Temporary nature-based carbon removal can lower peak warming in a well-below 2°C scenario

There is growing recognition that meeting the climate objectives of the Paris Agreement will require the world to achieve net-zero carbon dioxide emissions around or before mid-century. Nature-based climate solutions (NbCS), which aim to preserve and enhance carbon storage in terrestrial or aquatic ecosystems, are increasingly being evoked as a potential contributor to net-zero emissions targets. However, there is a risk that any carbon that we succeed in storing in land-based systems could be subsequently lost back to the atmosphere as a result of either climate-related or human-caused disturbances such as wildfire or deforestation. Here we quantify the climate effect of NbCS in a scenario where land-based carbon storage is enhanced over the next several decades, and this stored carbon is then returned to the atmosphere during the second half of this century. We show that temporary carbon sequestration has the potential to decrease the peak temperature increase, but only if implemented alongside an ambitious mitigation scenario where fossil fuel CO₂ emissions were decreased to net-zero during the time that NbCS-sequestered carbon remained stored. We also demonstrate the importance of non-CO₂ climate effects of NbCS implementation; decreases in surface albedo that result from temporary reforestation, for example, have the potential to counter almost half of the climate effect of carbon sequestration. Our results suggest that there is some climate benefit associated with NbCS, even if the carbon storage is temporary, but only if implemented as a complement (and not an alternative) to ambitious fossil fuel CO₂ emissions reductions.