UPDATE: The New York Times did not recognize that other drafts of this report had been circulating informally for months, and misidentified the version they had been supplied with. The version they "published" was previously available.

In 1990, during the presidency of the first George Bush, Congress passed the Global Change Research Act. Along with reorganizing government-funded climate research, the Act stipulates that, every four years, the federal agencies involved provide an update on the state of climate science.

It has been four years, and the next report's draft has been completed and has undergone scientific vetting.

The draft paints a grim picture of how the US is already dealing with a variety of issues related to climate change and how much worse most of those issues will get during the coming decades. And the report places the blame squarely on humanity's greenhouse gas emissions.

This message won't go over well with the administration of President Donald Trump, which has a number of members who are openly hostile to the scientific community's conclusions. As a result, a lot of people are worried that the report will never be formally published or its conclusions will be watered down by further edits. These are the fears that undoubtedly prompted someone to leak the draft to The New York Times.

The report

The Times has placed the draft online, despite the "DO NOT CITE, QUOTE, OR DISTRIBUTE" warning on the top of every page. But really, there's not much here that hasn't already been available to the public—in many ways, the report is just a condensed, US-centric version of the IPCC reports. The process for producing it involved NASA, NOAA, and the DOE organizing a group of scientists to act as lead authors who produced chapters focused on issues like extreme weather and sea level rise. The report even echoes the IPCC's language for describing risk, using "very likely" to mean a 90-percent probability, for example.

The report's conclusions are also in line with those of every other scientific evaluation of climate change:

Thousands of studies conducted by tens of thousands of scientists around the world have documented changes in surface, atmospheric, and oceanic temperatures; melting glaciers; disappearing snow cover; shrinking sea ice; rising sea level; and an increase in atmospheric water vapor. Many lines of evidence demonstrate that human activities, especially emissions of greenhouse (heat-trapping) gases, are primarily responsible for recent observed climate changes.

The report notes that, since the 2013 version was released, each of the succeeding years topped the one previous to become the new warmest year on record. All but one of the years this century lie at the top of the list of warmest years on record (only 1998 joins them on that list). And, while it's often suggested that this is all part of a natural cycle, the draft states, "no natural cycles are found in the observational record that can explain the observed changes in climate."

The US focus, however, makes it clear just how the overall trends of the planet play out through a set of complicated regional effects. While the globe is up by about 0.9 degrees Celsius since good records started in 1865, the US' contiguous 48 states have only seen 0.7 degrees Celsius of warming, with the West Coast warming faster than the East. Meanwhile, the Arctic is warming twice as fast as the rest of the globe, which has made Alaska the state that has been most affected by climate change.

But even if you don't live in Alaska, the report indicates that you may already be experiencing the result of Arctic warming. "The climate of the Arctic and the climate of the continental United States are strongly connected through atmospheric-circulation patterns," the draft notes.

Later, the draft states: "While the Arctic may seem physically remote to those living in other regions of the planet, the climatic effects of perturbations to Arctic sea ice, land ice, surface temperature, snow cover, and permafrost affect the amount of warming, sea level change, carbon cycle impacts, and potentially even weather patterns in the lower 48 states."

Brace for impact

The report notes that our previous emissions have already committed us to 0.3 degrees Celsius of warming before the planet can reach a new equilibrium. Even under scenarios in which we reduce our emissions considerably, we're likely to see a 1.4 degree Celsius rise over the next few decades. While that may seem like a small number, it's important to note that it's double what the US has experienced already, and the US is already feeling significant effects from the warming climate.

The draft notes that, while extreme cold waves have gone down, extreme heat waves have become more common. Heavy precipitation events—in which lots of rain falls in a short period of time—have increased both in frequency and intensity (this is worst in the Northeast). The report says that, in the four years since the prior iteration, we've dramatically improved our ability to detect the influence of climate change on extreme weather events. So we're likely to see more things being tied specifically to the climate going forward.

The oceans aren't doing great either. The report covers ocean acidification, in which carbon dioxide that dissolves in water lowers its pH, as well as the prospects of expanded oxygen-poor zones. Sea-level rise is already causing problems, as the draft tracks the growth of "nuisance flooding," where some communities are already experiencing regular flooding due to high tides. This will also get worse, as the report expects anywhere from 30 centimeters to 1.2 meters of sea-level rise by the end of the century.

Even more concerning is that the authors have very high confidence in the lower bound, meaning we'll almost certainly see at least 30 centimeters. The report has far less confidence in the upper bound, meaning it's possible we could experience much more than 1.2 meters of sea-level rise.

And those are just the issues we already know about. An entire section of the report is titled: "There is a significant possibility for unanticipated changes." The report groups those changes into two categories. The first is that, because certain aspects of the climate are connected, continued warming could lead to multiple problems occurring either simultaneously or in rapid succession—think increased nuisance flooding accompanied by extreme precipitation.

The other category involves the climate experiencing tipping points in which it suddenly shifts to a different behavior. Both of these issues are possible but, by their very nature, difficult to predict.

Just click “Publish”

According to The Times, the report's authors consider it complete, and the US' National Academies of Science have reviewed and approved it. The report's publication is also required by law. But it's not clear whether the Trump administration will go along with this.

To begin with, Trump has appointed a number of people who either mistrust or are openly hostile to the conclusions of the scientific community. Those appointees include the heads of the Environmental Protection Agency and the Department of Energy—the latter of those being one of the departments responsible for producing the report. In addition, a recent report indicates that the Department of Agriculture has ordered its staff to stop using the term "climate change." (Trump has also nominated a former talk-show host who doesn't accept the science behind climate change to a key post in the USDA).

There's the possibility that Trump will attempt to ignore Congress and simply never release the report. But the more likely prospect is that the report will be heavily edited to water down its conclusions as well as its discussion of how the Paris Agreement (which Trump has renounced) could help matters. Which is almost certainly why someone has chosen to leak the report.