This article is originally posted on Sofar Ocean.
For years (and we mean many years), the ocean helped us mitigate the early effects of human emissions by absorbing greenhouse gases, like carbon dioxide and heat, from the atmosphere. As a result, more than 90 percent of the warming that happened on Earth between 1971 and 2010 occurred in the ocean. A selfless act by Mother Nature, but it's catching up to us.
Marine species are being impacted by climate change and ocean acidification, although their level of vulnerability varies due to differences in species’ sensitivity, adaptive capacity and exposure to climate hazards. Due to limited data on the biological and ecological attributes of many marine species, as well as inherent uncertainties in the assessment process, climate change vulnerability assessments in the marine environment frequently focus on a limited number of taxa or geographic ranges. As climate change is already impacting marine biodiversity and fisheries, there is an urgent need to expand vulnerability assessment to cover a large number of species and areas. Here, we develop a modelling approach to synthesize data on species-specific estimates of exposure, and ecological and biological traits to undertake an assessment of vulnerability (sensitivity and adaptive capacity) and risk of impacts (combining exposure to hazards and vulnerability) of climate change (including ocean acidification) for global marine fishes and invertebrates. We use a fuzzy logic approach to accommodate the variability in data availability and uncertainties associated with inferring vulnerability levels from climate projections and species’ traits. Applying the approach to estimate the relative vulnerability and risk of impacts of climate change in 1074 exploited marine species globally, we estimated their index of vulnerability and risk of impacts to be on average 52 ± 19 SD and 66 ± 11 SD, scaling from 1 to 100, with 100 being the most vulnerable and highest risk, respectively, under the ‘business-as-usual’ greenhouse gas emission scenario (Representative Concentration Pathway 8.5). We identified 157 species to be highly vulnerable while 294 species are identified as being at high risk of impacts. Species that are most vulnerable tend to be large-bodied endemic species. This study suggests that the fuzzy logic framework can help estimate climate vulnerabilities and risks of exploited marine species using publicly and readily available information.
Assessments of the combined ecological impacts of ocean acidification and warming (OAW) and their social and economic consequences can help develop adaptive and responsive management strategies in the most sensitive regions. Here, available observational and experimental data, theoretical, and modelling approaches are combined to project and quantify potential effects of OAW on the future fisheries catches and resulting revenues and employment in the UK under different CO2 emission scenarios. Across all scenarios, based on the limited available experimental results considered, the bivalve species investigated were more affected by OAW than the fish species considered, compared with ocean warming alone. Projected standing stock biomasses decrease between 10 and 60%. These impacts translate into an overall fish and shellfish catch decrease of between 10 and 30% by 2020 across all areas except for the Scotland >10 m fleet. This latter fleet shows average positive impacts until 2050, declining afterwards. The main driver of the projected decreases is temperature rise (0.5–3.3 °C), which exacerbate the impact of decreases in primary production (10–30%) in UK fishing waters. The inclusion of the effect of ocean acidification on the carbon uptake of primary producers had very little impact on the projections of potential fish and shellfish catches (<1%). The <10 m fleet is likely to be the most impacted by-catch decreases in the short term (2020–50), whereas the effects will be experienced more strongly by the >10 m fleet by the end of the century in all countries. Overall, losses in revenue are estimated to range between 1 and 21% in the short term (2020–50) with England and Scotland being the most negatively impacted in absolute terms, and Wales and North Ireland in relative terms. Losses in total employment (fisheries and associated industries) may reach approximately 3–20% during 2020–50 with the >10 m fleet and associated industries bearing the majority of the losses.
The _Fifth Assessment Report of the Intergovernmental Panel on Climate Change_highlights that climate change and ocean acidification are challenging the sustainable management of living marine resources (LMRs). Formal and systematic treatment of uncertainty in existing LMR projections, however, is lacking. We synthesize knowledge of how to address different sources of uncertainty by drawing from climate model intercomparison efforts. We suggest an ensemble of available models and projections, informed by observations, as a starting point to quantify uncertainties. Such an ensemble must be paired with analysis of the dominant uncertainties over different spatial scales, time horizons, and metrics. We use two examples: (i) global and regional projections of Sea Surface Temperature and (ii) projection of changes in potential catch of sablefish (Anoplopoma fimbria) in the 21st century, to illustrate this ensemble model approach to explore different types of uncertainties. Further effort should prioritize understanding dominant, undersampled dimensions of uncertainty, as well as the strategic collection of observations to quantify, and ultimately reduce, uncertainties. Our proposed framework will improve our understanding of future changes in LMR and the resulting risk of impacts to ecosystems and the societies under changing ocean conditions.
The impact of ocean acidification on fisheries is a relatively new issue facing decision-makers, and one for which very little empirical data is available to draw upon. This paper demonstrates how, despite the lack of knowledge, well-established methods of bioeconomic modelling and decision analysis can be applied to address the challenge. A decision support framework is developed, incorporating a dynamic age-structured bioeconomic model together with a set of decision tables applicable in the absence of known probabilities of future change. With such a model it is possible to trace ocean acidification as an additional stressor, specifically on fisheries targeting calcifier species, such as many high value mollusks. We do so by shifting growth and natural mortality parameters into time varying functions of ocean acidity (pH), as forecasted by climate scenarios reported by the Intergovernmental Panel on Climate Change (IPCC). Possible effects of ocean acidification on calcifier species with various life cycles were modeled beginning with initial biological parameters of the growth and mortality dynamic functions reflecting differences in individual growth, natural mortality and species longevity. The analysis illustrates how fishery outcomes depend on the extent of ocean acidification and the life cycle of calcifier species. Results also indicate that under uncertainty, there is value in taking precautionary management measures, such as reducing fishing intensity. (Full Publication)
There is an urgent need to increase global renewable energy production as a method of lowering greenhouse gas (GHG) emissions in order to avoid the more devastating effects of climate change and ocean acidification. The latest figures from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), suggest that the international community must reduce anthropogenic GHG emissions by 40 to 70 percent from 2010 levels by 2050, and should aim for near zero emissions by 2100. This would likely keep temperature change below 2°C relative to pre-industrial levels, and would therefore reduce the risk of predicted effects of climate change, such as inland flooding, extreme weather events, food security, and the loss of marine and coastal ecosystems and biodiversity.