"Natural" solutions could speed up climate change mitigation, with risks, compared to emissions reductions alone. Additional options are needed.

<p>Mitigation of climate change by intentionally storing carbon in tropical forests, soils and wetlands, and by reducing greenhouse gas fluxes from these settings has been promoted as rapidly deployable and cost-effective.  This approach, sometimes referred to as "natural" mitigation, could keep post-industrialization warming below 1.5°C, when coupled with reductions in fossil fuel emissions, as confirmed here with a simple numerical model of future emissions.  However, such mitigation could cease in response to changes in future climate, land use or natural resource policies, or there could be CO₂ released from reservoirs of stored carbon.  Model simulations suggest cumulative emissions could be similar, under scenarios where carbon storage ceases, or stored carbon is released, to emissions expected in the absence of any natural mitigation.  If climate change is to be minimized, low-risk natural mitigation (e.g. by reducing deforestation) should be considered, as emissions targets that could limit warming to 1.5°C cannot be met without mitigation of this magnitude.  However, additional mitigation options should also be considered that can reduce CO₂ emissions and remove CO₂ from the air (and store it permanently) and/or reduce the temperature of the atmosphere or the ocean.</p>