An international body of nearly 100 climate scientists convened by the United Nations have issued a stern warning to the rest of the world.

Unless governments around the globe undertake “unprecedented” action to reverse it, Earth’s temperatures will soar upwards of 1.5-degrees Celsius, or 2.7 degrees Fahrenheit, over preindustrial levels by the end of the century.

Warming above that threshold, the scientists write, could trigger the near-total loss of the world’s tropical coral reefs and the collapse of ice sheets in Antarctica and Greenland that would send sea levels soaring.

In short, the scientists say the world has only a dozen years to tackle climate change to avoid some of its most devastating effects.

That is the tough-love conclusion of the U.N.’s Intergovernmental Panel on Climate Change, or IPCC, in a major consensus report released Sunday evening after days of discussions last week between scientists and government officials meeting in South Korea.

The IPCC, seen as a definitive source on the state of climate science, outlined a path to keeping temperatures under those levels.

Because of that, write The Post’s Chris Mooney and Brady Dennis, the report “is being received with hope in some quarters because it affirms that 1.5 degrees Celsius is still possible.” Many observers abroad see President Donald Trump’s decision to withdraw the United States from the Paris climate accord as a backward step by the world’s second biggest emitter of carbon dioxide.

But the path to reverse the rising temperatures is arduous. And, so far, even nations with leaders who acknowledge the severity of climate change have not pledged to do enough under the 2015 Paris climate accord that would prevent 1.5 degrees of warming, according to the scientists.

Even if the world’s governments muster the political will to fully address the problem – and that is a very big “if” – they will still need technical knowhow not yet invented to curb the emissions of climate-warming gases enough to keep the world under that crucial 1.5-degree mark. Among the steps the IPCC calls for are:

Getting more than half of the world’s electricity from renewable sources, like solar and wind power, in just over 10 years. Right now only about a quarter of all power comes from renewables.

Phasing out the burning of coal, the most carbon-intensive form for power generation, almost entirely by the middle of the century.

Implementing a technique, only theoretical at the moment, of pulling the greenhouse gas carbon dioxide from the air by turning plants into fuel and storing some of the resulting emissions underground.

Reining in the emissions of another greenhouse gas, methane, from the cultivation of cattle, rice and other agricultural products – even as farmers need to feed a growing global population.

Re-planting trees on wide swaths of the world already cut for raising livestock and other activities.

Right now, the world is not on track to stay under the 1.5-degree mark. The new report throws cold water on the idea current Paris promises will be enough to stop some of the most severe effects of global warming. Existing promises under the Paris agreement, which give countries wiggle room to come up with ways of meeting emissions targets, would lead to about 3 degrees Celsius of warming by 2100.

“It’s like a deafening, piercing smoke alarm going off in the kitchen,” Erik Solheim, executive director of the U.N. Environment Program, told The Post. “We have to put out the fire.”