"Fluctuating climate is a hallmark of Earth." Heresy! Next thing you know, they'll be claiming that the sun has something to do with it! Oh, wait...they just did:
There is a wealth of evidence pointing to dramatic short-term climate change on Earth over the last few million years. Much of this climate change is driven by variations of Earth’s orbit around the Sun with characteristic frequencies known as Milankovitch cycles. Robust evidence for orbitally driven climate change, however, becomes rare as one descends deep into Earth time. We studied an exceptional record of climate change as recorded in 1.4-billion-year-old marine sediments from North China. This record documents regular changes in subtropical/tropical Hadley Cell dynamics. These changes in dynamics controlled wind strength, rainfall, and ocean circulation, translated into cyclic variations in sediment geochemistry, much like the orbital control on climate today and in the recent past.
These scientists must have missed the memo. AlGore's going to be vewy upset with them. Because human activity!