A Closer Look at Available Studies for Policymaking
In the most recent special report of the Intergovernmental Panel on Climate Change (IPCC) on the 1.5°C climate goal, four so-called illustrative model pathways have been described and evaluated. In these, population scenarios are used, which build on the population projections of 2010. Since they are much too optimistic, significantly less land area will be available per person in the future than described by these scenarios.
Especially those scenarios allowing to reach the 1.5°C climate goal rely on so-called negative-emission technologies, two prominent being BECSS (bio-energy with carbon capture and storage) and AR (afforestation and reforestation). Both require significant land area to grow biomass. If the population growth would follow even only the medium variant of the projections, this land area would not be available without increasing the number of undernourished people.
Also the energy scenarios used assume carbon-dioxide emissions, which reduce significantly faster than can be reached today, again because they build on older data. Since fostering sustainable energy technologies has not been realized as previously assumed, the starting point is actually worse and the efforts higher than depicted by the scenarios.
Also in the recent Sustainable Energy Strategy of the EU and the underlying studies, only the medium variant of population growth is applied. Thus any development slightly worse than that would mean that the goals cannot be reached with the means presented.
Overall, the current guidelines for policymakers draw a significantly too optimistic picture. While the consequences of the climate change may be properly described, for the projections of population growth and sustainable energy transition only too optimistic scenarios (IPCC) or scenarios at the optimistic side of possible future development (EU) are taken as basis. Consideration of worse scenarios that can nevertheless realistically occur is lacking. Thus the challenges ahead of humanity may be much more dramatic than expected.
The discussion presented here is based on a publication in ChemBioEng Reviews:
Pfennig, A.: Sustainable Bio- or CO2-Economy: Chances, Risks, and Systems Perspective.
ChemBioEng Reviews (2019) 6(3), 90-104.