Was der Verbleib des CO2 in der Atmosphäre und die Langfristwirkung betrifft fand ich dem Hinweis von Michael Mann ganz interessant. Auch wenn er die Chancen für eine globale Reduktion im erforderlichen Maße nicht sehr optimistisch sieht.

"Until recently, Mann explained in The Guardian, scientists believed the climate system—a catch-all term for the interaction among the Earth’s atmosphere, oceans, and other parts of the biosphere—carried a long lag effect. This lag effect was mainly a function of carbon dioxide remaining in the atmosphere and trapping heat for many decades after being emitted. So, even if humanity halted all CO2 emissions overnight, average global temperatures would continue to rise for 25 to 30 years, while also driving more intense heat waves, droughts, and other climate impacts. Halting emissions will take at least twenty years, under the best of circumstances, and so humanity was likely locked in to at least 50 more years of rising temperatures and impacts.
Research over the past ten years, however, has revised this vision of the climate system. Scientists used to “treat carbon dioxide in the atmosphere as if it was a simple control knob that you turn up” and temperatures climb accordingly, “but in the real world we now know that’s not what happens,” Mann said. Instead, if humans “stop emitting carbon right now … the oceans start to take up carbon more rapidly.” The actual lag effect between halting CO2 emissions and halting temperature rise, then, is not 25 to 30 years but, per Mann, “more like three to five years.”
In short, this game-changing new scientific understanding suggests that humanity can turn down the heat almost immediately by slashing heat-trapping emissions. “Our destiny is determined by our behavior,” said Mann, who finds that information “empowering.”
Of course, this glimmer of hope is only empowering if humans—especially those with governmental and policy-making positions—actually act. Mann has said before, and he reiterated in The Guardian interview, that a second presidential term for Trump would be “game over” for the climate. That’s not Mann’s partisan judgement, he insisted. It’s straightforward math.
To prevent a catastrophic rise in global temperature, humanity must cut emissions in half by 2030, Mann said, citing 2018’s landmark report by the UN’s Intergovernmental Panel on Climate Change. That will require a rate of change “unprecedented” in human history, according to the IPCC scientists: emissions had to fall by 5 percent year after year. But if a re-elected Trump spent an additional four years pushing the world’s biggest economy in the opposite direction, hitting the 2030 target would become “essentially impossible,” Mann said. If emissions don’t begin falling until 2025, they would have to decline by roughly 15 percent every year over the following five years. “That may be, although not physically impossible, societally impossible,” Mann said. “It just may not be economically possible or socially viable to do it that [fast].” …."

https://www.cjr.org/co...

Ich verstehe die Berechnung nicht ganz? Die 2,7 Grad Steigerung der globalen Mitteltemperatur verteilt sich doch nicht gleich über die Welt. Um den Äquator steigen die Temperaturen weniger, auf den Halbkugeln mehr? Also werden wohl um den Äquator gar nicht so viele Gebiete verloren gehen und in Richtung der Pole wird das Klima wärmer und Siedlungsgebiete frei. Oder irre ich mich?

Es muss sich etwas tun.

Aber gab es schon einmal ein Beispiel, dass eine Modellierung über einen längeren Zeitraum auch so eintraf?

Keine der verlinkten Studien lässt den Schluss zu, dass in 75 Jahren 4 Milliarden auf der Flucht sind.