Global Carbon Emissions Reach New High: Acidic Oceans Dissolving Sea Life
December 3, 2012
Al Jazeera & Michael Marshall / The New Scientist
According to recent reports, atmospheric CO2 emissions rose about three percent last year, faster than any time in the last 300 million years. As 200 nations meet in Doha in an attempt to reach a non-binding agreement to control CO2 emissions, a University of Victoria climate scientist, warns: "We are losing control of our ability to get a handle on the global warming problem." Excess CO2 in the oceans already has raised acidity to the point that some marine life is dissolving.
Study: Global Carbon Emissions Reach New High
(December 3, 2012) -- Atmospheric carbon dioxide (CO2) emissions rose by about three percent last year, according to a new study. Last year, all the world's nations combined pumped nearly 38.2 billion tonnes of carbon dioxide into the air from the burning of fossil fuels such as coal and oil, according to new international calculations on global emissions published on Sunday in the journal Nature Climate Change.
Scientists say it will be unlikely for the world to limit temperature increases to 2 degrees Celsius (3.6 degrees Fahrenheit).
Three years ago, nearly 200 nations set the 2-degree Celsius temperature goal in a non-binding agreement. Negotiators now at a conference under way in Doha, Qatar, are trying to find ways to reach that target.
Andrew Weaver, a climate scientist at the University of Victoria in Canada who was not part of the study, said: "We are losing control of our ability to get a handle on the global warming problem."
Other research has warned of potentially catastrophic effects from a temperature rise of this kind. Chronic droughts and floods would bite into farm yields, violent storms and sea-level rise would swamp coastal cities and deltas, and many species would be wiped out, unable to cope with habitat loss.
The overwhelming majority of the increase in emissions last year was from China, the world's biggest carbon dioxide polluter. Of the planet's top 10 polluters, the US and Germany were the only countries that reduced their carbon dioxide emissions.
Developed countries have largely stabilised their emissions since 1990, the benchmark year used in the UN Framework Convention on Climate Change negotiations, the study said. But this achievement has been eclipsed by emissions by China, India, Brazil and Indonesia and other developing economies, which are turning to cheap, plentiful coal to power their rise out of poverty.
In 1997, most of the world agreed to an international treaty, known as the Kyoto Protocol, that required developed countries such as the US to reduce greenhouse gas emissions by about five percent when compared with the baseline year of 1990. But countries that are still developing, including China and India, were not limited by how much carbon dioxide they expelled. The US never ratified the treaty.
In 1990, developing countries accounted for 35 percent of worldwide output of CO2, the principal "greenhouse" gas blamed for warming Earth's surface and inflicting damaging changes to the climate system. In 2011, this figure was 58 percent.
Animals Are Already Dissolving in Southern Ocean
Michael Marshall / The New Scientist
(November 25, 2012) -- In a small patch of the Southern Ocean, the shells of sea snails are dissolving. The finding is the first evidence that marine life is already suffering as a result of man-made ocean acidification.
"This is actually happening now," says Geraint Tarling of the British Antarctic Survey in Cambridge, UK. He and colleagues captured free-swimming sea snails called pteropods from the Southern Ocean in early 2008 and found under an electron microscope that the outer layers of their hard shells bore signs of unusual corrosion.
As well as warming the planet, the carbon dioxide we emit is changing the chemistry of the ocean. CO2 dissolves in water to form carbonic acid, making the water less alkaline. The pH is currently dropping at about 0.1 per century, faster than any time in the last 300 million years.
Lab experiments have shown that organisms with hard shells, such as corals and molluscs, will suffer as a result. To build their shells, corals and molluscs need to take up calcium carbonate from the water, but more carbonic acid means more hydrogen ions in the water. These react with carbonate ions, making them unavailable to form calcium carbonate.
The most vulnerable animals are those, like pteropods, that build their shells entirely from aragonite, a form of calcium carbonate that is very sensitive to extra acidity. By 2050, there will be a severe shortage of aragonite in much of the ocean. Aragonite is still relatively plentiful in most of the ocean, but Tarling suspected that some regions might already be affected by shortages.
He visited the Southern Ocean near South Georgia where deep water wells up to the surface. This water is naturally low in aragonite, meaning the surface waters it supplies are naturally somewhat low in the mineral – although not so much so that it would normally be a problem. Add in the effect of ocean acidification, however, and Tarling found that the mineral was dangerously sparse at the surface.
"It's of concern that they can see it today," says Toby Tyrrell of the National Oceanography Centre in Southampton, UK. Aragonite-depleted regions are still rare, but they will become widespread by 2050, says Tarling. The polar oceans will change fastest, with the tropics following a few decades after. "These pockets will start to get larger and larger until they meet," he says.
Tyrrell says the Arctic will become undersaturated with respect to aragonite before the Antarctic. Patches of undersaturation have already been seen, for instance off the north coast of Canada in 2008. The only way to stop ocean acidification is to reduce our CO2 emissions, Tyrrell says.
It has been suggested that we could add megatonnes of lime to the ocean to balance the extra acidity. However, Tyrrell says this is "probably not practical" because the amounts involved – and thus the costs – are enormous.
Journal reference: Nature Geoscience, DOI: 10.1038/ngeo1635
Oceans Acidifying at Unprecedented Speed
Michael Marshall / The New Scientist
(March 1, 2012) -- Humanity's greenhouse gas emissions may be acidifying the oceans at a faster rate than at any time in the last 300 million years. The sheer speed of change means we do not know how severe the consequences will be. As well as warming the planet, carbon dioxide seeps into the oceans and forms carbonic acid. As a result the water becomes more acidic.
The pH is currently dropping by about 0.1 per century. This ocean acidification harms organisms such as corals that rely on dissolved carbonate to make their shells. It also disrupts behaviour in some animals.
Bärbel Hönisch of Columbia University in Palisades, New York, and colleagues used the chemical record preserved in rocks to gauge previous ocean acidification events.
The best match for current changes was the Palaeocene-Eocene thermal maximum of 55 million years ago, when vast amounts of methane were released into the atmosphere causing rapid global warming, ocean acidification, and mass extinction. But even then, it took at least 3000 years for ocean pH to drop by 0.5. "That is an order of magnitude slower than today," Hönisch says.
The 300-million-year period that Hönisch and colleagues studied includes the biggest extinction of them all: the end-Permian extinction. This event, 252 million years ago, wiped out up to 96 per cent of marine species. But it probably had other causes.
Acidification is not the only threat to the oceans from greenhouse gases, says Nicolas Gruber of the Swiss Federal Institute of Technology Zurich in Switzerland. Marine life also faces a threat from rising water temperatures and less dissolved oxygen.
"We have to think about these effects co-occurring," Gruber says. While we have information on the consequences of each individual factor, we have no idea what the combined effect will be.
Journal reference: Science, DOI: 10.1126/science.1208277
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