Just as extreme weather events have altered course over time, due in part to climate change, so have researchers sought new models and techniques to predict such variability of events. Kerry Emanuel discussed several new models that estimate hurricane risk and damages in current and future climates during an EPIC seminar on May 20th.
A professor of atmospheric science at MIT, Emanuel illustrated that current models for predicting extreme weather events, particularly hurricanes, are outdated because they are based on historical patterns of recorded hurricanes. As climate change is increasingly affecting the rate and characteristics of extreme weather events, these older models therefore become less robust. Using a strictly statistical approach based on existing landfalling storm data does not readily predict the rising possibility of experiencing category 3, 4 or 5 hurricanes, which cause the most damage. Moreover, there are too few high intensity events in the historical hurricane database to make statistically robust risk assessments, even in the current climate.
Instead, researchers at MIT are now proposing new climatological simulation models based on the physics of hurricanes that might be better at predicting such occurrences, Emanuel said. Using a simulation model approach, researchers can now incorporate a higher number of variables that could influence the rate of future extreme weather occurrences. For example, one forecasting test using this model suggests that the increased risk of hurricane surges is closely associated with, but not entirely due to, higher sea levels even if the hurricane climate stays the same, Emanuel said.
Another method that can supplement the simulation models in predicting hurricanes is a field called paleotempestology, which looks at the earth’s geophysical history in an attempt to reconstruct past hurricane activity. By extending the data on past hurricanes well beyond the historically documented occurrences, a more robust estimate of hurricane risk can be made and one can also assess the impact of climate variability on hurricanes over time.
Finding better fitting models to predict hurricanes and other extreme weather events has a significant impact on assessing and insuring against such risk. New methods of predicating hurricanes must also be accompanied by reforms in insurance policies, some of which have been kept at artificially low prices for political reasons, Emanuel said.
“There is such a distortion of insurance markets by politics that even without climate change we are very badly prepared for hurricane risks,” Emanuel said. “We are underwriting massive developments on the coastline that wouldn’t occur if there were a free market of insurance rates, because it would have been too expensive.”
Regardless of the model used for assessing this type of risk, however, it is clear that hurricanes vary with climate and the threat of more frequent and more powerful hurricanes will surely increase in this century, Emanuel said.