Before Katrina hit the US three hurricanes had already reached Category 4 or 5 across the Gulf of Mexico*, a total which is unprecedented for so early in the season. Katrina was initially a weak Category 1 hurricane when it crossed Florida. It wasn’t until it passed over the warm Gulf waters that it picked up strength, peaking at Category 5 with winds of over 100 miles per hour when it struck New Orleans. A lot of fingers are pointing to global warming.
The main factor in the formation of a hurricane is sea surface temperature. Warm water, and the subsequent instability in the lower atmosphere, is the energy source of hurricanes. According to researchers at the Georgia Institute of Technology and the US National Center for Atmospheric Research, in the past 35 years the number of Category 4 and 5 hurricanes worldwide has almost doubled. The change occurred as global sea-surface temperatures rose over the same period. Peter Webster, one of the researchers at the centre, said that ‘in the 1970s, there was an average of about 10 Category 4 and 5 hurricanes per year globally. Since 1990, the number of Category 4 and 5 hurricanes has almost doubled, averaging 18 per year globally.’ These intense storms made up about 20% of all hurricanes in the 1970s, but over the past decade they have accounted for around 35%.
Webster also pointed out that the 0.5ºC rise between 1970 and 2004 in sea surface temperatures was likely to be down to global warming. Since the 1970s global sea-surface temperatures have risen from 0.25 to 0.5 degrees Celsius in hurricane seasons depending on the region. A 1.7°C rise in sea-surface temperature is projected for later this century. These figures sound small but in fact, when the ocean warms by half a degree Celsius, wind speeds increase by 3%. This will continue and accelerate, with huge losses in human life, especially in coastal areas. In 2004 hurricanes killed 60 people in the US and caused $45 billion of damage. It was already well known that New Orleans is one of the most vulnerable places on earth to the effects of global warming.
Although there have been fewer hurricanes and tropical cyclones worldwide over the past decade, the North Atlantic has averaged eight to nine hurricanes each year, compared to six to seven for the decade before. Category 4 and 5 hurricanes in the North Atlantic have increased at a faster than average rate: by 56% between 1975 and 2004. What is more, although there are fewer hurricanes today than a decade ago, now they are significantly stronger and more destructive. It may be no coincidence that sea surface temperatures have risen the most in this period.
In the wake of Katrina a debate is taking place among US scientists about the effect of global warming. The section of the US ruling class that plays down or even denies the role of global warming is losing its credibility. This was highlighted when Kerry Emmanuel, a scientist from Massachusetts who was a leader of the climate change sceptics, switched sides in the debate and publicly recognised the manmade damage already being done. A number of prominent scientists are asserting that global warming has probably already made hurricanes more severe. Kevin Trenberth of the National Center for Atmospheric Research has said that ‘to unequivocally state that global warming has nothing to do with what’s going on in Katrina, is totally irresponsible in my view.’ Neither side, however, sees the solution to the problem. Both receive government funding in one way or another and so they ignore the cause of global warming and environmental destruction: capitalism and imperialism. This is the enemy we need to fight if we are to prevent more and worse catastrophes.
Louis Brehony
* Hurricane strength is measured from 1-5, with 5 being the strongest.
HURRICANE RITA
As we go to press, the destruction caused by Hurricane Rita was much less than expected, although Texan oil installations have suffered considerable damage. At one stage a Category 5 hurricane, by the time it hit land in eastern Texas and western Louisiana it had moderated to Category 2. The relief effort is now being focused on redeeming Bush’s plummeting polling ratings and federal agencies are pulling out all the stops. After the Katrina disaster, the local population took no chances. Two million people fled the affected areas in advance, causing 100-mile long traffic jams. The evacuation of Houston was a fiasco: cars ran out of petrol – and so did the petrol stations. More than 20 pensioners died when a bus exploded on the freeway: the stop-start traffic overheated the brakes which caught fire, and, in turn, ignited the patients’ oxygen tanks. They were the first casualties of the evacuation effort, where the state throws responsibility on to individuals to organise their own escape. The return will no doubt be equally chaotic.
FRFI 187 October / November 2005
