Short answers, pulled from the story.
The soil carbon feedback is the release of carbon from soils in response to global warming, and it functions as a positive climate feedback because the released carbon drives further warming. An increased rate of soil respiration is the main cause of this response.
Global soils hold roughly two to three times more carbon than the Earth's atmosphere, which is why shifts in soil carbon release matter for understanding future climate change.
Measurements imply that 4 degrees Celsius of warming increases annual soil respiration by up to 37 percent.
An observation-based study conducted since 1991 at Harvard suggests a release of about 190 petagrams of soil carbon from the top 1 meter of Earth's soils by 2100. That amount is the equivalent of roughly two decades of greenhouse gas emissions from fossil fuel burning, driven by changes in microbial communities under elevated temperatures.
The compost-bomb instability is a tipping point identified in a 2011 study, describing explosive soil carbon releases from peatlands tied to a unique stable soil carbon equilibrium for any fixed atmospheric temperature. Researchers predict peatlands will shift from a carbon sink to a carbon source this century, yet peatland ecosystems are still omitted from major Earth system and integrated assessment models.
Current climate models do not account for the biochemical heat released during microbial decomposition. Global decomposition models also insufficiently incorporate soil animals, including insects and worms, and their interactions with microbial communities.