The day after their CNN presidential debate, former President Donald Trump cited a wildly inaccurate figure about sea levels to mock President Joe Biden’s debate claim that “the only existential threat to humanity is climate change.”
Trump said at a Friday rally in Virginia that “global warming is fine,” rejecting the view of the overwhelming majority of scientists.
And he said of Biden: “He said it again last night, that global warming is an existential threat. And I say that the thing that’s an existential threat is not global warming, where the ocean will rise – maybe, it may go down, also – but it may rise one eighth of an inch in the next 497 years, they say. One eighth.” He added what appeared to be a joke: “Which gives you a little bit more waterfront property if you’re lucky enough though.”
Facts First: Trump’s claim about the expected pace of sea level rise is not even close to correct. The global average sea level is currently rising more per year than Trump claimed that people say it will rise “in the next 497 years.”
NASA reported in March that the current global average sea level rise in 2023 was 0.17 inches per year, more than double the rate in 1993. And a World Meteorological Organization report this year said the rate of sea level rise between 2014 and 2023 was about 0.19 inches per year.
In other words, sea level rise is already more than an eighth of an inch annually – and it is accelerating. NASA found a jump of 0.3 inches between 2022 and 2023.
Gary Griggs, a University of California, Santa Cruz professor of earth and planetary sciences who studies sea level rise, said last year that Trump’s similar claims “can only be described as totally out of touch with reality” and that Trump “has no idea what he is talking about.”
Sea levels rise by different amounts in different locations. For the US, sea levels are expected to rise particularly fast for the east coast and Gulf of Mexico coast – and Trump’s state of Florida, which is bordered by both of those coasts, is expected to be affected more severely than many other coastal states.
In fact, Trump’s claims about sea levels are highly inaccurate for the area near Mar-a-Lago, which is on the Atlantic. Griggs noted in a June email that data from the closest National Oceanic and Atmospheric Administration tide gauge to Mar-a-Lago shows an increase of an eighth of an inch roughly every nine months.
Trump has made similar claims since his last presidential campaign - sometimes saying the estimate is an eighth of an inch increase over 200, 250, 300 or 400 years.
Trump has also previously made the joke about rising seas creating more waterfront property. In reality, rising sea levels are expected to have devastating consequences not only for many seafront properties but for areas further inland – rendering some communities uninhabitable and others more dangerous, increasing the frequency and reach of flooding, making hurricanes more destructive, and damaging infrastructure and ecosystems.
