A new global review reveals that over 850 billion tons of carbon are stored more than a foot below the soil surface. This deep reservoir holds 50 to 60 percent of the carbon found in the top three feet of soil, yet it is largely ignored by standard IPCC accounting and national carbon markets. While this deep carbon is generally stable due to mineral bonding, it faces risks from rising temperatures and the priming effect, where new organic matter triggers the release of ancient carbon. Researchers suggest that deep-rooted crops and specific soil management techniques could optimize this long-term storage.
