Climate change enthusiasts are convinced that man-made global warming poses a near-term environmental disaster. Yet gloom-and-doom forecasts about the fate of the Earth are hardly new, and few have proven accurate.

In 1798 the Rev. Thomas Malthus predicted that mass starvation would strike England in the 19th century because population growth would inevitably overwhelm food production. It didn’t happen.

Or recall the dire predictions by experts in the 1970s that the world was running out of oil and that prices would skyrocket and stay high for decades.

These views were supported by analyses from the CIA and a boatload of geologists who believed in the so-called “peak oil” theory.

But the experts were wrong. Adjusted for inflation, a barrel of crude oil today is cheaper than it was in 1980, which is arguably one of the most pro-consumer developments in recent economic history.

And now we are told that the world is on the brink of environmental disaster due to man-made global warming.

The conventional wisdom, repeated endlessly in the popular press, is that the Earth is heating dangerously because we burn fossil fuels and that this will generate devastating droughts, fires, floods, and rising ocean levels. (The oceans are currently rising by about one-eighth of an inch per year).

In response, several prominent politicians have developed multitrillion-dollar plans to “do something.” Those who question those plans, or the theory that temperature increases are man-made, are often smeared as immoral or antiscience.

Yet there is really only one policy-relevant question in the entire climate-change debate: does the increased use of fossil fuels—and the consequent increase in carbon dioxide emissions—contribute significantly to the increase in the Earth’s surface temperature?

The scientific evidence on warming is reasonably clear: since 1880, the atmospheric temperature has increased slightly more than 1 degree Celsius.

Over those many decades, there have been periods of warming, periods of cooling, periods where no major changes occurred, and more recently, a relatively modest but sustained period of warming. No real debate here.

But can this recent warming be reasonably correlated with increased fossil-fuel use? After all, C02 is a relatively minor greenhouse gas (0.041 percent by volume), and any statistical association of specific levels of carbon emissions with specific temperature changes historically has not been compelling.

For example, while CO2 emissions have steadily increased for many decades (much of it from expanding industrial activity in India and China), the Earth’s temperature, though trending upward, has varied markedly.

More specifically, while CO2 growth rates have been almost five times greater since World War II than before, the average annual temperature increase since 1945 has been roughly the same as it was before 1945.

All of this would imply that increased CO2 levels may not be the sole (or perhaps even the primary) factor driving changes in global temperatures.

Yet if CO2 is not the primary cause of temperature change, then the entire economic and political case for carbon taxes and other regulations on CO2 emissions is severely weakened.

Why should we increase the price of energy generated from oil and natural gas (let alone consider the multitrillion-dollar costs of any Green New Deal) if reducing emissions in the United States (or even the rate of emissions) would produce no discernable net benefit to society?

After all, one thing is certain in this entire debate. Any important restriction on the use of fossil fuels would raise the price of almost everything and hurt low-income families the most, despite any political promises to the contrary.

Some of us are old enough to remember the major print media (Time, Newsweek, etc.) scare stories concerning global cooling in the early 1970s.

We were all going to freeze in the dark unless the government did something about the coming mini-ice age. But cooler heads prevailed, and we didn’t rush to judgment with massive environmental regulation—which would have been a disaster.

Let’s take a breath and adopt that same cautious approach with respect to the current controversy.