The devastating scenes from Houston in the aftermath of Hurricane Harvey are sadly recognizable to anyone who lived through Hurricane Sandy in NYC or survived Katrina in New Orleans. That the country has endured three of these catastrophes in less time than it takes a person to graduate from high school is deeply troubling, but Dr. Charles Greene, professor of Earth and Atmospheric sciences at Cornell, says that even without another Sandy, NYC increasingly faces the possibility of similar destruction here, thanks to weather systems getting stuck over our heads, most likely as a result of climate change.
According to Greene, while Sandy and Harvey had some differences, what made them similar was the way the storms were affected by high-pressure weather blocks. The blocks themselves were the result of arctic warming and a lack of sea ice, which slowed down the jet stream, factors that then helped divert or trap the storms in place.
In the case of Sandy, a high-pressure block in the Labrador Sea kept Sandy from taking the traditional route out to sea that many late-season hurricanes tend to take, and instead forced the hurricane towards New York and New Jersey, which Greene said hadn't ever been seen before. Similarly, in Harvey's case, the lack of sea ice and a slow jet stream meant that a hurricane that would usually blow through Houston and into west Texas was trapped over the city for days.
"We can't be absolutely sure, and can't say beyond a shadow of a doubt, that this will keep happening," Greene told Gothamist. "But the preponderance of evidence is that this is from climate change."
It's difficult to say, according to Greene, whether a blocking system will again encounter a hurricane in the way that led to Sandy. But, he said, "we could get a system set up so we get a tremendous amount of rainfall" and see other extreme weather events because of blocking systems. And with these new weather events, Greene said that "what we have to think about now is not just the intensity, but the duration of a storm. That can really be devastating," as was seen in the almost non-stop rain over Houston.
While Greene called New York "tremendously vulnerable," in the same way so many coastal cities are, he also said that of all the major such cities he knows of, the city is "really aware of the situation and is trying to come to grips with it." Greene did warn that it would be difficult and expensive to deal with projected storm surges and flooding from climate change, referencing the possibility of the extremely expensive New York Harbor Storm-Surge Barrier. But he also suggested that and other changes would be worthwhile, when considered in light of the $60 billion in damage caused by just one Sandy-level superstorm.
There are also tough decisions ahead for city leaders and residents about where people will live in the future. Calling beaches "rivers of sand," Greene said that in his opinion "people are living in a lot of places where they shouldn't be, particularly on barrier islands." While Greene didn't call for a full-scale retreat from the shore and from beaches, he did say that the conversations about the risks of living there "just have to happen."
"We as a scientific community can tell you what our best estimate is for what the sea level rise and inundation will look like over the coming decade. And people need to decide how much risk they're willing to live with," Greene said. He also said that if he was figuring to live past 2050, "I'd have a real problem living in some of those areas near the shoreline. Because you're almost guaranteed to have some severe events near you in your lifetime."
And yet, Greene sees signs of hope, like the feasibility of shifting the country's light vehicle fleet to completely electric by 2040 or 2050 to significantly reduce carbon emissions—a direction NYC is already moving in. And while Greene told us that we're so far along in carbon pollution that carbon will have to somehow be captured from the atmosphere and stored, he suggested that could be accomplished by both a new technology to make carbon fiber from carbon sucked from the air, and a microalgae project that he's working on which would also turn the algae into a new liquid fuel source. Change is mostly a matter of political will, he said.
"I'm actually an optimist, even though these impacts are terrible," Greene concluded. "It just takes political will to solve them, but right now we're battling vested interests who want to move on with business as usual."
