TADEAS:
Last week’s SPM report makes stronger statements than previous IPCC assessment summaries, but then again the situation is now much worse. Thousands of scientists have spent hundreds of thousands of hours developing the six full reports on which the SPM is based. Much of what was done is lost or downplayed in the SPM, though some strong messages survived, including that more than 3.3 to 3.6 billion people are living in places “highly vulnerable” to climate impacts and new extremes.
But there is a tendency to put into future tense what should be present tense. The SPM says that warming of more than 1.5 degrees would be devastating for Earth’s people and ecosystems, but that is already the case because a number of crucial climate systems have already passed their tipping points at the current level of warming of 1.2 degrees. A search of key words relating to system tipping points and their consequences in the SPM is instructive: “feedback” appears once, “cascade” and “hothouse” not at all, “tipping” gets one mention, as does “Antarctic”.
There is no admission that limiting warming of 1.5 degrees is not a desirable outcome and would involve, amongst many outcomes, eventual sea-level rises measured in many metres and likely in the tens of metres.
And again, the SPM says that beyond the 1.5 degrees threshold, scientists have found that climate disasters will become so extreme that people will not be able to adapt. But that is already happening. People are already fleeing from desertification of the dry subtropics, from unprecedented drought, and from the salination of their land, today.
In the report and the media commentary, there has been confusion about the feasibility of keeping warming below 1.5 degrees. Given the projected increases in emissions in the short term, which may not plateau till this decade’s end, and then remain high, the world is not within co-ee of keeping warming to 1.5 degrees (or even 2 degrees), and talk of 1.5 degrees is really about scenarios that involve significant overshoot and then trying to cool back to 1.5 degrees by century’s end.