Editor's note: This article is the last of a three-part series by John Carey. Part 1, "Storm Warning: Extreme Weather Is a Product of Climate Change," was posted on June 28. Part 2, "Global Warming and the Science of Extreme Weather," was posted on June 29.

Extreme weather events have become both more common and more intense. And increasingly, scientists have been able to pin at least part of the blame on humankind's alteration of the climate. What's more, the growing success of this nascent science of climate attribution (finding the telltale fingerprints of climate change in extreme events) means that researchers have more confidence in their climate models—which predict that the future will be even more extreme.

Are we prepared for this future? Not yet. Indeed, the trend is in the other direction, especially in Washington, D.C., where a number of members of Congress even argue that climate change itself is a hoax.

Scientists hope that rigorously identifying climate change's contribution to individual extreme events can indeed wake people up to the threat. As the research advances, it should be possible to say that two extra inches (five centimeters) of rain poured down in a Midwestern storm because of greenhouse gases, or that a California heat wave was 10 times more likely to occur thanks to humans' impacts on climate. So researchers have set up rapid response teams to assess climate change's contribution to extreme events while the events are still fresh in people's minds. In addition, the Intergovernmental Panel on Climate Change (IPCC) is preparing a special report on extreme events and disasters, due out by the end of 2011. "It is important for us emphasize that climate change and its impacts are not off in the future, but are here and now," explained Rajendra Pachauri, chair of the IPCC, during a briefing at United Nations climate talks in Cancún last December.

The message is beginning to sink in. The Russian government, for instance, used to doubt the existence of climate change, or argue that it might be beneficial for Russia. But now, government officials have realized that global warming will not bring a gradual and benign increase in temperatures. Instead, they're likely to see more crippling heat waves. As Russian President Dmitry Medvedev told the Security Council of the Russian Federation last summer: "Everyone is talking about climate change now. Unfortunately, what is happening now in our central regions is evidence of this global climate change, because we have never in our history faced such weather conditions."

Doubts persist despite evidence

Among the U.S. public, the feeling is different. Opinion pollsand anecdotal reports show that most Americans do not perceive a threat from climate change. And a sizable number of Americans, including many newly elected members of Congress, do not even believe that climate change exists. Extreme weather? Just part of nature, they say. After all, disastrous floods and droughts go back to the days of Noah and Moses. Why should today's disasters be any different? Was the July 23, 2010, storm that spawned Les Scott's record hailstone evidence of a changing climate, for instance? "Not really," Scott says. "It was just another thunderstorm. We get awful bad blizzards that are a lot worse."

And yes, 22 of Maryland's 23 counties were declared natural disaster areas after record-setting heat and drought in 2010. "It was the worst corn crop I ever had," says fourth-generation farmer Earl "Buddy" Hance. But was it a harbinger of a more worrisome future? Probably not, says Hance, the state's secretary of agriculture. "As farmers we are skeptical, and we need to see a little more. And if it does turn out to be climate change, farmers would adapt." By then, adaptation could be really difficult, frets Minnesota organic farmer Jack Hedin, whose efforts to raise the alarm are "falling on deaf ears," he laments.

Many scientists share Hedin's worry. "The real honest message is that while there is debate about how much extreme weather climate change is inducing now, there is very little debate about its effect in the future," says Michael Wehner, staff scientist at Lawrence Berkeley National Laboratory and member of the lead author teams of the interagency U.S. Climate Change Science Program's Synthesis and Assessment reports on climate extremes. For instance, climate models predict that by 2050 Russia will have warmed up so much that every summer will be as warm as the disastrous heat wave it just experienced, says Richard Seager of Columbia University's Lamont–Doherty Earth Observatory. In other words, many of today's extremes will become tomorrow's everyday reality. "Climate change will throw some significant hardballs at us," says Martin Hoerling, a research meteorologist at the National Oceanic and Atmospheric Administration's Earth System Research Laboratory in Boulder, Colo. "There will be a lot of surprises that we are not adapted to."

A dusty future

One of the clearest pictures of this future is emerging for the U.S. Southwest and a similar meteorological zone that stretches across Italy, Greece and Turkey. Work by Tim Barnett of the Scripps Institution of Oceanography, Seager and others predicts that these regions will get hotter and drier—and, perhaps more important, shows that the change has already begun. "The signal of a human influence on climate pops up in 1985, then marches on getting strong and stronger," Barnett says. By the middle of the 21st century, the models predict, the climate will be as dry as the seven-year long Dust Bowl drought of the 1930s or the damaging 1950s drought centered in California and Mexico, Seager says: "In the future the drought won't last just seven years. It will be the new norm."

That spells trouble. In the Southwest the main worry is water—water that makes cities like Los Angeles and Las Vegas possible and that irrigates the enormously productive farms of California's Central Valley. Supplies are already tight. During the current 11-year dry spell, the demand for water from the vast Colorado River system, which provides water to 30 million people and irrigates four million acres (1.6 million hectares) of cropland, has exceeded the supply. The result: water levels in the giant Lake Mead reservoir dropped to a record low in October (before climbing one foot, or 30 centimeters, after torrential winter rains in California reduced the demand for Colorado River water). Climate change will just make the problem worse. "The challenge will be great," says Terry Fulp, deputy regional director of the U.S. Department of the Interior's Bureau of Reclamation's Lower Colorado Region. "I rank climate change as probably my largest concern. When I'm out on my boat on Lake Mead, it's on my mind all the time."

The Southwest is just a snapshot of the challenges ahead. Imagine the potential peril to regions around the world, scientists say. "Our civilization is based on a stable base climate—it doesn't take very much change to raise hell," Scripps's Barnett says. And given the lag in the planet's response to the greenhouse gases already in the atmosphere, many of these changes are coming whether we like them or not. "It's sort of like that Kung Fu guy who said, 'I'm going to kick your head off now, and there's not a damn thing you can do about it,'" Barnett says.

Grassroots action

Although efforts to fight climate change are now stalled in Washington, many regions do see the threat and are taking action both to adapt to the future changes and to try to limit the amount of global warming itself. The Bureau of Reclamation's Lower Colorado Region office, for instance, has developed a plan to make "manageable" cuts in the amounts of water that the river system supplies, which Fulp hopes will be enough to get the region through the next 15 years. In Canada, after experiencing eight extreme storms (of more than one-in-25-year intensity) between 1986 and 2006, Toronto has spent hundreds of millions of dollars to upgrade its sewer and storm water system for handling deluges. "Improved storm drains are the cornerstone of our climate adaptation policy," explains Michael D'Andrea, Toronto's director of water infrastructure management.

In Iowa, even without admitting that climate change is real, farmers are acting as if it is, spending millions of dollars to alter their practices. They are adding tile drainage to their fields to cope with increased floods, buying bigger machinery to move more quickly because their planting window has become shorter, planting a month earlier than they did 50 years ago, and sowing twice as many corn plants per acre to exploit the additional moisture, says Gene Takle, professor of meteorology at Iowa State University in Ames. "Iowa's floods are in your face—and in your basement—evidence that the climate has changed, and the farmers are adapting," he says.

Local officials have seen the connection, too. After the huge floods of 2008, the Iowa town of Cedar Falls passed an ordinance requiring that anyone who lives in the 500-year flood plain must have flood insurance—up from the previous 200-year flood requirement. State Sen. Robert Hogg wants to make the policy statewide. He also is pushing to restore wetlands that can help soak up floodwaters before they devastate cities. "Wetland restoration costs money, but it's cheaper than rebuilding Cedar Rapids," he says. "I like to say that dealing with climate change is not going to require the greatest sacrifices, but it is going to require the greatest foresight Americans have ever had."

Right now, that foresight is more myopia, many scientists worry. So when and how will people finally understand that far more is needed? It may require more flooded basements, more searing heat waves, more water shortages or crop failures, more devastating hurricanes or other examples of the increases in extreme weather that climate change will bring. "I don't want to root for bad things to happen, but that's what it will take," says one government scientist who asked not to be identified. Or as Nashville resident Rich Hays says about his own experience with the May 2010 deluge: "The flood was definitely a wake-up call. The question is: How many wake-up calls do we need?"

Reporting for this story was funded by the Pew Center on Global Climate Change.