A roadmap to make the land sector carbon neutral by 2040

A study published in Nature Climate Change, unveils a land sector roadmap laying out critical actions on forests, farming, and food systems the world should take to veer away from spiking global temperatures. The study is the most comprehensive exploration of the contribution of land to the 1.5°C target to date, and the first of its kind to offer a point-by-point identification of specific land use actions, their related geographies, and implementation pathways to reduce land use emissions by 50% per decade between 2020 and 2050. The actions outlined will also contribute to climate adaptation and the achievement of the UN Sustainable Development Goals (SDGs).

IIASA researchers took the lead on the technical aspects of the study, which employed integrated assessment models, and assessed 24 land management practices that offer the most mitigation potential along with other social and environmental benefits. The international team of researchers mapped out priority actions countries could take to zero out emissions from the land sector by 2040 to limit global temperatures from spiking beyond 1.5°C. The six priority actions outlined in the study include reducing deforestation, peatland drainage and burning, and mangrove conversion by 70% by 2030; restoring forests, drained peatlands, and coastal mangroves; improving forest management and agroforestry; enhancing soil carbon sequestration in agriculture across all agricultural countries; reducing consumer food waste in developed and emerging countries; and shifting one in five people to primarily plant-based diets by 2030.

The analysis indicates that sustainable land management through these actions could contribute 30% of the mitigation needed to achieve the goal of keeping temperatures below 1.5°C as set out in the Paris Agreement. This is on top of the 30% of carbon emissions that land already sequesters naturally. The authors however note that the window of opportunity is getting smaller and the longer we delay action, the lower our chances will be to achieve the Paris Agreement goals, and the higher the burden we put on our natural and food systems.

"The roadmap foresees a phased approach where first actions to avoid emissions are prioritized. This means concentrating on avoiding deforestation in hotspot geographies such as Brazil and Indonesia. More high-tech options on carbon removal from the atmosphere need to be tested and piloted today. However, large scale deployment is not expected to happen within the next decade given current realities of the international climate policy regime," explains IIASA Ecosystems Services and Management (ESM) Program researcher Michael Obersteiner, one of the study authors.

According to study lead author Stephanie Roe, an alumna of the IIASA Young Scientists Summer Program (YSSP) and an environmental scientist at the University of Virginia, keeping the planet under 2°C will require us to halve emissions every decade, and also remove a huge amount of CO₂ already in the atmosphere.

"Restoring forests, peatlands, wetlands and agricultural soils is immediately viable, proven at scale, and provides many other benefits compared to other climate solutions. However, we will also need to develop and pilot additional negative emissions technologies -- like direct air capture and low-impact bioenergy with carbon capture and storage (BECCS) -- to sustainably remove more carbon from the atmosphere in the future. Otherwise, we will rely more and more on our natural systems. The land can and already does a lot, but it can't do it all. Research and investment in negative emissions technologies today will be critical for assisting in their sustainable deployment in the future," she says.

If countries were to implement the roadmap, the land sector could become carbon neutral by 2040 and a net carbon sink by 2050. The land sector currently emits about 11 GtCO₂e per year (about 25% of global emissions). With this roadmap, it will be a net carbon sink of about three GtCO₂ per year by 2050. Together, these actions would mitigate 15 GtCO₂e per year -- about 50% from reducing emissions and 50% from additional carbon uptake by land. While the authors emphasize that countries worldwide can contribute to better land management, they conclude that actions in the US, the EU, Canada, China, Russia, Australia, Argentina, India, Brazil, and other tropical countries are particularly important due to their large mitigation potentials.

"This study does a great job in reconciling global climate stabilization pathways with bottom-up mitigation potential assessments to develop an actionable roadmap for the land use sector to become carbon neutral by 2040," concludes coauthor Stefan Frank, who is also a researcher in the IIASA ESM Program.

Going beyond similar climate roadmaps focused strictly on climate benefits, the study identifies actions that deliver wins beyond greenhouse gas emissions cuts and removals, while building on and updating the IPCC land report, which argued that forest destruction, bad farming practices and unsustainable diets, in addition to fossil fuels, must be tackled together to avoid climate chaos. Several of the authors who worked on developing the roadmap were IPCC land report contributors.