That would explain the so-much warmer winters we have been having lately.
What, you mean we haven't been having warmer winters? They're actually colder???
It must be Bush's fault, then!
That's a specious answer. Global temperatures are indeed rising, even if local temperatures may in some cases drop. Why this is happening and what if anything we should do about it is the question. But nobody, certainly not the President, doubts that the former is happening.