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This wasn't unpredicted, at least not in principle. Sulfur aerosols have been a component of climate models for decades, and were already known to be a major ne

This wasn't unpredicted, at least not in principle. Sulfur aerosols have been a component of climate models for decades, and were already known to be a major negative forcing term counteracting something like 1/3 of human-caused warming. See for example [1], an IPCC report from 2021 that shows sulfur aerosols contributing 0.5 C of cooling in the industrial era. Deliberately adding such aerosols to the upper atmosphere (where they're less harmful than ground-level pollution), which volcanic eruptions already do, is one of a few major geoengineering proposals to counteract climate change. [1] https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6...

dr_dshiv 2y ago
But the mechanism is different, so far as I understand. The sulfur rich fuels supports marine cloud brightening and ship tracks. (Low clouds reflect heat, while high clouds absorb) The loss of the ship tracks accounts for a big jump in the warming effects of shipping. https://ntrs.nasa.gov/api/citations/20220015136/downloads/Yuan_Science_advances_format_Yuan_shiptrack.pdf https://ntrs.nasa.gov/api/citations/20220015136/downloads/Yu...
- aeroman 2y ago
  The mechanism is different from the impact of sulphur in the stratosphere (where there are no clouds), but it is the same as the mechanisms that have caused the majority of the aerosol cooling (a brightening of clouds). The same ze of the cooling has long been uncertain though. It depends a lot on assumptions you make about the pre-industrial atmosphere,something that we don't have great observations of.
JumpCrisscross 2y ago
> Deliberately adding such aerosols to the upper atmosphere Sulfur in the atmosphere causes acid rain. We can deliberately seed clouds much less damagingly than by encouraging sulphur emissions.
vintermann 2y ago
Artificial volcanic winters, that's something.

dr_dshiv 2y ago

But the mechanism is different, so far as I understand. The sulfur rich fuels supports marine cloud brightening and ship tracks. (Low clouds reflect heat, while high clouds absorb) The loss of the ship tracks accounts for a big jump in the warming effects of shipping. https://ntrs.nasa.gov/api/citations/20220015136/downloads/Yuan_Science_advances_format_Yuan_shiptrack.pdf https://ntrs.nasa.gov/api/citations/20220015136/downloads/Yu...

aeroman 2y ago
The mechanism is different from the impact of sulphur in the stratosphere (where there are no clouds), but it is the same as the mechanisms that have caused the majority of the aerosol cooling (a brightening of clouds). The same ze of the cooling has long been uncertain though. It depends a lot on assumptions you make about the pre-industrial atmosphere,something that we don't have great observations of.

JumpCrisscross 2y ago

> Deliberately adding such aerosols to the upper atmosphere Sulfur in the atmosphere causes acid rain. We can deliberately seed clouds much less damagingly than by encouraging sulphur emissions.

vintermann 2y ago

Artificial volcanic winters, that's something.