Posts Tagged 'review'

Strengthened scientific support for the Endangerment Finding for atmospheric greenhouse gases

We assess scientific evidence that has emerged since the U.S. Environmental Protection Agency’s 2009 Endangerment Finding for six well-mixed greenhouse gases and find that this new evidence lends increased support to the conclusion that these gases pose a danger to public health and welfare. Newly available evidence about a wide range of observed and projected impacts strengthens the association between the risk of some of these impacts and anthropogenic climate change, indicates that some impacts or combinations of impacts have the potential to be more severe than previously understood, and identifies substantial risk of additional impacts through processes and pathways not considered in the Endangerment Finding.

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Regional action plan on ocean acidification for Latin America and the Caribbean

Representatives of 14 countries from Latin America and the Caribbean attended the first regional meeting of the Ocean Acidification international Reference User Group (OAiRUG), hosted by Invemar in Santa Marta, Colombia, held on 19th – 21st March 2018. Funded by the Prince Albert II Foundation as part of a long-term strategy of His Serene Highness, with additional support from the International Atomic Energy Agency, and held in collaboration IUCN and the Latin American Ocean Acidification Network (LAOCA), the purpose of the meeting was to bring together leading international and regional scientists, experts from affected maritime industries, leaders in environmental protection and management, and representatives from civil society to create a step-change in how the region can respond to this modern-day ocean-impact challenge. Attended by over 50 invited delegates, for the first time the OAiRUG proceedings were also streamed live by Invemar to Facebook and the Colombia National Parks channel attracting an online audience of over 8000 people across the three days.

Continue reading ‘Regional action plan on ocean acidification for Latin America and the Caribbean’

Global bioevents and the Cretaceous/Paleogene boundary in Texas and Alabama: stratigraphy, correlation and ocean acidification

Highlights
• This paper discusses the K/Pg in terms of surface water acidification caused by the K/Pg impact event. This is coupled with a new model for, and correlation of, the events recorded in a number of areas both proximal to the impact and distal. In particular the model is based on fieldwork in Texas.

Abstract
With increasing levels of atmospheric pCO2 the oceans are becoming progressively more acidic, with the impact of a lowered pH beginning to affect the calcification of numerous invertebrate groups, including foraminifers, pteropods, heteropods and calcareous nannoplankton. Research on the ecology of foraminifera in the Mediterranean Sea, Gulf of California, Caribbean Sea and elsewhere has shown how modern assemblages are responding to acidification. Experimental work in mesocosms and laboratory cultures are also adding to our knowledge of the response to pH changes. Near Ischia (Italy), natural CO2 vents amongst sea grass meadows are creating low pH environments in which it is possible to observe the response of benthic foraminifera. At a pH of 7.8 the foraminiferal assemblages are already becoming less diverse and below pH 7.6 there are often no calcite-secreting benthic foraminifera. In the Gulf of California, in a deeper-water setting, natural CO2 (and methane) vents are also lowering sea floor pH. The foraminifera show the impact of this change, although the relatively high carbonate saturation ensures that calcite-secreting foraminifers are able to live and reproduce in these relatively low pH environments, only becoming impacted by dissolution effects once dead. Using data from the Cretaceous–Paleogene boundary in Texas, Alabama and north-west Europe it is clear that the plankton was severely impacted by surface water acidification while the relatively shallow water benthic foraminifera show little change and no visible signs of post-mortem dissolution due to ocean acidification.

Continue reading ‘Global bioevents and the Cretaceous/Paleogene boundary in Texas and Alabama: stratigraphy, correlation and ocean acidification’

Biogeochemical processes and inorganic carbon dynamics

In this chapter, we will first refresh the basics of inorganic carbon chemistry in water and seawater, then introduce alkalinity and buffering, and discuss how biological processes and mineral formation are impacted and impact carbon dioxide in marine systems. Ocean acidification is introduced to the reader.

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Ocean acidification research in Estonia: challenges and opportunities

Anthropogenic carbon dioxide (CO2) emissions to the atmosphere are causing a decrease in the average surface global ocean pH, also known as ocean acidification. Our understanding of the global impacts of ocean acidification on marine ecosystems is growing rapidly. In the Baltic Sea area, however, the vast majority of studies have so far focused on the effects of eutrophication on marine ecosystems. Less is known about the changing carbon chemistry due to increasing CO2 concentrations in seawater, which could influence Baltic Sea marine ecosystems. The present study focuses on Estonian waters, located in the northeastern part of the Baltic Sea. The aim of this article is to summarize the existing knowledge on ocean acidification research in Estonia as well as to highlight the opportunities and challenges for future research. One key challenge is that the present national marine monitoring of carbonate chemistry in Estonia is not following best practices. The lack of proper seawater carbonate chemistry data in the study area is strongly limiting the ability to design relevant biological experiments and forecast future changes. So far, the effect of ocean acidification on marine biota in the Estonian coastal waters is mostly unexplored. However, several sensors for measurements of carbonate chemistry variables as well as laboratory facilities for conducting ocean acidification experiments are now available.

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Perspective on the response of marine calcifiers to global warming and ocean acidification—behavior of corals and foraminifera in a high CO2 world “hot house”

The CO2 concentration of air has increased over the last two centuries and recently surpassed 400 ppm. Carbon cycle models project CO2 concentrations of 720 to 1000 ppm for the IPCC intermediate scenario (RCP 6.0), resulting in an increase in global mean temperature of ~ 2.6 °C and a decrease in seawater pH of ~ 0.3. Together, global warming and ocean acidification are often referred to as the “evil twins” of climate change, potentially inducing severe threats in the near future. In this paper, our discussion is focused on the response of two major calcifiers, foraminifera and corals, which contribute much to the global carbonate burial rate. Photosymbiosis is regarded as an adaptive ecology for living in warm and oligotrophic oceans, especially for reef-building corals and larger reef-dwelling benthic foraminifera. As a consequence of global warming, bleaching may be a global threat to algal symbiont-bearing marine calcifying organisms under conditions of high temperature and light intensity. If CO2 is dissolved in seawater, the partial pressure of CO2 in seawater (pCO2) and dissolved inorganic carbon (DIC) increases while pH and the saturation state of carbonate minerals decreases without any change in total alkalinity. Generally, marine calcifying organisms show decreases in calcification rates in response to acidified seawater. However, the response often differs depending on situations, species, and life-cycle stage. Some benthic foraminifera showed a positive response to low pH conditions. The Acropora digitifera coral calcification of adult branches was not reduced markedly at higher pCO2 conditions, although calcification tended to decrease versus pCO2 in both aposymbiotic and symbiotic polyps. New analytical technologies help identify important constraints on calcification processes. Based upon Ca isotopes, the transport path of Ca2+ and the degree of its activity would predominantly control the carbonate precipitation rate. Visualization of the extracellular pH distribution shows that proton pumping produces the high internal pH and large internal–external pH gap in association with foraminiferal calcification. From the perspective of a long-term change in the Earth’s surface environment, foraminifera seem to be more adaptive and robust than corals in coping with ocean warming and acidification but it is necessary to further understand the mechanisms underlying variations in sensitivity to heat stress and acidified seawater for future prediction. Since CO2 is more soluble in lower temperature seawater, ocean acidification is more critical in the polar and high-latitude regions. Additionally, older deep-water has enhanced acidity owing to the addition of CO2 from the degradation of organic matter via a synergistic effect with high pressure. With current ocean acidification, pH and the saturation state of carbonate minerals are decreasing without any change in total alkalinity. However, in the Earth’s history, it is well known that alkalinity has fluctuated significantly. Therefore, it is necessary to quantitatively reconstruct alkalinity, which is another key factor determining the saturation state of carbonate minerals. The rapid release of anthropogenic CO2 (in the present day and at the Paleocene/Eocene boundary) induces severe ocean acidification, whereas in the Cretaceous, slow environmental change, even at high levels of pCO2, could raise alkalinity, thereby neutralizing ocean acidification.

Continue reading ‘Perspective on the response of marine calcifiers to global warming and ocean acidification—behavior of corals and foraminifera in a high CO2 world “hot house”’

Free Ocean CO2 Enrichment (FOCE) experiments: scientific and technical recommendations for future in situ ocean acidification projects

Highlights

• Recommendations for FOCE systems are proposed based on past experience.
• Field testing the system design is essential; a backup power supply is recommended.
• Replicate treatment enclosures; focus on a core set of common scientific hypotheses.
• Accurately monitor carbonate chemistry; allow sufficient time for CO2 equilibration.
• FOCE can inform conceptual and quantitative models of ecosystem responses to CO2

Abstract

Free Ocean CO2 Enrichment (FOCE) experiments are a relatively recent development in ocean acidification research, designed to address the need for in situ, long-term, community level experiments. FOCE studies have been conducted across different marine benthic habitats and regions, from Antarctica to the tropics. Based on this previous research we have formed some core operating principles that will aid those embarking on future FOCE experiments. FOCE studies have potential to provide important insight into the effects of ocean acidification that can add to or refine conclusions drawn from laboratory or single species studies because they are conducted in situ on intact assemblages. Scaling up from sub-organismal and individual effects to also include indirect impacts on the ecosystem and ecosystem services, make FOCE experiments essential in filling in current knowledge gaps in our understanding of ocean acidification. While FOCE systems are complex, relatively costly, and somewhat difficult to operate, the challenges they pose are tractable and they have proven to be a useful approach in ocean acidification research. The aim of this paper is to draw from the experiences of past FOCE experiments and provide practical advice for designing, building and operating a FOCE experiment. Some of the most important recommendations include: field testing the system design; having a backup power supply; using replicate treatment enclosures; monitoring and maintaining the chemistry appropriately; allowing sufficient time to achieve near CO2 equilibrium conditions; and having a scientific focus with a core set of hypotheses. Future FOCE experiments could focus on longer durations, multiple factors, and testing more intact benthic marine communities and ecosystems. We hope this paper will encourage further FOCE deployments and experiments, as well as provide some guidelines to improve future FOCE studies and advance ocean acidification research.

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