The latest National Climate Assessment, released just last week, aims to plant yet another seed of climate catastrophism into the mind of the public. Predictably, its worst-case scenarios got huge play in the media. After all, disaster sells.

But the doomsday scenarios that animated talking heads throughout the weekend aren’t just highly unlikely; they’re close to impossible. For example, the report speculated that climate “inaction” could result in as much as a 10 percent drop in U.S. gross domestic product by 2100. Admittedly, a lot can happen in 82 years. But a 10 percent drop in GDP is more than twice the loss suffered during the Great Recession.

How could things get so bad? Well, put garbage in, and you’ll get garbage out. The study, funded in part by climate warrior Tom Steyer, calculates these costs by assuming that the world will be 15 degrees Fahrenheit warmer by 2100. That mind-boggling assumption is even higher than the worst-case scenario predicted by the United Nations Intergovernmental Panel on Climate Change. In other words, it is completely unrealistic.

Other scary projections in the National Climate Assessment rely on a theoretical climate trajectory known as Representative Concentration Pathway 8.5 (RCP 8.5) — one of four trajectories that climatologists use to estimate the effects of different greenhouse-gas concentrations.

To put it plainly, RCP 8.5 assumes a combination of extreme factors — all bad — that are not likely to all coincide. It assumes “the fastest population growth (a doubling of Earth’s population to 12 billion), the lowest rate of technology development, slow GDP growth, a massive increase in world poverty, plus high energy use and emissions.”

This extraordinary scenario assumes a massive increase in coal consumption — completely ignoring the dramatic increase in natural-gas production from the shale revolution. It also ignores technological innovations that continue to occur in nuclear and renewable technologies.

When taking a more realistic view of the future of conventional fuel use and increased greenhouse-gas emissions, the doomsday scenarios vanish. Climatologist Judith Curry recently wrote, “Many ‘catastrophic’ impacts of climate change don’t really kick at the lower CO2 concentrations, and RCP 8.5 then becomes useful as a ‘scare’ tactic.”

The National Climate Assessment insists that climate change is already taking a heavy toll, and things will only get worse. Global warming has worsened heat waves and wildfires, it claims. And we’ll be seeing more hurricanes and floods, too.

But last year’s National Climate Assessment on extreme weather tells a different story. As University of Colorado Boulder professor Roger Pielke Jr. pointed out in a Twitter thread in August 2017, there were no increases in drought, no increases in frequency or magnitude of floods, no trends in frequency or intensity of hurricanes, and “low confidence for a detectable human climate change contribution in the Western United States based on existing studies.”

It’s hard to imagine all of that could be flipped on its head in a matter of a year.

The reality, however, is that all of the currently favored proposals for combatting climate change carry significant costs and (here’s the even more important part) would do nothing to mitigate warming, even if there were a looming catastrophe like the National Climate Assessment imagines.

Just last month, the Intergovernmental Panel on Climate Change proposed a carbon tax of between $135 and $5,500 by the year 2030. An energy tax of that magnitude would bankrupt families and businesses and undoubtedly catapult the world into economic despair.

These policies would simply divert resources away from more valuable use, such as investing in more robust infrastructure to protect against natural disasters or investing in new technologies that make Representative Concentration Pathway 8.5 even more of an afterthought than it already should be.

It’s human nature to ponder what-ifs and worse-case scenarios. Every time I board a flight, I think about the plane going down. But I know the statistical likelihood of that happening is near nil. And I certainly don’t go around spreading misinformation about how unsafe planes are.

Climate alarmists, however, see things differently. They want the world to share their concerns and seem willing to say “whatever it takes” to get people on board. But propagating improbabilities isn’t science. It’s irresponsible and does a disservice to the climate discussion broadly.