NEW YORK - On April 14, a massive storm swept down out of the Rocky Mountains into the Midwest and South, spawning more than 150 tornadoes that killed 43 people across 16 states (Capital Weather Gang, 4/18/11). It was one of the largest weather catastrophes in United States history—but was soon upstaged by an even larger storm, the 2011 Super Outbreak that spread more than 300 tornadoes across 14 states from April 25 to 28 (including an all-time one-day record of 188 twisters on April 27), killing 339 people, including 41 in Tuscaloosa, Alabama (CNN, 5/1/11).
Ensuing weeks saw Texas wildfires that had been burning since December expand to consume more than 3 million acres (Texas Forest Service, 6/28/11; CNN, 4/25/11), plus record flooding along the Mississippi River, which couldn’t contain the water from April’s storms on top of the spring snowmelt. On May 22, a super-strong F5 tornado killed 153 people as it flattened a large part of Joplin, Missouri (National Weather Service Weather Forecast Office, 5/22/11) ; in the first two weeks of June, a heat wave broke temperature records in multiple states, and the Wallow fire became the largest in Arizona state history (Washington Post, 6/14/11).
It was an unprecedented string of severe weather: By mid-June, more than 1,000 tornadoes had killed 536 people (NOAA, 6/13/11), nearly as many deaths as in the entire preceding decade. And it was only natural to ask: Were we seeing the effects of climate change?
Most scientists would say yes, or at least “probably.” The Intergovernment Panel on Climate Change, a global scientific body that has been a target of conservatives despite a record of soft-pedaling its findings to avoid controversy (Extra!, 7/8/07), warned on February 2, 2007, “It is very likely that hot extremes, heat waves and heavy precipitation events will continue to become more frequent.” (In science-speak, “very likely” refers to a certainty of greater than 90 percent, and is as near as you get to a definitive conclusion.) Other forecasts (e.g., Environment America, 9/8/10) have projected that wet regions will receive record rainfall thanks to increasing evaporation, while dry ones get record drought, as climate patterns shift to accommodate the new normal.
Yet despite these dire predictions, U.S. media were hesitant to investigate the links between climate change and this spring’s extreme weather. Much coverage settled for the cheap irony of contrasting extreme phenomena, as when NBC’s Saturday Today show meteorologist Bill Karins (6/11/11) quipped:
Feast or famine’s been the rule this spring. The northern half of the country, we’ve dealt with the heavy rain, the record snow pack that’s now melting in the northern Rockies. That’s causing the flooding. The southern half of the country, you would love some of that rain.
Even news reports that probed deeper into the causes of the spring’s extreme weather, though, often stopped short of looking at climate factors. A Chicago Tribune story (4/29/11) headlined, “Why April Record for Twisters? Experts Call It Random, Say Nature Varies,” noted that “some meteorologists” blame the periodic weather pattern known as La Niña, but then cited other scientists as saying the tornado outbreak was just random variation, with University of Illinois meteorologist Bob Rauber saying, “Global warming is occurring, but this is not a manifestation of it.”
On the CBS Evening News (6/9/11), meanwhile, John Blackstone noted, “Perhaps the biggest weather troublemaker has been in the Gulf of Mexico, where sea surface temperatures have been almost 2 degrees [Fahrenheit] above average. That warm, moist Gulf air meeting the powerful jet stream created the string of tornadoes that killed 525 people.” Yet, asked by anchor Scott Pelley why the Gulf of Mexico is hotter than usual, Blackstone replied only: “Well, it’s related to the drought in the South—in the South-Southwest, with little clouds, lots of sunshine, the waters warming up and those warm waters could add energy to this hurricane season as well.”
But while La Niña is a natural cyclical variation, the warming Gulf is not—at the very least, it’s exacerbated by the global warming trend, which has pumped at least four times the heat energy into the oceans that it has into the atmosphere (NPR, 3/19/08). As National Center for Atmos-pheric Research climatologist Kevin Tren-berth explained to Extra!, the air over oceans now averages 1 degree Fahrenheit warmer and 4 percent wetter than it was before 1970. “So there is more warm moist air from the Gulf flowing into all spring storms that travel across the U.S. That destabilizes the air, provides fuel for thunderstorms and converts some thunderstorms into supercell storms, which in turn provide the environment for tornadoes to form.”
The easiest connection for most reporters to make was with heat waves, probably because they match best with the popular image of “global warming.” “Intense hot conditions will increase dramatically over the next 30 years,” ABC News’ Jim Avila (6/8/11) reported after June’s record-setting heat wave. “Climatologists say it’s clear: Global warming is beginning to show itself in plain sight.”
For other extreme weather events, though, climate change only merited occasional mention. The wildfires that raged out of control across the Southwest in May and June were mostly covered as an unexpected natural disaster, without much thought of causes; in one exception, the Arizona Republic (6/12/11) fixed the blame squarely on the state having too many trees—a charge also brought up by the New York Times (6/11/11), which reported that, among other things, “Some [residents and experts] complained that it was environmentalists who had caused the forests to become tinderboxes by preventing the thinning of trees as they sought to protect wildlife.”
This common conservative claim, Climate Progress blogger Joe Romm noted (6/12/11), was refuted in a 2006 paper (Science, 8/16/06) that found that fires were increasing the most at higher elevations, where forest restoration is less of an issue, but where warmer temperatures have a huge impact by melting winter snows earlier and increasing summer drought.
In fact, scientists have long predicted that one result of climate change would be a dramatic increase in Western wildfires, as Pete Spotts of the Christian Science Monitor explained in a rare article making such connections (6/9/11). The National Academy of Sciences projected (7/16/10) that a 1-degree Celsius increase in global temperatures—just half the best-case scenario in most climate models—could more than triple the acreage burned by wildfires in the U.S. West. Washington Post blogger Jason Samenow (6/14/11) reported on this study, but it went unmentioned in the newspaper’s wildfire coverage.
Similarly, a NASA wildfire model released last year (10/27/10) projected that climate change would lead to an increase of fires in the U.S. West of between 30 and 60 percent by 2100. “I want you to think a little bit of fire as a metaphor for the many things that climate change holds for us,” NASA earth sciences director Peter Hildebrand told a conference in Colorado in early April—though the only reporter to note this statement was environmental journalist Brendon Bosworth on his self-titled blog (4/8/11).
As for tornadoes, news coverage was openly dismissive of their connection to climate change. A New York Times Q & A following the Joplin tornado (5/25/11) asked: “Can the intensity of this year’s tornadoes be blamed on climate change?” and answered “Probably not. Over all, the number of violent tornadoes has been declining in the United States, even as temperatures have increased.”
Indeed, while the number of reported tornadoes has steadily risen in recent years, prior to this year the number of strong tornadoes (category F4 or F5) had not, leading most scientists to conclude that the rising totals for weak storms are merely a result of more thorough reporting, thanks to sprawling development in tornado-prone regions that has put more people within sighting distance. And because the mechanics of tornado generation are poorly understood—and they depend on vertical temperature differential, so a warming lower atmosphere would predict more tornadoes, but a warming upper atmosphere would tend to reduce them—most scientists say that stronger and more frequent tornadoes can’t be definitively linked to climate.
Still, Trenberth told the blog Think Progress (4/29/11) that it’s “irresponsible” not to mention climate change in tornado coverage. “The basic driver of thunderstorms is the instability in the atmosphere: warm moist air at low levels with drier air aloft,” he told the site. “With global warming, the low-level air is warm and moister and there is more energy available to fuel all of these storms.”
Most reporters, though, chose to stick to the narrower question of whether these particular tornadoes were caused by climate change—which, given all the factors involved to create any particular storm, is impossible to answer, except in the sense in which all weather today is the product of a warmed climate.
“Contributing to the thrashing were the La Niña conditions in the Pacific Ocean, unusually warm ocean temperatures in the Gulf of Mexico and the increase of moisture in the atmosphere caused by the warming climate,” wrote the Washington Post (6/15/11) on the spring’s tornadoes, fires and floods. The piece cited National Oceanographic and Atmo-spheric Administration climate director Thomas Karl as “caution[ing] against focusing on any single cause for the unusual chain of events,” quoting him as saying that “clearly these things interconnect.”
Karl also featured prominently in an article by the New York Times’ John Broder (6/15/11) that reported, “Government scientists said Wednesday that the frequency of extreme weather has increased over the past two decades, in part as a result of global warming,” but quickly added that scientists “were careful not to blame humans for this year’s rash of deadly events.” Broder’s only evidence: Karl’s statement that “since 1980, indeed, extreme climatological and meteorological events have increased. But in the early part of the 20th century, there was also a tendency for more extreme events followed by a quiet couple of decades.”
The story’s headline: “Scientists See More Deadly Weather, but Dispute the Cause.” (Broder later apologized to Romm—Climate Progress, 6/18/11—for what he called a “crappy headline.”)
In fact, though, Karl had previously made clear that climate change would result in more extreme weather. “How climate change will be felt by you and impact your neighbors is probably going to be through extreme weather and climate events,” he told EarthSky (3/15/10). “We may be fine for many years, and all of a sudden, one particular season, one particular year, the extremes are far worse than we’ve ever seen before.”
In many ways, articles like Broder’s parallel the decades-long public debate over carcinogens: It’s just as difficult to say whether any one person’s cancer was caused by pollutants as whether one weather event was caused by climate change. And in both cases, statistical studies have a literally fatal drawback: By the time you’ve gathered enough data, it’s too late to prevent the consequences.
Scientists, then, may conclude that it’s “too soon to tell” exactly how climate change affects tornadoes and other severe weather, but that’s not the same as saying it has no effect. As Trenberth tells Extra! of the spring’s string of catastrophes: “Much of what goes on is natural variability and weather. But there is a component from human influences through global warming. While it may be modest, it is real and significant.”
As noted, the role of climate change in the spring’s severe weather wasn’t entirely ignored. The Christian Science Monitor (6/9/11), in its report on Arizona wildfires that had “blackened an area half the size of Rhode Island,” called them “the latest poster child for what some scientists see as a long-term trend toward larger, longer-lived wildfires in the American West,” noting that “climate change appears to be an important contributor.”
Urgency was left to op-ed pages: Climate activist Bill McKibben wrote a scathing op-ed in the Washington Post (5/23/11) that sarcastically suggested: “It’s very important to stay calm. If you got upset about any of this, you might forget how important it is not to disrupt the record profits of our fossil fuel companies.” Environmental writer Chip Ward wrote an opinion piece on CBS News.com (6/16/11): “Global warming, global weirding, climate change—whatever you prefer to call it—is not just happening in some distant, melting Arctic land out of a storybook. It is not just burning up far-away Russia. It’s here now.” (CBS News’ television programs, meanwhile, never once mentioned climate change in their coverage of the spring’s wildfires.)
One example of how to cover the story differently came from the Edmonton Journal (5/17/11), where columnist Graham Thomson wrote:
No scientist can guarantee that any of these events are caused by human-induced climate change. Climate change is all about trends.
However, the trends are consistent: The atmosphere is warming, the climate is changing and we are largely responsible through our burning of fossil fuels.
Even Thomson, though, didn’t try to suggest that we change our behavior to prevent extreme weather from becoming the norm.
Similarly, when the New York Times editorial page weighed in on what can be done about climate change (6/1/11), it was to praise the city of Chicago for building more rooftop gardens and adding air conditioning to classrooms as part of “long-term preparations for a warmer, stormier climate.” Never mind that the electricity needed to power air conditioners is a major contributor of carbon emissions, or that air conditioning in schools is unlikely to do much to stem the additional 166 to 2,217 annual deaths that researchers Roger Peng and Francesca Domenici estimate Chicago will suffer by the end of the century as the result of climate change (Environmental Health Perspectives, 5/11).
And then there was the counsel given by Nightline anchor Bill Weir (4/26/11), who bent over backwards to avoid definitive conclusions on the causes of the deadly weather: