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Scientists Foresee Stronger Hurricanes

Global Warming Is Expected to Raise Hurricane Intensity

The New York Times, Sept. 30, 2004

Global warming is likely to produce a significant increase in the intensity snd rainfall of hurricanes in coming decades, according to the most comprehensive computer analysis done so far.

By the 2080's, seas warmed by rising atmospheric concentrations of heat-trapping greenhouse gases could cause a typical hurricane to intensify about an extra half step on the five-step scale of destructive power, says the study, done on supercomputers at the Commerce Department's Geophysical Fluid Dynamics Laboratory in Princeton, N.J. And rainfall up to 60 miles from the core would be nearly 20 percent more intense.

Other computer modeling efforts have also predicted that hurricanes will grow stronger and wetter as a result of global warming. But this study is particularly significant, independent experts said, because it used half a dozen computer simulations of global climate, devised by separate groups at institutions around the world. The long-term trends it identifies are independent of the normal lulls and surges in hurricane activity that have been on display in recent decades.

The study was published online on Tuesday by The Journal of Climate and can be found at .gfdl.noaa.gov/reference/bibliography/2004/tk0401.pdf.

The new study of hurricanes and warming "is by far and away the most comprehensive effort" to assess the question using powerful computer simulations, said Dr. Kerry A. Emanuel, a hurricane expert at the Massachusetts Institute of Technology who has seen the paper but did not work on it. About the link between the warming of tropical oceans and storm intensity, he said, "This clinches the issue."

Dr. Emanuel and the study's authors cautioned that it was too soon to know whether hurricanes would form more or less frequently in a warmer world.

Even as seas warm, for example, accelerating high-level winds can shred the towering cloud formations of a tropical storm.

But the authors said that even if the number of storms simply stayed the same, the increased intensity would substantially increase their potential for destruction.

Experts also said that rising sea levels caused by global warming would lead to more flooding from hurricanes - a point underlined at the United Nations this week by leaders of several small island nations, who pleaded for more attention to the potential for devastation from tidal surges.

The new study used four climate centers' mathematical approximations of the physics by which ocean heat fuels tropical storms.

With almost every combination of greenhouse-warmed oceans and atmosphere and formulas for storm dynamics, the results were the same: more powerful storms and more rainfall, said Robert Tuleya, one of the paper's two authors. He is a hurricane expert who recently retired after 31 years at the fluid dynamics laboratory and teaches at Old Dominion University in Norfolk, Va. The other author was Dr. Thomas R. Knutson of the Princeton laboratory.

Altogether, the researchers spawned around 1,300 virtual hurricanes using a more powerful version of the same supercomputer simulations that generates Commerce Department forecasts of the tracks and behavior of real hurricanes.

Dr. James B. Elsner, a hurricane expert at Florida State University who was among the first to predict the recent surge in Atlantic storm activity, said the new study was a significant step in examining the impacts of a warmer future.

But like Dr. Emanuel, he also emphasized that the extraordinary complexity of the oceans and atmosphere made any scientific progress "baby steps toward a final answer."

Global warming may spur fiercer hurricanes-experts

Reuters News Service, Sept. 15, 2004

WASHINGTON, Sept 15 (Reuters) - As Hurricane Ivan and its powerful winds churned through the Gulf of Mexico, scientists told Congress on Wednesday that global warming could produce stronger and more destructive hurricanes in the future.

Global warming will increase the temperature of ocean water that fuels hurricanes, leading to stronger winds, heavier rains and larger storm surges, the researchers told the Senate Commerce Committee.

However, the increase in ocean temperatures is unlikely to boost the average number of Atlantic hurricanes that form each year, they said.

Hurricane Ivan forced millions of people to evacuate a 400-mile (645 km) stretch of the U.S. Gulf Coast. The storm is classified as a Category 4 hurricane with maximum sustained winds of 135 mph (215 km/h) and has been blamed for 68 deaths and extensive damage in the Caribbean.

Ivan will be the third major storm to batter the U.S. Gulf region during the past month. It is expected to make landfall early on Thursday.

The Republican-led panel heard testimony from several scientists who said emissions known as greenhouse gases were gradually raising the earth's temperature and would contribute to more extreme weather including flooding, drought and changing storm patterns.

"Warmer water temperatures will promote more intense tropical storms, but not necessarily make the frequency of those storms greater," said Dan Cayan, a research meteorologist at the University of California in San Diego.

"An increase of even a degree or so in the right environment would cause intensities to increase," he said.

Some members of Congress, scientists and environmental groups contend that global warming is upsetting environmental balances by altering fragile weather patterns in the world.

However, 10 climatologists and scientists sent a letter to Sen. John McCain, the Arizona Republican who heads the committee, saying there is no scientific evidence of a link between severe weather -- such as hurricanes, blizzards and heat waves -- and global warming. They argued that warmer periods of temperatures have actually led to a decline in the number and severity of storms.

"We suggest that natural variability of storminess is the cause of Florida's recent hurricane disasters," they wrote. "In such times there is an emotional tendency to pin blame somewhere."

McCain said during the hearing that human activities are contributing to global warming and require "real reductions" in greenhouse gas emissions. The United States is the world's biggest producer of the gases, which come from automobiles, power plants and other sources.

Sen. Joseph Lieberman, a Connecticut Democrat, and McCain have introduced bipartisan legislation that would set nationwide emissions limits for transport, utilities and other sectors. The bill has been stalled in the Senate.

President George W. Bush refused to join the 1997 Kyoto treaty on greenhouse gases, saying it would be too costly to the economy.

More fierce hurricanes may loom on horizon

CNN.com, Sept. 3, 2004

As Hurricane Frances bears down on the United States, weather trackers are sounding the alarm. Yet Frances may only be the first in a series of large, powerful storms to march across the Atlantic in coming years.

The arrival of hurricanes like Charley and Frances within weeks of each other is a rare anomaly, but some meteorologists say more storms like Frances -- both very intense and very large -- are possible.

"Over the past few years, we've seen an increasing trend toward greater activity in the Atlantic Basin and increased strength in storms," said Marshall Shepherd, a research meteorologist at NASA's Goddard Space Flight Center. "[That] has been leading us to believe that we are going to start seeing more intense hurricanes. That may be bearing itself out right now."

A combination of natural cycles and warming ocean temperatures from global warming may be fueling the destructive storms. Scientists like Shepherd employ an array of satellites, aircraft and computer models to answer those questions in their mission to comprehend the Earth's climate.

"Compared to 20 years ago, we've seen dramatic improvement in our track forecasting," Shepherd said. "But we still have a long way to go."

The legendary storms appear in the Atlantic Ocean like clockwork between June and November.

The hurricanes batter coastlines, destroying homes, coastal towns and beaches over their lifetimes during which they can expend the energy of 10,000 nuclear bombs, according to NASA's Earth Observatory. Although scientists track, monitor and probe them relentlessly, they can do little about them.

Since 1900, Atlantic hurricanes have cut a swath of destruction across the region, accounting for billions of dollars in damage and more than 71,000 deaths, said the National Oceanographic and Atmospheric Administration.

A torrent of new meteorological data is leading to a better understanding of the physics of hurricanes. Recently developed technology can identify the precise wind direction and rainfall in different parts of the storm. At the same time, sharp-eyed satellites and sophisticated computer models offer unprecedented views inside the giant vortexes.

What they have found is making hurricane-hunting more about science than guesswork.

The National Hurricane Center reports that its forecasts of a storm's predicted landfall have been steadily improving over the past 50 years.

For three-day forecasts, the average margin of error is now about 200 nautical miles, just half of what it was in 1964. Daily predictions are also improving. Today, the average margin of error is just 85 nautical miles, the Center reported.

Disaster coordinators still advise those in the potential path of many hurricanes to evacuate. Although measures can be taken to secure property, little can be done against the worst hurricane winds that can exceed 150 mph and send floodwaters many miles inland.

"[With] enough money, you can build buildings resistant against the wind," said Andy Coburn, associate director of the Duke University program for the study of developed shorelines. "The force of water is completely different. We don't have the technology or the economic feasibility that can withstand the forces of moving water."

America's infatuation with coasts, and the dense population centers on the Eastern Seaboard, mean that it will not escape hurricanes' wrath. If storm intensity and frequency pick up, the country could be in for a wild ride.

Coburn offered only one solution. "Get the hell out of the way," he said.