More Severe Atlantic Hurricanes in Store

We know the oceans are getting warmer. There has been a lot of debate about what this will do in regards to hurricanes, though. The principle reason for this dispute is a lack of data. But, a new study of sediment layers from a Massachusetts salt pond resulted in a record of hurricanes over the years that can be compared to the sea surface temperature record. By analyzing the sedimentary layers they were able to identify severe storms and compiled a record going back 2000 years. They were able to identify 35 severe storms over that period.

At Salt Pond, three coarse grained event beds deposited in the historical interval are consistent with severe hurricanes in 1991 (Bob), 1675, and 1635 C.E., and provide modern analogs for 32 other prehistoric event beds. Two intervals of heightened frequency of event bed deposition between 1400 and 1675 C.E. (10 events) and 150 and 1150 C.E. (23 events), represent the local expression of coherent regional patterns in intense-hurricane–induced event beds. Our synthesis indicates that much of the western North Atlantic appears to have been active between 250 and 1150 C.E., with high levels of activity persisting in the Caribbean and Gulf of Mexico until 1400 C.E. This interval was one with relatively warm sea surface temperatures (SSTs) in the main development region (MDR). A shift in activity to the North American east coast occurred ca. 1400 C.E., with more frequent severe hurricane strikes recorded from The Bahamas to New England between 1400 and 1675 C.E. A warm SST anomaly along the western North Atlantic, rather than within the MDR, likely contributed to the later active interval being restricted to the east coast.

Doing a straight average gives you an average of 1.75 severe storms per century. But, the record shows the storms were not evenly distributed. There were an average of 3.6 severe storms per century from 1400 to 1675 and an average of 2.3 severe storms per century between 150 and 1150. These just happened to be warm periods. In comparison, the remaining 750 years in the record had an average of .28 severe storms per century.

So, when the sea surface temperature was low, there were .28 severe storms per century. When the sea surface temperature was high, there were 2.3 and 3.6 storms per century. Take a look at the sea surface temperature anomaly and draw your own conclusion: