A major climate change report from the United Nations has an attention-grabbing message for policymakers around the world, especially in countries with lots of vehicles, factories and electric plants that emit "greenhouse gases" from burning oil, natural gas or coal. News coverage reinforces the dire, urgent tone. "Nations will need to take 'unprecedented' actions to cut their carbon emissions over the next decade, according to a landmark report by the top scientific body studying climate change," says The Washington Post's first sentence. "Final call to save the world from 'climate catastrophe,'" says a British Broadcasting Corp. headline. The New York Times is similarly stark: The study "paints a far more dire picture of the immediate consequences of climate change than previously thought and says that avoiding the damage requires transforming the world economy at a speed and scale that has ‘no documented historic precedent.'"

The report from the UN Intergovernmental Panel on Climate Change was requested as part of a 2015 Paris climate agreement to combat global warming by shifting to alternative fuels. The new study by a group of scientists describes a world of worsening food shortages and wildfires, and a mass die-off of coral reefs as soon as 2040 — a period well within the lifetime of much of the global population. It says sweeping changes in energy, transportation and industrial emissions are required to ward off the worst impacts of global warming, which is widely linked to atmospheric damage from burning what are called "fossil fuels."

If greenhouse gas emissions continue at the current rate, study authors predict, the atmosphere will warm up by as much as 2.7 degrees Fahrenheit (1.5 degrees Celsius) above preindustrial levels by 2040. That’s likely to flood ocean coastlines, intensify droughts and risk famine from reduced crop yields. Poverty would rise in some areas. Parts of Manhattan and Miami could be underwater without costly coastal defenses. Avoiding the most serious damage requires transforming the world economy within a few years, the experts warn.

While it's technically possible to achieve the rapid changes needed to avoid 2.7 degrees of warming, the specialists acknowledge that it's politically unlikely. Difficult steps include heavy taxes or fines for carbon dioxide emissions, for instance. Lawmakers in China, the European Union and California have enacted carbon pricing programs, but "such a move would be almost politically impossible in the [full] United States, the world's largest economy and second-largest greenhouse gas emitter behind China," writes The New York Times. President Trump, who mocks the science of human-caused climate change, vows to increase the burning of coal and says he'll withdraw from the Paris agreement signed three years ago by Barack Obama's secretary of state, John Kerry.

Study co-leader says: "We've delivered a message to the governments. It's now their responsibility . . . to decide whether they can act on it. What we've done is said what the world needs to do." -- Jim Skea, co-chair of the UN panel and a United Kingdom environmental professor

UN secretar-general says: "If we do not change course in the next two years, we risk runaway climate change. . . . Our future is at stake." -- António Guterres of Portrugal

Panel member says: "This report makes it clear: There is no way to mitigate [reduce] climate change without getting rid of coal." -- said Drew Shindell, climate scientist at Duke University in Durham, N.C.