Former President Donald Trump arrives for campaign rally at Greenbrier Farms on June 28 in Chesapeake, Virginia.
CNN  — 

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 risi?ng?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.