The report is the 10th of 21 due to be issued by the body, which the skeptical George Bush administration set up late in 2002 to review the validity of climate-change science before making policy decisions.
At the time, environmentalists accused the administration of using the programme as a way to drag its feet on the issue.
"The evidence is pretty convincing that the models give a good simulation of climate," New Scientist quoted lead author David Bader of the Lawrence Livermore National Laboratory in California, as telling reporters.
He admits that the report did not examine predictions of future climate change. Nor did it address policy issues, which will be left to the next administration.