Check out this article which makes an unsensational, plausible case for concern about global cooling. The greenhouse gases keep increasing and yet the temperature keeps dropping. According to this article, the culprit is a lack of sunspots. Sunspots apparently cause the earth to receive more solar warmth than would otherwise be the case.
Certainly the past year has been unusually cold, in many places around the world. Snow fell in unlikely places like Baghdad and Buenos Aires. One year does not a trend make, but it is possible to argue that an ice sheet a mile thick covering much of North America is normal and we've been enjoying a brief respite between Ice Ages.
