Two preprints out for open peer review on climate impacts of 2020 IMO low-sulfur marine fuel regs find different results:
Skeie et al find 0.06 to 0.09 w/m^2 forcing, while Quaglia and
@danvisioni.bsky.social find 0.2 w/m^2. Another paper will be out in Geophysical Research Letters shortly.
The Skeie et al study looks at five different climate models (CESM2, two versions of NASA GISS ModelE, NorESM2, and OsloCTM3), with two different runs of each (sans OsloCTM3). They just calculate effective radiative forcing, but not temperature response: egusphere.copernicus.org/preprints/20...
The Quaglia and Visioni paper looks at a single model (CESM2), and find a higher radiative forcing (0.2 w/m^2) and a strong temperature effect (~0.15C). They argue that this could explain a sizable part of unusual global temperature anomalies in 2023: egusphere.copernicus.org/preprints/20...
In addition, a new paper by Gettelman et al should be out shortly in Geophysical Research Letters (its cited in the new Forster et al paper: essd.copernicus.org/articles/16/...) which finds 0.12 w/m^2 forcing and a relatively small temperature effect (~0.03C in 2023) zenodo.org/records/1072...
So what can we take away from all these new papers with disagreeing assessments? Well, this is how science works! When we have a mystery lots of different groups approach it with different tools and often get different answers.
Its by synthesizing all these different studies over time that we will get to the truth (or at least as close as we can in a world of deep uncertainty!).
