Posts Tagged 'mitigation'

Enhanced rates of regional warming and ocean acidification after termination of large‐scale ocean alkalinization

Termination effects of large‐scale Artificial Ocean Alkalinization (AOA) have received little attention because AOA was assumed to pose low environmental risk. With the Max‐Planck‐Institute Earth System Model, we use emission‐driven AOA simulations following the Representative Concentration Pathway 8.5 (RCP8.5). We find that after termination of AOA warming trends in regions of the Northern hemisphere become ∼50% higher than those in RCP8.5 with rates similar to those caused by termination of solar geoengineering over the following three decades after cessation (up to 0.15 K/year). Rates of ocean acidification after termination of AOA outpace those in RCP8.5. In warm shallow regions where vulnerable coral reefs are located, decreasing trends in surface pH double (0.01 units/year) and the drop in the carbonate saturation state (Ω) becomes up to one order of magnitude larger (0.2 units/year). Thus, termination of AOA poses higher risks to biological systems sensitive to fast‐paced environmental changes than previously thought.

Continue reading ‘Enhanced rates of regional warming and ocean acidification after termination of large‐scale ocean alkalinization’

National environmental limits and footprints based on the Planetary Boundaries framework: the case of Switzerland

Highlights

• Planetary Boundaries: going from bio-physical to related socio-economic indicators.
• Setting limits at country level considering the role of countries and people needs.
• Limits and footprints are computed for the world and for a case study: Switzerland.
• Global priorities: Climate Change, Ocean Acidification, Biodiversity, Nitrogen Loss.

Abstract

The Planetary Boundaries concept is a recent scientific framework, which identifies a set of nine bio-physical limits of the Earth system that should be respected in order to maintain conditions favourable to further human development. Crossing the suggested limits would lead to drastic changes in human society by disrupting some of the ecological bases that underlie the current socio-economic system. As a contribution to the international discussion, and using the case of Switzerland, this study proposes a methodology to apply the Planetary Boundaries concept on the national level. Taking such an approach allows to assess the environmental sustainability of the socio-economic activities (e.g. consumption) by the inhabitants of a country in a long-term global perspective, assuming that past, current and future populations on Earth have similar “rights” to natural resources. The performance of countries is evaluated by comparing the country limits with their environmental footprints according to a consumption-based perspective. An approach was developed to: i) better characterise the Planetary Boundaries and understand which limits can effectively be currently quantified; ii) identify related socio-economic indicators for which both country limits and footprints can be computed; iii) compute values for limits, footprints and performances (at global and country level); and iv) suggest priorities for action based on the assessment of global and national performances. It was found that Switzerland should, as a priority, act on its footprints related to Climate Change, Ocean Acidification, Biodiversity Loss and Nitrogen Loss. The methodology developed herein can be applied to the analysis of other countries or territories, as well as extended to analyse specific economic sectors.

Continue reading ‘National environmental limits and footprints based on the Planetary Boundaries framework: the case of Switzerland’

Role of technology in ocean acidification: monitoring, water-quality impairments, CO2 mitigation, and machine learning

Ocean acidification (OA), or the reduction in the pH of the ocean, is driven by increasing carbon dioxide concentration in the atmosphere and local pollution. There is already evidence of the detrimental impact of OA on marine organisms. As further increases in atmospheric CO2 and changes in water quality are expected, it is crucial to develop and implement advanced technologies that enable better monitoring, allow for understanding of adaptation potential of the organisms, and facilitate the use of mitigation strategies toward predicted environmental changes. Collaboration of marine and computer scientists, engineers, and citizens is needed to develop innovative sustainable technologies to mitigate and reduce future increase of CO2.

Continue reading ‘Role of technology in ocean acidification: monitoring, water-quality impairments, CO2 mitigation, and machine learning’

Metal fractionation in marine sediments acidified by enrichment of CO2: a risk assessment

Highlights

• Acidification related to CO2 leakages modifies the geochemistry of metals.
• Mobilization of metals from sediment into the water column is associated with their speciation.
• Sediments from Huelva Estuary have relevant concentrations of As, Cu, Pb and Zn.
• Risk assessment code analysis revealed that Zn presents the highest potential risk.

Abstract

Carbon-capture and storage is considered to be a potential mitigation option for climate change. However, accidental leaks of CO2 can occur, resulting in changes in ocean chemistry such as acidification and metal mobilization. Laboratory experiments were performed to provide data on the effects of CO2-related acidification on the chemical fractionation of metal(loid)s in marine-contaminated sediments using sequential extraction procedures. The results showed that sediments from Huelva estuary registered concentrations of arsenic, copper, lead, and zinc that surpass the probable biological effect level established by international protocols. Zinc had the greatest proportion in the most mobile fraction of the sediment. Metals in this fraction represent an environmental risk because they are weakly bound to sediment, and therefore more likely to migrate to the water column. Indeed, the concentration of this metal was lower in the most acidified scenarios when compared to control pH, indicating probable zinc mobilization from the sediment to the seawater.

Continue reading ‘Metal fractionation in marine sediments acidified by enrichment of CO2: a risk assessment’

An assessment of direct dissolved inorganic carbon injection to the coastal region: a model result

The amount of carbon dioxide (CO2) in the atmosphere has increased in the past 60 years and the technology of carbon capture and storage (CCS) has recently been extensively studied. One of the strategies of CCS is to directly inject a high dissolved inorganic carbon (DIC) concentration (or high partial pressure of carbon dioxide, pCO2) solution into the ocean. However, the carbonate dynamics and air-sea gas exchange are usually neglected in a CCS strategy. This study assesses the effect of a DIC-solution injection by using a simple two end-member model to simulate the variation of pH, DIC, total alkalinity (TA) and pCO2 between the river and sea mixing process for the Danshuei River estuary and Hoping River in Taiwan. We observed that the DIC-solution injection can contribute to ocean acidification and can also lead the pCO2 value to change from being undersaturated to oversaturated (with respect to the atmospheric CO2 level). Our model result also showed that the maximum Revelle factors (Δ[CO2]/[CO2])/(Δ[DIC]/[DIC]) among varied pH values (6–9) and DIC concentrations (0.5–3.5 mmol kg−1) were between pH 8.3 and 8.5 in fresh water and were between 7.3 and 7.5 in waters with a salinity of 35, reflecting the changing efficiency of dissolving CO2 gas into the DIC solution and the varying stability of this desired DIC solution. Finally, we suggest this uncoupled Revelle factor between fresh and salty water should be considered in the (anthropogenic) carbonate chemical weathering on a decade to century scale.

Continue reading ‘An assessment of direct dissolved inorganic carbon injection to the coastal region: a model result’

Adaptation strategies to climate change in marine systems

The world’s oceans are highly impacted by climate change and other human pressures, with significant implications for marine ecosystems and the livelihoods that they support. Adaptation for both natural and human systems is increasingly important as a coping strategy due to the rate and scale of ongoing and potential future change. Here, we conduct a review of literature concerning specific case studies of adaptation in marine systems, and discuss associated characteristics and influencing factors, including drivers, strategy, timeline, costs, and limitations. We found ample evidence in the literature that shows that marine species are adapting to climate change through shifting distributions and timing of biological events, while evidence for adaptation through evolutionary processes is limited. For human systems, existing studies focus on frameworks and principles of adaptation planning, but examples of implemented adaptation actions and evaluation of outcomes are scarce. These findings highlight potentially useful strategies given specific social–ecological contexts, as well as key barriers and specific information gaps requiring further research and actions.

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Model‐based assessment of the CO2 sequestration potential of coastal ocean alkalinization

The potential of coastal ocean alkalinization (COA), a carbon dioxide removal (CDR) climate engineering strategy that chemically increases ocean carbon uptake and storage, is investigated with an Earth system model of intermediate complexity. The CDR potential and possible environmental side effects are estimated for various COA deployment scenarios, assuming olivine as the alkalinity source in ice‐free coastal waters (about 8.6% of the global ocean’s surface area), with dissolution rates being a function of grain size, ambient seawater temperature, and pH. Our results indicate that for a large‐enough olivine deployment of small‐enough grain sizes (10 µm), atmospheric CO2 could be reduced by more than 800 GtC by the year 2100. However, COA with coarse olivine grains (1000 µm) has little CO2 sequestration potential on this time scale. Ambitious CDR with fine olivine grains would increase coastal aragonite saturation Ω to levels well beyond those that are currently observed. When imposing upper limits for aragonite saturation levels (Ωlim) in the grid boxes subject to COA (Ωlim = 3.4 and 9 chosen as examples), COA still has the potential to reduce atmospheric CO2 by 265 GtC (Ωlim = 3.4) to 790 GtC (Ωlim = 9) and increase ocean carbon storage by 290 Gt (Ωlim = 3.4) to 913 Gt (Ωlim = 9) by year 2100.

Continue reading ‘Model‐based assessment of the CO2 sequestration potential of coastal ocean alkalinization’


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OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book