[orwin]

Okay, so I'll try to explain how does global/troposphere warming works:

The earth must radiate all the energy it gets from the sun (else we break physics).

A third of the sun's radiation is reflected directly.

The rest have to be radiated. Calculation show that the temperature needed to radiate the excess energy is 155K. Also, plank's law make that this radiation is mostly infrared.

The atmosphere (GHG concentration especially) makes that the point of emission of the energy is not the earth surface, but high up in the troposphere. The temperature this point need to reach is 155K. To reach that, the point below has to reach 156K, the one below 157... (it's not really discrete values, and it's not really temperature but energy, but I'm both simplifying and explaining in a language I never used for physics or math before).

So, rising the number of Co2 molecules at that altitude (and especially higher) will move the point of emission up. But that new point of emission isn't at 155K yet! So for a while, the earth will absorb more energy than what it's emitting, until the new point of emissions reach 155K.

Its high school physics tbh.

[hashxyz]

So basically the balancing point at which CO2-based heating stops is bounded by this 155K number, which I’m assuming relates to something really hot and bad on the surface. This means that with just this model we will all die.

Can we not just seed clouds to reflect lots of energy back into space though? Maybe that is a stupid idea, but I could come up with 10 ideas like that and maybe someone could come up with an idea like that, but which actually works.

[orwin]

The temperature on the surface depends on the altitude the surplus heat is emitted. This altitude is variable but is constantly increasing as Co2 concentration at high altitude rises (it rises by osmosis, and basically the current concentration is what was on the surface 20 years ago).

We have to issues:

we don't know how the feedback loops work: we are jumping into the unknown, we have no data to predict the risks: the only thing we know is that between the last ice age (1km ice sheet over Canada, Sweden) and the climate we had for 10000 years, until 1850, the difference in global temperature was 3,5K (2% increase).

The second issue: the transition lasted 10000 to 20000 years. We are on a real, really fast track and making the same transition in 100/200 years.

Now my opinion : we aren't doomed as a specie. In fact, I'm pretty sure mammals can thrive in jurassic era temperatures. But I do expect a lot of death because the transition is way, way to fast. We are unprepared. And a lot of species will disappear. Also Zooplankton is dying because marine CO2 concentration is too high and the ocean is too acid for zooplankton to form shells from CaCO, which is an issue caused by CO2 but unrelated to tropospheric warming.

Climate engineering is way harder than that (we want to avoid acid rain, reducing direct sunlight will reduce photosynthesis, so as long as we have famine, we want to avoid it too. Augmenting the albedo on the surface is an OK option in hot countries).