Newswise — While melting Arctic sea ice and glaciers have become a symbol of climate change, new research from the University of Massachusetts Amherst indicates that highland forests in Costa Rica could also be seriously affected by future changes in climate, reducing the number of species in a region famous for its biodiversity.
"Central America is a major, emerging "hot spot" in the tropics where climate change impacts on the environment will be pronounced, and the loss of species associated with climate has already been identified," says doctoral candidate Ambarish Karmalkar of the UMass Amherst Climate System Research Center. He recently attended the first conference organized in Costa Rica to study this issue. "We have completed a regional climate model showing that many areas of Costa Rica will become warmer and drier as climate change accelerates, and these changes will be amplified at higher elevations."
Additional members of the research team include Raymond Bradley, a professor of geosciences at UMass Amherst, and Henry Diaz of the National Oceanic and Atmospheric Administration. According to Karmalkar, Costa Rica has a unique geography that supports a stunning array of plants, animals and insects. The land begins at sea level on both the western Pacific coast and the eastern Caribbean coast, rising to over 3,000 meters above sea level in the central mountain range. As the land rises, differences in temperature and precipitation caused by elevation create an array of distinct ecosystems stacked on top of each other, each one housing a unique biological community.
Above 1,000 meters, rising air creates a continual cloud layer that constantly bathes the vegetation in horizontal precipitation, allowing plants and animals to survive the dry season from December to April. These cloud forests are essential to maintaining freshwater resources in Costa Rica, and the height at which the clouds develop is a critical factor for these ecosystems. Since they are highly dependant on temperature and precipitation, these ecosystems are particularly vulnerable to climate change.
To predict the effects of climate change, a regional modeling system capable of accommodating the complex topography of Central America was chosen. After validating the computer model using rainfall and temperature data collected in Central America between 1961 and 1990, the team looked at what would happen if carbon dioxide in the atmosphere doubled. The results of this medium-to-high scenario, called the A2 scenario in reports issued by the Intergovernmental Panel on Climate Change, were striking.
"If carbon dioxide levels double, this region will not only experience an increase in temperature of more than three Kelvins, but all future temperatures will likely be higher than the complete range of present-day temperatures," says Karmalkar. "In addition, the model simulation indicates that high elevation Pacific slopes and the Caribbean lowlands will receive up to 30 percent less precipitation. Simulations also indicate an overall increase in the height of the cloud base of up to 300 meters."
According to Karmalkar, as temperatures rise, various ecosystems will try to migrate to where they are comfortable, moving in an upslope direction in this case. As they migrate, plants and animals will disturb other species, and eventually run out of space as they reach the top of the mountains. The result may be a loss of many species that can't survive the new conditions.
"After the extinction of the golden toad sometime between 1987 and 1989, corresponding with a warm event in the Pacific Ocean, scientists began relating climate change to the loss of biodiversity in Costa Rica," says Karmalkar. "Since then, the Monteverde Institute has been documenting biological changes that could be related to climate change."
Karmalkar plans to study the entire region of Central America, determining large climate dynamics of the region and how that will change in the future. "Central America has a unique annual cycle of precipitation, with a midsummer drought that occurs during July and August," says Karmalkar. "Knowing how climate change will affect this cycle will be important for agriculture, which is an integral part of the economy of the region."
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Geophysical Research Letters, June 2008 (Jun-2008)