washingtonpost.com
Global Warming Did It! Well, Maybe Not.
We're stuck on the notion that climate change is the culprit every time a natural disaster strikes. But that's just muddying the waters.

By Joel Achenbach
Sunday, August 3, 2008

We're heading into the heart of hurricane season, and any day now, a storm will barrel toward the United States, inspiring all the TV weather reporters to find a beach where they can lash themselves to a palm tree. We can be certain of two things: First, we'll be told that the wind is blowing very hard and the surf is up. Second, some expert will tell us that this storm might be a harbinger of global warming.

Somewhere along the line, global warming became the explanation for everything. Right-thinking people are not supposed to discuss any meteorological or geophysical event -- a hurricane, a wildfire, a heat wave, a drought, a flood, a blizzard, a tornado, a lightning strike, an unfamiliar breeze, a strange tingling on the neck -- without immediately invoking the climate crisis. It causes earthquakes, plagues and backyard gardening disappointments. Weird fungus on your tomato plants? Classic sign of global warming.

You are permitted to note, as a parenthetical, that no single weather calamity can be ascribed with absolute certainty (roll your eyes here to signal the exasperating fussiness of scientists) to what humans are doing to the atmosphere. But your tone will make it clear that this is just legalese, like the fine-print warnings on the flip side of a Lipitor ad.

Some people are impatient with even a token amount of equivocation. A science writer for Newsweek recently flat-out declared that this year's floods in the Midwest were the result of climate change, and in the process, she derided the wishy-washy climatologists who couldn't quite bring themselves to reach that conclusion (they "trip over themselves to absolve global warming").

Well, gosh, I dunno. Equivocation isn't a sign of cognitive weakness. Uncertainty is intrinsic to the scientific process, and sometimes you have to have the courage to stand up and say, "Maybe."

Seems to me that it's inherently impossible to prove a causal connection between climate and weather -- they're just two different things. Moreover, the evidence for man-made climate change is solid enough that it doesn't need to be bolstered by iffy claims. Rigorous science is the best weapon for persuading the public that this is a real problem that requires bold action. "Weather alarmism" gives ammunition to global-warming deniers. They're happy to fight on that turf, since they can say that a year with relatively few hurricanes (or a cold snap when you don't expect it) proves that global warming is a myth. As science writer John Tierney put it in the New York Times earlier this year, weather alarmism "leaves climate politics at the mercy of the weather."

There's an ancillary issue here: Global warming threatens to suck all the oxygen out of any discussion of the environment. We wind up giving too little attention to habitat destruction, overfishing, invasive species tagging along with global trade and so on. You don't need a climate model to detect that big oil spill in the Mississippi. That "dead zone" in the Gulf of Mexico -- an oxygen-starved region the size of Massachusetts -- isn't caused by global warming, but by all that fertilizer spread on Midwest cornfields.

Some folks may actually get the notion that the planet will be safe if we all just start driving Priuses. But even if we cured ourselves of our addiction to fossil fuels and stabilized the planet's climate, we'd still have an environmental crisis on our hands. Our fundamental problem is that -- now it's my chance to sound hysterical -- humans are a species out of control. We've been hellbent on wrecking our environment pretty much since the day we figured out how to make fire.

T his caused that: It would be nice if climate and weather were that simple.

But "one can only speak rationally about odds," Kerry Emanuel, a climatologist at the Massachusetts Institute of Technology who has studied hurricanes and climate change, told me last week. "Global warming increases the probabilities of floods and strong hurricanes, and that is all that you can say."

Emanuel's research shows that in the past 25 years, there's been an uptick in the number of strong storms, though not necessarily in the number of hurricanes overall. Climate models show that a 1-degree Celsius rise in sea-surface temperatures should intensify top winds by about 5 percent, which corresponds to a 15 percent increase in destructive power. The tropical Atlantic sea surface has warmed by 0.6 degrees Celsius in the past half-century.

At my request, Emanuel ran a computer program to see how much extra energy Hurricane Katrina had because of increases in sea-surface temperature. His conclusion: Katrina's winds were about 2 percent stronger in the Gulf, and not significantly stronger at landfall. Maybe climate change was a factor in generating such a storm, or in the amount of moisture it carried, but the catastrophe that Katrina caused in New Orleans can more plausibly be attributed to civil engineers who built inadequate levees, city planning that let neighborhoods materialize below sea level and Bush administration officials who didn't do such a heckuva job.

Let's go back to those Iowa floods. Humans surely contributed to the calamity: Farmland in the Midwest has been plumbed with drainage pipes; streams have been straightened; most of the state's wetlands have been engineered out of existence; land set aside for conservation is being put back into corn production to meet the demands of the ethanol boom. This is a landscape that's practically begging to have 500-year floods every decade.

Was climate change a factor in the floods? Maybe. A recent report from the National Oceanic and Atmospheric Administration said that heavier downpours are more likely in a warming world. Thomas Karl, a NOAA scientist, says that there has been a measurable increase in water vapor over parts of the United States and more precipitation in the Midwest.

But tree-ring data indicate that the state has gone through a cycle of increasing and decreasing rainfall for hundreds of years. The downpours this year weren't that unusual, according to Harry J. Hillaker Jr., the Iowa state meteorologist. "The intensity has not really been excessive on a short-term scale," he said. "We're not seeing three-inch-an-hour rainfall amounts."

This will be a wet year (as was last year), but Iowa may not set a rainfall record. The wettest year on record was 1993. The second wettest: 1881. The third wettest: 1902.

Iowa is an awkward place to talk about global warming, because the state has actually been a bit cooler in the summer than it was in the first half of the 20th century. Hillaker says the widespread shift to annual plants (corn and soybeans) and away from perennial grasses has altered the climate. The 10 hottest summers in Iowa have been, in order, 1936, 1934, 1901, 1988, 1983, 1931, 1921, 1955, 1933 and 1913. Talk about extreme weather: One day in 1936, Iowa set a state record with a high temperature of 117 degrees. And no one blamed it on global warming.

Rest assured, we may find ways to ruin the planet even before the worst effects of global warming kick in. The thing that gets you in the end is rarely the thing you're paying attention to.

The basic problem is that there are so many of us now. Four centuries ago, there were about 500 million people on Earth. Today there are that many, plus 6 billion. We're rapidly heading toward 9 billion. Conservatives say that we just need to focus on maintaining free markets and let everything sort itself out through the miracle of the invisible hand. But the political tide is turning against unfettered free markets and toward greater regulation. Climate-change policy is part of that: Somehow we've got to embed environmental effects into the cost of energy sources, consumer goods and so on. The market approach by itself has let us down.

Viewed broadly, it appears that humans are environment-destroying creatures by nature. The notion of the prelapsarian era in which we lived in perfect harmony with nature has been effectively shattered by such scientists as Jared Diamond, the author of "Collapse," and Tim Flannery, who wrote "The Future Eaters." If everything gets simplified and reduced to a global-warming narrative, we'll be unable to see the trees for the forest.

Consider the June issue of Scientific American, where you'll find a photograph of a parched lake, the mud baked into the kind of desiccated tiles that scream "drought." The caption says: "Climate shift to unprecedentedly dry weather, along with diversion of water for irrigation, has converted this former reservoir in China's Minqin County into desert."

Um . . . "this former reservoir?" Look closely, and you can see concrete walls in the background. This is not a natural place: It's a manufactured landscape. Here's a wild guess: This part of China is an environmental disaster that has very little to do with climate change and very much to do with high population and intensifying agriculture.

Last week, we saw reports of more wildfires in California. Sure as night follows day, people will lay some of the blame on climate change. But there's also the minor matter of people building homes in wildfire-susceptible forests, overgrown with vegetation due to decades of fire suppression. That's like pitching a tent on the railroad tracks.

The message that needs to be communicated to these people is: "Your problem is not global warming. Your problem is that you're nuts."

You should definitely worry about global warming. But you don't need to worry about global warming when your house is on fire.

achenbachj@washpost.com

Joel Achenbach is a reporter on The Post's national staff and blogs at washingtonpost.com/achenblog.

View all comments that have been posted about this article.

© 2008 The Washington Post Company