So when do we get to the real question - what to do about it?

No one has gone there yet.

Possibly, because there isn't one.

No, dumping ice cubes into the water near Florida isn't the answer.

We had ample opportunity to avert catastrophe. We chose short-term profits instead. So now, there is little that can be done. Even if we stop all emissions today, the global temperature will continue to rise for another 20 years just from the CO2 we've already dumped into the atmosphere. It's possibly, or probably, worse than that since we have in all likelihood set several feedback loops into motion.

The best we can do at this point is cut CO2 emissions as rapidly as possible and hope for the best. In reality, that works out to just hoping for the best because we still seem disinclined to cut emissions.

Summing up: Our civilization is going to collapse. Prepare as best you can.

When scientists give estimates for how long carbon dioxide (CO2) lasts in the atmosphere, those estimates are often intentionally vague, ranging anywhere from hundreds to thousands of years.1 The reason for the murky timeline is that CO2 molecules, once they enter the air, follow different paths and can last for radically different amounts of time.

Unlike some other atmospheric gases, CO2 mostly does not break down into smaller molecules while in the atmosphere. Methane, for instance—another important greenhouse gas—reacts with oxygen to turn into CO2 and water within a matter of years, and that process can be observed and measured. But CO2 molecules typically linger until something absorbs them from the air.2 Some are quickly taken up by the ocean, plants, and soil.3 Other atmospheric carbon sticks around for generations.4

“The first 10% goes quickly, but it's not very much of it. The second part goes on a scale of centuries to millennia, but that only gets 80% of it,” says Ed Boyle, a professor of ocean geochemistry at MIT. He says the last of the carbon dioxide that enters the atmosphere takes tens of thousands of years to leave.

Of course, scientists can’t track individual carbon dioxide molecules for thousands of years. But since the 1950s, we have had the tools to precisely measure the concentration of CO2 in the atmosphere. From there, scientists use a combination of measurement methods and models to determine how much CO2 is taken up by the Earth’s plants, soil, and water, a process called the “carbon cycle.” Scientists must also calculate how much carbon is released on the same time-scale, taking into account human activities that release carbon, like burning fossil fuels, as well as natural ones, like plant decay and wildfires.

EDIT

https://climate.mit.edu/ask-mit/how-do-we-know-how-long-carbon-dioxide-remains-atmosphere

It pushed up lots of calcium carbonate that absorbs co2. That shift happened over a much longer time frame than our co2 increase. With that life had time to adjust and evolve. Our best chance is artificial snow in the northern and southern areas to increase the albedo, the Earth's ability to reflect sunlight back. We face the risk of actual environmental collapse ontop of social collapse. Worst case fear is the methane hydrate in the arctic ocean triggering runaway warming leading to the oceans them selves evaporating. That happened in the Pemerin Extinction. These shifts can happen over very short timeframes, like 12 to 15 years.

https://arctic-news.blogspot.com/p/runaway-warming.html?m=1

“We’ll see,” Dessler agrees. “The next few months will tell us if we’ve really broken the climate.”

Anyone is going to change their habits and lifestyle in order to actually do something toward slowing the demise of the biosphere or anything.

Prepare as best you can indeed.

James Kunstler