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Climate scientists: Get ready for more Harveys


Image: National Weather Service

Climate science is obviously a very imprecise discipline when it comes to making very time-specific forecasts. No one can predict at this point what the impacts of climate change will be in a particular place at a particular time.

But when it comes to charting probabilities over time, it’s clear that rising global temperatures will continue to help intensify many of the destructive storms like Hurricane Harvey that do occur. Dr. Joe Romm of Think Progress explains in an article entitled “Climate change made every stage of Hurricane Harvey more horrific” [2]:

“Climate change worsened the unprecedented disaster unfolding in Houston from Hurricane Harvey,” as climatologist Michael Mann [3] said in an email to ThinkProgress. “And unrestrained climate change means we will see many more Harveys in the future.”

Like a baseball player on steroids [4], our climate system is breaking records at an unnatural pace. Global warming is juicing storms — a key reason Harvey is the second 1-in-500-year superstorm in 16 years (and fourth 100-year rainstorm [5] since spring 2017). And like a baseball player on steroids, it’s the wrong question to ask whether any given home run is “caused” by steroids.

Every stage of Harvey — the rapid intensification that makes for a forecasting nightmare, the brutal storm surge, and the unprecedented rainfall — were worsened by global warming. In fact, there’s been so much rain, the National Weather Service had to update their color maps to cover it all.

Hurricanes “extract heat energy from the ocean to convert it to the power of wind, and the warmer the ocean is, the stronger a hurricane can get if all other conditions that it needs to exist are present,” meteorologist and former hurricane hunter Jeff Masters explained last month [6] on Living on Earth. “So, scientists are confident that as we continue to heat up the oceans, we’re going to see more of these high-end perfect storms.”

Let’s look at some of the latest climate science. The first stage of a hurricane is formation and intensification. Harvey spun up from a tropical depression to a Category 4 superstorm in two days as it crossed Gulf of Mexico waters that were 2.7 – 7.2°F warmer [7] than “normal” (the 1961-1990 baseline).

The latest research says global warming is driving this trend. “Storms are intensifying at a much more rapid pace than they used to 25 years back,” explained [8] the author of a 2012 study [9]. “They are getting stronger more quickly and also [to a] higher category. The intensity as well as the rate of intensity is increasing.”

This warming-driven trend toward more rapid intensification is very worrisome. “The vast majority (79 percent) of major storms” are rapid intensification storms,” and “the most intense storms” are those that undergo rapid intensification according to a 2016 study [10]. And rapid intensification makes it much harder to predict and plan for superstorms….

While we aren’t seeing more total hurricanes, we are seeing more of the Category 4 or 5 super-hurricanes, the ones that historically have done the most damage and destroyed entire coastal cities. We’re also seeing a sharp rise in the most damaging storm surges, whereby even a Category 1 hurricane (such as Sandy) can cause unprecedented damage.

On our current path of unrestricted carbon pollution, NOAA researchers have determined [11] that parts of the East Coast would see Sandy-level storm surges every year by mid-century.