Archive for August, 2010

Ocean acidification is a Misnomer

A good way to excite people is to tell them that something is becoming more ‘acid,’ as ‘the oceans are undergoing acidification and this is a potential environmental catastrophe.’

The UN Intergovernmental Panel on Climate Change (IPCC), the leading proponent of the doom of global warming, states that the mean pH of surface waters ranges between 7.9 and 8.3 in the open oceans, so the oceans remain alkaline. It is dishonest to present to a lay audience that any perceived reduction in alkalinity means the oceans are turning to acid. (1) Since the pH of the oceans is higher than neutral (pH = 7), this means the oceans are alkaline. The pH scale ranges from 0 to 14; pH 6 is ten times more acid than pH 7 and pH 5 is a hundred times more acid than pH 7. (2)
Continue reading ‘Ocean acidification is a Misnomer’

CO2 emission needs to be curbed to limit ocean acidification: Experts

Scientists have called for rapid curbing of carbon dioxide emission levels in order to limit ocean acidification as well as global warming.

Dr. Toby Tyrrell of the University of Southampton’s School of Ocean and Earth Science and colleagues used computer models to quantify the likely response of ocean acidification to a range of carbon dioxide emission scenarios, including aggressive mitigation.

“Our computer simulations allow us to predict what impact the timing and rapidity of emission reductions will have on future acidification, helping to inform policy makers,” said Tyrrell.

“The oceans absorb around a third of carbon dioxide emissions, which helps limit global warming, but uptake of carbon dioxide by the oceans also increases their acidity, with potentially harmful effects on calcifying organisms such as corals and the ecosystems that they support,” he added.
Continue reading ‘CO2 emission needs to be curbed to limit ocean acidification: Experts’

A sea of change: Ocean acidification threatening coastal waters

There’s something unexpected happening to our oceans. The chemistry of the seawater is changing due to too much carbon dioxide. It’s called “ocean acidification,” and researchers are now finding evidence of this change in our coastal waterways.

The increasing rate and amount of our carbon dioxide (CO2) emissions is progressively affecting the ocean system, causing the acidity of sea water to increase — a number one priority to many carbon and climate scientists. Researchers at NOAA’s Pacific Marine Environmental Laboratory (PMEL) in Seattle have been studying this global problem for more than three decades and continue to monitor ocean acidification in all the world’s oceans from coral reefs to deep North Pacific waters.
Continue reading ‘A sea of change: Ocean acidification threatening coastal waters’

Classroom resources & slideshow: ocean acidification

Ocean acidification is a phenomenon related to current global climate changes and is becoming a major threat to marine ecosystems ranging from tropical coral reefs to the chilly waters of the Antarctic.

In this lesson, students observe and investigate the mechanisms driving ocean acidification. The lesson and lab make connections to basic chemical principles such as acids/bases and the pH scale.
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Neoproterozoic ice ages, boron isotopes, and ocean acidification: Implications for a snowball Earth

The Neoproterozoic Earth underwent at least two severe glaciations, each extending to low paleomagnetic latitudes and punctuating warmer climates. The two widespread older and younger Cryogenian glacial deposits in Namibia are directly overlain by cap carbonates deposited under inferred periods of high atmospheric carbon dioxide concentrations. Oceanic uptake of carbon dioxide decreases ocean pH; here we present a record of Cryogenian interglacial ocean pH, based on boron (B) isotopes in marine carbonates. Our data suggest a largely constant ocean pH and no critically elevated pCO2 throughout the older postglacial and interglacial periods. In contrast, a marked ocean acidification event marks the younger deglaciation period and is compatible with elevated postglacial pCO2 concentration. Our data are consistent with the presence of two panglacial climate states in the Cryogenian, but indicate that each had its own distinct environmental conditions.
Continue reading ‘Neoproterozoic ice ages, boron isotopes, and ocean acidification: Implications for a snowball Earth’

Niche dimensions in fishes: an integrative view

Current shifts in ecosystem composition and function emphasize the need for an understanding of the links between environmental factors and organism fitness and tolerance. The examples discussed here illustrate how recent progress in the field of comparative physiology may provide a better mechanistic understanding of the ecological concepts of the fundamental and realized niches and thus provide insights into the impacts of anthropogenic disturbance. Here we argue that, as a link between physiological and ecological indicators of organismal performance, the mechanisms shaping aerobic scope and passive tolerance set the dimensions of an animal’s niche, here defined as its capacity to survive, grow, behave, and interact with other species. We demonstrate how comparative studies of cod or killifish populations in a latitudinal cline have unraveled mitochondrial mechanisms involved in establishing a species’ niche, performance, and energy budget. Riverine fish exemplify how the performance windows of various developmental stages follow the dynamic regimes of both seasonal temperatures and river hydrodynamics, as synergistic challenges. Finally, studies of species in extreme environments, such as the tilapia of Lake Magadi, illustrate how on evolutionary timescales functional and morphological shifts can occur, associated with new specializations. We conclude that research on the processes and time course of adaptations suitable to overcome current niche limits is urgently needed to assess the resilience of species and ecosystems to human impact, including the challenges of global climate change.
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Modeling deep ocean shipping noise in varying acidity conditions

Possible future changes of ambient shipping noise at 0.1–1 kHz in the North Pacific caused by changing seawater chemistry conditions are analyzed with a simplified propagation model. Probable decreases of pH would cause meaningful reduction of the sound absorption coefficient in near-surface ocean water for these frequencies. The results show that a few decibels of increase may occur in 100 years in some very quiet areas very far from noise sources, with small effects closer to noise sources. The use of ray physics allows sound energy attenuated via volume absorption and by the seafloor to be compared.
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Gulf of Maine changing

The Gulf of Maine is and always has been an essential part of the coastal New England economy. Throughout history, the bounty of the Gulf of Maine has fluctuated due to fishing pressures, technology and species’ popularity. As these changes have affected some parts of the Gulf of Maine ecosystem more than others, New England fishermen and lobstermen have adapted by shifting their efforts to different parts of the ecosystem. But what would happen if the entire Gulf of Maine ecosystem changed at once?

We may soon find out. Excess carbon dioxide, or CO2, in our atmosphere is causing ocean acidification. The ocean absorbs atmospheric CO2, and when CO2 mixes with seawater, carbonic acid develops. Increasing CO2 in the atmosphere has subsequently increased the acidity of seawater, lowering its pH. And the oceans are expected to become even more acidic over the next 200 years, as CO2 levels in the atmosphere continue to rise. In fact, atmospheric CO2 levels are predicted to nearly double over that time.
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The “other” carbon problem — ocean acidification

Humankind’s assault on the oceans continues apace. A short time ago, we considered the loss of 40% of the phytoplankton in the oceans since 1950. In my post How We Wrecked The Oceans, marine ecologist Jeremy Jackson explains why he believes the sea will be devoid of fish and other large marine organisms sometime in the 2040s. And now comes the “other” carbon problem—acidification of the oceans.

As we burn fossil fuels, carbon dioxide (CO2) is released into the atmosphere. Everyone knows that part, but what they often don’t know is that the oceans act as a enormous carbon “sink” which absorbs as much as 1/3rd of the released carbon dioxide. So the CO2 is no longer acting as a greenhouse gas in the atmosphere, which sounds good, but unfortunately, we have shifted the problem of dealing with the excess gas from the air to the oceans. Through some fairly simple chemistry, the oceans are becoming more acidic as a result. In other words, through a natural process, the ocean becomes a giant waste dump for our fossil fuel emissions.
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Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms

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.
Continue reading ‘Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms’

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Ocean acidification in the IPCC AR5 WG II

OUP book