The UN Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) - An ocean science-policy interface standing the test of time.

Addressing the wide range of marine pollution problems facing the global ocean requires a continual transfer of credible, relevant and timely scientific information to policy and decision makers in coastal and ocean management. The United Nations GESAMP (Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection) is a long-standing scientific advisory group providing such information on a wide range of marine topics and emerging issues of concern to ten UN Sponsoring Organizations. This paper presents an overview of GESAMPs operation and examples of its current work. The group's scientific output is often cited by national governments, inter-governmental groups, and a range of non-governmental groups. Given the growing concerns about ocean health and the impacts of many stressors in an era of climate change, the development of timely and effective ocean policy and decision making would benefit from wider recognition and application of GESAMPs work.

Deep-sea impacts of climate interventions.

Ocean manipulation to mitigate climate change may harm deep-sea ecosystems.

Use of aircraft in ocean alkalinity enhancement.

Ocean Alkalinity Enhancement (OAE) is a proposed Negative Emissions Technology (NET) to remove atmospheric CO2 through the dispersion of alkaline materials (e.g.: calcium hydroxide, slaked lime, SL) into seawater, simultaneously counteracting ocean acidification. This study considers aircraft discharge of SL and its consequent dry deposition, extending to the marine environment a technique used in freshwater. A feasibility analysis assesses potential, costs, benefits, and disadvantages, considering scenarios with different assumptions on aircraft size, discharge height and duration, and wind conditions. Due to the small size of SL particles (median diameter 9 µm), the dispersion from aircraft is highly enhanced by wind drift; the smallest SL particles may drift thousands of kilometres, especially if discharged from elevated altitudes. This could pose problems related to powders particles settling on remote lands. Although calcium hydroxide maximum concentration into water (from 0.01 to 82 mg L-1) is for almost all the scenarios lower than the most stringent threshold for the ecosystem impacts on a 96-h exposure, the ecologically sensitive sea surface microlayer (SML) should be considered in detail. The high CO2 emissions of the Landing to Take-Off Cycle (LTO) of the aircraft and their limited payload lead to a significant CO2 penalty, ranging in analysed scenarios between 28% and 77% of the CO2 removal potential; very fast discharge could reduce the penalty to 11% - 32%. Preliminary cost analysis shows that the cost of the SL discharge through aircraft is high, between € 30 and € 1846 per ton of CO2 removed (neglecting the lime cost), substantially higher than the cost for discharge by surface vessels resulting from previous studies, which restricts the practical use of this strategy.

Anatomy of a decision III: Evaluation of national disposal at sea program action level efficacy considering 2 chemical action levels.

The potential performance (i.e., ability to separate nontoxic from toxic sediments) of a range of international Disposal at Sea (DaS) chemical Action Levels (ALs) was compared using a sediment chemical and toxicological database. The use of chemistry alone (without the use of further lines of evidence) did not perform well at reducing costs and protecting the environment. Although some approaches for interpreting AL1 results are very effective at filtering out the majority of acutely toxic sediments, without subsequent toxicological assessment, a large proportion of nontoxic sediments would be unnecessarily subjected to treatment and containment, and a number of sublethally toxic sediments would be missed. Even the best tiered systems that collect and evaluate information sequentially resulted in the failure to catch at least some sublethally or acutely toxic sediments. None of the AL2s examined were particularly effective in distinguishing between non-, sublethally, or acutely toxic sediments. Thus, this review did not support the use of chemical AL2s to predict the degree to which sediments will be toxic. Integr Environ Assess Manag 2017;13:1086-1099.© 2017 The Authors. Integrated Environmental Assessment and Management Published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Can the benefits of physical seabed restoration justify the costs? An assessment of a disused aggregate extraction site off the Thames Estuary, UK.

Physical and biological seabed impacts can persist long after the cessation of marine aggregate dredging. Whilst small-scale experimental studies have shown that it may be possible to mitigate such impacts, it is unclear whether the costs of restoration are justified on an industrial scale. Here we explore this question using a case study off the Thames Estuary, UK. By understanding the nature and scale of persistent impacts, we identify possible techniques to restore the physical properties of the seabed, and the costs and the likelihood of success. An analysis of the ecosystem services and goods/benefits produced by the site is used to determine whether intervention is justified. Whilst a comparison of costs and benefits at this site suggests restoration would not be warranted, the analysis is site-specific. We emphasise the need to better define what is, and is not, an acceptable seabed condition post-dredging.