Committed warming describes how much future warming can be expected from historical emissions due to inertia in the climate system. It is usually defined in terms of the level of warming above the present for an abrupt halt of emissions. Owing to socioeconomic constraints, this situation is unlikely, so we focus on the committed warming from present-day fossil fuel assets. Here we show that if carbon-intensive infrastructure is phased out at the end of its design lifetime from the end of 2018, there is a 64% chance that peak global mean temperature rise remains below 1.5 °C. Delaying mitigation until 2030 considerably reduces the likelihood that 1.5 °C would be attainable even if the rate of fossil fuel retirement was accelerated. Although the challenges laid out by the Paris Agreement are daunting, we indicate 1.5 °C remains possible and is attainable with ambitious and immediate emission reduction across all sectors.
Climate Change, Ocean Acidification, and Ocean Warming
Coastal communities experience a wide array of environmental and social changes to which they must constantly adapt. Further, a community's perception of change and risk has significant implications for a community's willingness and ability to adapt to both current and future changes. As part of a larger study focusing on the adaptive capacity of communities on the Andaman Coast of Thailand, we used Photovoice to open a dialogue with communities about changes in the marine environment and in coastal communities. This article presents the results of two exploratory Photovoice processes and discusses prospects for using the Photovoice method for exploring social and environmental change. Changes examined included a number of broader environmental and social trends as well as ecological specifics and social particularities in each site. Participants also explored the social implications of environmental changes, the impacts of macro-scale processes on local outcomes, and emotive and active responses of individuals and communities to change. Photovoice is deemed a powerful method for: examining social, environmental, and socio-ecological change, triangulating to confirm the results of other scientific methods, revealing novel ecological interactions, and providing input into community processes focusing on natural resource management, community development, and climate change adaptation.
Vulnerability and adaptation to climate change have become a dominant theme in development and conservation research and work. Yet coastal communities are facing a wider array of different stressors that affect the sustainability of natural resources and the adaptive capacity of local residents. The ability of communities and households to adapt is influenced by the nature, number, and magnitude of the changes with which they have to contend. In this paper, we present the range of 36 socio-economic (i.e. economic, social, governance and conflict) and biophysical (i.e. climate change and other environmental) stressors that emerged from qualitative interviews in seven coastal communities on the Andaman coast of Thailand. These stressors were then integrated into a quantitative survey of 237 households wherein participants were asked to rate the level of impact of these stressors on household livelihoods. Ratings showed that economic and some climate change stressors – extreme weather events and changes in rainfall patterns and seasons – were scored higher than other stressors. The paper also examines the relationships between community and various individual and household characteristics – such as gender, age, livelihoods, levels of social capital, and socio-economic status – and the perceived level of impacts of various stressors on household livelihoods. Overall, community and livelihoods had the most differentiated impacts on perceptions of stressors but few other prominent patterns emerged. In conclusion, this paper discusses the implications of the results for current climate change vulnerability and adaptation policy and practice in Thailand and elsewhere.
Ocean acidification and warming are known to alter, and in many cases decrease, calcification rates of shell and reef building marine invertebrates. However, to date, there are no datasets on the combined effect of ocean pH and temperature on skeletal mineralization of marine vertebrates, such as fishes. Here, the embryos of an oviparous marine fish, the little skate (Leucoraja erinacea), were developmentally acclimatized to current and increased temperature and CO2 conditions as expected by the year 2100 (15 and 20°C, approx. 400 and 1100 µatm, respectively), in a fully crossed experimental design. Using micro-computed tomography, hydroxyapatite density was estimated in the mineralized portion of the cartilage in jaws, crura, vertebrae, denticles and pectoral fins of juvenile skates. Mineralization increased as a consequence of high CO2 in the cartilage of crura and jaws, while temperature decreased mineralization in the pectoral fins. Mineralization affects stiffness and strength of skeletal elements linearly, with implications for feeding and locomotion performance and efficiency. This study is, to my knowledge, the first to quantify a significant change in mineralization in the skeleton of a fish and shows that changes in temperature and pH of the oceans have complex effects on fish skeletal morphology.
Ocean acidification (OA) occurs when carbon dioxide (CO2) dissolves into oceans. OA and climate change are both caused by anthropogenic CO2 emissions, and many scientists consider them equally critical problems. We assess if preexisting beliefs, ideologies, value predispositions, and demographics affect OA perceptions among the U.S. public. Nearly 80% of respondents know little about OA, but concern increased following a message explaining OA and climate change, especially among females, liberals, and climate change believers. OA information seeking intentions and research support were also greater among females, liberals, and climate change believers. We discuss implications for efforts to increase OA public awareness.
1. Global warming and overexploitation both threaten the integrity and resilience of marine ecosystems. Many calls have been made to at least partially offset climate change impacts through local conservation management. However, a mechanistic understanding of the interactions of multiple stressors is generally lacking for habitat‐forming species; preventing the development of sound conservation strategies.
2. We examined the effectiveness of no‐take marine protected areas (MPAs) at enhancing structural complexity and resilience to climate change on populations of an overexploited and long‐lived octocoral. We used long‐term data over eight populations, subjected to varying levels of disturbances, and Integral Projection Models to understand how the interaction between overfishing and mass‐mortality events shapes the stochastic dynamics of the Mediterranean red coral Corallium rubrum.
3. MPAs largely reduced colony partial mortality (i.e. shrinkage), enhancing the structural complexity of coral populations. However, there were no significant differences in individual mortality or population growth rates between protected and exploited populations. In contrast, warming had detrimental consequences for the long‐term viability of red coral populations, driving steady declines and potential local extinctions due to sharp effects in survival rates. Stochastic demographic models revealed only a weak compensatory effect of MPAs on the impacts of warming.
4. Policy implications. Our results suggest that marine protected areas (MPAs) are an effective local conservation tool for enhancing the structural complexity of red coral populations. However, MPAs may not be enough to ensure red coral's persistence under future increases in thermal stress. Accordingly, conservation strategies aiming to ensure the persistence and functional role of red coral populations should include management actions at both local (well‐enforced MPAs) and global scales (reductions in greenhouse gas emissions). Finally, this study unravels the divergent demographic consequences that can arise from multiple stressors and highlights the key role of demography in better understanding and predicting the consequences of combined impacts for vulnerable ecosystems.
The oceans and fisheries are strongly impacted by climate change and acidification, and will increasingly be so. Four multilateral funds have been created under the climate change regime in order to support developing countries’ adaptation. These funds finance a number of projects mostly or partly related to marine and coastal fisheries. They include measures of a structural nature meant to modify laws, policies or strategies and to improve one’s understanding of climate change impacts on fisheries; measures to improve fish stocks’ resilience to climate change, by reducing harvesting and ecosystem-related stressors; and measures to improve fishing communities’ resilience in terms of food security and livelihoods. A majority of the marine fisheries projects focuses on the countries that are most vulnerable to the impacts of climate change on marine fisheries. However, many vulnerable countries still do not receive financial support for adaptation in the marine fisheries sector. The four multilateral funds operate with insufficient and unequal levels of transparency regarding several stages of projects’ cycles; this raises issues of efficiency and accountability. The four funds also do not provide a harmonized and searchable marker dedicated to fisheries; this lack of transparency makes it impossible for the international community to comprehensively monitor progress in the implementation of Sustainable Development Goals 13 and 14. In any case, the existence of adaptation projects focused on coastal and marine fisheries may serve to promote the mainstreaming of ocean-related questions into the climate change regime.
Ocean warming (OW) and ocean acidification (OA) are threatening coral reef ecosystems, with a bleak future forecast for reef‐building corals, which are already experiencing global declines in abundance. In contrast, many coral reef sponge species are able to tolerate climate change conditions projected for 2100. To increase our understanding of the mechanisms underpinning this tolerance, we explored the lipid and fatty acid (FA) composition of four sponge species with differing sensitivities to climate change, experimentally exposed to OW and OA levels predicted for 2100, under two CO2Representative Concentration Pathways. Sponges with greater concentrations of storage lipid, phospholipids, sterols and elevated concentrations of n‐3 and n‐6 long‐chain polyunsaturated FA (LC PUFA), were more resistant to OW. Such biochemical constituents likely contribute to the ability of these sponges to maintain membrane function and cell homeostasis in the face of environmental change. Our results suggest that n‐3 and n‐6 LC PUFA are important components of the sponge stress response potentially via chain elongation and the eicosanoid stress‐signalling pathways. The capacity for sponges to compositionally alter their membrane lipids in response to stress was also explored using a number of specific homeoviscous adaptation (HVA) indicators. This revealed a potential mechanism via which additional CO2 could facilitate the resistance of phototrophic sponges to thermal stress through an increased synthesis of membrane‐stabilizing sterols. Finally, OW induced an increase in FA unsaturation in phototrophic sponges but a decrease in heterotrophic species, providing support for a difference in the thermal response pathway between the sponge host and the associated photosymbionts. Here we have shown that sponge lipids and FA are likely to be an important component of the sponge stress response and may play a role in facilitating sponge survival under future climate conditions.
Two key drivers, ocean warming and ocean acidification, affect the oceans and adds to the climate change adversely. International legal and policy instruments contain certain measures to tackle these growing effects. China is also committed to addressing the effects of climate change on the oceans. The overlapping of different systems has, however, created some difficulties in practice and further coordination is urgently required. This paper uses qualitative methods to investigate China's legal practices in addressing the effects of climate change and their impact on the oceans. The study considers newly introduced policies and recent actions launched by the Chinese Government to chart a clearer picture of the current practices. To this end, it is concluded that the ultimate solution in avoiding the worsening effects of climate change on the oceans would be to reduce the emission of greenhouse gases worldwide, and China aims to take advantage of playing leading role in such efforts.
The annual sea surface temperature increased at a rate of 0.038 to 0.074 °C/year in recent decade, and pH decreased at a rate of 0.012–0.014/year in two coastal waters of the South China Sea. Therefore, a culture experiment was conducted to study the effects of acidification and warming on coral calcification rates. The calcification of three coral species were significantly reduced during the exposure to elevated CO2, while other three coral species were not significantly affected. The reef coral Pocillopora damicornis was resistant to high CO2, but was not able to survive during the exposure to 33 °C in our culture experiments. Our findings suggested that some corals might not survive in tropical areas if coral could not adapt to warming rapidly, and subtropical coastal waters with temperature of <30 °C will serve as refugia for the corals resistant to high CO2 at the end of this century.