That’s the tidbit that had me scratching my damn head too. From the department computer, no less.

Geologist here. It’s not a new concept that we’ve learned that the earth goes through climate cycles—often times on top of climate cycles, and the cycles are very well documented, explained by natural processes, and the records are pretty thorough and we know a lot of this stuff because of the study of stable isotopes.

One such example of that is Milankovitch Cycles. Those are on the order of about 100,000 years and they are changes in the orbit of the earth (orbit, axial tilt, and wobble) around the sun and are affected by other planets in the solar system. The orbit of earth goes from being nearly circular to elliptical.

And that’s just one example on the order of magnitude of every 100,000 years. But there are many others, and these are also very well documented and explained. The reason we’re in very big trouble with climate change is because even though we very well understand these cycles and the history of climate on earth, given these extensive records and regular cycles, the planet should be gradually cooling towards another ice age, but we are not—we’re getting warmer. This pattern falls outside the normal paradigm, and climate change is anthropogenic in nature (manmade; because of humans).

These cycles and shifts are not brand new information. What is pretty new is the fact that there’s too much excess carbon dioxide in the atmosphere from burning fossil fuels, and unless we find a way to curb that behavior and sequester already existing carbon dioxide in our atmosphere, the hotter it will get and the harder to survive on this planet this will be.