Hi Colin, Great question! We are extremely certain that low-altitude subtropical clouds cool the climate by reflecting sunlight but not having a strong impact on the amount of heat escaping to space. Unfortunately for us, this type of cloud is projected to become less common as sea surface temperatures warm — the loss of these clouds leads to additional warming (positive feedback). Marine cloud brightening, on the other hand, is a proposal to use sea salt aerosol to make these clouds more reflective when they do occur, and potentially make them occur more frequently/over larger areas. This would cool the climate by increasing the amount and/or brightness of these clouds (negative forcing).
In short: increasing low-altitude clouds leads to cooling (MCB) and decreasing them leads to warming (positive feedback to global warming). Cheers, Michael On Tuesday, March 28, 2023 at 11:44:25 AM UTC-4 Colin Forrest wrote: > From AR6 WG 1 full report ch 7 page 926.......... > > An assessment of the low-altitude cloud feedback over the subtropical > oceans, which was previously the major source of uncertainty in the > net cloud feedback, is improved owing to a combined use of climate > model simulations, satellite observations, and explicit simulations > of clouds, altogether leading to strong evidence that this type of > cloud amplifies global warming. > > How does this square will the modelling of MCB which predicts a cooling > effect from increasing this type of cloud cover ? > > Best Wishes, Colin Forrest > > PS the reference for my previous post on SSPs and climate forcing was > wrong. It's om page 926, not 928 > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/450ac82b-3fa4-43e3-ab77-c0583ae02664n%40googlegroups.com.
