"There is a great deal of uncertainty associated with climate predictions and, although temperature changes during this century are consistent with global warming predictions, they remain within the range of natural variability."
Uncertainty is a reliable feature of climate science, but the statement that temperature changes during this century "remain within the range of natural variability" is decidedly and verfiably false. This represents a flagrant misrepresentation and politicization of science.
The Union of Concerned Scientists addresses the question thusly:
It was bad enough that the Conservative Party was prepared to flout the truth in challenging climate science. It is a scandal that the Tories should have forced a formerly reputable scientific institution like Environment Canada to do the same.
The Role of Natural Variability
Human-induced warming is superimposed on natural processes to produce the observed climate. Because these natural fluctuations (which are always present) play a role in determining the precise magnitude and distribution of temperature in a particular year, record warmth in any one year is not in itself highly significant. What is noteworthy, however, is that global average temperatures experienced a net rise over the twentieth century, and the average rate of this rise has been increasing. When scientists attempt to reproduce these twentieth century trends in their climate models, they are only able to do so when including human-produced heat-trapping emissions in addition to natural causes.