Hedging our bet on forest permanence

Abstract Forests currently absorb a quarter of anthropogenic carbon emissions. Moreover, establishing additional forests is presently the most cost-effective and scalable option for carbon removal services. Thus, mitigation pledges and scenarios aiming for the Paris Agreement climate goals became heavily dependent on maintaining the existing forest carbon sink and expanding it further . However, a mounting body of evidence questions the permanence of the carbon stored in forests under the pressure of both climate change and direct human intervention. Here we show that rapid decarbonization can secure mitigation goals despite potential carbon loss of forest disturbances. Yet, the projected CO 2 price to stay below 1.5°C of warming is 71$/tCO 2 higher (+22%) compared to a world without increasing disturbance trends. Likewise, it entails a 20% (-1.2GtCO 2 /yr) reduction in allowed yearly emissions and an expansion of 69 million hectares (+17%) of dedicated mitigation land. Responding late to the disturbance, rather than taking preemptive action, doubles the projected cost and effort until mid-century in multiple key sectors. Our results underline the urgent need to safeguard forests for the economic feasibility of the Paris Agreement climate goals. Deferring fossil fuel phase-out leaves us ill-prepared if trends of increasing forest disturbance rates continue.