Summary/Abstract
The starting point of this paper is the Paris Agreement under the UNFCCC agreed upon in 2015 and its global temperature goal. It highlights that the current pathway of decarbonization would result in a sharp temperature increase by 2100 that would result in unacceptable risks of climate change. Those risks cannot be properly addressed by adaptation activities as long as there are no reliable expectations of the climate changes expected over the lifetime of current projects. The paper informs about such recently published projections that suggest that global surface temperatures will increase by approximately 5 °C (9 °F) over pre-industrial temperatures by the year 2100 and discusses options to bridge the gap to the goals specified in the Paris Agreement. In this context also two main geoengineering options carbon dioxide removal (CDR) and solar radiative management (SRM) and their associated risks are considered. At the center of the paper two proposals are made on a limited use of geoengineering that should finally help meet the goals of the Paris Agreement without increasing risks of geoengineering unduly, provided that decarbonization is significantly accelerated beyond the plans included in current National Determined Contributions. One conclusion is that geo-engineering can only provide a small contribution to meeting the goals of the Paris Agreement and that the main contribution needs to come from enhanced mitigation action. The paper also highlights how recommendations of the Financial Stability Board could contribute to result in the necessary shift of investments to accelerate GHG emission reduction and informs about a recent initiative to establish the necessary governance framework to manage geoengineering.