Sulfur oxides have a strong but short lasting athmosheric cooling effect. Vulcanic eruptions provide test of that. Lignite or "brown coal" has a reputaion as a paricularly "dirty" fuel, not least for its very high sulfur content. Now, for estimations of "climate footprint", the numbers given for methane seem to imply that atmosheric breakdown/washout time does not matter much. So what is the climate footprint of burning lignite, including the effect of sulfur pollution?
Sulfur dioxide, as such, does not cool the atmosphere. The cooling comes about when the sulfur dioxide is oxidized in the presence of moisture to produce dilute sulfuric acid in the form of aerosol; reflection of solar radiation from the aerosol is what then cools the planet.
It's not a good bargain ecologically. The sulfuric acid is a major culprit in acid rain, and sulfur emissions do great harm to ecological systems.
The sulfur content in lignite coal is not all that high. Compared with bituminous coal, lignite actually has about the same or less sulfur per unit of energy output. See the table below from Ref. (https://doi.org/10.1016/j.coal.2019.103336).
- Julia Kagiliery, Somsubhra Chakraborty, Autumn Acree, David C. Weindorf, Eric C. Brevik, Nicolas A. Jelinski, Bin Li, Cynthia Jordan (2019). "Rapid quantification of lignite sulfur content: Combining optical and X-ray approaches". International Journal of Coal Geology 216, 103336. ISSN 0166-5162, https://doi.org/10.1016/j.coal.2019.103336.