Climates that have existed in some parts of Earth may disappear, while novel new types of climate could develop in other areas as the planet continues to warm, according to a new study.
Such changes could endanger plants and animals living in affected areas, although there also may be new opportunities in some regions, explained John Williams, an assistant professor of geography at the University of Wisconsin, Madison.
Using global change forecasts prepared for the Intergovernmental Panel on Climate Change, a team of researchers led by Williams used computer models to estimate how climates in various parts of the world would be affected. Their findings are being published in this week's online edition of Proceedings of the National Academy of Sciences.
The IPCC, representing the world's leading climate scientists, reported in February that "warming of the climate system is unequivocal, as is now evident from observation of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.''
Tropical regions in particular may face unexpected changes, particularly the rain forests in the Amazon and Indonesia, Williams' researchers concluded.
This was surprising, Williams said in a telephone interview, since the tropics tend to have little variation in weather.
That also means that temperature changes of one or two degrees Celsius in these regions might have more impact than a change of three or four degrees in a region that is accustomed to regular changes.
Species living in tropical areas may be less able to adapt, he said, but said that is speculative and needs further study.
Areas like the southeastern United States and the Arabian peninsula might also be affected, the researchers said.
And they said mountain areas such as in Peruvian and Colombian Andes and regions such as Siberia and southern Australia face a risk of climates disappearing altogether.
That does not mean these regions would have no climate at all, rather that their climate would change and the conditions currently in these areas would not occur elsewhere on Earth.
That would pose a risk to species living in those areas, Williams observed.
If some regions should develop new climates that do not now exist, that might provide an opportunity for species that live there, Williams said. "But we can't make a prediction, because it's outside our current experience and outside the experience of these species,'' he said.
Alan Robock, a professor of environmental sciences at Rutgers University, welcomed the report, calling it the first he has seen "that not only looks at species extinctions, but also looks at regions where novel climates will appear.''
"While the idea of novel climates may seem like a positive consequence of humans using the atmosphere as a sewer and causing rapid, unprecedented climate change, I would argue that mitigation of our pollution should be an even stronger reaction to these results,'' said Robock, who was not part of the research team.
"The potential consequences and how these new regimes will be populated are poorly known, and the potential for new threats to humans through disease vectors could be a real danger,'' he said.
