Have you ever thought about how dinosaurs lived on a warm, swampy Earth and how we live on one that’s cold enough to keep pretty much the entirety of Greenland and Antarctica buried under kilometers-thick sheets of solid ice and wondered, hmm, how did we get from there to here? The short answer is that it took 50 million years of declining atmospheric carbon dioxide concentrations and dropping temperatures, not to mention building an ice sheet or two. For the longer story of the last 50 million years of climate change, including some of the reasons why, catch this episode of our podcast with Dr De La Rocha! You’ll hear about plate tectonics and continental drift, silicate weathering, carbonate sedimentation, and the spectacular effects the growth of Earth’s ice sheets have had on Earth’s climate. There are also lessons here for where anthropogenic global warming is going and whether or not its effects have permanently disrupted the climate system. Fun fact: the total amount of climate change between 50 million years ago and now dwarfs what we’re driving by burning fossil fuels, and yet, what we’re doing is more terrifying, in that it’s unfolding millions of times faster.
!!Nerd alert!! If you're interested in the primary scientific literature on the subject, these four papers are a great place to start:
-Dutkiewicz et al (2019) Sequestration and subduction of deep-sea carbonate in the global ocean since the Early Cretaceous. Geology 47:91-94.
-Müller et al (2022) Evolution of Earth’s plate tectonic conveyor belt. Nature 605:629–639.
-Rae et al (2021) Atmospheric CO2 over the last 66 million years from marine archives. Annual Review of Earth and Planetary Sciences 49:609-641.
-Westerfeld et al (2020) An astronomically dated record of Earth’s climate and its predictability over the last 66 million years. Science 369: 1383–1387.