The 1.5°C target can also be met using less negative emissions

Researchers from PBL Netherlands Environmental Assessment Agency and Utrecht University draw these conclusions in an article in Nature Climate Change. Studies into the objectives of the Paris Climate Agreement usually indicate that, in addition to rapid emission reductions, there is also a need for large-scale negative emission efforts, such as reforestation and bioenergy with carbon capture and storage. Many negative emission efforts require substantial areas of land, which may have consequences for the global food supply and for nature. Using the IMAGE model, PBL and Utrecht University have now elaborated alternative pathways to achieve the objectives of the Paris Climate Agreement.

Negative emissions lead to extensive land use

The Paris Climate Agreement aims to limit the global temperature rise to well below 2 °C, and preferably to 1.5 °C. This objective requires a considerable reduction in greenhouse gas emissions. Therefore, scenarios focusing on the Paris target almost always involve methods to remove CO₂ from the atmosphere, the so-called negative emissions. When considering the negative emissions that would be needed at the end of the century, calculations quite often result in amounts that are so large that they can have negative consequences for food supply or nature. The question is whether these can be limited.

Exploring alternative scenarios with computer models

It is possible to explore alternative scenarios by using computer models. Normally, the models are mainly used for finding the best possible combination of measures to meet the climate target. In this study, however, researchers from PBL and Utrecht University explore all sorts of alternative scenarios that could lead to fewer negative emissions. This would involve, for example, lifestyle changes, additional reductions in non-CO₂ greenhouse gases, such as methane, and increased use of renewable energy.

Achieving less negative emissions is possible, but not down to zero

The new IMAGE scenarios show that there are several pathways towards achieving the 1.5 °C target. This provides more flexibility as to the formulation of policies. Most of the new scenarios depend less on negative emissions than the default solution. One of the assumptions in the lifestyle-change scenario is that of a reduction in meat consumption to the level that is recommended for a healthy human diet. This leads to a decline in methane emissions from cows and the freeing up of land that is now used for producing animal feed. These land areas may be used for reforestation or bioenergy production. However, the scenarios also show that it is wise to continue to develop technology for negative emissions.

Exploring the pros and cons

‘We can use the results to compare the advantages and disadvantages of the standard scenario with those of the alternatives’, says Detlef van Vuuren, project manager of the IMAGE project and professor at Utrecht University. ‘It is clear that each pathway comes with its own challenges. For example, a change in dietary habits entails a large-scale change in the global food system. In any case, each scenario shows a clear break with past trends.’ Many of the alternative scenarios do seem to be compatible with reaching other UN sustainability goals, such as those related to nature, the global food supply and health. ‘This is important in order to increase social support for far-reaching climate policies. In developing countries, in particular, the agenda of the Sustainable Development Goals is just as important for the future as climate policy’, Detlef van Vuuren adds.