Posted: Nov 21, 2022 7:44 am
by OlivierK
THWOTH wrote:I guess it depends on what we mean by credible. The 2022 IPCC full Climate Change mitigation report (PDF 105MB) (see Chapter 2) said there is only one credible pathway to limiting warming to 1.5°C (>50% confidence, or; more likely than unlikely) - a truly massive reduction in fossil fuel extraction and use by 2030 accompanied by serious measures to achieve global net zero by 2050. However...

"Global GHG emissions in 2030 associated with the implementation of nationally determined contributions (NDCs) announced prior to COP26 would make it likely that warming will exceed 1.5°C during the 21st century. Likely limiting warming to below 2°C would then rely on a rapid acceleration of mitigation efforts after 2030. Policies implemented by the end of 2020 are projected to result in higher global GHG emissions than those implied by NDCs. (high confidence)."

IPCC AR6 Summary for Policymakers Headline Statements B.6

In short, what isn't credible are governments' policy commitments to reducing global GHGs, and the longer they leave it the harder it becomes.

So we have to understand what credibility is here, and not let policy makers or the media etc conflate it with possibility.

If we don't reach net zero until 2050, then we have 3 more decades of rising CO2e, which translates to 3 more decades of warming at or above current rates, which would take us to 1.7C, or possibly more. Then even if we achieve net zero in 2050, that doesn't stop warming, because we'll still have 400ppm+ C02/500ppm+ CO2e in the atmosphere, which means we're headed for close to another 1C by 2100. It's wishful thinking to suggest that we can have lower than current rates of warming with higher than current GHG levels.