whether the wind is blowing past the convection zone without going into it — can cause one model to have a drought in a particular region, while another model does not. You have to be careful when talking about precipitation; there is natural variability, from year to year and from decade-to-decade.”
Drier weather could worsen summertime droughts in the region and leave forests more susceptible to wildfires and fires set for land-clearing.
Scholars believe changes in levels of precipitation has played a significant role in the human history of Central America. Some archeologists tie the downfall of classical Maya civilization to a combination of deforestation and drought which reduced the viability of agriculture in the region.
Hundreds of fires are burning across Central America according to NASA satellite images and reports from the ground. Fires have been detected in Mexico, Guatemala, El Salvador, Honduras, and Nicaragua. Every spring farmers use fires to clear thousands of hectares of forest and scrub land for agricultural use. Burning vegetation not only makes land available for planting but releases enough nutrients to support vigorous crop growth for the season. However, as generally practiced, such techniques are associated with erosion and biodiversity loss.
After experiencing one of the most devastating coral bleaching events on record during September and October of 2005, reefs in the Caribbean are under attack from deadly diseases according to Reuters. According to scientists in Puerto Rico, bleaching was both widespread and intense with colonies representing 42 species completely white in many reefs. Surveys show 85 to 95 percent of coral colonies were bleached in some areas, while reefs in Grenada suffered close to 70 percent bleaching in some areas. Reefs in the British and American Virgin Islands were affected to a lesser extent.
This article used press materials from the UCLA