Texas coast

Galveston Island State Park

By Bill Dawson
Texas Climate News

Memorial Day is the unofficial start of the summer vacation season, which means beach visits for lots of Americans. The mass pilgrimage to mix sun, sand and salt water for hot-weather fun gets into full swing by July 4, of course.

It’s fitting, then – at least for those who welcome a little more sobering climate news along with their coastal recreation – that a study released on the eve of Independence Day this week has calculated that rising sea levels could cost the planet up to $27 trillion by the end of the century.

The researchers projected global costs could reach that total if the world community fails to hold atmospheric warming to less than 2 degrees Celsius. By most expert accounts, meeting the 2-degree goal, which was set in the Paris Climate Agreement, will require an enormous crash campaign to slash climate-warming pollution by phasing out fossil-fuel use over just the next few decades.

The new study is hardly the first projection of the costs that higher sea levels propelled by global warning will bring. Last month, TCN reported on other analysts’ recent estimate that chronic coastal flooding could affect more than 82,000 Texas homes by 2100. It was part of a general examination of risks facing U.S. coastal real estate.

The new study, published July 3 in the journal Environmental Research Letters, was led by the U.K.’s National Oceanographic Centre and adopted a global perspective. The researchers compared future sea-level-rise costs under one high-emission scenario and two scenarios that envision the achievement of two different goals in the 2015 Paris accord, signed by 195 nations.

The Paris pact’s principal goal is avoid the worst impacts of climate change by keeping global warming below a 2-degrees-Celsius jump in the world’s average temperature above pre-industrial levels. A second target calls for “pursuing efforts to limit the temperature increase to 1.5 degrees C” because that would “significantly reduce the risks and impacts.”

Under the high-emission scenario – that is, exceeding a 2-degree increase – the researchers projected a range of possible outcomes. Within that range was a median sea-level rise of 2.8 feet (0.86 meters), which would bring increased costs of $14 trillion by 2100. A “worst-case” average rise in ocean levels in the high-emission range would be about 1.8 meters and bring $27 trillion in costs.

Countries defined by the World Bank as “upper middle income,” like China, would be hit with the biggest costs, the scientists said, while richer countries with more coast-protection infrastructure would have lower costs.

Meeting the 1.5-degree goal, considered exceedingly difficult if not impossible by many experts, would hold median sea-level rise to 1.7 feet (0.52 meters) and therefore reduce costs, the researchers projected.

Developing and island nations with significant populations in low-lying coastal areas pushed for including the 1.5-degree limit as a secondary goal in the Paris Agreement. Besides routine flooding of inhabited areas, rising sea levels will mean more damaging storm surges during hurricanes and other tropical disturbances, scientists say.

The new study’s projected sea-level increases “will have a negative effect on the economies of developing coastal nations and the habitability of low-lying coastlines,” said Svetlana Jevrejeva, the lead author. Many other researchers expect rising seas and additional climate-change impacts in such nations will spur increased migration to richer and less hazard-prone areas.

“More than 600 million people live in low-elevation coastal areas, less than 10 meters above sea level,” Jevrejeva added. “In a warming climate, global sea level will rise due to melting of land-based glaciers and ice sheets, and from the thermal expansion of ocean waters. So, sea level rise is one of the most damaging aspects of our warming climate.”

The U.K.-based Climate News Network provided some contextual information to show that the new study, dramatic as it may seem, is actually more modest in its projections than some earlier studies:

The conclusions [Jevrejeva] and her colleagues reached sound hair-raising and possibly far-fetched. But an earlier study put the possible global cost by 2100 of coastal flooding at nearly four times more than the [National Oceanographic Centre] team – $100 trillion.

Another group of researchers suggested that if global warming continued at its present rate it could start a process in Antarctica which would lead ultimately to sea level rise of almost three meters.


Bill Dawson is the founder and editor of Texas Climate News

Image credit: Yinan Chen / Wikimedia Commons