Thread by @rstackjr

Simple fact: If we continue to release CO2 into the atmosphere, the atmosphere will get warmer. This was demonstrated way back in the 1850's by Foote and later Tyndall. CO2 concentrations have increased from 280ppm to 410ppm and we have seen clear evidence of warming. 1/8

We know humans are to blame for this increase due to the unique signature of isotopic carbon released from burning fossil fuels (C13/C12 ratio). 2/8

We also know that there is a shitload of carbon and methane locked up in permafrost and methane hydrates, and we know Earth's albedo is changing due to the melting arctic ice cap. We also know there are tipping points which will cause these to be released. 3/8

There are other tipping points as well which will self-reinforce the warming trend. What we don't know is quite where those tipping points are. 4/8

If those tipping points are reached they will start a process of rapid "runaway" warming, blowing past the "safe" 2 degrees Celsius threshold. Then we are looking at a nightmare scenario of making some regions of the planet incompatible with most current forms of life. 5/8

Now, while I cannot state with certainty what will be the fate of our civilization, it stands to reason that this runaway warming scenario will not be compatible with TODAY'S civilization, which is tuned to our current climate state. 6/8

Civilization strongly depends on our environment - the water we drink, the food we eat, the air we breathe, the hospitable places to build our towns and cities. All of these will be stressed - and are already starting to become stressed. 7/8

So there is an existential threat to our civilization as we know it. The outsize nature of the threat demands action, as the risk of it becoming reality continues to increase. We simply cannot hope and wish it away. Our descendants are counting on us to act. 8/8

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