It may seem like a funny report to dump on the public on Black Friday, when most Americans care more about recovering from Thanksgiving dinner than they do about adapting to the grave conclusions of climate science. Indeed, who ordered the report to come out today?

It’s a good question with no obvious answer.

The report is blunt: Climate change is happening now, and humans are causing it. “Earth’s climate is now changing faster than at any point in the history of modern civilization, primarily as a result of human activities,” declares its first sentence. “The assumption that current and future climate conditions will resemble the recent past is no longer valid.”

At this point, such an idea might be common wisdom—but this does not make it any less shocking, or less correct. For centuries, humans have lived near the ocean, assuming that the sea will not often move from its fixed location. They have planted wheat at its time, and corn at its time, assuming that the harvest will not often falter. They have delighted in December snow, and looked forward to springtime blossoms, assuming that the seasons will not shift from their course.

Now, the sea is lifting above its shore, the harvest is faltering, and the seasons arrive and depart in disorder.

The report tells this story, laying simple fact on simple fact so as to build a terrible edifice. Since 1901, the United States has warmed 1.8 degrees Fahrenheit. Heat waves now arrive earlier in the year and abate later than they did in the 1960s. Mountain snowpack in the West has shrunk dramatically in the past half century. Sixteen of the warmest 17 years on record have occurred since 2000.

This trend “can only be explained by the effects that human activities, especially emissions of greenhouse gases, have had on the climate,” the report says. It warns that if humans wish to avoid 3.6 degrees of warming, they must dramatically cut this kind of pollution by 2040. On the other hand, if greenhouse-gas emissions continue to rise, then the Earth could warm by as much as 9 degrees by 2100.

“It shows us that climate change is not a distant issue. It’s not about plants, or animals, or a future generation. It’s about us, living now,” says Katharine Hayhoe, an author of the report and an atmospheric scientist at Texas Tech University.

The report visits each region of the country, describing the local upheavals wrought by a global transformation. Across the Southeast, massive wildfires—like those seen now in California—could soon become a regular occurrence, smothering Atlanta and other cities in toxic smog, it warns. In New England and the mid-Atlantic, it says, oceanfront barrier islands could erode and narrow. And in the Midwest, it forecasts plunging yields of corn, soybeans, wheat, and rice.