The truth about hurricanes: Will we see more like Hurricane Bill?

Hurricanes are nothing new, but the kinds of storms (and their number) seem to be getting more serious.

With Hurricane Bill recently shutting down beaches and prompting warnings up and down the Atlantic Coast, and major disasters such as Hurricane Katrina a not-so-distant memory, one wonders: What’s the deal? Are hurricanes getting more numerous and more severe or are we just more aware of them? And if there are more, why?

Read on to have your most pressing (swirling, surging, or raging) questions answered.

Are storms increasing in frequency or intensity?

Globally, there are an average of 90 tropical storms per year, and that number doesn’t seem to be changing much.  In the north Atlantic, however, there is a clear increase in the number of storms.  From 1850-1990, the average was 10 tropical storms per year, including five full-fledged hurricanes.  Since 1998 that number has increased to about 15 storms per year, with an average of eight morphing into hurricanes.

In terms of severity, there is a significant global trend towards more intense storms.  In 2005, the Washington Post reported that the number of category 4 and 5 storms nearly doubled in the previous 35 years.

What do the categories really mean?

Meteorologists commonly use what is known as the Saffir-Simpson Hurricane Scale to label hurricane severity.  Hurricane categories are based on wind speed.  The two most severe categories are 4 and 5. Wind speeds for category 4 hurricanes range from 131-155 miles per hour, and category 5 storms are everything with wind speeds of 156 mph and above.

What areas are at risk?

All coastal areas (Atlantic and Pacific) in the United States are at risk for hurricanes, most especially the Gulf Coast region in the southeastern United States. Inland areas can also see severe storms, as in 1995 when Hurricane Opal brought 100 mph winds to Atlanta, Georgia and tornadoes in Maryland.

Is global warming to blame?

The debate as to whether increased frequency and intensity of storms is the result of human interaction is still ongoing.

Ocean temperature increase as a result of global warming may be a major contributing factor. A recent Nature study reports that the average tropical ocean temperature has risen by about 0.5 degree C since 1970.  Every full degree in temperature increase, Nature approximates, will lead to a 31% global increase in the rate of category 4 and 5 hurricanes.

Some scientists predict that ocean temperatures could be raised over 2 degrees by 2100—a scary outlook for stormy weather.

Of course, there is still a lot of controversy. Historical records of hurricane intensity are not stellar, and therefore it’s hard for today’s scientists to judge whether the current storm trends have happened before. Besides, the frequency and intensity of Atlantic hurricanes depend on a lot more complicated factors than merely ocean surface temperature.

The Intergovernmental Panel on Climate Change rated the probability of a link between global warming and hurricanes as “more likely than not” in a 2007 report.

What can we do?

Prepare, prepare, prepare. At this point, the best plan is simply to stay aware of storm developments (the Atlantic hurricane peak season is from mid-August to late October), and ensure our families and communities have basic hurricane safety plans and strategies in place.

As Hurricane Katrina tragically demonstrated, we can probably never be fully prepared for a severe storm. However, the more steps we can take to make our buildings and infrastructure stronger, and manage resources more wisely, the better.  Also, as always, be aware of your personal greenhouse gas emissions and carbon footprint to do your part to reverse the effects of global climate change.

More from ecomii:

• Extreme weather linked to global warming
• Reduce, reuse, and recycle to lower carbon emissions
• Save money and conserve energy in your home
• Global warming and the greenhouse effect
• Catch energy vampires

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