Robert Henson ★★★
Just about exactly what I wanted: a readable and concise overview of the major points in climate change. Didn’t really wow me with anything, and perhaps could have been slightly more readable, but otherwise a fairly good intro.
My major takeaways:
Carbon dioxide takes a long time to leave the atmosphere (half-life of 100+ years), so anything we emit is /essentially/ permanently warming the globe.
On geographic timescale the climate has changed radically, but stayed relatively steady for the last tens of thousands of years.
Human activity is boosting greenhouse gas to levels unprecedented in recent history, and perhaps more importantly, at unprecedented rates. Very little time for the system to adjust.
Other gases may be more potent (e.g. methane), but largely exit the atmosphere faster, making CO2 a particularly troubling gas.
Essentially the high half life of CO2 means we can’t really emit any of it without effecting the climate. There is no sustainable rate of emission. We must, eventually, drop all emission to zero or face a continually warming planet.
Groups and conventions have generally pushed for goals targeted at limiting warming to 2 °C or less by 2100. We have taken essentially no action to achieve this, and are likely to blow past the limits that would help make this a reality.
IPCC has determined a cumulative carbon budget of 1000 metric gigatons of post-industrial carbon emissions gives us a 66% chance of achieving 2 °C. As of 2017, we’ve already emitted about 575 metric gigatons.
Looks like we are up to 641 gigatons through 2019. Energy related CO2 emissions, 1990-2019 – Charts – Data & Statistics - IEA
That’s the big picture. Tactically, there is a bit of uncertainty around exactly what the effects of warming will be. We are headed to a climate of constant change, not a one-time shift to a warmer equilibrium.
Any particular policy change can have unexpected impacts. E.g., switching from high efficiency gas car to electric car could actually be worse if that electricity is generated by coal. (p. 447)
Other tidbits.
Deforestation is an emissions factor, not just a conservation topic. Tearing out trees removes a carbon collection source. It also releases carbon as the trees are burned and the soil is dug up.
There are a few doomsday-ish feedback loops we could conceivably trigger, e.g. Potential significant climate change positive feedback loops.