Short answers, pulled from the story.
Research suggests global warming could trigger the release of about 190 petagrams of carbon from the top meter of Earth's soils by the year 2100. This amount equals all greenhouse gas emissions from fossil fuel burning over the past two decades combined.
The primary driver is an increased rate of soil respiration where microbes break down organic matter faster as temperatures rise. Data implies that a temperature increase of 4 degrees Celsius boosts annual soil respiration by up to 37 percent.
Measurements from a long-term study in Harvard, Massachusetts, began tracking soil behavior in 1991. That research suggests global warming could trigger the release of about 190 petagrams of carbon from the top meter of Earth's soils by the year 2100.
A study published in 2011 identified a phenomenon known as compost-bomb instability affecting peatland ecosystems. This concept describes a tipping point capable of causing explosive releases of stored soil carbon into the air when fixed atmospheric temperatures maintain unique stable equilibriums for soil carbon levels.
Soils contain approximately two to three times more carbon than exists in the entire Earth's atmosphere. When soil respiration rates increase due to warming, significant portions of this hidden stock enter the air as carbon dioxide.