After a draft copy of the 2017 Climate Assessment Report leaked recently, people are left wondering exactly what it is and why it’s important.


Under the Global Change Research Act of 1990, the U.S. Global Change Research Program, an inter-governmental agency, is required to research and produce a report that shows the impact of global climate change. The study is conducted by hundreds of scientists and reviewed by multiple government agencies, including NASA and the National Science Foundation.
Despite federal policy mandating an assessment to be released every four years, only three have been issued: once under President Bill Clinton in 2000 and twice under President Barack Obama in 2009 and 2014. (President George W. Bush’s administration was sued for delaying the report’s release.)
There’s speculation whether or not the current White House will sign off on the report’s official release (which is scheduled for the fall), given the Trump administration’s pullback from the Paris climate accord and its push to increase fossil fuel production.
The leaked version of the 2017 report, which was first published by the New York Times, repeats similar warnings of increased greenhouse gas emissions as earlier assessments. But it also uses extremely blunt language regarding the cause, stating that humans are “extremely likely” to be the dominant producers of this pollution.
And according to the latest report, global temperatures have risen 1.2 degrees, in the past 30 years — human involvement accounting for at least 1.1 degrees of that increase.
Environmental Protection Agency Administrator Scott Pruitt has publicly said that he does not think carbon emissions cause climate change, writing in the National Review that, “scientists continue to disagree about the degree and extent of global warming and its connection to the actions of mankind.”
Regardless of political actions or ideologies on global climate change, these reports are accepted by the scientific community as a whole and are used to inform policymakers.


All issuances of the climate report have been in consensus: Global greenhouse gas emissions and global temperatures have increased dramatically in the past century, due in large part to humans burning fossil fuels.
“The human impact on [global warming] is clear,” states the 2000 analysis — the first published report. “[Increased carbon emissions] resulted from the burning of coal, oil, and natural gas, and the destruction of forests around the world to provide space for agriculture and other human activities.”
The initial report gave warning that U.S. temperatures would rise by up to 9 degrees within the next 100 years if greenhouse gas emissions weren’t curbed.
The 2009 report echoed the same language, stating that human involvement was the largest contributor, but its findings were more dire as carbon emissions continued to rise during the years of the Bush administration. That report concluded that there could be an increase of up to 11 degrees by 2100.
By 2014, when the most recent report was officially published, the evidence was clear to scientists that action needed to be taken, as authors of the report found that certain areas of the U.S., specifically within America’s heartland, were going to experience 2 to 4 degree increases in temperature over the next few decades.


The Obama administration seemingly worked to make climate change policy its primary legacy. In 2009, after the second climate report was released, Obama pledged to reduce the U.S.’s carbon emissions by 2020 and reduce its carbon emissions levels 17 percent below 2005 levels.
Four years later, when the third climate report was under consideration by Obama, the Executive Office of the President released a broad action plan aimed at specifically cutting carbon emissions.
These reactions to the climate reports were dramatically different to actions taken by President Bush. That administration hastily exited the Kyoto Protocol (a global climate change treaty), partnered with Exxon-Mobil‘s leaders to craft U.S. climate change policy and cast doubt among the public that humans were to blame for global climate change.
In contrast, polls conducted during the past three years reveal that more Americans believe humans are to blame for climate change. Furthermore, a March 2017 Gallup poll found that more than 70 percent support alternative energy over traditional fossil fuels.
Which means that Americans are likely to continue curbing greenhouse gas emissions, regardless of whether or not the climate assessment report receives an official stamp of approval.
MORE: Can the U.S. Reduce Its Carbon Emissions?