tagged w/ calcium carbonate
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Current rate of acidification faster than at any time during the past 300 million years
The world’s oceans are acidifying at 10 times the rate measured during some previous major climate shifts, a change that doesn’t bode well for many familiar ocean species.
“What we’re doing today really stands out,” said researcher Bärbel Hönisch, referring to emissions of climate-altering greenhouse gases. Hönisch is lead author of a recent paper that compares the current episode of acidification with four other great extinction events.
“We know that life during past ocean acidification events was not wiped out. New species evolved to replace those that died off. But if industrial carbon emissions continue at the current pace, we may lose organisms we care about—coral reefs, oysters, salmon, said Hönisch, a paleoceanographer at Columbia University’s Lamont-Doherty Earth Observatory.
Published in Science, the study is the first of its kind to survey the geologic record for evidence of ocean acidification over this vast time period.
The decisions we make over the next few decades could have significant implications on a geologic timescale,” said Richard Feely, an oceanographer at the National Oceanic and Atmospheric Administration. It may take decades before ocean acidification’s effect on marine life shows itself, he explained. Until then, the past is a good way to foresee the future.
“These studies give you a sense of the timing involved in past ocean acidification events—they did not happen quickly,” he said.
The oceans act like a sponge to draw down excess carbon dioxide from the air; the gas reacts with seawater to form carbonic acid, which over time is neutralized by fossil carbonate shells on the seafloor. But if CO2 goes into the oceans too quickly, it can deplete the carbonate ions that corals, mollusks and some plankton need for reef and shell-building.
That is what is happening now. In a review of hundreds of paleoceanographic studies, a team of researchers from five countries found evidence for only one period in the last 300 million years when the oceans changed even remotely as fast as today: the Paleocene-Eocene Thermal Maximum, about 56 million years ago.
Previous research showed that, within a span of about 5,000 years, a mysterious surge of carbon doubled atmospheric concentrations, pushed average global temperatures up by about 6 degrees celsius, and dramatically changed the ecological landscape.
Carbonate plankton shells littering the seafloor dissolved, leaving brown mud that was the telltale sign for paleoclimatologists who discovered the layer near Antarctica.
As many as half of all species of benthic foraminifers, a group of single-celled organisms that live at the ocean bottom, went extinct, suggesting that organisms higher in the food chain may have also disappeared, said study co-author Ellen Thomas, a paleoceanographer at Yale University who was on that pivotal Antarctic cruise.
“It’s really unusual that you lose more than 5 to 10 percent of species over less than 20,000 years,” Thomas said. “It’s usually on the order of a few percent over a million years.” During this time, scientists estimate, ocean pH—a measure of acidity–may have fallen as much as 0.45 units. (As pH falls, acidity rises.)
In the last hundred years, atmospheric CO2 has risen about 30 percent, to 393 parts per million, and ocean pH has fallen by 0.1 unit, to 8.1–an acidification rate at least 10 times faster than 56 million years ago, according to Hönisch.
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In a recent study, scientists from Stony Brook University found that the larvae of bay scallops and hard clams grow best at pre-industrial pH levels, while their shells corrode at the levels projected for 2100. Off the U.S. Pacific Northwest, the death of oyster larvae has recently been linked to the upwelling of acidic water there.
In parts of the ocean acidified by underwater volcanoes venting carbon dioxide, scientists have seen alarming signs of what the oceans could be like by 2100. In a 2011 study of coral reefs off Papua New Guinea, scientists writing in the journal Nature Climate Change found that when pH dropped to 7.8, reef diversity declined by as much as 40 percent. Other studies have found that clownfish larvae raised in the lab lose their ability to sniff out predators and find their way home when pH drops below 7.8.
“It’s not a problem that can be quickly reversed,” said Christopher Langdon, a biological oceanographer at the University of Miami who co-authored the study on Papua New Guinea reefs. “Once a species goes extinct it’s gone forever. We’re playing a very dangerous game.”
More at the linkCurrent rate of acidification faster than at any time during the past 300 million... more
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The ocean is a delicate place, and tiny changes to its composition can cause serious devastation.
Adding carbon to the atmosphere contributes to global warming and climate change. Another less-discussed impact is ocean acidification—whereby carbon molecules diffuse into the ocean from the atmosphere, causing a steady rise in acidity—even though the impacts are already being felt by many species.
The beautiful blue sea slug, seen here, is one such creature. Blue sea slugs feed on the poisonous Portuguese man of war jellyfish, meaning that an ocean without them would be an ocean with a lot more stinging jellyfish.
This is 1: Blue Sea Slug
More at the link
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The link to humans and the food chain each of these species represents should make people understand just how acidification is affecting us as well.The ocean is a delicate place, and tiny changes to its composition can cause serious... more
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Global warming has often been discussed with regard to its effects for life on land: increased temperatures and heat waves, increased weather extremes, less but more intense rainfall, drought and forest fires.
Water, however, remains less considered. Even discussions of floods or rising sea levels, which focus on water, study mainly their consequences for land inhabitants.
Yet oceans, it is well known, cover three quarters of the earth's surface. And oceans have absorbed about a quarter of all carbon dioxide (CO2) emissions, one of four main greenhouse gases causing global warming. This absorption of CO2 is integrally related to the three major factors impacting the oceans: global warming, ocean acidification and decreasing amounts of oxygen. As a result, the current situation of the oceans is dire. And its impact will be severe not only for marine life but also for all life -- plant, animal and human -- on land.
Ocean Acidification
Carbon dioxide (CO2) exists naturally in the air. But through the use of fossil fuels, in particular coal and oil, the amount of CO2 in the air has increased exponentially since the Industrial Revolution began.
As the oceans absorb carbon from the air, their chemistry changes. This process is known as ocean acidification, and it has brutal consequences for marine and land life.
Oceanographers estimate that before the use of fossil fuels, the ocean's PH balance, which measures its acidity, had been relatively stable for the past 20 million years. During the last great extinction of marine life, which occurred 55 million years ago, 50 percent of some groups of deep sea animals were wiped out.
But the current levels of carbon being absorbed by the oceans is far higher than the levels being absorbed then.
A United Nations Environment Program (UNEP) report released in 2010 on the "Environmental Consquences of Ocean Acidification" and based on studies conducted over the past two decades off the coast of Hawai'i has confirmed that the increased CO2 concentration levels in the ocean mirror the increased CO2 levels in the atmosphere.
Ocean Acidification and Phytoplankton
Already the increased levels of ocean acidification have led to a loss of phytoplankton and of coral reefs. And losses of phytoplankton and of coral reefs have a ripple effect.
First, much marine life relies on them for nourishment. Flounder, haddock, pollock, salmon and shrimp all eat phytoplankton. Humans eat many of these fish. Krill eat phytoplankton and whales eat krill. So a decrease in one threatens the liveilhood of the other.
Second, phytoplankton also absorbs carbon dioxide. Phytoplankton floats along the ocean's surface absorbing CO2 as land plants do in photosynthesis. As the CO2 is absorbed, the plant dies and sinks to the ocean floor, releasing CO2 along the way. Cold water can hold higher levels of CO2 than warmer water, so most of the CO2 released, which turns water acidic, is to be found along the ocean floor. But this acidic water does not stay at the ocean's floor. During an upswell, it rises to the surface and even the shore. Its acidity is deadly for the shells of marine life, such as shrimps, clams and oysters.
If the smallest part of the food chain is affected by ocean acidification, it ripples all the way up the food chain, making the largest part of the food chain vulnerable.
"Since the time before the industrial revolution," says the National Resource Defense Council's Lisa Suatoni, "ocean acidity has increased 30 percent."
And the bad news does not end there: According to oceanographers, the water rising from the ocean's depths holds CO2 that has accumulated over the past decades. Thus, in coming years, the increased levels of CO2 absorbed by the oceans will re-emerge as increased ocean acidification reaching the shores. Higher levels of cean acidification have already led to tremendous problems for the oyster industry. In the summer of 2007 oyster harvests began to plummet in the Pacific Northwest. The situation was extreme. The oyster hatcheries were keen to find the culprit, which turned out to be ocean acidification.
More at the linkGlobal warming has often been discussed with regard to its effects for life on land:... more
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The oil spill in the Gulf of Mexico is a disaster, but it may pale compared to what scientists say is brewing in the world's oceans due to everyday consumption of fossil fuels.
The billions of tonnes of carbon dioxide sent wafting into the atmosphere each year through the burning of oil, gas and coal are profoundly affecting the oceans, says a series of reports published Friday in the journal Science.
One says there is mounting evidence that "rapidly rising greenhouse gas concentrations are driving ocean systems toward conditions not seen for millions of years, with an associated risk of fundamental and irreversible ecological transformation."
Another says that the effects are already rippling through the food web in Antarctica.
And a third says humans, and their ever-increasing carbon emissions, are acidifying the ocean in a "grand planetary experiment" that could have devastating impacts.
Marine scientists Ove Hoegh-Guldberg, at the University of Queensland in Australia, and John Bruno, at University of North Carolina, describe how the oceans act as a "heat sink" and are slowly heating up along with the atmosphere as greenhouse gas emissions climb.
The warming, they say, is "likely to have profound influences on the strength, direction and behaviour" of major ocean currents and far-reaching impacts on sea life.
The oceans also soak up close to a third of the carbon dioxide that humans put into the atmosphere and it reacts with sea water to form acidic ions. The rising acidity "represents a major departure from the geochemical conditions that have prevailed in the global ocean for hundreds of thousands, if not million of years," the scientists report.
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"The impacts of anthropogenic (human) climate change so far include decreased ocean productivity, altered food web dynamics, reduced abundance of habitat-forming species, shifting species distributions and a greater incidence of disease," they say.
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A news report, accompanying the Science papers on the oceans, says by increasing the ocean's acidity "humans are caught up in a grand planetary experiment" that could take a "potentially devastating toll on marine life." The rising acidity could erode the calcium carbonate shells and skeletons of corals, mollusks and some algae and plankton — and there is some evidence it is already starting to occur.
Read more: http://www.ottawacitizen.com/technology/Carbon%20emissions%20having%20harmful%20lasting%20impact%20oceans%20Reports/3166754/story.html#ixzz0rYITQnUEThe oil spill in the Gulf of Mexico is a disaster, but it may pale compared to what... more
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The increasing acidity of the world's oceans - and that acidity's growing threat to marine species - are definitive proof that the atmospheric carbon dioxide that is causing climate change is also negatively affecting the marine environment, says world-renowned Antarctic marine biologist Jim McClintock, Ph.D., professor in the University of Alabama at Birmingham (UAB) Department of Biology.
"The oceans are a sink for the carbon dioxide that is released into the atmosphere," says McClintock, who has spent more than two decades researching the marine species off the coast of Antarctica. Carbon dioxide is absorbed by oceans, and through a chemical process hydrogen ions are released to make seawater more acidic.
"Existing data points to consistently increasing oceanic acidity, and that is a direct result of increasing carbon dioxide levels in the atmosphere; it is incontrovertible," McClintock says. "The ramifications for many of the organisms that call the water home are profound."
A substance's level of acidity is measured by its pH value; the lower the pH value, the more acidic is the substance. McClintock says data collected since the pre-industrial age indicates the mean surface pH of the oceans has declined from 8.2 to 8.1 units with another 0.4 unit decline possible by century's end. A single whole pH unit drop would make ocean waters 10 times more acidic, which could rob many marine organisms of their ability to produce protective shells - and tip the balance of marine food chains.
"There is no existing data that I am aware of that can be used to debate the trend of increasing ocean acidification," he says.
McClintock and three co-authors collected and reviewed the most recent data on ocean acidification at high latitudes for an article in the December 2009 issue of Oceanography magazine, a special issue that focuses on ocean acidification worldwide. McClintock also recently published research that revealed barnacles grown under acidified seawater conditions produce weaker adult shells.
Antarctica as the Ground Zero for Climate Change
McClintock says the delicate balance of life in the waters that surround the frozen continent of Antarctica is especially susceptible to the effects of acidification. The impact on the marine life in that region will serve as a bellwether for global climate-change effects, he says.
"The Southern Ocean is a major global sink for carbon dioxide. Moreover, there are a number of unique factors that threaten to reduce the availability of abundant minerals dissolved in polar seawater that are used by marine invertebrates to make their protective shells," McClintock says.
"In addition, the increased acidity of the seawater itself can literally begin to eat away at the outer surfaces of shells of existing clams, snails and other calcified organisms, which could cause species to die outright or become vulnerable to new predators."
One study McClintock recently conducted with a team of UAB researchers revealed that the shells of post-mortem Antarctic marine invertebrates evidenced erosion and significant loss of mass within only five weeks under simulated acidic conditions.
McClintock says acidification also could exert a toll on the world's fisheries, including mollusks and crustaceans. He adds that the potential loss of such marine populations could greatly alter the oceans' long-standing food chains and produce negative ripple effects on human industries or food supplies over time.
"So many fundamental biological processes can be influenced by ocean acidification, and the change in the oceans' makeup in regions such as Antarctica are projected to occur over a time period measured in decades," McClintock says.
contThe increasing acidity of the world's oceans - and that acidity's growing... more
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Climate change is depriving coral reefs across the globe of the building materials used to make their shells. Current plans to curb greenhouse gas emissions may not be enough to fix the problem, according to new research.
The daily life of corals is a constant battle against erosion. The reef builders patch up holes in their shells, left by nibbling sea creatures, using a mineral called calcium carbonate. To keep up with repairs, corals in the wild usually require three times as much of the mineral as sheltered corals grown in laboratories.
Before the industrial revolution, says Ken Caldeira of Stanford University, 98% of all corals lived in waters above the required calcium carbonate threshold.
But the situation is changing, according to Caldeira, who has built a model to study how greenhouse gas emissions tinker with the chemistry of open water oceans.
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Oceans are becoming saturated with Co2 and corals are suffering for it. This is important because corals play a very important role in the health of our oceans, which in turn plays a very important role in the health of the web of life in our oceans, which then plays a vital role in our own health. Mitigating carbon emissions is now key: how many times does it have to be said?
The impasse between what politicians in this country want and what this world now needs is vast and bringing dangerous consequences to us. We can no longer afford to ignore scientific warnings regarding the deterioration of our oceans, and we cannot wait until politicians see it as politically expedient to do something or until we have passed the point of no return.
Besides carbon mitigation and freezing emissions, I believe we need a major global tree planting initiative to be undertaken. Planting trees in areas of great deforestation can help to return many of the carbon sinks that have been lost to us from illegal logging practices and overconsumption. This would then hopefully help to balance the amount of Co2 in the atmosphere instead of most of it being soaked up by oceans. This is a human made catastrophe and only humans can reverse it. Hopefully, it is not too late.Climate change is depriving coral reefs across the globe of the building materials... more
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The cement that buttresses coral reefs, giving them the strength to withstand crashing waves and other onslaughts, may stop forming as oceans acidify under increased carbon dioxide in the atmosphere.
Researchers have already predicted that a more acidic ocean will make it more difficult for corals to build their calcium carbonate skeletons. The new finding suggests that the reef's broader structure may also suffer because a lower pH reduces the formation of the reef's cement binder. The binder is made from calcium carbonate that precipitates out of ocean water when it rushes through the pores of coral skeletons.
"Until now, we've mostly addressed acidification in terms of what it does to the living organism," said study author Joan Kleypas of the National Center for Atmospheric Research in Boulder, Colo.
"Here we're finding that the reef structure itself can certainly feel the effect of ocean acidification, even if the biology somehow finds a way to cope with acidification. This is mainly an inorganic process, so we're looking at something that will happen regardless of what the biology does."
The cement that buttresses coral reefs, giving them the strength to withstand crashing... more
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"For eons, the world’s oceans have been sucking carbon dioxide out of the atmosphere and releasing it again in a steady inhale and exhale. The ocean takes up carbon dioxide through photosynthesis by plant-like organisms (phytoplankton), as well as by simple chemistry: carbon dioxide dissolves in water. It reacts with seawater, creating carbonic acid. Carbonic acid releases hydrogen ions, which combine with carbonate in seawater to form bicarbonate, a form of carbon that doesn’t escape the ocean easily.
Crew members aboard the R/V Roger Revelle retrieve a CTD rosette from the frigid waters of the Southern Ocean. As the device is lowered into the ocean, electronic instruments measure salinity, temperature, and depth. Each of the white bottles collects seawater at different depths for detailed analysis. (Photograph ©2008 Brett longworth.)
As we burn fossil fuels and atmospheric carbon dioxide levels go up, the ocean absorbs more carbon dioxide to stay in balance. But this absorption has a price: these reactions lower the water’s pH, meaning it’s more acidic. And the ocean has its limits. As temperatures rise, carbon dioxide leaks out of the ocean like a glass of root beer going flat on a warm day. Carbonate gets used up and has to be re-stocked by upwelling of deeper waters, which are rich in carbonate dissolved from limestone and other rocks.
In the center of the ocean, wind-driven currents bring cool waters and fresh carbonate to the surface. The new water takes up yet more carbon to match the atmosphere, while the old water carries the carbon it has captured into the ocean.
The warmer the surface water becomes, the harder it is for winds to mix the surface layers with the deeper layers. The ocean settles into layers, or stratifies. Without an infusion of fresh carbonate-rich water from below, the surface water saturates with carbon dioxide. The stagnant water also supports fewer phytoplankton, and carbon dioxide uptake from photosynthesis slows. In short, stratification cuts down the amount of carbon the ocean can take up."
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Good article about the scientific research that goes into determining the natural and human factors behind Co2 absorption and balance in our oceans. And as this article illustrates, humans will have to mitigate their emissions of Co2 in order for our oceans to continue to be able to balance Co2 in a way that sustains them, our planet, and all species that depend on them for life."For eons, the world’s oceans have been sucking carbon dioxide out of the... more
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