Roger Pielke Jr;
Back in April, THB broke the news to the world that the only three official reference scenarios used for the past 15 years in much of climate research, assessment and policy had been retired. The CMIP71 conclusion that RCP8.5, SSP5-8.5, and SSP3-7.0 were “implausible” was huge news.
Today, I share more big news about how official climate scenarios continue to evolve.
CMIP7 has just published the final versions of its new scenarios as they have emerged from integrated assessment models (IAMs), updating the placeholders that accompanied their April announcement. The final versions — once again — dramatically reduces the cumulative carbon dioxide emissions from fossil fuels from the April placeholders.
The table below shows just how large these changes are in gigatons (Gt) of carbon dioxide emitted from the burning of fossil fuels to 2100 — both in terms of the highest cumulative emissions across the scenario set (in the first bullet below) and in terms of the scenarios designated as reference or current policy […]
Do read the whole thing, including the conclusions at the end: The massive scale-back of projected future carbon dioxide emissions means, all else equal, less future changes in climate; As a consequence, there will surely be enormous political pressures placed on the climate science community to create projections with greater changes in climate, based on factors other than carbon dioxide emissions
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