Ocean-based approaches can help close mitigation gaps

The ocean provides resources key to human health and well-being, including food, oxygen, livelihoods, blue spaces, and medicines. The global threat to these resources posed by accelerating ocean acidification is becoming increasingly evident as the world’s oceans absorb carbon dioxide emissions. While ocean acidification was initially perceived as a threat only to the marine realm, here we argue that it is also an emerging human health issue. Specifically, we explore how ocean acidification affects the quantity and quality of resources key to human health and well-being in the context of: (1) malnutrition and poisoning, (2) respiratory issues, (3) mental health impacts, and (4) development of medical resources. We explore mitigation and adaptation management strategies that can be implemented to strengthen the capacity of acidifying oceans to continue providing human health benefits. Importantly, we emphasize that the cost of such actions will be dependent upon the socioeconomic context; specifically, costs will likely be greater for socioeconomically disadvantaged populations, exacerbating the current inequitable distribution of environmental and human health challenges. Given the scale of ocean acidification impacts on human health and well-being, recognizing and researching these complexities may allow the adaptation of management such that not only are the harms to human health reduced but the benefits enhanced.

. Anthropogenic climate change is projected to lead to ocean warming, acidification, deoxygenation,\nreductions in near-surface nutrients, and changes to primary production, all of which are expected\nto affect marine ecosystems. Here we assess projections of these drivers of environmental change\nover the twenty-first century from Earth system models (ESMs) participating in the Coupled Model\nIntercomparison Project Phase 6 (CMIP6) that were forced under the CMIP6 Shared Socioeconomic\nPathways (SSPs). Projections are compared to those from the previous generation (CMIP5) forced\nunder the Representative Concentration Pathways (RCPs). A total of 10 CMIP5 and 13 CMIP6 models are used in\nthe two multi-model ensembles. Under the high-emission scenario SSP5-8.5, the multi-model global\nmean change (2080–2099 mean values relative to 1870–1899) ± the inter-model SD in sea\nsurface temperature, surface pH, subsurface (100–600 m) oxygen concentration, euphotic\n(0–100 m) nitrate concentration, and depth-integrated primary production is\n+3.47±0.78 ∘C, -0.44±0.005, -13.27±5.28,\n-1.06±0.45 mmol m−3 and -2.99±9.11 %, respectively. Under the\nlow-emission, high-mitigation scenario SSP1-2.6, the corresponding global changes are\n+1.42±0.32 ∘C, -0.16±0.002, -6.36±2.92,\n-0.52±0.23 mmol m−3, and -0.56±4.12 %. Projected exposure of the marine\necosystem to these drivers of ocean change depends largely on the extent of future emissions,\nconsistent with previous studies. The ESMs in CMIP6 generally project greater warming,\nacidification, deoxygenation, and nitrate reductions but lesser primary production declines than\nthose from CMIP5 under comparable radiative forcing. The increased projected ocean warming results\nfrom a general increase in the climate sensitivity of CMIP6 models relative to those of\nCMIP5. This enhanced warming increases upper-ocean stratification in CMIP6 projections, which\ncontributes to greater reductions in upper-ocean nitrate and subsurface oxygen ventilation. The\ngreater surface acidification in CMIP6 is primarily a consequence of the SSPs having higher\nassociated atmospheric CO2 concentrations than their RCP analogues for the same\nradiative forcing. We find no consistent reduction in inter-model uncertainties, and even an\nincrease in net primary\nproduction inter-model uncertainties in CMIP6, as compared to CMIP5.

Marine plastic pollution is present in all oceans, including remote oceanic islands. Despite the increasing number of articles on plastic pollution in the last years, there is still a lack of studies in islands, that are biodiversity hotspots when compared to the surrounding ocean, and even other recognized highly biodiverse marine environments. Articles published in the peer reviewed literature (N = 20) were analysed according to the presence of macro (>5 mm) and microplastics (<5 mm) on beaches and the marine habitats immediately adjacent to 31 islands of the Atlantic Ocean and Caribbean Sea. The first articles date from the 1980s, but most were published in the 2000s. Articles on macroplastics were predominant in this review (N = 12). Beaches were the most studied environment, possibly due to easy access. The main focus of most articles was the spatial distribution of plastics associated with variables such as position of the beach in relation to wind and currents. Very few studies have analysed plastics colonization by organisms or the identification of persistent organic pollutants (POPs). Islands of the North/South Atlantic and Caribbean Sea were influenced by different sources of macroplastics, being marine-based sources (i.e., fishing activities) predominant in the Atlantic Ocean basin. On the other hand, in the Caribbean Sea, land-based sources were more common.Copyright © 2018 Elsevier Ltd. All rights reserved.

Perspectives for risk management and adaptation have received ample attention in the recent IPCC Special Report on Changes in the Oceans and Cryosphere (SROCC). However, several knowledge gaps on the impacts of abrupt changes, cascading effects and compound extreme climatic events have been identified, and need further research. We focus on specific climate change risks identified in the SROCC report, namely: changes in tropical and extratropical cyclones; marine heatwaves; extreme ENSO events; and abrupt changes in the Atlantic Meridional Overturning Circulation. Several of the socioeconomic impacts from these events are not yet well-understood, and the literature is also sparse on specific recommendations for integrated risk management and adaptation options to reduce such risks. Also, past research has mostly focussed on concepts that have seen little application to real-world cases. We discuss relevant research needs and priorities for improved social-ecological impact assessment related to these major physical changes in the climate and oceans. For example, harmonised approaches are needed to better understand impacts from compound events, and cascading impacts across systems. Such information is essential to inform options for adaptation, governance and decision-making. Finally, we highlight research needs for developing transformative adaptation options and their governance.

Strong decreases in greenhouse gas emissions are required to meet the reduction trajectory resolved within the 2015 Paris Agreement. However, even these decreases will not avert serious stress and damage to life on Earth, and additional steps are needed to boost the resilience of ecosystems, safeguard their wildlife, and protect their capacity to supply vital goods and services. We discuss how well-managed marine reserves may help marine ecosystems and people adapt to five prominent impacts of climate change: acidification, sea-level rise, intensification of storms, shifts in species distribution, and decreased productivity and oxygen availability, as well as their cumulative effects. We explore the role of managed ecosystems in mitigating climate change by promoting carbon sequestration and storage and by buffering against uncertainty in management, environmental fluctuations, directional change, and extreme events. We highlight both strengths and limitations and conclude that marine reserves are a viable low-tech, cost-effective adaptation strategy that would yield multiple cobenefits from local to global scales, improving the outlook for the environment and people into the future.