Blame Global Warming For Florida's Hurricane Conga Line

by Stephen Leahy

(IPS) -- Hurricane Ivan, the powerful storm that killed at least 120 people in the Caribbean and southern United States, may be a harbinger of the Earth's hotter future, say experts.

"As the world warms, we expect more and more intense tropical hurricanes and cyclones," said James McCarthy, a professor of biological oceanography at Harvard University.

Large parts of the world's oceans are approaching 27 degrees C or warmer during the summer, greatly increasing the odds of major storms, McCarthy told IPS.

When water reaches such temperatures, more of it evaporates, priming hurricane or cyclone formation. Once born, a hurricane needs only warm water to build and maintain its strength and intensity.

Over the last 100 years, the Earth has warmed by about .6 degrees C, according to the 2001 report by the Intergovernmental Panel on Climate Change (IPCC), an international scientific body that studies the relationship between human activity and global warming.

The IPCC report was based on research by more than 2,500 scientists from about 100 countries who determined that emissions of gases such as carbon dioxide act as a blanket that prevents much of the sun's energy from dissipating into space.

Much of the extra energy from this "greenhouse effect" is being absorbed by the oceans.

The "proof" that the oceans are warming is the fact that global sea levels have risen 3.1 cm in the past 10 years, said Kevin Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research in Boulder, Colorado.

Water expands when heated, and sea levels are expected to continue rising by as much as 50 cm by 2100.

While the warming of the oceans is not uniform -- the North Pacific and North Atlantic are a bit cooler -- the hurricane-producing mid-Atlantic and Caribbean oceans have warmed significantly.

"Global warming is creating conditions that are more favourable for hurricanes to develop and be more severe," said Trenberth.

Will that result in more Category 4 or 5 storms like Ivan?

"That's the logical conclusion, although it may be somewhat controversial," he said.

Before it struck Cuba a glancing blow, Ivan was a Category 5 on the Saffir-Simpson scale, which rates hurricanes from 1 to 5 according to wind speeds and destructive potential. Category 5 hurricanes have winds that blow continuously above 250 kilometers an hour. Ivan's gusts topped 320 kilometers an hour at times, making it the sixth most powerful hurricane on record for the Atlantic Basin.

Hurricane Ivan's 12-day rampage killed 70 people in the Caribbean and 50 in the United States. It will be some time before the full extent of the damage is known, but some estimates put it at $10 billion for the United States alone.

As emissions of greenhouse gases continue to trap more and more of the sun's energy, that energy has to be dissipated, resulting in stronger storms, more intense precipitation and higher winds, says McMcarthy.

However, the statistical record of hurricanes hitting the U.S. shows a decrease in the past 50 years.

Most hurricanes do not strike land, McCarthy points out, and up until the past 25 years, with the advent of satellite tracking, there was scant data on the storms.

But there is abundant evidence of an unprecedented number of severe weather events in the past decade, McCarthy says. In 1998, Hurricane Mitch killed nearly 20,000 people in Central America, and more than 4,000 people died during disastrous flooding in China. Bangladesh suffered some of its worst floods ever the following year, as did Venezuela. Europe was hit with record floods in 2002, and then a record heat wave in 2003.

More recently, Brazil was struck by the first-ever recorded hurricane in the South Atlantic last March.

"Weather records are being set all the time now. We're in an era of unprecedented extreme weather events," McCarthy said.

Historical weather patterns are becoming less useful for predicting the future conditions because global warming is changing ocean and atmospheric conditions.

"In 30 to 50 years' time, the Earth's weather generating system will be entirely different," he predicted.

What hasn't changed in the United States is the public's lack of concern about climate change, said Ross Gelbspan, a Pulitzer Prize-winning reporter and author of two books on global warming, most recently one titled: "Boiling Point: How Politicians, Big Oil And Coal, Journalists and Activists Are Fueling the Climate Crisis -- And What We Can Do to Avert Disaster."

Sharp reductions of emissions of greenhouse gases like carbon dioxide on the order of 70 percent are urgently needed to minimise the impacts, Gelbspan said.

But despite the recent destructive series of hurricanes and tornadoes, global warming is off the radar screen of the U.S. presidential election campaign, he said.

Gelbspan is not surprised at this, given the power and influence of the fossil fuel lobby in Washington, which he outlines in great detail in his book.

"America's oil and coal industries receive more than $20 billion a year in subsidies," he said. "Imagine what could be done if that money was invested in green energy."