Washington - Climate change is happening “primarily as a result of human activities” and its damaging impacts — severe droughts, deadly wildfires, monster tropical storms, punishing heat waves — “are already being felt in the United States.” That’s not me talking. It’s the conclusion of the U.S. government, in an alarming new report the Trump administration doesn’t want you to read.

It can be no accident that the 1,656-page "Impacts, Risks and Adaptation" section of the latest blue-ribbon National Climate Assessment was released on the day after Thanksgiving, a graveyard of a news cycle when many Americans are focused on turkey sandwiches and Black Friday deals.

The report provides stunning new evidence for what we already knew: President Trump’s climate-change policy — ignore, obfuscate, delay, deny — amounts to environmental vandalism on a tragic scale.

Surely aware of what was coming, the president used his Twitter feed on Wednesday to pose as a weatherman and launch a preemptive attack: "Brutal and Extended Cold Blast could shatter ALL RECORDS — Whatever happened to Global Warming?"

Answer: It's here, it's all around us and it's getting worse.

Since the beginning of the 20th century, the report notes, global average temperature has increased by 1.8 degrees and global average sea level has risen by about 8 inches. These changes are accelerating. By the year 2100, if action is not taken to curb carbon emissions, the temperature rise could total 9 degrees and the sea level rise could exceed 4 feet.

Trump and other deniers can no longer claim with a straight face that no warming is taking place, since nine of the hottest 10 years on record have come since 2005. Instead, they try to blame some as-yet unknown natural cycle. But the new climate assessment notes that "observational evidence does not support any credible natural explanations."

Instead, "the evidence consistently points to human activities, especially emissions of greenhouse or heat-trapping gases, as the dominant cause," according to the report. As I have shouted until I am blue in the face, the atmospheric concentration of carbon dioxide has risen from around 280 parts per million at the beginning of the Industrial Revolution to more than 400 parts per million now. That is an astonishing 40 percent increase since humankind began burning fossil fuels on a massive scale.

This is no coincidence and involves no guesswork. Scientists can directly and precisely measure carbon dioxide concentrations during past eras by drilling ice cores in Antarctica or Greenland and analyzing air bubbles trapped within. According to records maintained by the National Oceanic and Atmospheric Administration, ice cores show that over the past 800,000 years, levels of atmospheric carbon fluctuated between 170 and 300 parts per million — until recently zooming off the charts.

Resist any temptation to write all this off as scientific gobbledygook. Pay attention to the numbers, which are important and not very hard to follow. Denialist officials and commentators who throw up their hands and say "I'm not a scientist" are being disingenuous. There is no real scientific debate about the existence of climate change or the fact that human activity is driving it.

There is, however, a political debate about what to do. Trump is determined to accelerate climate change by boosting the production and use of coal — the "dirtiest" widely used fuel, in terms of carbon emissions — and keeping oil prices low. This is the dumbest, most short-sighted policy imaginable.

Trump visited California to see first-hand the destruction of the horrific Camp Fire, which killed at least 85 people — with the death toll expected to rise as more remains are found — and destroyed more than 14,000 homes. According to the new climate assessment, the cumulative forest area burned in the western United States by wildfires since 1984 is fully double what it would have been if climate change had not occurred.

No, wildfires are not getting worse because not enough raking is being done, as Trump weirdly insisted. They are getting worse because of climate change.

So are tropical storms, flash floods and heat waves. Trump claims to be all about economic growth. But the new report predicts that "climate change is expected to cause growing losses to American infrastructure and property and impede the rate of economic growth over this century." It adds that "annual losses in some economic sectors are projected to reach hundreds of billions of dollars."

The report sounds one more ominous note: Thus far, climate scientists' dire predictions have proved to be conservative. The world is on fire. We have a president who plays with matches.

Eugene Robinson