Published Wednesday, March 11, 2020

History shows that sea-level rise is modest

By James Brodell

Costa Rica always has had a hard time countering exaggerations and flat out false information generated in the international media. That goes for the real estate business, too, because both industries are linked.

Those who purchase property and perhaps retire here usually first learned of the country's charms as tourists.

A recent concern of tourists and expats is sea-level rise. Even many long-time expats or snowbirds who own properties along the country's fabled Pacific or Caribbean costs have expressed concern that their investment might be washed away due to rising oceans. The international media does not help.

The internet is filled with scare stories about how the seas will wash away Costa Rican coastal land. Even the prestigious Reuters said that the danger is real. IPS News Service reported that the Caribbean will inflict damage on the coastal town of Cienaguita. Even a local website says that “Scientist are saying that coastal residents of Costa Rica could face a significant sea level increase possibly up to  three to six feet which would inundate many of the existing beach properties which hold concessions in the maritime zones. And the  port city of Puntarenas could be under water.”

Data provided through the U.S. National Oceanic and Atmospheric Administration are far less dramatic. That agency tracks sea level and maintains links online to measurement stations around the world. In Costa Rica, the National University maintains three stations in Costa Rica: in Quepos, in Limón and on distant Cocos Island. The Centro de Investigación en Ciencias del Mar y Limnología at the University of Costa Rica concentrates on other scientific aspects of the oceans, such as pesticide impact on fish and the prevalence of plastic in the seas.

Two of the stations that provide data to the  Oceanic and Atmospheric Administration have been keeping track of their local oceans for decades. The station at Balboa, Panamá, at the Pacific end of the famous canal has done so since 1908. At the other end of the canal on the Atlantic, a station at Cristobal began gathering data a year later and did so for 72 years. The U.S. agency gives both stations high marks for completeness.

The Balboa data, supplied by the  Panama Canal Commission says the sea-level trend there is an increase of 1.43 millimeters per year from 1908 to 2018, which is equivalent to a change of 0.47 feet in 100 years. The Cristobal data, also provided via the canal commission, says there has been a steady increase of 1.41 millimeters per year, which is equivalent to a change of 0.46 feet in 100 years.

Sea level measurement is a difficult task because the ocean's level continually changes. In addition, the land benchmarks that are the basis for the measurements may change, too. A YouTube video once claimed incorrectly that the ocean at Boco del Toro in northeastern Panamá near the Costa Rican border was rising drastically. In fact, later investigation showed that the land had subsided due to earthquake activity. In the United States, subsidence also is true of some lands along the coast of the Gulf of Mexico. Elsewhere some land is rebounding after the weight of Ice Age glaciers have vanished and sea level measurements are reduced. The land height also can be changed by the pumping of ground water or petroleum.

The oceans also expand based on temperature.

Because water seeks its own level, the long-term measurements out of Panamá can be considered to be very similar to the sea levels on Costa Rica's Caribbean and Pacific coasts.

Costa Rica, of course, has embarked on an effort to become carbon neutral by 2050 in an effort to reverse the warming climate. Those involved in this effort also suggest that older sea level data are not good predictors because the rate of sea level rise is expected to increase. At this date the arctic snowfall is well within normal ranges, so immediate drastic changes are unlikely.

Editor's note: Mr. Brodell, founder and long-time editor of A.M. Costa Rica, can be reached at: