It's hard to tie weather to climate. While news media often speculate that a major catastrophe such as Hurricane Sandy or Hurricane Katrina may be related to global warming, scientists caution that any one weather event is more properly viewed as a response to transient conditions.
Still, the patterns are real. And this week, scientists are pointing out that frequent small floods can be analyzed statistically, and that the link to climate change and sea level rise is reasonable to draw. The New York Times has a report (see: "Seas Are Rising at Fastest Rate in Last 28 Centuries," by Justin Gillis).
"The rise in the sea level contributes only in a limited degree to the huge, disastrous storm surges accompanying hurricanes like Katrina and Sandy," the Times reported. "Proportionally, it has a bigger effect on the nuisance floods that can accompany what are known as king tides. The change in frequency of those tides is striking. For instance, in the decade from 1955 to 1964 at Annapolis, Md., an instrument called a tide gauge measured 32 days of flooding; in the decade from 2005 to 2014, that jumped to 394 days. Flood days in Charleston jumped from 34 in the earlier decade to 219 in the more recent, and in Key West, Fla., the figure jumped from no flood days in the earlier decade to 32 in the more recent." (Below, amateur YouTube video of storm flooding in West Islip on Long Island, New York in January 2016.)
The Times article is based on two scientific efforts. One, a paper in PNAS, the Proceedings of the National Academy of Sciences of the United States of America, is authored by a team of scientists including Rutgers University climate scientist Robert Kopp and German physics professor Stefan Rahmstorf of Potsdam University (see: "Temperature-driven global sea-level variability in the Common Era"). The researchers looked at centuries of geological evidence to conclude that recent sea level rise has kept pace with rising global temperatures. Kopp told the Times, “Physics tells us that sea-level change and temperature change should go hand-in-hand. This new geological record confirms it.” Said Rahmstorf: “I think we can definitely be confident that sea-level rise is going to continue to accelerate if there’s further warming, which inevitably there will be... Ice simply melts faster when the temperatures get higher. That’s just basic physics.”
The second report is an analysis of routine tidal flooding records conducted by Benjamin Strauss of the organization Climate Central (see: "The Human Fingerprints on Coastal Floods"). Strauss wrote: "From 1950 through 2014, out of the 8,726 actual nuisance flood days that our analysis identified, 5,809 of them — two-thirds — would not have taken place if you remove Kopp et al.’s central estimate of human-caused global sea level rise. Even using a low estimate — one more than 95 percent likely to be too low — more than 3,500 of the flood days would not have taken place."
The lesson for the future, the scientists say, is clear: Routine seaside flooding is here to stay, it's going to get worse, and coastal dwellers have no choice but to adapt.