Environmental activists, mainstream media outlets, and many scientists routinely claim governments must take drastic action to prevent rapidly rising seas. They claim unless humans are forced to stop using fossil fuels, low-lying islands and coastal areas will soon be swamped beneath the waves.
To back up their claims, they cite statements (pdf) from the Intergovernmental Panel on Climate Change (IPCC) asserting it is “very likely” sea level rise has accelerated since the middle of the 20th century in response to warming caused by rising greenhouse gas emissions. The IPCC, however, bases its claim on computer model projections instead of measured, real-life data.
Data lend little support to the claim seas are rising at a historically unusual or increasingly rapid rate. Global sea levels have risen by approximately 400 feet since the beginning of the end of the most recent ice age (approximately 20,000 years ago). Historically, sea levels have fluctuated over hundreds of thousands of years, having nothing whatsoever to do with fossil fuel emissions.
Research shows most of the islands making up nations such as Tuvalu and the Maldives are gaining, not losing, landmass. A peer-reviewed study that examined 600 coral reef islands in the Pacific and Indian Oceans reported approximately 40 percent of those islands remained stable and 40 percent grew. More evidence can be inferred from the fact that the populations on these island nations and the coastal United States are increasing instead of fleeing. Moreover, in those places, they’re putting up new, expensive buildings and associated infrastructure daily.
A 2019 report (pdf) by Craig Idso, David Legates, and the late S. Fred Singer confirms sea levels have not been rising at an unusual rate in recent years. After examining long-term data from tidal gauges and other sources, Idso, Legates, and Singer write, “the highest quality coastal tide gauges from around the world show no evidence of acceleration since the 1920s.”
The difference between data recorded by the global tidal gauge system and projections made by supposed climate authorities is because “[l]ike ice melting, sea-level rise is a research area that has recently come to be dominated by computer models,” the authors write. “Whereas researchers working with datasets built from long-term coastal tide gauges typically report a slow linear rate of sea-level rise, computer modelers assume a significant anthropogenic forcing and tune their models to find or predict an acceleration of the rate of rise.”
Human actions, such as the construction of barriers, channeling of rivers, conversion of coastal wetlands into densely populated metropolitan areas, and draining of coastal aquifers for human consumption (which causes land subsidence) have undoubtedly made some coastal regions and populations more vulnerable to rising seas. Nonetheless, there is little evidence increased greenhouse gas emissions are contributing to ocean rise.
In a 2017 Heartland Institute study, geophysicist Dennis Hedke analyzed data from 10 coastal cities with relatively long and reliable sea-level records. He found there was no correlation between changes in sea levels at these locations and rising carbon dioxide levels.
For some cities, the rate of sea level rise has remained virtually constant, neither increasing nor declining appreciably from the rates experienced before humans began adding substantial amounts of greenhouse gases to the atmosphere. Other cities, such as Ceuta, Spain, have experienced very little sea level rise over the past century, exhibiting almost a flat trend line well below the historic rate of global sea level rise of approximately seven inches per century. Other cities, such as Sitka, Alaska, have experienced falling sea levels. Still others, such as Atlantic City, New Jersey, have experienced a large, rapid increase in sea levels.
The point is different areas around the world are having different experiences with sea levels, with differences in the rate of sea level rise being largely the result of localized conditions, not global climate change.
Our knowledge of previous interglacial cycles indicates seas will continue rising unless and until the next ice age comes. Like the apocryphal King Canute knew, human efforts to try to stop the rising tides are bound to fail; nature, not humanity, rules the seas.
It makes sense to prepare for rising seas by hardening coastal areas, discouraging ill-advised coastal development, and making people living along coasts aware investments made there could be swallowed by rising water. Ending the use of fossil fuels and giving ever-larger governments increasing power over people’s lives will not stop the seas from rising; it will only make people poorer and less free.