Monday, April 09, 2018

NOAA Report: Today’s Damaging Floods Will Be Tomorrow’s High Tides


https://www.wunderground.com/cat6/noaa-report-todays-damaging-floods-will-be-tomorrows-high-tides

Bob Henson · March 28, 2018

Disruptive tidal flooding that now affects the U.S. Gulf and Atlantic coastlines on 3 to 6 days per year will strike as often as 80 to 180 days a year by the 2040s, according to a major report from NOAA’s National Ocean Service released in February. These increases will be driven mainly by global sea level rise, the report notes—although human-produced climate change itself is not mentioned in the report (see commentary below)

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Based on these values, just a modest one-foot increase in sea level will be enough to transform minor nuisance floods to damaging moderate floods. A further increase in sea level by 1.3 feet will make today’s minor flood a destructive major flood.

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Climate change raises the stakes greatly when it comes to high-tide flooding. As oceans expand and ice sheets melt, global sea level has risen by an average of about 3 mm (0.12”) per year since the 1990s (see our February 15 post), but the rate has been accelerating. If this acceleration were to continue through the end of the century, global sea level rise between 2005 and 2100 would be about 65 cm (26”), more than double the rise of 11” that would occur if sea level rise stayed constant at 3 mm/yr. There’s a real risk that global sea level could rise by a meter (39”) or more this century, especially if Antarctic ice sheets poking into the ocean are destabilized by warming waters.

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Even under the intermediate low scenario, which the planet may well vault past, we can expect high-tide flooding virtually every day by the 2090s along the western U.S. Gulf Coast, and on two out of three days along the northeast U.S. Atlantic coast. Under the intermediate scenario, high-tide flooding is possible every other day by the 2040s along the western Gulf Coast and one out of every three days along the Northeast coast by the 2040s, which arrive just 22 years from now.

The U.S. West Coast and the Pacific and Caribbean Islands are also in line for a dramatic boost in high-tide flooding, although the more rugged coastal topography means it will take till later this century for the more significant effects to kick in. High-tide flooding is projected to reach near-daily levels by the 2090s along the West Coast and in the U.S. Caribbean Islands.

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In this powerful and sobering NOAA report, the lack of direct mention of the main cause of current global sea level rise—climate change produced by fossil fuel emissions—is itself striking, especially in the context of other developments. For example, Bloomberg reported on March 15 that FEMA’s strategic plan for 2018-2022 omits all mention of climate change, which had been prominent in the agency’s prior strategic plan.

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The new NOAA and FEMA documents are hitting the streets after more than a year of climate-change dismissal and denial fostered at the top levels of the current presidential administration, most notably by President Donald Trump and EPA Administrator Scott Pruitt. Similar forces have been at play at the state level over the past few years. For example, legislators in North Carolina voted in 2012 to allow use of only historical trends rather than the expected climate-change-driven acceleration when planning for the risk of coastal sea-level rise. And in Florida, state officials reported being ordered not to use the terms “climate change” and “global warming” in official communications, including reports.

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It’s human nature to ignore warnings unless they are reinforced in a variety of ways. Scientists ought to be free to invoke human-produced climate change as little or as much as they see fit in a given context. However, as long as a significant fraction of Americans continues to push climate change out of mind, there’s a case to be made for explicitly noting that it’s a real thing.

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