Greenhouses gases that trap heat and drive climate change have reached a record high, the UN World Meteorological Organization (WMO) announced on Thursday.

Gases such as carbon dioxide, methane, and nitrous oxide absorb heat and radiate energy that warms the surface of the Earth. According to the WMO, the last time CO2 levels were as high as they are now was 3-5 million years ago, when surface temperatures were 2-3°C warmer and sea levels were 10-20 meters higher.

Perhaps even more alarming is there is no sign of a reversal of the trend, the organization found.

To put that in perspective, a sea level rise of just six meters would put parts of Florida and the east coast underwater, according to the National Oceanic and Atmospheric Administration. A rise in surface temperatures by 3°C, predicted to occur by the end of the century if not sooner, would lead to a largely uninhabitable Earth.

“Without rapid cuts in CO2 and other greenhouse gases, climate change will have increasingly destructive and irreversible impacts on life on Earth,” said WMO Secretary-General Petteri Taalas in a statement. “The window of opportunity for action is almost closed.”

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The WMO’s Greenhouse Gas Bulletin is published annually, and this year’s dire findings will inform UN climate change negotiations being held in early December in Poland. The goal of that meeting is to implement the guidelines of the 2015 Paris Climate Change Agreement, which the US abandoned in 2017 at President Donald Trump’s behest.

As for what Trump’s thoughts on the WMO report might be, we don’t really have to guess. On Wednesday night, Trump tweeted a message that implied nippy November weather meant that climate change wasn’t real.