Gregg Easterbrook

“Tornadoes are currently on a frightening upswing.” That could have been written yesterday — but was written 12 years ago, by your columnist, in the November 8, 1999 issue of The New Republic.

The onslaught of tornadoes is not some sudden, unexpected bolt out of the blue. I wrote about tornadoes a dozen years ago because 1998 and 1999 were terrible years for tornadoes. Now three of the last 12 years have been terrible for tornadoes, and the 1950-2010 trend isn’t so great either.

This spring’s tornado activity has been awful. At least 116 people died in Joplin, Missouri, on Sunday during an unusually strong and large tornado. A portion of Tuscaloosa, Alabama was destroyed by a tornado last month. Many tornadoes hit the Ozarks region in April. There were 875 confirmed tornadoes in April, triple the previous April high of 267, in 1974. So far 481 Americans have been killed by tornadoes this spring.

In recent decades, the installation of a Doppler radar warning system in tornado-prone areas has tended to reduce fatalities — sirens get people’s attention. But even 24 minutes of warning, which Joplin received on Sunday, may not be sufficient for a tornado that was a hard-to-believe half a mile across. (The touch-down part of a tornado is rarely more than 100 yards wide.) More disturbing tornado facts are here.

Weather patterns include random variation: some recent years have been mild for tornadoes. Before this spring, the worst tornado sequence in U.S. annals came in 1953, when atmospheric greenhouse gas levels were lower than today. Nevertheless, there are reasons to think tornadoes are a harbinger of climate change.

For years, pundits and politicians have claimed that strong hurricanes prove global warming. In this 2005 speech, Al Gore asserted, “The scientific community is warning us that the average hurricane will continue to get stronger because of global warming.” Gore went on to compare hurricanes to al qaeda. But not only have four of the last five Atlantic hurricane seasons been quiet, the 20th century showed no trend of rising Atlantic hurricane frequency or intensity.

Pundits and politicians attach significance to hurricanes because they are visual events — hurricane courses can be predicted, and their arrivals on shore televised. Tornadoes come and go so quickly, they are almost impossible to catch on film. But their comings and goings may be warnings of climate malfunction.

What’s causing the tornado tsunami of 2011? This spring, the jet stream has shifted south and east of its typical position. That brings the cold, dry air on the north edge of the jet stream into more contact with the warm, moist air masses on its south edge, around the Gulf of Mexico. The result is rotating thunderstorms — sometimes, as happened in the Ozarks in April, forming day after day in succession.

Surely there have been times in the past when the jet stream shifted east and south: this may or may not be related to greenhouse gases. But greenhouse gas levels in the atmosphere are rising, and weather variations are rising — not just tornadoes, but droughts and deluge rains. Chances are two plus two equals four.

It is important to bear in mind that climate change, not global warming, is the threat. They seem like the same thing but are not.

The mild warming of the past 100 years — about 1 degree Fahrenheit globally averaged — was good for crop yields, and moderated demand for energy. (Power use for warming on cold days exceeds power use for cooling on hot days). If all that happens is continued mildly rising temperatures, that might be beneficial.

Changing climate is another matter altogether. Climate change can bring more tornadoes, increase droughts in some places while increasing floods in other places — all three impacts are being observed. Long-term shifts in rainfall patterns might turn breadbasket regions into crop-failure regions. Our increasingly globalized economy is dependent on air travel and air cargo. What if storms and turbulence begin to make flying conditions unfavorable not once in a long while, but often?

Despite what the talk radio and Tea Party types say, there is strong scientific consensus that human activity has begun to alter Earth’s climate. Here is the latest statement on this matter, from the National Academy of Sciences last week.

The United States Congress — dedicated to its twin goals of doing nothing, while collecting campaign contributions — needs to act on greenhouse gases. These tornadoes are not originating from Oz.

Photo: Damaged homes and cars are seen after a devastating tornado hit Joplin, Missouri May 24, 2011. A monster tornado killed at least 116 people in Joplin, when it tore through the heart of the small Midwestern city, ripping the roof off a hospital and destroying thousands of homes and businesses. REUTERS/Eric Thayer

The fifth anniversary of Hurricane Katrina, coupled with the mild hurricane Danielle tracking toward Bermuda, turns thoughts toward cyclones.

In May, before the current Atlantic hurricane season began, forecasts were for Armageddon. This year’s hurricane season could be “very active” (Jane Lubchenco, head of the National Oceanic and Atmospheric Administration) or “very very active” (CNN) or “a hell of a year” with “quite high” numbers of intense storms (William Gray, head of the hurricane prediction center at Colorado State University).

What has actually happened so far? A below-average season of two hurricanes, neither one intense.

The totals should change, though. September can be the peak month for Atlantic hurricanes. But three of the last four years have shown below-average hurricane activity in the Atlantic, and 2010 is shaping up as another below-average season.

What’s going on here? Wasn’t global warming supposed to spawn ultra-monster hurricanes? That’s what Al Gore started claiming five years ago. Similar assertions have been heard from other quarters, too.

Of course, just because Al Gore says something doesn’t mean it’s untrue. So what is going on?

The media loves predictions of deadly hurricanes. Each spring NOAA, CSU and other organizations issue hurricane forecasts; in recent years nearly all such forecasts have been alarming; the alarming forecasts are played up. If hurricane season ends without calamity, there are never follow-up stories noting the predictions were wrong, because newspapers and newscasts want to feature the next spring’s alarming predictions.

The media loves hurricanes, period. Hurricanes make great television! Fierce winds, lapping waves, correspondents in heavy rain gear shouting to be heard. Plus because hurricanes take days to form, there’s time to put newscasting resources in their paths: good luck positioning cameras in the path of a tornado. I don’t think it is too cynical to say that cable news is rooting for destructive hurricanes, though rooting for a kind of Hollywood fantasy hurricane which causes widespread cinematic-quality destruction but doesn’t kill anyone.

Predictions are worthless. The below mini-chart shows the pre-hurricane-season predictions of NOAA and CSU, followed by actual results. (I use the upper bound for NOAA, which sometimes issues vague predictions such as “three to seven” hurricanes, which is like predicting, “the Dow Jones will either rise or fall.” I use the seasons-start predictions by CSU, which has a sneaky habit of altering its forecasts once the season is nearly over and most of the trend is already known.)

Note that in the six years before the current season, only two of the 12 major predictions turned out to be correct. Since the likely numerical range of hurricanes is fairly small – the 50-year average is six hurricanes, three intense – you’d think some predictions would be right by sheer chance. Instead the leading experts in the field have been wrong on 10 of their last 12 projections, and are on track to be totally wrong this year.

Predictions get attention anyway. Last year Colorado State analyzed its predictions and for the last 25 years discerned only a “modest” improvement over simply predicting every season would be average. As best I could determine, no major media outlet covered the release of this report showing that hurricane predictions are a complete waste of everyone’s time.

The sillier the prediction, the better. Colorado State has gotten press for this website, which claims to generate a scientific likelihood of hurricane landfalling by U.S. county.  The page offers absurdly hyper-specific predictions, such as a “18.7 percent probability” that a hurricane will strike Harrison County, Mississippi, this year, or a “2.4 percent probability” that a hurricane will cross Essex County, New Jersey. Numbers such as these are gibberish, not science — since what’s to the right of the decimal point cannot possibly have statistical significance, and what’s to the left is pure guesswork. But the pseudo-science feel makes for a nice source of stories for local newscasters. (“Researchers Say Hurricane Might Strike Maine.”)

Hurricanes have been awful long before artificial global warming. The extremely strong Great Hurricane of 1780 killed about 27,500 people, at a time when the Western Hemisphere was far less populous — and when artificial greenhouse gas emissions were not a factor. The Category Four Galveston hurricane of 1900 killed 8,000 people, and occurred when greenhouse gas levels in the atmosphere were much lower than today. The 1938 Long Island hurricane left 800 dead and $4.6 billion in property damage (stated in 2010 dollars), also occurring before coal and oil use could have altered nature.

Hurricanes don’t show any pattern clearly linked to greenhouse gases. A terrible hurricane year (2005) or an eerily quiet year (2009) doesn’t prove anything one way or the other. Nor does the larger trend. For the last 60 years, decade-by-decade averages have been roughly the same. A good summary is here.

But you should still worry. Just because climate change hasn’t yet caused more or stronger hurricanes does not mean they will not happen. The evidence for climate change is strong. If sea surface temperatures are the key to hurricanes, as some researchers think, then hurricanes should get worse, because sea surface temperatures are rising. Then again, climate change might make cold fronts less cold, while reducing the difference between high- and low-pressure areas, and those factors could reduce hurricane incidence or intensity.

This 2005 paper by a researcher at the National Center for Atmospheric Research, published just before Katrina, takes the view that rising sea-surface temperatures will cause stronger hurricanes and also more rain. This 2009 paper, from a researcher affiliated with the same organization, takes the view that hurricane activity will decline in a warmer world.

This recently released study, from the Geophysical Fluid Dynamics Laboratory at Princeton — gotta love that name — splits down the middle, forecasting that climate change will increase hurricane activity but slowly, requiring decades or longer. (The Princeton paper is also a rare example of presenting scientific information in a way intended to be comprehensible and accessible.)

Perhaps the Princeton paper would cause you to think, “If hurricanes won’t get worse until 2050, then I don’t need to care about this.” You do.

One of the big questions of global warming is whether there will be tipping points — natural thresholds that cause climate change to accelerate. If the Princeton paper’s view is correct, by the time the tipping point for hurricanes is reached, it will be too late to reverse the effect — because greenhouse gas levels in the air will be too high.
Bottom line: instant-doomsday hurricane panic isn’t supported by science. But greenhouse gas regulation is.

Photo caption: Waves crash upon rocks as weather conditions worsen due to a low pressure system passing through the area along the coastline in Port Fourchon, Louisiana July 5, 2010. There was a “high chance” it will become the second named storm of the 2010 Atlantic hurricane season before it makes landfall in the Terrebonne Parish area near Caillou Bay early Monday evening, the U.S. National Hurricane Center said . REUTERS/Sean Gardner