Why land – a scarce resource – is so important for climate protection

A new study quantifies, for the first time, the interrelationships and competing objectives of two major areas of action for reducing greenhouse gas emissions: the phase-out of fossil fuels and measures taken on natural land, such as farmland, forests and wetlands. It demonstrates how a well-balanced policy mix can keep costs low for both people and nature. The study, conducted at the Potsdam Institute for Climate Impact Research (PIK), was published today in Nature Sustainability.

Land-based climate protection includes, for example, the cultivation of biomass for biofuels or for carbon removal (through capture and storage of CO₂ sequestered from the atmosphere). It also involves the protection of ecosystems and the restoration of forests, soils, wetlands and peatlands as carbon sinks, and the reduction of methane and nitrous oxide emissions in agriculture. “With a transformation in the land sector, even a slower energy transition, involving lower adaptation costs, can achieve the same climate target,” explains PIK researcher Leon Merfort, lead author of the study. “However, land-based measures have their limits – we must also take into account food security, the water cycle and biodiversity. Our analysis shows how to strike a balance.”

Using a model that integrates the economy, the energy system, land use and climate, the research team calculated various future scenarios by varying the mitigation measures in the land sector. One key finding is that without a significant contribution from land-based greenhouse gas reductions, the target of limiting global heating to 1.5°C by 2100 – following a temporary overshoot – can no longer be achieved.

Recommendation for a cautious policy mix

The study emphasises just how important the scarce resource of land is for global climate action. The researchers illustrate this with an example based on the aim of limiting the temperature increase to a maximum of 1.7°C relative to pre-industrial levels, and assuming a global carbon price is used as a tool for the energy transition. The carbon price would then have to rise to 400 dollars per tonne of CO₂ by 2040 if no land-based climate protection measures are implemented. The costs of such a policy – in terms of lost consumption in the period 2025 to 2100 – would amount to 3.5 percent relative to a “business-as-usual” baseline scenario. The same target can also be achieved with a carbon price of just 130 dollars, and a 1.3 percent consumption loss, if every possible measure is taken in land-based climate protection.

What this means in concrete terms, however, is that “depending on implementation, the land area required for biomass cultivated for climate protection would then range from 66 million to just over 300 million hectares in 2050”, notes Alexander Popp, Head of the Land Use Transition Lab at PIK. “To put this in perspective, France covers a total of 63 million hectares and Argentina 278 million hectares. To maintain the food supply, this would have to be accompanied by significantly more intensive agriculture. On top of that, the geographical distribution would be problematic: the potential for land-based climate protection lies largely in the Global South, where food shortages, water scarcity and biodiversity loss are already particularly pressing issues.”

Weighing up a faster and more expensive energy transition against greater land-based climate protection thus produces conflicting objectives. The research team has analysed various scenarios, and ultimately recommends a possible compromise: a policy mix that combines energy recovery using residual materials, supplemented by a limited amount of cultivated biomass for energy recovery, with capped pricing for methane and nitrous oxide, and comprehensive global forest conservation.

Guidance for policymakers

The findings suggest that this cautious approach would largely avoid the negative side-effects of land-based climate protection. Limiting global heating to 1.7°C would then be achievable, according to the model calculations, with a carbon price of 180 dollars in 2040 and a 1.5 percent loss of consumption between 2025 and 2100.

“Policymakers must resolve a wide range of conflicting objectives: emissions reductions must be achieved as a matter of urgency, whilst at the same time the burdens must be distributed fairly,” emphasises PIK researcher Nico Bauer, co-author of the research paper. “Our modelling study quantifies these conflicting objectives and can provide guidance. What we fail to achieve in the land sector must be offset in the energy sector, otherwise emissions threaten to drive temperatures even higher in the future. The summer of 2026 has starkly demonstrated the drastic consequences of this. Any losses in prosperity must therefore be weighed against the costs of climate protection.”