On average, the U.S. is 2 degrees Fahrenheit warmer than it was 40 years ago.
Twice as many record highs have been set in the past decade as record lows in the U.S.
By 2050, record highs could outpace record lows by 20-to-1 in the U.S. By the end of the century, the ratio could jump to 100-to-1 if greenhouse gas emissions continue unabated.
A warmer world increases the odds of extreme precipitation, in part because a warmer atmosphere can hold more moisture and release more of it during rainstorms and snowstorms.
Heavy precipitation, both rain and snow, is happening more often than it used to.
Heat-related extreme events are on the rise around the globe, and climate change has increased significantly the odds of some specific events, including the killer European heat wave of 2003 and the Russian heat wave of 2010.
Source: Climate Central research organization
A string of 100-plus-degree days is scorching the region.
Record-breaking heat burned 16 Tennessee counties and broke 25 heat records in 2011. The same year had record-breaking rainfall in 21 counties and a total of 27 broken rainfall records, along with seven more broken snowfall records.
Extreme drought and landmark wildfires descended last year on Georgia.
It's not random, and it's not a fluke, according to experts. It's climate change.
And in East Tennessee it's going to get even hotter -- perhaps hotter than the rest of the planet.
"Based on the various models we have in hand, we know this area is expected to heat up actually more than the entire globe is," said Gregory Vickrey, director of the North Chickamauga Creek Conservancy. "If the average ambient temperature of the globe is going to be a minimum of 2 degrees Celsius higher, we're going to face 2.8 degrees Celsius higher here -- just in East Tennessee."
That's just over 5 degrees Fahrenheit.
While 0.8 of a degree Celsius doesn't sound like much, it can have far-reaching impacts.
Wildlife will migrate differently in an effort to survive. Crops that once flourished will wither under bouts of heat, flood and drought. Because of that, the cost to plant, grow and successfully harvest them will rise, and could lead to a price hike at the grocery store.
Industrial and power plants that use river and stream water for cooling will have to make adjustments as river flows and temperatures change. Wildfire and extreme weather disasters such as the 2010 Nashville flood and the 2011 spring tornadoes in the Chattanooga area will be more prevalent.
Those possible scenarios combined with the actual numbers of record heat, rainfall, drought and snowfall have gotten the attention of local groups, agencies and governments. And they're not just aware of the situation; they're taking action by inventorying the plants and animals there now.
But one question keeps popping up.
In general, according to Texas Tech climatologist Katherine Hayhoe, who has done climate-modeling studies at the school, many midlatitude areas are expected to warm faster -- and Tennessee, North Georgia and North Alabama are midlatitude.
Vickrey's group made the East Tennessee extrapolations using a free program on the Internet -- Climate Wizard -- that is based on the work of the Intergovernmental Panel on Climate Change, a group Hayhoe calls "the highest authority in the climate world."
Hayhoe said the program's extrapolations are based on three factors: global human activities and energy use, how the climate will respond to those and how conditions in East Tennessee, or any study area, have behaved in relation to global conditions in the past.
The program is "a great visual tool that I advocate because it helps us see how the choices we make affect us right where we live in the places we love," she said.
With the software, the North Chickamauga Creek Conservancy found that predicted changes in weather conditions may "force the humidity that's sitting over the Gulf [of Mexico] up in this area more," said Vickrey, who worked as a consultant and activist on climate issues for three years before coming to the conservancy.
"It's going to make it far more intense for this part of the world," he said.
One recent study, "Killer Summer Heat" by the National Resources Defense Council, predicts that more than 150,000 Americans could die by the end of this century because of excessive heat caused by climate change. The study predicts rising temperatures could cause more than 10,000 additional heat-related deaths in Memphis by 2099.
"Since preindustrial times, we're already up 1 degree Celsius, and we see the havoc it's wreaking weatherwise around the world," Vickrey said. "We see what it's doing to the polar ice caps. We see how species are more apt to move more frequently than they have been in the past. We see more invasive species."
The conservancy isn't waiting for more evidence. With 140 square miles of land in ownership and easements, the group is undertaking a comprehensive inventory of plants and animals. Vickrey thinks of it as a baseline and model for future study of climate adaptation.
"Even though we're a small organization, we feel like if we can integrate that into our planning, and that it will be something we can pass on to other organizations and ask them to do the same," he said.
A 2010 progress report of the nation's Interagency Climate Change Adaptation Task Force, convened in 2009 by the Obama administration, says the scope, severity and pace of future climate change impacts are difficult to predict.
"However, observations and long-term scientific trends indicate ... projected impacts include more frequent heat waves and high-intensity precipitation events, rising sea levels, ocean acidification, and more prolonged droughts," the report states. "The year-round average air temperature in the United States has already risen by more than 2 degrees F over the past 50 years and is projected to increase further in the future. On average, wet areas of the United States will become wetter and dry areas will become drier."
To prepare, federal agencies -- including leading carbon dioxide producer Tennessee Valley Authority -- have been preparing a climate change adaptation action plan for the President's Executive Office of Management and Budget. The reports were due Saturday.
TVA is the nation's largest public power company, serving 8.7 million residents of the Tennessee Valley. One of its 11 coal-fired power plants, Cumberland Fossil Plant northwest of Nashville, ranked eighth in the nation in carbon dioxide emissions in 2007.
But TVA's John Myers, director of environmental policy and regulatory affairs, said the utility has reduced its carbon emissions overall by 24 percent since 2008. Myers said the OMB's first-ever required report asks federal agencies to look at both their risks and opportunities in light of climate change, and the report likely will be made public in a couple of months.
As an electricity provider, TVA, with its many coal plants, had to prepare that report with two things in mind: carbon reduction plans and power generation plans.
"We've already done a lot to reduce our CO2 [by 24 percent since 2008] as we reduced coal generating plants," Myers said. "And one of our key areas is a reliable electric supply as we look at hotter, wetter and drier times."
He said TVA took lessons from the 2011 spring tornadoes that ripped apart the transmission grid in Alabama and Mississippi and strengthened its power-delivery system, and also has taken actions to reduce its "water footprint" -- the amount of water that coal and nuclear plants take from rivers for power production and cooling.
Tennessee, Georgia and Alabama wildlife and environment regulatory groups also have prepared reports for their respective state officials about the effects of higher temperatures.
"Tennessee's wildlife and natural resources face a serious threat from climate change," according to a factsheet from the Tennessee Wildlife Resources Agency.
The state stands to lose high elevation forest trees, brook trout and migratory songbirds while suffering larger floods and longer droughts, TWRA states.
Georgia's report, from a consultant, said that, in addition to losing crops and facing storm costs on its extensive rail, highway and airline transportation infrastructures, the state could lose billions of dollars and 5,000 jobs to a projected 20-inch rise in sea level along its 100-mile coastline.
Alabama can expect similar changes, according to factsheets by the U.S. Environmental Protection Agency.
Like Vickrey, many environmental activists are concerned that the region and the country are being lulled by reports, not real change.
The real key, according to Steven Smith, a veterinarian who in 1985 formed the Southern Alliance for Clean Energy, is energy efficiency -- not carbon-free, but not waste-free either nuclear power, as TVA's president and CEO Tom Kilgore and Sen. Lamar Alexander have suggested.
"Global climate change is so serious that all energy needs to be brought up and considered," Smith said. "The problem is nuclear power, when compared with other options, in my view doesn't move to the front of the list. It's so costly and risky it moves, in my view, to the back of the list. And energy efficiency should move to the front of list. Conservation makes most sense."
Water, too, is a concern.
On Thursday, the Southern Alliance for Clean Energy and several other groups presented a report by the River Network, a conservation group, about the amount of water used to produce electricity. The report said producing the amount of electricity used by the average U.S. household took five times the amount of water used by that household in a month.
Smith said his frustration, though, isn't just with utilities and politicians. Many people are saying that global warming isn't real even though numbers and trends are clearly identifiable.
"We don't have another planet to migrate to, yet people fall into these petty, politically minded arguments," he said. "At what point do people begin to say, 'Look -- we have to do something'?"
But Hayhoe said local region studies like the one by the North Chickamauga Creek Conservancy can help local communities begin talking about adaptation.
"We often think of climate change as this global issue, and we think it's removed from our everyday life, but it isn't," she said. "That's why studies like this one are very important. We as individuals control 40 percent of the nation's emissions. So our choices really do make a difference."