"Larger swings in the jet stream allow frigid air from the Arctic to plunge farther south, as well as warm, moist tropical air to penetrate northward," Francis wrote in Yale University's Environment 360 blog. That's pretty much what happened this week, a spectacular collision of Arctic and tropical weather fronts.
A recent article in the journal Oceanography shed more light on the consequences of Arctic ice melt. Charles Greene at Cornell University and others wrote that fundamental changes in the behavior of the jet stream will "stack the deck in favor of severe winter weather outbreaks in the United States and Europe into the foreseeable future."
Urgent remedial action
There needs to be urgent remedial action to mitigate the effects, said Oppenheimer, such as raising subway entrances and reinforcing the lower floors of buildings. At the moment, Oppenheimer said, there's a lot of evaluation of hazards and too little action to address them.
After a sudden deluge in 2007 that closed part of the subway system, the New York Metropolitan Transit Authority committed more than $30 million to raise ventilation grates and redesign the entrances to some subway stations. It's also spent heavily on pumps, but a substantial surge would soon overcome such remedial measures. And beside the subway lines, power transformers and fiber-optic networks are vulnerable to flooding.
More ambitious actions would have far-reaching political and economic consequences. New York State's Sea Level Rise Task Force was created in 2007 and delivered its report to the Legislature on the last day of 2010. Among its key recommendations was greater reliance on natural protection such as marshland and a tightening of zoning laws to prevent the loss of such features.
New York City disagreed with the panel's more critical recommendations, saying it did "not recognize the differences between undeveloped areas and densely populated cities." The city's task force rejected the idea of limiting development as prohibitively expensive.
Other ideas aimed at protecting New York include:
Douglas Hill of the Storm Surge Research Group at Stony Brook University has proposed a chain of massive sea barriers in Long Island Sound that could be closed to prevent flooding whenever a storm surge threatens.
One would be close to the Verrazano-Narrows Bridge. (The Thames Barrier in London performs such a role in a more modest way.) But the cost would probably exceed $10 billion; a barrier in Venice cost $7 billion.
-- Another recommendation would be tougher regulations on where industrial and chemical plants can be situated, improving the design of buildings to make lower levels flood-proof (known as freeboard in the insurance industry) and "soft edges" that better break wave action.
-- Stronger and maybe higher sea walls around more vulnerable parts of Manhattan might also help.
The current sea walls are about 4 to 5 feet above the average sea level. Many were built at the beginning of the last century. A New York Times article from August 1901 marveled at "The Massive Sea Wall Which Will Encompass Manhattan."
"It will be many generations, perhaps centuries, before the wall ... will have to be rebuilt or will even require any extensive repairs," the Times reported then. That was before climate change became part of the lexicon. New York City's "Vision 2020" plan warned that sea walls and other shoreline structures are likely to need more frequent repair because of more damaging storms.
Will Sandy drive political debate about climate change?
According to a recent Pew Research Center poll, 67% of Americans believe the Earth is warming.
That number is up slightly since 2010, but it's 10 percentage points less than in 2006. Among both Democrats and Republicans, the percentage has declined, as has the number (now 64%) who say it's a serious problem.
The lack of debate about climate change in the presidential election campaign has been "unfortunate," said the Nature Conservancy's Marshall.
But Marshall said she believes Americans are getting to the point of recognizing what they see for what it is.
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