Land management for carbon sequestration offers an opportunity to avoid about 0.5°C of warming if landowners have full economic incentives to participate in a global greenhouse gas mitigation policy. In an energy-only policy aimed at about 550 ppm CO₂- eq stabilization the additional 0.5°C of avoided warming brings the world close to staying below the 2°C above preindustrial target. While greater incentives for mitigation from energy and land would be needed to actually meet the 2°C target even holding temperature to 2.2°C or so would be a great improvement over the path we are on now. Even with success at the 21^st meeting of the Conference of the Parties (COP21) in Paris in 2015, we would still be heading toward a global mean surface temperature increase is in the range of 1.9 to 2.6°C (central estimate 2.2°C) by mid-century relative to the pre-industrial level (1860–1880 mean), and 3.1 to 5.2°C (central estimate 3.7°C) by 2100. This preliminary assessment awaits a full interpretation of the implications of agreements at COP21 with greater clarity on just what countries pledges mean and how they will be implemented. But this first look estimates that the COP21 pledges would shave about 0.2°C more from warming compared with previous international commitments. From that perspective, a half-degree of avoided warming from land carbon sequestration and avoided deforestation, if we could achieve it, is significant. The relatively small contribution from the COP21 agreement says less about the significance of the commitments—many countries stepped up and offered important goals that will mean changes in their energy systems—but rather more about the challenge of weaning the global economy from its dependence on greenhouse gas emitting activities. It also highlights that no source (or potential sink) can be ignored.

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