Thongchai Thailand

Ocean Acidification by Fossil Fuel Emissions

Posted on: September 29, 2018




















  1. The dramatic ocean acidification event in the Paleocene-Eocene Thermal Maximum (PETM) [LINK] , may have inspired climate science to paint a similar scenario for the current episode of climate change and to claim that “combustion of fossil fuels has enriched levels of CO2 in the world’s oceans and decreased ocean pH” and that such acidification is causing dangerous detrimental effects on coral, shellfish, and on the oceanic ecosystem in general. These effects of the use of fossil fuels are cited as the rationale for climate action in the form of reducing or eliminating the use of fossil fuels. Citations below.
  2. Here we present empirical evidence from 124,813 measurements of ocean CO2 concentration expressed in millimoles per liter (MM/L) provided by the Scripps Institution of Oceanography. The data are presented in Figure 1. They show a rising trend in the CO2 concentration of oceans at depths of 50 to 5000 feet. The temperatures at which these measurements were made vary from 5C to 25C. The CO2 concentrations are therefore adjusted for these temperature differences and the temperature adjusted concentrations are shown in the third panel of Figure 1.
  3. If fossil fuel emissions are responsible for these changes, we expect to find a correlation between the rate of emissions and changes in oceanic CO2 at an annual time scale. Figure 2 displays the rate of annual emissions and the corresponding annual changes in oceanic CO2. The correlation corrected for trend effects is shown in the third panel of Figure 2. No evidence is found that changes in oceanic CO2 are related to fossil fuel emissions at an annual time scale.
  4. A further test of human cause is presented in Figure 3. If the source of the ocean’s CO2 enrichment is the atmosphere, we should find a concentration gradient with higher concentrations closer to the surface. No such gradient is found.
  5. We conclude that no evidence is found in these data that the observed increase in the inorganic CO2 concentration of the oceans is related to fossil fuel emissions. The full text of this study may be downloaded from  [ACADEMIA.EDU]  or [SSRN.COM]
  6. It is likely that the ocean acidification hypothesis entered the climate change narrative by way of the PETM climate change event when extensive and devastating ocean acidification had occurred as described in a related post [LINK] . However, there is no parallel between PETM and AGW that can be used to relate the characteristics of one to those of the other. In the case of ocean acidification in the PETM event, the source of carbon was a monstrous release of either methane hydrates from the sea floor along with geothermal heat of some form or perhaps both heat and carbon directly injected into the ocean from the mantle. The event caused the ocean to lose all its elemental oxygen by way of carbon oxidation and to become not just acidified but acidic. Much of the carbon dioxide was also vented to the atmosphere and that caused atmospheric CO2 to rise precipitously.  But this correspondence of ocean acidification in the presence of rising atmospheric CO2 does not apply to AGW. Such parallels usually drawn to relate rising atmospheric CO2 to ocean acidification overlooks the reversal in direction. Whereas PETM started in the ocean and spread to the atmosphere, the AGW event started in the atmosphere and is thought to have spread to the oceans. The evidence presented here does not support this hypothesis. For details about the PETM, please see the related post on the Paleocene-Eocene Thermal Maximum event [LINK] .
  7. What the PETM shows us is that the ocean is able to acidify itself to a much greater extent with natural causes by using carbon and heat from the bottom of the ocean or from the mantle. This reference event, rather than supporting human caused ocean acidification, serves instead as a caution against the simplistic assignment of human cause to all observed changes in the ocean.






  1. 2005: Orr, James C., et al. “Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms.” Nature 437.7059 (2005): 681. Today’s surface ocean is saturated with respect to calcium carbonate, but increasing atmospheric carbon dioxide concentrations are reducing ocean pH and carbonate ion concentrations, and thus the level of calcium carbonate saturation. Experimental evidence suggests that if these trends continue, key marine organisms—such as corals and some plankton—will have difficulty maintaining their external calcium carbonate skeletons. Here we use 13 models of the ocean–carbon cycle to assess calcium carbonate saturation under the IS92a ‘business-as-usual’ scenario for future emissions of anthropogenic carbon dioxide. In our projections, Southern Ocean surface waters will begin to become undersaturated with respect to aragonite, a metastable form of calcium carbonate, by the year 2050. By 2100, this undersaturation could extend throughout the entire Southern Ocean and into the subarctic Pacific Ocean. When live pteropods were exposed to our predicted level of undersaturation during a two-day shipboard experiment, their aragonite shells showed notable dissolution. Our findings indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously.
  2. 2007: Hoegh-Guldberg, Ove, et al. “Coral reefs under rapid climate change and ocean acidification.” science 318.5857 (2007): 1737-1742. Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.
  3. 2008: Anthony, Kenneth RN, et al. “Ocean acidification causes bleaching and productivity loss in coral reef builders.” Proceedings of the National Academy of Sciences (2008). Ocean acidification represents a key threat to coral reefs by reducing the calcification rate of framework builders. In addition, acidification is likely to affect the relationship between corals and their symbiotic dinoflagellates and the productivity of this association. However, little is known about how acidification impacts on the physiology of reef builders and how acidification interacts with warming. Here, we report on an 8-week study that compared bleaching, productivity, and calcification responses of crustose coralline algae (CCA) and branching (Acropora) and massive (Porites) coral species in response to acidification and warming. Using a 30-tank experimental system, we manipulated CO2 levels to simulate doubling and three- to fourfold increases [Intergovernmental Panel on Climate Change (IPCC) projection categories IV and VI] relative to present-day levels under cool and warm scenarios. Results indicated that high CO2 is a bleaching agent for corals and CCA under high irradiance, acting synergistically with warming to lower thermal bleaching thresholds. We propose that CO2 induces bleaching via its impact on photoprotective mechanisms of the photosystems. Overall, acidification impacted more strongly on bleaching and productivity than on calcification. Interestingly, the intermediate, warm CO2 scenario led to a 30% increase in productivity in Acropora, whereas high CO2 lead to zero productivity in both corals. CCA were most sensitive to acidification, with high CO2 leading to negative productivity and high rates of net dissolution. Our findings suggest that sensitive reef-building species such as CCA may be pushed beyond their thresholds for growth and survival within the next few decades whereas corals will show delayed and mixed responses.
  4. 2008: Fabry, Victoria J., et al. “Impacts of ocean acidification on marine fauna and ecosystem processes.” ICES Journal of Marine Science 65.3 (2008): 414-432. Oceanic uptake of anthropogenic carbon dioxide (CO2) is altering the seawater chemistry of the world’s oceans with consequences for marine biota. Elevated partial pressure of CO2 (pCO2) is causing the calcium carbonate saturation horizon to shoal in many regions, particularly in high latitudes and regions that intersect with pronounced hypoxic zones. The ability of marine animals, most importantly pteropod molluscs, foraminifera, and some benthic invertebrates, to produce calcareous skeletal structures is directly affected by seawater CO2 chemistry. CO2influences the physiology of marine organisms as well through acid-base imbalance and reduced oxygen transport capacity. The few studies at relevant pCO2 levels impede our ability to predict future impacts on foodweb dynamics and other ecosystem processes. Here we present new observations, review available data, and identify priorities for future research, based on regions, ecosystems, taxa, and physiological processes believed to be most vulnerable to ocean acidification. We conclude that ocean acidification and the synergistic impacts of other anthropogenic stressors provide great potential for widespread changes to marine ecosystems.
  5. 2009: Miller, A. Whitman, et al. “Shellfish face uncertain future in high CO2 world: influence of acidification on oyster larvae calcification and growth in estuaries.” Plos one 4.5 (2009): e5661. Human activities have increased atmospheric concentrations of carbon dioxide by 36% during the past 200 years. One third of all anthropogenic CO2 has been absorbed by the oceans, reducing pH by about 0.1 of a unit and significantly altering their carbonate chemistry. There is widespread concern that these changes are altering marine habitats severely, but little or no attention has been given to the biota of estuarine and coastal settings, ecosystems that are less pH buffered because of naturally reduced alkalinity.
  6. 2009: Doney, Scott C., et al. “Ocean acidification: the other CO2 problem.” Annual Review of Marine Science (2009). Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.
  7. 2010: Talmage, Stephanie C., and Christopher J. Gobler. “Effects of past, present, and future ocean carbon dioxide concentrations on the growth and survival of larval shellfish.” Proceedings of the National Academy of Sciences 107.40 (2010): 17246-17251. The combustion of fossil fuels has enriched levels of CO2 in the world’s oceans and decreased ocean pH. Although the continuation of these processes may alter the growth, survival, and diversity of marine organisms that synthesize CaCO3 shells, the effects of ocean acidification since the dawn of the industrial revolution are not clear. Here we present experiments that examined the effects of the ocean’s past, present, and future (21st and 22nd centuries) CO2 concentrations on the growth, survival, and condition of larvae of two species of commercially and ecologically valuable bivalve shellfish (Mercenaria mercenaria and Argopecten irradians). Larvae grown under near preindustrial CO2 concentrations (250 ppm) displayed significantly faster growth and metamorphosis as well as higher survival and lipid accumulation rates compared with individuals reared under modern day CO2 levels. Bivalves grown under near preindustrial CO2 levels displayed thicker, more robust shells than individuals grown at present CO2 concentrations, whereas bivalves exposed to CO2 levels expected later this century had shells that were malformed and eroded. These results suggest that the ocean acidification that has occurred during the past two centuries may be inhibiting the development and survival of larval shellfish and contributing to global declines of some bivalve populations.
  8. 2010: Kroeker, Kristy J., et al. “Meta‐analysis reveals negative yet variable effects of ocean acidification on marine organisms.” Ecology letters 13.11 (2010): 1419-1434. Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups. We used meta‐analytic techniques to explore the biological responses to ocean acidification, and found negative effects on survival, calcification, growth and reproduction. However, there was significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative responses than non‐calcifying organisms across numerous response variables, with the exception of crustaceans, which calcify but were not negatively affected. Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate. Organisms using one of the more soluble forms of calcium carbonate (high‐magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation was dependent on the taxonomic group. Our analyses suggest that the biological effects of ocean acidification are generally large and negative, but the variation in sensitivity amongst organisms has important implications for ecosystem responses.
  9. 2012: Narita, Daiju, Katrin Rehdanz, and Richard SJ Tol. “Economic costs of ocean acidification: a look into the impacts on global shellfish production.” Climatic Change 113.3-4 (2012): 1049-1063. Ocean acidification is increasingly recognized as a major global problem. Yet economic assessments of its effects are currently almost absent. Unlike most other marine organisms, mollusks, which have significant commercial value worldwide, have relatively solid scientific evidence of biological impact of acidification and allow us to make such an economic evaluation. By performing a partial-equilibrium analysis, we estimate global and regional economic costs of production loss of mollusks due to ocean acidification. Our results show that the costs for the world as a whole could be over 100 billion USD with an assumption of increasing demand of mollusks with expected income growths combined with a business-as-usual emission trend towards the year 2100. The major determinants of cost levels are the impacts on the Chinese production, which is dominant in the world, and the expected demand increase of mollusks in today’s developing countries, which include China, in accordance with their future income rise. Our results have direct implications for climate policy. Because the ocean acidifies faster than the atmosphere warms, the acidification effects on mollusks would raise the social cost of carbon more strongly than the estimated damage adds to the damage costs of climate change.
  10. 2013: Andersson, Andreas J., and Dwight Gledhill. “Ocean acidification and coral reefs: effects on breakdown, dissolution, and net ecosystem calcification.” Annual Review of Marine Science 5 (2013): 321-348. The persistence of carbonate structures on coral reefs is essential in providing habitats for a large number of species and maintaining the extraordinary biodiversity associated with these ecosystems. As a consequence of ocean acidification (OA), the ability of marine calcifiers to produce calcium carbonate (CaCO3) and their rate of CaCO3production could decrease while rates of bioerosion and CaCO3 dissolution could increase, resulting in a transition from a condition of net accretion to one of net erosion. This would have negative consequences for the role and function of coral reefs and the eco-services they provide to dependent human communities. In this article, we review estimates of bioerosion, CaCO3 dissolution, and net ecosystem calcification (NEC) and how these processes will change in response to OA. Furthermore, we critically evaluate the observed relationships between NEC and seawater aragonite saturation state (Ωa). Finally, we propose that standardized NEC rates combined with observed changes in the ratios of dissolved inorganic carbon to total alkalinity owing to net reef metabolism may provide a biogeochemical tool to monitor the effects of OA in coral reef environments.



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