Global Warming Predicted to Create Novel Climates

LARAMIE, Wyoming, March 27, 2007 (ENS) - Many current climate zones will vanish entirely by the year 2100, replaced by climates unknown today, according to new global warming research. The greatest changes are predicted for Amazonian and Indonesian rainforests, but areas such as the southeastern and western United States, northwestern Australia, and the Arabian Peninsula also would be affected.

Tropical and subtropical regions would experience new climates if current global warming trends continue, found University of Wyoming Professor Steve Jackson and his colleagues at the University of Wisconsin. The scientists assessed the risk of novel and disappearing climates during the next 100 years.

University of Wyoming botany professor Steve Jackson (Photo courtesy U. Wyoming)
"The frightening thing about our analysis is that it shows that climate change will take us into uncharted waters," says Jackson, a professor in the University of Wyoming Department of Botany who specializes in the ecological consequences of climate change.

Jackson conducted the study with University of Wisconsin professor of atmospheric and oceanic sciences John Kutzbach and geographer Jack Williams.

The scientists used climate models and greenhouse gas emission scenarios from the most recent assessment by the Intergovernmental Panel on Climate Change released in February.

They found that under both the high-end and low-end emissions scenarios, many regions would experience climate changes large enough to drive major ecological transformations - pine forest would turn into grassland, or rainforest would become savanna.
Williams likens today's environmental analysts to 15th century European mapmakers confronted with the New World, struggling to chart unknown territory.

"We want to identify the regions of the world where climate change will result in climates unlike any today," Williams says. "These are the areas beyond our map."

"In a few decades, climates in many areas will be unlike any in our current experience," Jackson said. "That poses huge challenges for predicting economic, agricultural, and ecological consequences."


Wyoming grasslands would be at greater risk of droughts if climate change continues. (Photo courtesy Wyoming Land Rush)
He says that under the high-end scenario, the entire American West, including Wyoming, will experience climate changes of sufficient magnitude to disrupt existing ecological communities.

"The entire region is projected to experience higher temperatures in both summer and winter, drier in the summer, and wetter in the winter," Jackson says. "The higher temperatures and drier summers could increase Wyoming's risk of drought and wildfires."

Changes will occur so quickly that it will be difficult to prepare for them, he says.

"This work helps highlight the significance of changes in the tropics," complementing the extensive attention already focused on the Arctic, said Kutzbach. "There has been so much emphasis on high latitudes because the absolute temperature changes are larger."

However, Kutzbach explains, normal seasonal fluctuations in temperature and rainfall are smaller in the tropics, and even "small absolute changes may be large relative to normal variability."

"The rapid rate of change will be disruptive. Some changes may be beneficial in some places. For example, there could be more water available in some areas," Jackson says. "But many of the changes will be unpleasant and disruptive. Most ecosystems aren't geared to adapt to rapid changes of this magnitude."

Tropical mountains and near polar regions such as the Peruvian and Colombian Andes, Siberia, South Africa, and southern Australia face a risk that their existing climates will disappear altogether.


The Amazon rainforest, already imperiled by logging and land clearing for agriculture and ranching, would be completely changed if global warming continues. (Photo courtesy WWF)
The researchers found that existing climates will disappear from as much as 48 percent of the terrestrial globe; novel climates will develop in up to 39 percent of the Earth's land mass, and these changes are generally concentrated in the tropics - the places of highest biodiversity and ecosystem complexity.

Many regions facing the disappearance of their existing climates have been identified as biodiversity hotspots, suggesting that standard conservation solutions may fail to protect biodiversity in these areas.

"Many species will have no place to go," Jackson says.

Physical restrictions on species may also amplify the effects of local climate changes. The more relevant question, Williams says, becomes not just whether a given climate still exists, but "will a species be able to keep up with its climatic zone? Most species can't migrate around the world."

The work was funded by the National Science Foundation and the findings were published Monday in the "Proceedings of the National Academy of Sciences."

The new study confirms findings published in March 2006 by the global conservation organization WWF, which asserted that "climate change and deforestation could convert the majority of the Amazon rainforest into savannah, with massive impacts on the world's biodiversity and climate."

"Such changes would result in significant shifts in ecosystem types - from tropical forest to dry savannah - and loss of species in many parts of the Amazon," WWF said.

"A changing climate poses a substantial threat to the Amazon forests, which contain a large portion of the world's biodiversity," said Beatrix Richards, forests expert at WWF. "Threats here translate into threats to biodiversity at large. The world needs to urgently evaluate vulnerability to climate risks and integrate them into biodiversity conservation efforts."