Today's heat may be tomorrow's balmy weather, and while the Southeast may have more rain, it could come in such downpours the region still would face severe seasonal droughts like that of 2007.
The region's eastern hemlocks will disappear, along with fish such as Tennessee's brook trout and North Georgia's blue shiner. Hardwood forests will contain fewer oaks and more pines, and woodlands gradually could become more like savannas, as catastrophic fires become common.
These forecasts are part of new state and national reports released last month. Both reports say climate change spells significant challenges for landscapes, wildlife and people in Tennessee, Georgia and the entire Southeast.
"We need to understand climate change impacts are no longer hypothetical," said Dr. Thomas J. Wilbanks, a corporate research fellow at Oak Ridge National Laboratory and an author of the national report, "Global Climate Change Impacts in the United States."
The report, called "a game changer" by officials of the U.S. Environmental Protection Agency, is the first of its kind to state and document that climate change has begun.
"How we are by 2070 and 2080 will be determined by what we do between now and 2030," Dr. Wilbanks said Thursday. "We need to be well on the way to a solution in 20 years, or we will be putting our grandchildren in a situation where they will have to live in a very different world."
Tennessee and Georgia officials also are concerned.
"It could change the way the area looks," but the temperature and moisture changes will have more serious impacts that can't be seen, said Mark Thurman, a Tennessee Wildlife Resources Agency wildlife biologist and conservation planner in the Crossville, Tenn., office. Mr. Thurman helped write a new Tennessee report: "Climate Change and Potential Impacts to Wildlife in Tennessee."
With seasonal droughts and downpours expected to increase, water conservation "is a big issue for us," Mr. Thurman said.
"Anytime you start talking about drought, it touches home with everybody," he said. "A couple of summers ago on the Cumberland plateau, we had people running out of water."
Another unseen impact could be the bats in Tennessee's 9,000 caves.
"Some of those caves have Indiana bats, a federally listed bat," Mr. Thurman said. "The bats eat mosquitos and other insects, but they also are mammals like us. You have to say that, if our environment is becoming less suitable for another mammal, what does that mean for us?"
Jon Ambrose, assistant chief of the non-game conservation section in the Wildlife Resources Division of Georgia's Department of Natural Resources, said Georgia also will lose brook trout and other wildlife common to the cool mountain moisture of the Blue Ridge Mountains, the base of the Appalachians in North Georgia.
"We all realize climate change is going to be a complex issue to deal with," he said. "It's very important for state agencies and other organizations to take a good, long look at it."
Georgia, for instance, will take hard looks at expected weather changes in the Peach State's 2010 state wildlife action plan, he said.
The national report shows the annual average temperature in the Southeast has risen 2 degrees Fahrenheit since 1970, with the greatest seasonal increase in the winter months.
Records also show summer precipitation has decreased over almost the entire region, and the percentage of the Southeast in moderate to severe drought increased over the past three decades, according to the report.
At the same time, however, there has been an increase in heavy downpours and a 30 percent increase in fall precipitation over most of the region. Most of the Southeast's rain falls in autumn, and such heavy downpours can produce flooding.
Researchers say it will get worse.
"Continued warming is projected, with the greatest temperature increases in summer," the national report says. "The number of very hot days is projected to rise at a faster rate than average temperatures."
Average annual temperatures in the Southeast are projected to rise 4.5 degrees to 9 degrees, with a 10.5-degree increase in summer and a much higher heat index, according to the report. Sea-level rise is projected to accelerate, increasing coastal flooding and shoreline retreat.
The intensity of hurricanes is likely to increase, with higher wind speeds, rainfall intensity, and storm surge height and strength, the report says. The Southeast -- known as one of the most biologically rich regions of the nation with its many rivers -- has much to lose. And some of the loss will be land, according to the report.
Perhaps the most dramatic, Dr. Wilbanks said, is the expectation that, by 2050, the Gulf Coast between Galveston, Texas, and Mobile, Ala., will see a two- to four-foot rise in sea level as land sinks at the same time the sea rises.
"This is a serious economical impact with all of the industry there," Dr. Wilbanks said.
"We need to look at what actions we need to take," he said. "And we need to look at mitigation and adaptation at the same time together. We need to do whatever it takes ... that is safe."
n Projected increases in air and water temperatures will cause heat-related stresses for people, plants and animals.
n Decreased water availability is very likely to affect the region's economy as well as its natural systems.
n Sea-level rise and the likely increase in hurricane intensity and associated storm surge will be among the most serious consequences of climate change.
n Ecological thresholds are likely to be crossed throughout the region, causing major disruptions to ecosystems and to the benefits they provide to people.
n Quality of life will be affected by increasing heat stress, water scarcity, severe weather events and reduced availability of insurance for at-risk properties.
Source: Global Change Research Program