An important part of the climate change debate is that the thermal heating of the oceans and the increased melting of land-based glacial ice will lead to higher sea levels that will seriously threaten some coastal communities. Cities such as Miami have been urged to make substantial infrastructure investments in order to help mitigate the future costs of increased ocean flooding.
The latest report from the Intergovernmental Panel on Climate Change (IPCC) of the United Nations concludes that ocean levels could rise between 2 and 3 feet by 2100. A similar report in 2017 from the National Oceanic and Atmospheric Administration (NOAA) suggests that the “global mean sea level” increase could be as much as 6 to 8 feet by the end of this century. Al Gore, in his 2006 book “An Inconvenient Truth,” famously opined that increased global warming might well produce a 20 foot increase in ocean levels sometime “in the near future.” And as the climate continues to warm—from the increased burning of fossil fuels presumably—these forecasts can sound alarming.
Satellite laser altimeter readings since 1993 and older tide gauge measurements all appear to confirm that global sea levels have risen by roughly .12 inches per year for several decades. If the rate of increase remains steady, 12 years from now by 2032–when some politicians claim that climate warming could well push the planet beyond the point of no return–ocean levels will have risen approximately 1.25 inches above where they are today. And eighty years from now, at the turn of the next century, sea levels would be about a foot or so higher than they are at the moment.
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Admittedly any acceleration in global warming could make all of these numbers higher (and an abatement of some warming could make these numbers lower) but even an unlikely doubling of ocean level outcomes by 2100 would still leave sea heights well short of a 2 foot increase.
Whether these projected increases are troubling or not is far from obvious, however. The general consensus among climatologists is that there is substantial risk that rising ocean levels in the near future will spill over and flood coastal properties and force substantial migrations of people along the coast to move further inland. Wouldn’t it be prudent, then, to impose carbon taxes (to cut emissions) and implement various coastal regulations in order to mitigate these inevitable property and migration costs?
The answer to these questions by some economists and climate skeptics is: It all depends. After all, any substantial increase in sea levels must occur in discrete, fairly small marginal increments (roughly one/eighth of an inch per year) over many decades; this would give society a reasonable amount of time to observe, to plan and to adjust. Investing or regulating now for something that may or may not happen many decades from now can be just as risky as doing nothing. In addition, it is difficult to argue that the 3 inch increase in ocean levels predicted to occur over the next 24 years will produce calamity when ocean levels have risen nearly that much since 1990 without any radical societal disruption.
The carbon tax issue is even more ambiguous. First, despite the media reporting, there is still serious debate over whether carbon dioxide, a relatively minor greenhouse gas (.042% by volume), contributes significantly to global warming. Second, absent some world-wide enforceable agreement, carbon taxes in the U.S. would accomplish only some de minimus reduction in total emissions. If the oceans are rising, carbon taxes in the U.S. are not a politically attractive or even practical short-term solution.
But are the ocean levels even rising? Some climate skeptics, such as Niles-Axel Morner, the former head of the Paleogeophysics Department at Stockholm University, have long maintained that while sea levels certainly have been variable over the last 50 years, there has been no significant upward trend. Professor Morner holds that laser measurements from satellites have failed adequately to take into account important solar and planetary forces that systematically overstate actual ocean heights.
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Moreover, Morner has published empirical evidence (International Journal of Earth and Environmental Sciences, 2017) that concludes– based on his study of sea levels in the Fiji Islands–that there are “no traces of (a) present rise in sea levels; on the contrary, full stability.” And while Morner’s theories have been criticized, his unique observational data appears to support the notion that the risk of any doomsday coastal flooding due to global warming may be overstated.
Morner aside, what if anything, should be done about the alleged threat posed by higher ocean levels? One proposal, consistent with a free market approach to the problem, would be to swiftly terminate certain government programs (below cost insurance) that create perverse incentives to build and then re-build coastal properties. Another would be to err on the side of caution and fortify several U.S. nuclear plants which may be especially vulnerable to ocean flooding. However, the enactment of carbon taxes in the U.S. (but not in the rest of the world) or proposals to invest in expensive flood-abatement programs in major coastal cities does not yet seem warranted.
This op-ed was originally published in Vero Beach 32963.
