In the wake of Katrina, the subject of Global Warming has come back into the news. Hurricanes get their power from the a variety of factors, but central among them is the existence of ocean waters heated up to above 79° F.
Some, like Sterling Burnett, a senior fellow with the National Center for Policy Analysis, want to downplay the role of Global Warming in causing more severe hurricanes:
At the 27th annual National Hurricane Conference, University of Colorado atmospheric scientist Dr. William Gray explained that nature is responsible for hurricane cycles, not humans. Periodically changing ocean circulation patterns, he explained, led to the cycle of increasing hurricane activity that the world is currently experiencing. 2004’s above average hurricane season was part of a completely natural and normal cycle that scientists have monitored for more than 100 years. In fact, for about the past 25 years there has been a relative lull in hurricane activity in the U.S.
We have recently begun to emerge from that cycle into a more active cycle of hurricane activity like those from the 1930s through 1950s. Indeed, according to the National Hurricane Center, category 3, 4 and 5 hurricane numbers peaked in the 1930s, 1940s and 1950s with an average of 9 per decade. In the 1940s alone, 23 hurricanes hit the U.S. mainland, 8 were category-3 or stronger storms. By contrast, since the 1980s when environmentalists first began to argue that humans were causing catastrophic climate change, the number of category 3 or higher hurricanes have averaged 5 per decade.
Well, such an authoritative statement from an avowed right-wing think tank is certain to be free from a pro-corporate, pro-pollution bias, right? But then others, as noted in an article in today’s Oregonian, beg to differ:
Climate experts who examined records of hurricanes during the past 35 years reported this week that the strongest hurricanes — categories 4 and 5, and Katrina was a 4 — had increased sharply as a percentage of all hurricanes arising worldwide. That’s over a time period during which tropical ocean surface waters rose about a half a degree Celsius.
“The potential for more Katrina-type events is on the trend,” said researcher Greg Holland of the National Center for Atmospheric Research in Boulder, Colo. “Who knows? Had this trend not been there, Katrina might have been a Category 2 or a Category 3.”
Kerry Emanuel, a hurricane expert at Massachusetts Institute of Technology, in August published a study in the journal Nature that signaled the trend to more destructive cyclones resulting from warmer oceans.
… Still, it is the mix of warmer oceans and more people along coastlines that leads Emanuel to say, “Global warming is loading the dice.”
Loading the dice and risking people’s lives. So, what do we have to look forward to?
The surface layer of tropical oceans has warmed by about a half-degree Celsius since 1970, but it’s impossible to predict how much warmer the oceans will become as the heat-trapping greenhouse gas carbon dioxide builds up in the atmosphere from the increased burning of petroleum and coal. Advanced computer simulations of the earth’s climate predict that tropical sea surface temperature will rise an additional 1 or 2 degrees over the next 80 years. As a result of that projected warming, the latest and most detailed climate simulations also predict an increase in highly destructive Category 5 hurricanes.
As early as 1987, climate scientists theorized that the warming of the earth’s oceans due to our rising output of greenhouse gases could boost the destructiveness of hurricanes. By 2004, many computer simulations of the earth’s atmosphere have predicted the same effect. Then in August, a study by Emanuel put forth evidence of a near doubling of hurricane power since the mid-1970s, based on records of hurricanes since the 1950s in the Atlantic and Western Pacific. Emanuel showed a tight link between storm intensity and sea surface temperatures — as predicted by theory and computer modeling.
A newer study reported today in the journal Science found a pronounced shift toward more intense hurricanes in all of the world’s oceans. Researchers analyzed hurricane records based on satellite images made since 1970. The frequency of cyclones varied from year to year and over longer cycles in some oceans, such as the Pacific, where activity peaked in the mid-1990s and then dropped steeply. They found no overall global trend in frequency. But in every ocean basin they found a shift toward stronger hurricanes. Category 4 and 5 hurricanes have almost doubled in number and in proportion, rising from 20 percent to more than 35 percent.
Ooh, fun stuff!
In this whole debate about Global Warming (if by “debate” you mean “damn near full consensus of the scientific community, desperately trying to talk some sense into corporate-polluter interests”) I keep trying to tell remind people that we are talking about massively complex, highly unpredictable systems that defy any sort of short-term prediction. We only have reliable weather data going back about one hundred years, and we’re talking about Global Warming effects that may take hundreds more years to fully realize and measure. We have geologic and paleontologic data going back eons, but we’ve only had the massive pollution and environmental degradation of human industry for a little longer than a century.
When an anti-Global Warming position is offered, stating that there’s “no scientific evidence” of the harms of Global Warming, they may be technically correct, just as there is no definitive scientific evidence that the Big Bang occurred or humans evolved from lower life forms.
So I look at the issue in a common-sense manner. Does it make good sense to recklessly spoil the air, water, and land for short-term gain with no perspective on the long-term consequences? Even animals know it’s not wise to shit where you eat.
I also think of the weather in my lifetime and the anecdotes told by my parents and grandparents. Nampa, Idaho, my hometown, used to get maybe one or two days of 100°+ F days per summer; now streaks of 15 days over 100° F are not uncommon. Snowfall used to be very common during my childhood; now Idaho’s Treasure Valley rarely gets any snowfall that sticks.
Maybe human industry has a great effect on global weather patterns. Maybe it only has a tiny effect. But when we’re talking about our very civilization, shouldn’t we err on the side of caution? If 98% of Global Warming is caused by factors out of our control, wouldn’t it still be wise to reduce the 2% we’re contributing to our own destruction?
