by J. Curry, Mar 29, 2023 in ClimateChangeDispatch
The Intergovernmental Panel on Climate Change (IPCC) has issued a new Synthesis Report, with fanfare from the UN Secretary-General Antonio Guterres:
“The climate time-bomb is ticking but the latest IPCC report shows that we have the knowledge & resources to tackle the climate crisis. We need to act now to ensure a livable planet in the future.”
The new IPCC Report is a synthesis of the three reports that constitute the Sixth Assessment Report, plus three special reports. [emphasis, links added]
This Synthesis Report does not introduceany new information or findings.
While the IPCC Reports include some good material, the Summary for Policy Makers for the Synthesis Report weakly emphasizes justified findings on climate impacts driven by extreme emission scenarios and politicized policy recommendations on emissions reductions.
The most important finding of the past five years is that the extreme emissions scenarios RCP8.5 and SSP5-8.5, commonly referred to as “business-as-usual” scenarios, are now widely recognized as implausible.
These extreme scenarios have been dropped by the UN Conference of the Parties (COP) to the UN Climate Agreement.
However, the new Synthesis Report continues to emphasize these extreme scenarios, while this important finding is buried in a footnote:
“Very high emission scenarios have become less likely but cannot be ruled out.”
The extreme emissions scenarios are associated with alarming projections of 4-5°C of warming by 2100.
The most recent Conference of the Parties (COP27) is working from a baseline temperature projectionbased on a medium emissions scenario of 2.5°C by 2100.
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