Sept. 23, 2005 — -- For some, the recent hurricanes are seen as God's warning to repent.
Some preachers have said Katrina was meant to punish New Orleans for being a sin city. In Jerusalem, a prominent rabbi says the hurricanes are meant to punish President Bush. An Islamic Web site describes Katrina's destruction as God's fair punishment for America.
And others say it is no more than the natural, historical cycle of weather, that there have always been and always will be clusters of damaging hurricanes.
"This is just the way nature behaves and I find it astounding how tremendously lucky this country's been in the past 20 years in the lack of a major landfall," said Bill Gray, a professor of atmospheric science at Colorado State University. "People need to view this as a tragedy, an event of nature that occasionally occurs, and we shouldn't blame anybody for it."
But there is another explanation, one that is highly controversial, but in the last few weeks has gained significant scientific credibility.
Some people are pointing to global warming, saying that our use of fossil fuels has helped to heat up the planet and its seas, producing much stronger hurricanes.
Three new reports authored by prominent scientists -- published in the journals "Nature" and "Science" -- bolster that theory's credibility.
"There's good evidence to show that Category 4 and 5 storms indeed are becoming more common and a bigger part of the overall pictures of the hurricanes in the world," said Kevin Trenberth, a scientist at the government-funded National Center for Atmospheric Research.
Trenberth is the author of one of the papers, which links stronger hurricanes to warmer seas and global warming caused by humans. Global warming, he says, has caused increases in sea levels and in the temperature of the oceans, which increases water vapor in the atmosphere and provides fuel for massive storms.
Using buoys deployed across the world, along with satellites and other measurements, Unites States government scientists have tracked a steady increase in ocean temperature since about 1970.