Hurricanes and Climate Change

Jennifer Rennicks | June 1, 2012 | Climate Change, Extreme Weather

This blog is the first of a four-part series by Simon Mahan, Chris Carnevale and Jennifer Rennicks on hurricanes and energy. Future blogs will focus on Hurricanes and Wind Farms, Hurricanes and Coastal Adaptation, and Hurricanes and Oil Rigs.

Today officially marks the start of the 2012 Atlantic hurricane season — the six months each year when hurricanes, tropical storms and tropical depressions form in the Atlantic Ocean. While there’s nothing particularly magical about the time between June 1 and November 30 that precludes storms from brewing outside of this range, it is worth noting that neither Tropical Storm Alberto nor Tropical Storm Beryl waited for the official starting gun.  Thus, for the first time in more than 100 years, two tropical storms with high enough wind intensities to earn names have formed before the season officially began.

Perhaps it’s unsurprising Alberto soaked South Carolina’s coast in mid-May and Beryl drenched north Florida and Georgia over Memorial Day weekend before the official hurricane season and beginning of summer – it certainly felt like full-on summer because North America had experienced the warmest first four months of the year on record. In April, the global land-surface temperature was 2.5°F above the 20th century average and the United States experienced its third warmest April since record keeping began in 1895. It’s also worth noting that hurricanes aren’t the only natural phenomenon ‘starting a few weeks early’ this year: Louisiana was spraying for mosquitoes a month sooner, the Carolinas began harvesting strawberries more than two weeks early and birdwatchers everywhere were treated to the annual arrival of migratory songbirds anywhere from one to three weeks early.

But I digress; I was talking about hurricanes, and the 2012 hurricane season in particular. Despite the early start to this season and busyness of the past two seasons, experts are forecasting a ‘near normal’ year in terms of the number of predicted storms. Such forecasts are consistent with a growing scientific consensus that while hurricane frequency won’t necessarily increase (and may actually decrease — particularly Cat. 1, 2, and 3), the overall intensity of storms may increase (more Cat. 4 and 5), thus increasing their overall destructive capacity. Hurricanes may intensify as a result of human-induced climate change because warmer temperatures at the ocean surface which result from our addiction to fossil fuels feed hurricanes and make them stronger. A recent scientific study published in Nature concluded:

“Future projections based on theory and high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms…(and) modeling studies typically project substantial increases in the frequency of the most intense cyclones.”

Stronger, more intense storms due to warmer oceans wouldn’t be the only maritime impacts in a warming world. As the atmospheric levels of greenhouse gases increase, warming air temperatures will also cause land ice in Greenland, the Arctic and Antarctica to melt.  Glacial and ice-cap melt plus thermal ocean expansion will result in sea level rise. Even modest levels of sea level rise coupled with growing populations along our coasts means that increasing numbers of citizens, amounts of development and types of ecosystems in our coastal regions will be vulnerable to storm surges after hurricanes. Coastal zones aren’t the only region that will feel the impact of stronger hurricanes: the heavy rains that result from hurricanes may move hundreds of miles inland, increasing the risk of flooding. The wild card in all of these projections?  Positive feedback loops can increase the rate of warming which can, in turn, increase the intensity and rate of any of these impacts.

Check back next week as our blog features other pieces in the hurricanes and energy series to examine the connections between Hurricanes and Wind Farms, Hurricanes and Coastal Adaptation, and Hurricanes and Oil Rigs.

 

Jennifer Rennicks
Jennifer joined the Southern Alliance for Clean Energy in 2006 as federal policy manager and now directs policy and communication efforts of SACE and the Southern Alliance for Clean Energy Action…
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