The National Assessment on Climate Change is a report about global warming issued in 2002 by an agency of the US government.

The report, which echoes the conclusions of the UN Climate Panel (IPCC), claims to show conclusively that the global warming hypothesis is true.

Serious flaws in the report, however, were pointed out by a think tank , and in response the Office of Science and Technology Policy disavowed the report -- but has not ceased to distribute it.

The American Enterprise Institute stated that the climate models upon which NACC relies are invalid, and makes the following 3 claims about the climate models:

  1. They can't simulate the current climate
  2. They falsely predict greater and more rapid warming in the atmosphere than at the surface -- the opposite is happening (see e.g. [1])
  3. They predict amplified warming at both poles, but the south pole is cooling instead (see e.g. [1])

There are contradictory reports about the north pole. Some say that the ice cap has always had large expanses and that recent observations of a mile-wide gap in the ice is nothing unusual (a NYT article on a back page); others say that that the ice cap is shrinking (a NYT front page article).

One NASA scientist said in October 2003 that rising temperatures are causing polar ice caps to melt. (see e.g. [1]).