- - Monday, October 20, 2014


Environmental Protection Agency (EPA) Administrator Gina McCarthy visited Miami Beach recently to raise awareness about the need to “stop global warming” in order to save the region from dangerous sea-level rise.

“How are we going to pump our way out of this challenge if we don’t start now to take action to mitigate the release of carbon-pollution emissions, which is fueling this changing climate?” the EPA chief asked.

Ms. McCarthy clings to the outmoded belief that rapid human-caused global warming is occurring; that this will cause accelerated glacial melt, the oceans to expand, and global sea level to rise quickly; and that low-lying coastal areas of the United States will then be subjected to increasingly intense peak-tidal or storm-surge flooding. Drastically reducing our carbon-dioxide emissions is necessary to avoid this looming crisis, she asserts.

However, every step in Ms. McCarthy’s chain of reasoning is either wrong or misleading. No global (atmospheric) warming has occurred for the past 18 years. Independent measurements show that neither has there been significant ocean warming since at least 2003. As a consequence, the ocean is not expanding and cannot be causing extra sea-level rise.

Neither has the much-trumpeted prediction of an acceleration in the rate of sea-level rise taken place. Instead, a deceleration of the global rate of rise has occurred over the past few decades.

And all this despite a 9 percent rise in atmospheric carbon dioxide over the same period.

Despite the cessation of warming, accurate National Oceanic and Atmospheric Administration tide-gauge measurements show that sea level at specific U.S. coastal locations continues to rise at about historic rates. How can this be?

It is so because the idea that sea-level change is driven primarily by human greenhouse-gas emissions, global warming and ocean expansion is fallacious. Instead, rates of sea-level change at any given place are controlled mostly by the combination of the volume of water in the ocean (itself a function of global land-ice volume at any given time), by dynamic oceanographic features, such as movements in major ocean currents, and by the uplift or subsidence of the solid earth beneath any measuring station.

The only way the sort of sea-level rise feared by Ms. McCarthy is possible is if massive quantities of the Antarctic and Greenland ice caps melted. This did not happen even during the two-degrees Celsius warmer Holocene Optimum, 5,000 to 9,000 years ago, and the current trend is toward lower temperatures and greatly more expansive sea ice around Antarctica, the source of 90 percent of all ice on Earth.

In reality, the rate of sea-level rise today is now so low that adaptation is relatively easy, and certainly far more cost effective than restructuring our energy infrastructure on the off-chance that this will affect global climate and sea level.

The EPA administrator is likely basing her policies on reports such as those of the United Nations Intergovernmental Panel on Climate Change, which continue to project that global sea level will rise at an enhanced rate.

Or perhaps she actually takes seriously the speculative computer forecasts of the Union of Concerned Scientists, which, in its October report, “Encroaching Tides,” projected a 17-inch rise in sea level for Key West, Fla., over the next 50 years. Using questionable methods of measuring sea-level rise, and unrealistic future emission scenarios, the Union of Concerned Scientists predict an improbable fourfold increase in the current rate of sea-level rise for Key West.

A more sensible perspective is presented by the Nongovernmental International Panel on Climate Change, the reports of which are based on the findings of thousands of peer-reviewed scientific papers. A September 2013 report by the panel concluded, “Sea-level rise is not accelerating. The global average sea level continues to increase at its long-term rate of 1-2 millimeters per year globally.”

In any case, in terms of coastal management, sea-level change is not a global problem, as Ms. McCarthy seems to believe. It is a regional problem that requires solutions tailored to the events, needs and rates of local relative sea-level change of particular regions. Organizations such as the Intergovernmental Panel on Climate Change and the Union of Concerned Scientists are, therefore, wrong to promote the use of “global sea level” as an environmental-management tool.

Good coastal management rests not upon global averages or speculative computer projections, but upon an accurate knowledge of the geological, meteorological and oceanographic conditions at sites of interest.

As sea level continues its natural slow rise along America’s coasts, flooding owing to peak tides and storm surges will continue much as it has for the past century. The way to cope with any small increase in the magnitude of these events that may be caused by future sea-level rise is to apply and strengthen current strategies that increase coastal resilience.

Because of the construction of homes, businesses and other infrastructure in vulnerable coastal areas, providing enhanced resilience will be expensive for some jurisdictions. Miami Beach, for example, is planning to spend $500 million over the next five years on pumping stations to keep flooding at bay.

Such investments in adaptation to inevitable sea-level rise are worthwhile and, indeed, necessary. Ms. McCarthy’s plans to spend billions of dollars more on vainglorious attempts to stop the seas from rising at their natural rate are clearly not.

Bob Carter is former professor and head of the School of Earth Sciences at James Cook University in Australia. Tom Harris is executive director of the Canada-based International Climate Science Coalition.



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