Are Rising Ocean Levels an Existential Threat?

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. Swords Into Plowshares... Paul, Ron Best Price: $4.00 Buy New $15.99 (as of 11:36 UTC - Details)

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. Gun Control and the Se... Laurence M. Vance Buy New $5.95 (as of 11:36 UTC - Details)

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.