Monday, December 16, 2019

Thanks, Global Warming?

Here's a very cogent lecture from Dan Britt:

In it, he points out a few interesting things (actually, the whole lecture is interesting), including:
  • There's nothing "normal" about today's global climate. The Earth is usually much warmer than it is today. Today we occupy a relatively warm period in an Ice Age. Glaciation is a relatively rare event on geological timescales.
  • The big climate factors on a geological scale are the eccentricity of the Earth's orbit, the Earth's axial tilt, and the precession (wobble) of the poles. (the Milankovitch Cycles). Simplistically put, the major climate drivers are whether the pole is pointed at or away from the Sun when the Earth is closest to or farthest from the Sun. Other factors are basically "noise" within these trends.
  • Anthropogenic warming is certainly a real thing. Were it not for anthropogenic warming over the last 8,000 years, we would be well on our way to the next Ice Age.
I recommend you watch. However, Britt does ask a question that doesn't pop into my mind at all. He asks, "Do you like the coastlines where they are?" He asks it after having recently explained that where they are is highly unusual in Earth's history. That being the case, I would never expect them to stay there.

Given the Milankovitch cycles, we would be well on our way to another glacial Ice Age were not for anthropogenic global warming. We've experienced a cooling trend over 6,000 years, and we could expect it to continue for another 23,000 years. This begs the question of whether this major factor (orbital cycles) would not level off the carbon cycle (previously characterized as "noise"). And some models do predict that we would avoid an Ice Age entirely thanks to anthropogenic global warming.

On the scales we're talking about, whether human or geological, the coastlines have never been stable. It may be quixotic hubris to try to make something stable that has never been so in the history of History. So the question that does pop into my mind is, "Would I rather see Chicago buried under a half mile of glacial ice?" Because, frankly, it might be a clearly better long-term strategy for those on the coast to rent some U-Hauls knowing that they've got someplace warm to move to.

It's never as simplistic as "OMG! Things are going to change!" Things are going to change. But if you're pushing for zero-carbon emissions, they might not be likely to change in a way that makes you comfortable in the long term. Obviously, some more thought is called for.