Land-use emissions play a critical role in land-based mitigation for Paris climate targets

Abstract

Scenarios that limit global warming to below 2 °C by 2100 assume significant land-use change to support large-scale carbon dioxide (CO2) removal from the atmosphere by afforestation/reforestation, avoided deforestation, and Biomass Energy with Carbon Capture and Storage (BECCS). The more ambitious mitigation scenarios require even greater land area for mitigation and/or earlier adoption of CO2 removal strategies. Here we show that additional land-use change to meet a 1.5 °C climate change target could result in net losses of carbon from the land. The effectiveness of BECCS strongly depends on several assumptions related to the choice of biomass, the fate of initial above ground biomass, and the fossil-fuel emissions offset in the energy system. Depending on these factors, carbon removed from the atmosphere through BECCS could easily be offset by losses due to land-use change. If BECCS involves replacing high-carbon content ecosystems with crops, then forest-based mitigation could be more efficient for atmospheric CO2 removal than BECCS.

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“…), the level of emissions associated with land‐use change (Harper et al. ), the economics of rapidly scaling up an as yet commercially unviable technology (Smith et al. ; Turner et al.…”

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“…These are important in mitigation scenarios in order to compensate for GHG emissions in other sectors such as CH 4 in agriculture, residual fossil fuel use in certain transport modes, etc., which are extremely difficult to mitigate . In this context, BECCS is part of a portfolio of “negative emission” options such as afforestation and direct air capture, however, the trade‐offs concerning these options are still poorly understood . Scenarios which do not adopt any BECCS either have a less than 50% probability of staying within 1.5°C, or heavily depend on emission mitigation through significant technological and behavioral changes such as low population growth, severely reduced consumption, high energy efficiency, and systemic changes in energy demand …”

“…33,66 In this context, BECCS is part of a portfolio of "negative emission" options such as afforestation and direct air capture, however, the trade-offs concerning these options are still poorly understood. 72 Scenarios which do not adopt any BECCS either have a less than 50% probability of staying within 1.5°C, 68 or heavily depend on emission mitigation through significant technological and behavioral changes such as low population growth, severely reduced consumption, high energy efficiency, and systemic changes in energy demand. 73,74 Nonetheless, there is significant disagreement across scenarios concerning biomass deployment strategies.…”