
For quite a few years now, and especially since Hurricane Sandy in 2012, communities along the East Coast of the US have been preparing for the ever-larger storms that we’re told we can expect. Many attribute the coming increase in the size and frequency of hurricanes to climate change, but recent research shows there may be yet another cause.
A NOAA scientist, James Kossin, has been studying data on winds and ocean temperatures going back to 1947. He’s concluded that an inverse relationship exists between the number and intensity of storms generated in the Atlantic Ocean and the severity of those that actually reach the US coast. When conditions are right for producing major storms far out at sea, the mechanism of vertical wind shear tends to remove much of the energy from those storms before they reach the coast, creating a “buffer zone” for the coastal region.
As summed up in this article, “When the Atlantic is in its hurricane-producing phase, with low wind shear and high surface temperatures in its central region, the part along the American coast behaves in the opposite manner, with high wind shear and low surface temperatures that sap the storms’ energy.”
These conditions have prevailed for more than two decades. Conversely, when the storms generated in the Atlantic are relatively few and weak, the ones that do reach the coast are likely to gain wind speed and intensify as they approach land.
If his view of what’s happening in the Atlantic is correct, it’s difficult to predict when conditions will change and the coast will be likely to experience larger storms, but it appears that this is a natural cycle and the protection we’ve enjoyed since the early ’90s will eventually diminish. Kossin estimates that the hurricanes making landfall then are more likely to be Category 3 to Category 5 storms (Sandy was a Category 3 when it hit Cuba but had weakened significantly by the time it reached the US). This suggests that we should continue—or increase—whatever preparation we’re now making to protect our coasts and our infrastructure, or, as the article says, take “the prudent course of mending the roof while the sun is shining.”
The results of Kossin’s study have been published in Nature. You can also read about some of his earlier research on hurricanes, and possible effects of climate change on hurricane patterns, here.
Janice Kaspersen
Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines.