The UN’s hypothesis references a set of climate models. Each such model outputs a mathematical function which maps the time to the global average temperature. The UN’s Intergovernmental Panel on Climate Change (IPCC) calls such a function a “projection.”

A projection may be compared to the associated instrument readings. However, such a comparison does not render a projection or any subset of the elements of this projection true or false. Something is missing in a projection that is needed for determination of whether the associated model is a valid or invalid one.

The missing ingredient is the set of predictions that are made by the model. A prediction is a proposition which states the projected outcome of a statistical event. In such an event, a prediction is made, a specified period of time elapses and the outcome occurs. If the real outcome differs from the predicted one and the real outcome is observed, the associated model is falsified. That none of the IPCC’s models issue predictions (as the IPCC itself states in its 2007 report) signifies that none of these models are falsifiable. Thus, according to Popper, none of these models are scientific models.

As a basis for policy making, a model that is “scientific” under Popper’s definition of the term, has the merit of providing information about its own reliability. A non-scientific model has the demerit of providing none of this information.

In its “endangerment” finding of today (Dec. 7, 2009), the Obama administration reveals that the reliability of the models underlying the case for regulation is of no interest to it. Though it may lead to the loss of hundreds of trillions of dollars to the citizens of the U.S., this apparently is of no interest to Obama and his cabinet.