Description: Public fear for environmental and health impacts or potential leakage of CO2 from geological reservoirs is among the reasons why over the past decade CCS has not yet been deployed on a large enough scale so as to meaningfully contribute to mitigate climate change. Storage of CO2 under the seabed moves this climate mitigation option away from inhabited areas and could thereby take away some of the opposition towards this technology. Given that in the event of CO2 leakage for sub-seabed CCS the ocean would function as buffer for receiving this greenhouse gas, rather than the atmosphere, offshore CCS could particularly address concerns over the climatic impacts of CO2 seepage. In this paper we point out that recent geological studies confirm that leakage for individual offshore CCS operations may be highly unlikely from a technical point of view, if storage sites are well chosen, well managed and well monitored. But we argue that on a global long-term scale, for an ensemble of thousands or millions of storage sites, leakage of CO2 could take place in certain cases and/or countries for e.g. economic, institutional, legal or safety cultural reasons. We investigated what the impact could be in terms of temperature increase and ocean acidification if leakage would nevertheless occur, and addressed the question what the relative roles could be of on- and offshore CCS if mankind desires to divert the atmospheric damages resulting from climate change. For this purpose, we constructed a top-down energy-environment-economy model, with which we performed a probabilistic cost-benefit analysis of climate change mitigation with on- and offshore CCS as specific CO2 abatement options. One of our main conclusions is that even if there is non-zero leakage for CCS activity on a global scale, there is high probability that both onshore and offshore CCS could – on economic grounds – still account for anywhere between 20% and 80% of all future CO2 abatement efforts under a broad range of CCS cost assumptions.

Description: Given the variability of seasonal, annual, and in particular langer time-scales, the dispersal and fate of the river discharge and its influence on the hydrographical and sedimentological settings are the central tasks in understanding the Holocene history of the Laptev Sea shelf. The main goal of this study was to investigate short- and long-term environmental changes in the strongly coupled land-shelf system of the Laptev Sea using isotopic evidence in sediments and biogenic carbonates. In order to trace the modern spatial distribution of terrestrial organic matter, which is strongly affected by the riverine input and the thermal erosion of the ice-rich permafrost coast, stable carbon isotope ratios of total organic carbon in surface sediments were analyzed. The stable carbon isotope composition of surface sediments reveal a dominant impact of terrestrial organic matter on the modern depositional environment of the Laptev Sea shelf with distinct south to north and east to west gradients. Based on downcore 8 13Carg records in radiocarbon-dated sediment cores the spatial and temporal deposition of terrestrial organic matter during the past 12.7 ka is specified and can be related to depositional changes which occurred after the last glacial maximum when this region became flooded due to a global rising sea level. The major changes in the deposition of terrestrial organic matter occurred between 11 and 7 ka BP and comprise the main phase of the southward retreat of the coastline and river depocenters due to the postglacial sea level rise. Stable oxygen and carbon isotope profiles from recent and fossil bivalve shells were investigated in order to trace modern and past hydrographical conditions and their changes during the postglacial history of the Laptev Sea. The serial dissection of bivalve shell valves along their growth axis from the umbo towards the ventral margin provides an isotopic record of hydrographical and physiological changes during the life of the individual specimen. The oxygen isotopic profiles of modern bivalve species of Astarte borealis exhibit amplitude cycles interpreted as recording annual hydrographical cycles. Regarding the well-known relationship between the carbonate 8 180, temperature, and the isotopic composition of water (8180w), it is possible to relate isotopic phases to seasonal hydrographical phases like summer and winter. The within shell isotopic variations are mainly attributed to variations in the isotopic composition and in the salinity of bottom waters in the Laptev Sea. Seasonal temperature changes can be regarded of minor importance. Using a modern linear relationship between 8 180w and salinity of 0.50 %0/salinity, salinity records are reconstructed from the oxygen isotope records of the bivalve shells and can be directly compared with hydrographical parameters at the investigated sites. Carbon isotope profiles from modern specimens reveal a correspondence to the river breakup and to seasonal phytoplankton productivity. Trends towards lighter 8 13 C values through ontogeny suggest the effects of metabolic changes from a juvenile into a mature adult. Differences in the 8 13C of shell carbonate between the sites appear to reflect the regional distribution of the ö 13C of sedimentary organic matter. Given a good conformance between isotope profiles from modern bivalve shells and oceanographic observations, oxygen isotope profiles of radiocarbon bivalve shells from a sediment core from northeast off the Lena Delta are usecl to obtain in formation about passt hydrological conditions. Although isotope profiles from fossil bivalves of the Laptev Sea shelf reflect only a brief interval of time, they may offer new important insights into the paleohydrography during snapshots of the last 8.4 ka and their relation to the Holocene transgression. A reconstructed bottom water salinity of 29.5 at 8.4 ka BP indicates that the particular site was much more affectecl by riverine water than nowaclays causecl by the proximity to the coastline and to the paleo-1iver mouth. Due to the continuing southward retreat of the coastline ancl the Lena River mouth relative to the study site an increase in the bottom water salinity at 7.3 ka BP is reconstructecl. The oxygen isotope shell profile at 7.3 ka BP gives an evidence of a bottom water hydrography which is characterized by a high variability of summer and winter conditions on the level of modern bottom water conditions. The following time slices at 3.6 ka and 1.6 ka BP reveal that modern hydrological conditions are fully established. The presented salinity reconstruction enables us to make further presurnptions on the relative proximity of the study site to the coast and to the river rnouth during snapshot views of the Holocene history and thus can be related to the postglacial transgression of the Laptev Sea shelf.

Description: SIPRI’s Environment of Peace initiative focuses on managing the risks that are created by two interwoven crises: the darkening security horizon and the immense pressures being placed on the natural world and the systems that support life on earth. The Environment of Peace research report is an in-depth look at the evidence base and analysis of the policy report Environment of Peace: Security in a New Era of Risk, including many real-world case studies. The report is the result of two years’ work by more than 30 researchers, led and guided by some of the leading voices in the fields of environment and security. Accessibly designed, the new research report is available to download in four parts: Elements of a Planetary Emergency (part 1); Security Risks of Environmental Crises (part 2); Navigating a Just and Peaceful Transition (part 3); and Enabling an Environment of Peace (part 4). This part—Security Risks of Environmental Crises (part 2)—shows how combinations of environmental and security phenomena are generating complex risks. Through a theoretical framework informed by the literature, Cedric de Coning, Research Professor at the Norwegian Institute of International Affairs (NUPI), and his team explore different pathways from environmental stress to conflict and how the darkening security horizon and environmental crises are interacting to generate different types of risk: compound, cascading, emergent, systemic and existential. The analysis is supported by numerous case studies, spanning a variety of social-ecological systems and different types of risks. Part 2 also discusses options for responding to these complex risks.