lagging by about 800 years, much like we are seeing now. Every major cooling trend the planet has seen has occurred during unusually high CO2 levels and every major warming trend we have seen has started during low CO2 levels. This answer is closed to changes. This is done in rare cases when questions are being vandalized or answers have become debates. E-mail reopen @ answers.com (no spaces) if you would like it to be reopened.