Brannen's essay is extremely well-written, and kept me intrigued the entire time. I love how we take "leaps" back in time and progressively get to climates vastly different than our own with creatures very different than what currently inhabits Earth. This is also what I took to be the overarching moral of the piece: we won't destroy the planet in some existential end-of-life event because there is too much CO2 in the atmosphere. What is much more likely to happen is that the Earth's climate will radically change so that life will become incredibly difficult, if not impossible in large amounts of the globe given the current populations that we have in place.

I think that Brannen did exceptionally well at getting across this messaging. We need to stop presenting the climate crisis like an ultimatum that if we don't achieve our goals, everything will collapse. That might be the case in lots of areas of the world, but what is more likely to happen is that people will have to migrate in huge masses and there will be famine and hardships. Some will be lucky, but some won't be. That is the way of the world now and will be so even more unless we can work together to curb emissions.

Depicting the Earth as a wildly different place depending on tilt and atmospheric CO2 really helps us understand what we could be presented with, especially those who live directly connected to the land (farming, livestock, and even real estate dependent things). For example, when the Earth's "top half was aimed toward the sun during the closest part of its orbit":

The resulting Northern-summer warmth turned the Sahara green. Lakes, hosting hippos, crocodiles, turtles, and buffalo, speckled North Africa, Arabia, and everywhere in between.

When the Earth titled away, the following happend:

The green Sahara began to die, as it had many times before. Hunter-fisher-gatherers who for thousands of years had littered the verdant interior of North Africa with fishhooks and harpoon points abandoned the now-arid wastelands, and gathered along the Nile. The age of pharaohs began.

Climate, and the resulting prosperity or famine that has followed it, has drastically changed human history. Although Brennan says that "one must resist environmental determinism," we can't help but notice how much it could have influenced our growth as a species and society.

This all comes from a world that largely resembles our own, but as Brannen goes back in time, we start to see things we never could have imagined: forests and marsupials and alligators in the arctic. A planet with almost no ice at all, due to events that launched CO2 into the atmosphere. And the scary thing is that our best projections put us in the most bizzarre of these scenarios, where it's difficult to imagine what our world might really look like.

My final takeaway was that all of this is fantastic evidence collected from the geological record. It's dilligently collected by scientists and then analyzed by researchers across the world with different languages, political ideologies, goals, etc., yet there is an overwhelming consensus. We must hede the advice, but also be sure to notice that these are literally computer models that humans are writing. We can predict all we want, but computer models are primative tools to "predict" what might happen. But it's literally impossible for us to every collect all the evidence necessary and jam it into a metal disk. This is of course better than anything else we have, but as Bannen says, let's not fall into "environmental determinism" based upon human-written computer models.

I try to do alot to reduce my carbon footprint. I bike to work, walk to the store, collect compost, bring reusable containers everywhere I go. But I'm still hesitant about comparing our future world to these vastly different epochs in Earth's history. I imagine that before we could radically change the climate like this, we would face horrible famine or disease that would curb our growth. Or I'm wrong and these are legitimate future scenarios. I guess what I'm trying to say is that although we should hede the warning and do whatever we can to reduce our emissions, we have no idea what is in store for us other than some models that humans are writing into a computer. I think our environment is just a little too complicated to be accurate here.