The Party Line”
The worst Atlantic hurricane season on record still hadn’t ended when the American Geophysical Union held its fall meeting in San Francisco in December 2005. Twelve thousand scientists packed themselves into the Moscone Center, the city’s space-age mall of a conference facility, for lectures on topics such as the massive 2004 Sumatra-Andaman earthquake and the tsunami that it generated, and data beamed from NASA’s Mars rovers and the Cassini spacecraft. Many of the presentations were being given on the center’s upper levels, and security guards had to police the towering escalators just to prevent overcrowding.
MIT hurricane theorist Kerry Emanuel arrived on this scene riding a swell of fame that few researchers ever experience. A short man with striking blue-green eyes and a slightly surprised smile, Emanuel had just seen his latest work featured in a Time magazine cover story and would soon find it rated (along with the work of several colleagues) the top science story of the year by Discover. He was averaging five to ten media calls per week. Later, he would be named one of the hundred Most Influential People of 2006,” once again by Time. At the American Geophysical Union meeting, Emanuel had been slated to speak following another of Time’s most influential: NASA’s James Hansen, the nation’s best-known climate scientist and the man sometimes dubbed the father” of global warming.
The science presented at the average American Geophysical Union meeting features a heavy helping of catastrophe. Tornadoes, volcanoes, earthquakes, tsunamisthe proceedings offer a subject roster that Hollywood disaster-movie directors would appreciate. But that December, the cause of destruction at the front of everyone’s mind was the strongest and deadliest storm on Earth, a meteorological monstrosity capable of churning out as much power as all the world’s electricity generators combined: the tropical cyclone, typhoon, or, as we call it in the United States, the hurricane.
Katrina had wiped out New Orleans just a few months earlier.
On the day of Emanuel’s talkTuesday, December 6Hurricane Epsilon whirled on in the North Atlantic some 600 miles southwest of the Azores. The aimless cyclone had already executed a full loop, completely reversing its original westward trajectory, and now began a southwest turn. Epsilon wasn’t a particularly strong stormits maximum sustained winds peaked at around 85 miles per hourand it never seriously threatened land. But it was stubborn. Moreover, Epsilon had the distinction of being only the sixth hurricane ever recorded as occurring in the Atlantic during the month of December, as well as the twenty-seventh storm of a seemingly never-ending seasonso never-ending, in fact, that forecasters had resorted to Greek letters after pre-assigned storm nameslike Katrina, Rita, Wilmaran out.
At the National Hurricane Center in Miamia steel-reinforced concrete bunker of a building on the campus of Florida International University that was built to withstand Category 5 hurricanes and whose roof bristles with dishes and antennaethe experts awaited Epsilon’s demise. With it, they hoped, would come the official end to the devastating 2005 season, and more than a few sighs of relief.
Traditionally, the hurricane season in the Atlantic basinwhich comprises the North Atlantic, the Caribbean Sea, and the Gulf of Mexicobegins on June 1 and ends on November 30. In 2005, however, nature had already toppled such bookends. And now, despite days of forecasts predicting steady weakening, Epsilon had held on to hurricane strength and even put on a few small bursts of intensification.
I HAVE RUN OUT OF THINGS TO SAY . . .AND THIS ONE WILL BE SHORT,” wrote Cuban-born forecaster Lixion Avila in an exasperated 4:00 a.m. discussion of the storm’s progress, written in the all-caps and heavily elliptical style that remains the standard for weather communiqués.
EPSILON APPEARS TO STILL BE A HURRICANE...BUT JUST BARELY,” wrote forecaster Richard Knabb six hours later. THE END IS IN SIGHT,” echoed forecaster James Franklin at 10 that evening. IT REALLY REALLY IS.”
By the time Epsilon finally died downhaving been for five days a hurricane, a December recordKerry Emanuel had generated a tempest of his own in San Francisco. Speaking before a crowd of hundreds in one of the largest of the Moscone Center’s high-ceilinged conference rooms, the normally cautious and apolitical scientist fired a shot straight at the bosses of government forecasters like Avila, Knabb, and Franklin.
Earlier in the day, the audience had heard the wiry Midwestern climatologist James Hansen warn that global warming could cause the disintegration of the Greenland and West Antarctic ice sheets, triggering rises in sea level sufficient to inundate many of the globe’s heavily inhabited coastal areas. After a break, Emanuel launched into a seemingly typical scientific talk, constructed out of PowerPoint images rather than paragraphs. He flashed slides demonstrating that although global tropical cyclone numbers do not show any obvious trend up or downaveraging about eighty to ninety per year in the world’s six regularly active ocean basinsstorms in the Atlantic and the Northwest Pacific had grown stronger and longer lasting over the past several decades, closely tracking a trend of rising temperatures at the surface of the oceans.
To explain this phenomenon, Emanuel then introduced a series of equations. These probably meant little to the nonscientists in the audience, but to specialists capable of reading the equations as if they were sentences, the message was clear: Increasing hurricane strength is linked to human enhancement of the greenhouse effect.
The Earth’s atmosphere contains certain gases, such as carbon dioxide and water vapor, that have a very important property: They absorb infrared or longwave” radiation and also emit it in all directions. As a result, these gases play a crucial role in regulating the flux of energy to and from the planet. Even as the sun’s rays heat the Earth’s surface, the Earth also emits radiation in the infrared part of the spectrum, with a longer wavelength than that of visible light. The greenhouse gases” then absorb some of that outgoing heat radiation (which might otherwise escape into space), warm up, and emit more radiation back down toward the lower atmosphere and the Earth’s surface. In the process, these gases keep our planet much warmer than it would be if it lacked an atmosphere.
Through industrial processes such as smokestack and tailpipe emissions, humans have been steadily increasing the concentration of carbon dioxide and other greenhouse gases in the atmosphere. As a result, we’ve caused additional warming of the Earth’s surface, lower atmosphere, and oceansand that’s where hurricanes come into the picture. Since these storms draw their power from the energy stored in tropical ocean waters, warmer seas should (everything else being equal) make them stronger.
This hypothesisthat hurricanes would intensify in a warmer worldhad been around at least since 1987, published in that year by Emanuel himself. Theoretically based predictions, however, don’t hit you in the gut like hard data. And by 2005, Emanuel was going beyond such predictions. He was saying, it’s actually happening.
Anyone could see Emanuel’s findings had potentially enormous implications. When they strike land, and especially when they strike places where people live, strong hurricanes cause dramatically more destruction than weak ones. Hurricane damage doesn’t simply increase linearly with increasing wind speed; rather, it goes up much more steeply, in part because damaged structures (for example, the roof torn off a house) become missiles flung into other structures. It has been estimated that a land-falling Category 4 or 5 hurricane, with maximum sustained winds greater than 131 miles per hour, causes 64 times as much destruction as a Category 1 storm (winds from 74 to 95 mph) and 256 times as much as a mere tropical storm (winds up to and including 73 mph). Emanuel was telling his audience that we’re helping transform more and more hurricanes into monstrous citysmashers. If true, the discovery would rank as one of the most dramatic manifestations yet of human-caused global warmingand perhaps the most terrifying.
Emanuel’s scientific message was breathtaking enough, but he took it farther. He showed a slide featuring a statement from the man who was then director of the National Hurricane Center, Max Mayfield, asserting that the dramatic upswing in Atlantic hurricane activity since the year 1995 sprang from natural fluctuations” and was not enhanced substantially by global warming.” This Emanuel somewhat derisively dubbed the party line” of the Bush administration’s National Oceanic and Atmospheric Administration (NOAA), a branch of the Department of Commerce that includes the hurricane center as well as numerous other scientific and forecasting branches, ranging from the National Climatic Data Center to the National Marine Fisheries Service.
In his next slide, Emanuel juxtaposed the NOAA party line” with a statement he attributed to an unnamed agency scientist: I have been told not to speak with reporters about the connection between global warming and hurricanes without prior permission from NOAA management.” According to Emanuel, the unidentified scientist worked at the Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey, a hub for research on climate change employing sophisticated computer models of the atmosphere and the oceans. On the one hand, scientists at GFDL have pioneered a cutting-edge hurricane model that the forecasters in Miami rely heavily upon in their day-today storm tracking. But GFDL researchers have also taken a much longer view, producing a series of studies similarly suggesting that global warming will increase the strength of the average hurricane over the course of the twenty-first century.
Some in the audience had heard stories about NOAA stifling the ability of its scientists to speak freely to the media about hurricanes and global warming, or about global warming in general. They had also seen an agency publication claim a consensus” among its hurricane specialists on this question, asserting that they accepted what Emanuel had defined as the party line.” So the audience was primed for what came next. Emanuel, almost in passing, stated his opinion that NOAA really ought to stop censoring its scientists. It was antithetical to science (which thrives on the open exchange of ideas). It had to stop.
The statement was political, but it wasn’t delivered in a mode of political oratory. Emanuel didn’t bang his fist on the podium, much less raise it. That’s not his style. He simply resumed his presentation, neatly bracketing his political remark with hard science.
Nevertheless, Emanuel’s brief suspension of scientific etiquette had struck a chord. The room erupted with applause.
If Emanuel had issued a verbal challenge to the government’s hurricane forecasting community, the Atlantic would soon issue yet another meteorological one.
In his final dispatch on Epsilon, Lixion Avila had declared, I HOPE THIS IS THE END OF THE LONG LASTING 2005 HURRICANE SEASON.” It wasn’t. Several weeks later, the ocean and atmosphere served up Tropical Storm Zeta, noteworthy not for its strength but for its timing. The storm formed in the central Atlantic some 675 miles northwest of the Cape Verde Islands on December 30, fully a month after the season’s official endpoint. ALTHOUGH THE ATMOSPHERE SEEMS TO WANT TO DEVELOP TROPICAL STORMS AD NAUSEAM,” quipped forecaster James Franklin when Zeta appeared, THE CALENDAR WILL SHORTLY PUT AN END TO THE USE OF THE GREEK ALPHABET TO NAME THEM.”
The calendar did not put an end to Zeta, however. Like Epsilon, the storm didn’t die when it was supposed to. Zeta never became a hurricane, but it clung tenaciously to life. Frustrating and confounding forecasts, the storm stayed organized until January 6, 2006, in the process shattering a few last seasonal hurricane records. In his farewell to the storm and the 2005 seasonduring which he and his fellow storm-trackers had collectively put in hundreds of overtime hoursforecaster Stacy Stewart expressed his amazement and exhaustion alike:
I SUPPOSE IT IS ONLY FITTING THAT THE RECORDBREAKING
2005 ATLANTIC HURRICANE SEASON
ENDS WITH A RECORD BREAKING STORM. TODAY...
ZETA SURPASSED 1954 ALICE #2 AS THE LONGESTLIVED
TROPICAL CYCLONE TO FORM IN DECEMBER
AND CROSS OVER INTO THE NEXT YEAR. ZETA WAS
ALSO THE LONGEST-LIVED JANUARY TROPICAL CYCLONE.
IN ADDITION. . .ZETA RESULTED IN THE 2005
SEASON HAVING THE LARGEST ACCUMULATED CYCLONE
ENERGY...OR ACE . . . SURPASSING THE 1950
SEASON. SO. . .UNTIL THE 2006 SEASON BEGINS. . .
UNLESS ZETA SOMEHOW MAKES AN UNLIKELY MIRACLE
COMEBACK...THIS IS THE NATIONAL HURRICANE
CENTER SIGNING OFF FOR 2005. . .FINALLY.
It was, at long last, the end of a staggering hurricane year. And it was a beginning: the launch of a full-scale scientific and political battle over the relationship between hurricanes and global warming that would bring out the best, and occasionally the worst, in two groups of researchers whose areas of expertise overlap so much that they might be considered siblingsclimate scientists on the one hand, and hurricane and weather forecasters on the other.
This is their story, first set in its historical context and then told as it unfolded across the dramatic hurricane years of 2004, 2005, and 2006. It’s a narrative of scientific understanding developing in real time, in all of its inevitable messiness, under immense political pressure and in the full glare of media scrutiny. Scientists, like hurricanes, do extraordinary things at high wind speeds. Such conflicts may bring out their human side, but also inspire their very best work.
To grasp the roots of the present dispute, however, we must first glance back to the great American Storm Controversy” of the nineteenth century, which featured a divide between scientists similar in many respects to the one that exists today. And we must visit the heroic postWorld War II storm-flying era of hurricane research, when the mentors of the scientists embroiled in the current hurricaneglobal warming argument conducted their most important studies. This history reveals how longstanding personal and methodological schisms among meteorologists have, like a hurricane’s steering currents, helped guide us to the present momentand how they explain, at least as much as present-day political alignments, why the hurricaneclimate debate became so charged and even, at times, venomous.
Scientists disagree constantly, of course. That’s not news. But rarely has there been quite as much on the line. If we’re really making the deadliest storms on Earth still deadlier, it will represent one of humanity’s all-time greatest foot-shooting episodes. Short of a collapse of the Greenland or West Antarctic ice sheets, it’s hard to imagine many hypothesized manifestations of global warming more likely to shock the public, or to generate a call to action. The 1992 United Nations Framework Convention on Climate Change announced the goal of preventing dangerous anthropogenic interference with the climate system,” and while the term dangerous” was never explicitly defined, surely increasing the intensity of the average hurricane would fit the bill.
With stakes such as theseand with special interests on both sides eager to spin the latest science to their advantagethe circulation of ideas in the hurricaneglobal warming argument could easily attain gale force. Add to this an administration that has shown a strong tendency to suppress or twist inconvenient scientific information pertaining to global warming; a historically rooted and methodologically grounded rivalry between two groups of scientists studying the same meteorological phenomenon from very different vantage points; and a towering figure of American hurricane science, William Gray of Colorado State University, who rejects entirely the notion that humans have been causing substantial global warming, and whose students hold positions of great scientific influence; and you have the makings of the perfect hurricane.
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