I think there is a much greater chance of Nuclear Winter than there is of global warming or [non-anthropogenic] cooling.
Historically speaking, we are overdue for an ice age.
I can predict with absolute certainty that the world is getting warmer, or the world it getting colder, or it isn’t. But I know it is one of the three.
I can also predict with absolute certainty that no matter what happens, it will be Bush’s fault. Bush and those damned SUVs. Womyn and minorities will be hardest hit.
You can experience both nuclear winter and global cooling. And at this stage of the civilization, you tend to get both. And we are. The sun warms the planet every 100 k years allowing civization. Then the civilization collapses itself along with the falling solar warmth. And the temperature is not the major killer. Disease is. Similar cycles are probably occurring all over the universe where planets are positioned as the Earth is positioned.