As we count down to the 4th International Conference on Carbon Dioxide Removal in Milano, we are hosting a series of discussions on the research that will be shaping our sessions this June! 
This research develops a high-resolution modelling framework 
to assess the land requirements, deployment potential, and trade-offs of land-based Carbon Dioxide Removal pathways under different climate targets. 
By integrating methods such as BECCS, afforestation, biochar, and enhanced rock weathering into a spatially detailed assessment, 
fields the authors show that large-scale CDR deployment could intensify competition with food production 
and biodiversity conservation, while also highlighting the vital importance of diversified and regionally tailored CDR strategies to successfully reduce global land-use pressures! 
Read the full paper here: Link 
Full Abstract: Competing for land: mapping potentials and trade-offs of land-based carbon dioxide removal under climate targets
Authors: Oumaima Rhalem, Vassilis Daioglou, Jonathan Doelman, Meike Scherrenberg, Detlef van Vuuren
Most national climate pledges and climate change mitigation scenarios assessed by the IPCC assume substantial deployment of land-based carbon dioxide removal (CDR) to meet the Paris Agreement targets. This reliance implies a large land footprint: land-based CDR in national pledges and IPCC AR6 pathways can require land areas up to one billion hectares, comparable to today’s global cropland area. At these scales, land competition becomes a binding constraint, with trade-offs for food security, livelihoods, and biodiversity.
Integrated assessment models (IAMs) are widely used to evaluate the role of CDR in mitigation pathways, yet they often represent land-system constraints only crudely. Previous studies typically rely on models with simplified biophysical processes and coarse spatial resolution, obscuring sub-regional heterogeneity in land suitability and carbon dynamics. Additionally, most IAM studies assess only a few CDR options, potentially underestimating total removal potentials and overstating land competition. The emphasis is typically placed on land-intensive approaches like afforestation/reforestation (A/R) and bioenergy with carbon capture and storage (BECCS), while underrepresenting methods that can be co-deployed on agricultural lands, such as biochar and enhanced rock weathering (ERW).
We address these gaps by extending the IMAGE integrated assessment framework with a newly developed IMAGE-CDR module that directly couples the energy system model TIMER with the land system model IMAGE-Land/LPJmL. IMAGE-CDR estimates the spatial and temporal deployment of land-based CDR by allocating land across competing options subject to demand, biophysical potential, land suitability, deployment-rate limits, and economic feasibility. The module operates on a 5′×5′ global grid and represents fractional land allocation within each grid cell. Competition between CDR options is resolved through grid-cell-level net present value profitability ranking, while land scarcity and interactions with agriculture are captured through a land-cost supply curve that increases the opportunity cost of land as competition intensifies. IMAGE-CDR represents A/R, BECCS, ERW, and biochar.
Using scenario analysis, we compare the spatial deployment of land-based CDR across three mitigation pathways: (i) current policies, (ii) a stringent target with limited overshoot, and (iii) a less stringent target with high overshoot. We quantify method-specific removal trajectories, land footprints, and removal efficiency per unit of land, and identify regional hotspots of feasible deployment. We further assess interactions with food production and biodiversity conservation by mapping overlaps with cropland and conservation priority areas and quantifying impacts on food security and biodiversity. Our results inform the design of land-based CDR strategies by mapping feasible deployment and associated trade-offs across regions and mitigation pathways.
If massive land-based CDR requires up to a billion hectares of land, how should global governance balance the immediate corporate demand for carbon offsets against the fundamental right to food security and local biodiversity? 
