Wilfried Rickels

While limitation of temperature increase to 2° for climate change has again been confirmed on the recent meeting of the parties in Cancun (UNFCCC 2010), actual greenhouse gas emission (GHG) trends and corresponding reduction announcements challenge the credibility of this target. However, estimates of the World Energy Outlook (2010) show that society can still comply with this target by reducing emissions drastically in the near future and storing a significant amount of carbon in non-atmospheric reservoirs (IEA 2010). Non-atmospheric reservoirs include underground and geologic formations, trees, soils, and in particular the deep ocean and sub-seabed storage (Herzog et al. 2003). This central issue is addressed by phase II research topic “Carbon Sinks”, which seeks to investigate various promoted approaches and techniques for enhancing oceanic carbon uptake. The aim of this research topic is to investigate both the physical and the economic storage potential of the ocean and the seabed for different marine carbon sequestration technologies. A particular focus in the research topic is on the backflow of CO2 into the atmosphere on decadal to centennial time scales because carbon stored in non-atmospheric reservoirs may be released intendedly or unintendedly and leak back to the atmosphere. Moreover, this carbon leakage might have severe impacts on marine ecosystems. Due to this potential non-permanent characteristic of the reservoirs, both the storage and the carbon emission offsets generated are perceived as temporary or at least partially temporary. This means that only a fraction of the storage is permanent. Therefore, temporary carbon storage, although providing climate benefits in the short run, could lead to higher atmospheric carbon concentration in the future and might aggravate climate damages in the long run.