Severe Flooding More Likely Due to Global Warming
By Edwin L. Aguirre
When Hurricane Sandy devastated the East Coast, many people were quick to put the blame on global warming. After all, warm ocean waters are the fuel for such massive killer storms.
Not so fast, says climate science Assoc. Prof. Mathew Barlow of the Department of Environmental, Earth and Atmospheric Sciences.
“Most climate scientists, including myself, don’t like to try to link single events to the overall warming trend,” says Barlow.
He says a “superstorm” like Sandy is unusual, but such hurricanes would likely happen every now and then even in a climate with no warming, like the 1938 hurricane that wreaked havoc in the Northeast.
“What is fair to say is that, based on our current best understanding, the warming trend probably — but not definitely — makes such events more likely and stronger,” explains Barlow. “Until we have several unusual events, it’s hard to establish changes in probabilities. This is made more difficult by poor historical data for hurricane strength and occurrence, especially in the period before weather satellites.”
He notes that ocean surface temperatures and the associated evaporation are the engine of hurricanes, so increasing temperatures are likely to result in stronger, more frequent storms, but these may be partially offset by changes in other factors, such as wind shear, which suppresses hurricanes.
“I’d certainly bet more frequent and stronger, but I wouldn’t necessarily bet the metaphorical farm on it,” cautions Barlow.
He says one thing that is clear, though, is that rising sea levels, coupled with storm surges, will severely increase the flooding impacts in low-lying cities such as New Orleans, New York City and Boston even if hurricanes don’t change much.
“We are quite confident that sea-level rise will continue and probably accelerate, so from that perspective it is unambiguously a severe global warming problem, no matter what,” says Barlow.
He adds: “We have plenty of evidence that global warming is making significant changes in our climate, so I would call Sandy more of a wake-up call in understanding how big the impacts could be, and a likely harbinger of storms to come, rather than a stand-alone Exhibit A for global warming.”
Mitigating Climate Change Is the Key
“Our coastal communities, infrastructure and ecosystems are becoming increasingly vulnerable under a changing climate,” says biology Assoc. Prof. Juliette Rooney-Varga, director of UMass Lowell’s Climate Change Initiative.
“Rebuilding after Hurricane Sandy offers an opportunity to increase our resilience to future extreme events that we know are coming,” says Rooney-Varga. “It raises difficult questions about where it makes sense to rebuild or consider retreat from vulnerable areas, and how we can rebuild in ways that mitigate climate change and reduce our reliance on fossil fuels.”
She adds: “Ultimately, the key to avoiding the most damaging impacts of extreme weather and sea-level rise is to transition our economy away from coal, oil and natural gas that are the root cause of the impacts we are beginning to witness.”