History shows us that our normal temperature status is Ice Age conditions. In a 100,000 year cycle we spend about 85,000 years in the Ice age and about 15,000 years in a warmer period. Clearly the norm is an Ice Age.
We should be thankful that we are in a warm period but be working out how to keep the planet warm now rather than to cool it down. Its going to get very very cool all on its own.