With the winter solstice only days away, we are rapidly descending into darkness — but our growing gloom isn’t just due to the planet’s axial tilt away from the sun.

As the Global Carbon Project reported last week, greenhouse gas emissions worldwide shot up 1.6 percent in 2018 after having stabilized during the previous three years. The study by 100 scientists representing more than 50 academic and research institutions likened the spike in carbon dioxide levels to “a speeding freight train.”

These alarming findings comes on the heels of an equally troubling government report that warns higher temperatures likely will cause thousands of premature deaths, expose more people to foodborne and waterborne diseases, wipe out huge numbers of shellfish, destroy crops, and lead to more devastating floods, forest fires and severe weather. All these disastrous consequences could cost the U.S. economy hundreds of billons of dollars by the end of the century, the study concluded.

The report was to have been released in December, but the administration decided instead to make it public the day before Thanksgiving in hopes that people would be too preoccupied with their turkey dinners and football games to give it much thought.

The strategy seems to have worked. The report made headlines for a day or two and then, as have so many government studies, quickly began gathering dust.

Recently our president, who for years called global warming a hoax and infamously pulled the United States out of the Paris climate accord — the only country to do so — almost seemed poised recently to grudgingly concede the planet may indeed be growing warmer.

“I think something’s happening,” he told Lesley Stahl on “60 Minutes” in October. He then added, “Something’s changing, and it’ll change back again. I don’t think it’s a hoax. I think there’s probably a difference, but I don’t know that it’s man-made.”

A few weeks later, though, the president reverted to form when the jet stream dipped and brought in frigid weather across much of North America.

“Brutal and Extended Cold Blast could shatter ALL RECORDS,” Trump tweeted from his Mar-a-Lago club in balmy Florida. “Whatever happened to Global Warming?”

Meanwhile, he continues to favor increased coal mining and offshore oil drilling.

We can’t lay all the blame on our president, though. Rather, we should borrow a quip from the comic strip Pogo in 1953: "We have met the enemy and he is us."

Thanks to lower oil prices, people are driving more than ever, while ditching their small, fuel-efficient vehicles in favor of gas-guzzling behemoths. This trend has led Ford and GM to shut down production of fuel-efficient sedans in order to pump out more SUVs and trucks.

One proposal to reduce greenhouse gases — imposing a carbon tax, which had been endorsed by Al Gore, former members of Ronald Reagan’s Cabinet, economists from both parties and even Exxon Mobil — is losing sway among environmentalists, the website Politico reported last week.

“This month’s fuel-tax riots in Paris and the defeat of a carbon-fee ballot measure in Washington state show the difficulty of getting people to support a levy on the energy sources that heat their homes and power their cars,” it noted.

Oh, well, back to the drawing boards.

It occurs to me that all these dark thoughts result from what we used to call “winter blues” but now is diagnosed as Seasonal Affective Disorder.

After all, there’s a lot less sunlight to cheer us up.

Here in Connecticut, the sun won’t come up until 7:14 a.m. on Dec. 20 and will set a scant nine hours and eight minutes later at 4:22 p.m. Back on June 20, the sun rose at 5:15 a.m. and didn’t dip below the western horizon until 8:28 p.m., providing a whopping 15 hours and 12 minutes of emotionally restorative daylight.

No wonder I’m so cranky.

The arrival of the solstice means we’ve officially entered the winter season, but it also signals the start of longer daylight hours — which is why so many ancient cultures celebrated the event with festivals and rituals.

Me, I like cold weather and can’t wait for cross-country skiing, ice skating and just being outside in crisp, frigid weather.

Hey, I’m feeling more cheerful already.