Land-intensive carbon removal requires better siting to protect biodiversity

The study, published in Nature Climate Change and led by scientists at the Potsdam Institute for Climate Impact Research (PIK) analysed future projections across five large-scale modelling projects, as well as considering 135,000 species and 70 biodiversity hotspots, to produce spatial mapping of where land-based carbon removal may be sited in the future.

The authors’ approach allows for a risk–risk assessment, not only focusing on overlaps between biodiversity areas and land allocated to carbon dioxide removal (CDR), but also showing the positive impacts of CDR in avoiding climate impacts on biodiversity. The work on the biodiversity importance was led by the Wallace Initiative under Dr. Jeff Price, with researchers from the Tyndall Centre for Climate Change Research at the University of East Anglia and James Cook University, Australia.

In ambitious emissions reductions scenarios, where global warming returns to 1.5°C by 2100 after temporarily overshooting this limit, up to 13 percent of areas allocated to CDR would overlap with important biodiversity sites. The authors emphasise that this would not necessarily mean the loss of these areas, depending on the specific implementation of removals. Nevertheless, given how sensitive some species are to human intervention, this remains a concern.

Careful site selection for carbon removal is critical

“As the world warms, we should be responding by cutting emissions as quickly as possible, but we are also going to need to be scaling carbon removal,” said Ruben Prütz, a PIK researcher and lead author of the study. “We can see from our maps that CDR has the potential to encroach on the areas that shelter biodiversity from harm in a warmer world. Careful site selection for carbon removal is thus critical to preventing negative biodiversity outcomes.”

Increased land use change for carbon removal could also conflict with internationally agreed targets for biodiversity conservation. The 2022 Kunming-Montreal Global Biodiversity Framework aims to “bring the loss of areas of high biodiversity importance, including ecosystems of high ecological integrity, close to zero by 2030”.

Other carbon dioxide removal technologies, such as direct air carbon capture and storage, could supplement land-based options and reduce spatial competition , but these are in earlier phases of technological development and much more expensive.

Benefits for biodiversity through carbon dioxide removal

However, the risk–risk analysis also reveals that the effects of carbon removal on temperatures could have positive outcomes for biodiversity. The study shows that effective implementation of reforestation and BECCS could reduce the long-term loss of biodiversity due to climate factors by up to 25 percent, producing net benefits. But the authors stress that positive outcomes depend on the ability of these ecosystems to recover from higher peak temperatures, which is extremely uncertain.

“We have to recognise that our continued use of fossil fuels is both punishing us, as we suffer from extreme events and other climate impacts, and reducing the tools we have to implement solutions,” Prütz concluded.

Equity and land-based CDR

Land use change for carbon removal is also unequally distributed across different regions of the world. The models allocate up to 15 percent of biodiversity-relevant land in low and middle-income countries to forest-based carbon removal, compared to just 7 percent in wealthy countries.

“This puts a greater burden on the countries who have historically contributed less to emissions,” said Sabine Fuss, PIK researcher and a co-author of the paper. “It also stresses the need for international finance to flow from wealthier countries to those that need it for biodiversity protection, to safeguard a common good.”