A Project of The Annenberg Public Policy Center

Trump Mocks Global Warming, Lowballs Sea Level Rise

At a campaign rally, President Donald Trump mocked concerns about global warming, saying that oceans would rise just “[o]ne-eighth of an inch within the next 250 years.” Although Trump’s comment may have been a joke — and not intended to be a prediction of sea level rise — his figure is many times lower than scientific estimates.

According to the National Oceanic and Atmospheric Administration, global sea level is currently increasing by about an eighth of an inch per year, not an eighth of an inch over two-and-a-half centuries. The Trump campaign did not respond to a request for comment.

As several NOAA websites explain, climate change contributes to sea level rise through the melting of land ice, which includes glaciers and ice sheets, and because water expands when it’s warmer.

Trump’s remark came in Hershey, Pennsylvania, during a section of his speech bashing wind power — one of his favorite topics at rallies. This time, the president also jokingly referenced global warming, poking fun at people who are concerned about sea level rise.

Trump, Dec. 10: You’d have windmills all over the place if you had Crooked Hillary, they’d be knocking out those birds left and right. Those windmills, wah, wah wah. Darling, I want to watch television tonight and there’s no damn wind. What do I do? I want to watch the election results, darling, there’s no wind, the damn wind just isn’t blowing like it used to because of global warming, I think. I think it’s global warming. Global warming, no more wind, no more life! The oceans are going to rise. One-eighth of an inch within the next 250 years, we’re going to be wiped out! 

We’ve explained before that birds do fly into wind turbines and die, but cats or collisions with buildings kill more birds. The temporary absence of wind doesn’t mean that someone’s electricity goes out. Wind turbines feed into an electrical grid that collectively supplies power; operators can manage the grid to make sure there isn’t a lapse in coverage when it’s not windy.

Even if offered only in jest, Trump’s estimate of expected sea level rise is well below projections from scientists. Along with the NOAA estimate of the current rate of sea level rise, a recent special report from the U.N. Intergovernmental Panel on Climate Change, which reviewed and synthesized the scientific literature, concluded that sea level rise is likely to reach at least 1 foot by the end of the century. 

The report, which was released in September, pegged future sea level rise at 1 to 2 feet by 2100, relative to levels in 1986–2005, under a lower emissions scenario. That scenario, known as RCP2.6, has a 2-in-3 chance of limiting global warming to below 2 degrees Celsius above pre-industrial levels by 2100, which is the approximate goal set by the Paris Agreement. Under a higher emissions scenario, the report said, 2 to 3.5 feet of sea level rise are expected.

By 2300 — three decades after the president’s timeframe — sea level rise is likely to be 2 to 3.5 feet, even under lower emissions, according to the IPCC report. With higher emissions, the likely range is between a whopping 7.5 to 18 feet.

What will come to pass will depend not only on whether society curbs its greenhouse gas emissions, but also on how the planet reacts to the extra heat. Much of the uncertainty in these sorts of long-term projections of sea level rise is in how the ice sheets will respond — particularly Antarctica, which is not well understood by scientists. “Considering the consequences of sea level rise that a collapse of parts of the Antarctic Ice Sheet entails,” the report cautions, “this high impact risk merits attention.”

Of course, all of these estimates are for the global average sea level rise, when, in fact, what people will be dealing with on the ground may vary because of local factors. As we’ve noted before in our article about Delaware and its particular vulnerability to rising seas, some locales happen to be sinking, further exacerbating the challenge. This means that some places may be at an even higher risk from sea level rise than these numbers suggest, while others are at a lower risk.

What are the risks of sea level rise? One of the biggest concerns relates to flooding, which with higher water levels is becoming more severe and reaching further inland. When storms hit, it can mean more extreme storm surges, which can be deadlier to people and worse in terms of damage to property and ecosystems. In fact, Trump International Golf Links filed a permit to build a sea wall to protect its golf course in Doonbeg, Ireland, from “global warming and its effects,” specifically “the rate of sea level rise,” as Politico reported in 2016.

Even without a storm, sea level rise can cause problems, submerging low-lying roads or other pieces of infrastructure under water during periods of high tide. This is known as high tide, nuisance or sunny-day flooding. NOAA data show that much of the East Coast, including New York, where Trump owns real estate, is already seeing increases in the number of days per year with high tide flooding. 

Once-in-a-century sea level events are projected to happen, the IPCC special report says, “at least annually at most locations by 2100” regardless of the emissions level. And for small islands and many low-lying megacities, the timeline on that moves up — to 2050. In terms of sea level rise damage, the most at-risk large cities in the U.S. include New Orleans, Boston, New York and Miami, according to a 2018 paper cited in the special report.

Trump greatly underestimates the scale of the problem, and his dismissal of the dangers of sea level rise is not based in science.