Archive for the ‘CO2’ Category

<> on June 9, 2010 in Houma, Louisiana.

By Susannah Cullinane, CNN

The world’s oceans have become 26% more acidic since the start of the Industrial Revolution and continue to acidify at an “unprecedented rate,” threatening marine ecosystems, aquaculture and the societies that rely on them, scientists say.

In a report released Thursday, researchers say that carbon dioxide emissions from human activities such as fossil fuel burning are the primary cause of ocean acidification.

They say the rate of change may be faster than at any time in the last 300 million years, predicting that by 2100 there will have been a 170% increase in ocean acidity, compared to pre-industrial times.

The report is based on the findings from a September 2012 Symposium on the Ocean, at which 540 experts from 37 countries discussed research on ocean acidification, and has been updated with more recent research.

Unless carbon dioxide emissions are reduced, marine ecosystems will be damaged and the impact of climate change will be worsened, the scientists warn. “The only known realistic mitigation option on a global scale is to limit future atmospheric CO2 levels.”

The report says oceans currently act as a CO2 “sinkhole” absorbing approximately a quarter of emissions.

“As ocean acidity increases, its capacity to absorb CO2 from the atmosphere decreases. This decreases the ocean’s role in moderating climate change,” they write.

The increased acidity will also change the ocean environment, with evidence suggesting that some organisms will be less able to survive, while others, such as seagrass, may thrive.

Acidification is faster in Arctic waters because cold water is richer in CO2, while melting sea ice worsens the problem, they say.

“Within decades, large parts of the polar oceans will become corrosive to the unprotected shells of calcareous marine organisms,” the report says, while in the tropics the growth of coral reefs may be hampered.

“People who rely on the ocean’s ecosystem services are especially vulnerable and may need to adapt or cope with ocean acidification impacts within decades,” it says. “Tropical coral reef loss will affect tourism, food security and shoreline protection for many of the world’s poorest people.”

“Very aggressive reductions in CO2 emissions are required to maintain a majority of tropical coral reefs in waters favorable for growth,” the report says.

One of the report’s authors is Daniela Schmidt, from the University of Bristol, in the UK.

Schmidt said the research highlighted the impact acidification would have on biodiversity and aquaculture and the societies that rely on them for their food and economic well-being.

“We’re talking about countries that strongly depend on this, in warmer countries where there are complex problems with climate change as it is,” Schmidt said.

“What I’m hoping is that people realize that CO2 is not just a question of global warming. That we are acidifying the ocean at a rate that has been unprecedented — for millions and millions of years,” she said.

“The more CO2 emissions, the more acidification,” Schmidt said. “The ocean is in direct interchange with the atmosphere.”

If acidification continued to increase at its current rate, “you will definitely see damage,” she said. “The first signs we can already see today, in oyster farms off the West Coast of the United States.”

Schmidt said while 90% of the world’s ocean was in equilibrium with the atmosphere, some oyster hatcheries in this area were located in the 10% that wasn’t.

Oysters in the larval stage were much more vulnerable to damage, she said. “When (more acidic) water comes up and hits the hatchery, they close the whole thing.”

While tanks could be closed off to more acidic seawater, Schmidt said that by 2100 the issue would be there every day. “So we can’t just switch off that tap anymore.”

She said the report would be presented in Warsaw, Poland, on November 18, during the U.N. Conference of the Parties climate change meeting.

Schmidt said while she hoped the research would lead to stricter emissions limits, “the realist in me thinks that we’ve been discussing this for decades. This isn’t a problem that is just going to go away. It’s simple. The consequences are frightening.”

The 2012 symposium that led to the report was sponsored by the Scientific Committee on Oceanic Research, the Intergovernmental Oceanographic Commission of UNESCO, and the International Geosphere-Biosphere Programme.

http://www.cnn.com/2013/11/14/world/ocean-acidification-report/index.html?hpt=hp_t3

Advertisements

panic-attack

By JAMES GORMAN
Published: February 3, 2013
New York Times

In the past few years, scientists have learned a lot about fear from a woman who could not experience it. A rare illness had damaged a part of her brain known as the amygdala and left her eerily unafraid.

Both in experiments and in life, the woman, known as SM, showed no fear of scary movies, snakes, spiders or very real domestic assaults, death threats, and robberies at knife- and gunpoint.

Although she lived in an area “replete with crime, drugs and danger,” according to an earlier study, because she lacked a functioning amygdala, an evolutionarily ancient part of the brain long known to process fear, nothing scared her.

But recently SM had a panic attack. And the simple fact that she was able to feel afraid without a working amygdala, experts say, illuminates some of the brain’s most fundamental processes and may have practical value in the study of panic attacks.

SM’s moments of fear occurred during an experiment that involved inhaling carbon dioxide through a mask in amounts that are not harmful but create a momentary feeling of suffocation. Not only SM, but two other women, identified as AM and BG, identical twins with amygdala damage similar to SM’s, showed all the physical symptoms of panic, and reported that, to their surprise, they felt intense fear.

The researchers, who report on the experiment in the current issue of Nature Neuroscience, had hypothesized that SM would not panic. John A. Wemmie, a neuroscientist at the University of Iowa and the senior author of the paper, said, “We saw the exact opposite.”

Antonio Damasio, of the University of Southern California, who had worked with SM and some of the researchers involved in this study on previous papers but did not participate in this research, said he was delighted with the results. It confirmed his own thinking, he said, that while the amygdala was central to fear generated by external threats, there was a different brain path that produced the feeling of fear generated by internal bodily experiences like a heart attack. This idea was put forth in a 2011 paper about SM on which he was a co-author.

“I think it’s a very interesting and important result,” he said.

Dr. Joseph E. LeDoux, of New York University, who has extensively studied the amygdala but was not involved in the research, said in an e-mail, “This is a novel and important paper” in an area where there is much left to learn. He said scientists still did not understand “how the brain creates a conscious experience of fear,” whether the amygdala or other systems are involved.

SM scores in the normal range on I.Q. and other tests, and she voluntarily participated in this and earlier studies, all of which showed her lacking in any sort of fear response until now. In one, for example, she walked through a Halloween haunted house and never gasped, recoiled or screamed, as others did, when a person in a costume leapt out of the dark. She also did not seem to learn fear from life experiences.

So what was so unusual about carbon dioxide?

The answer seems to lie in the way the brain monitors disturbances in the world outside the body — snakes and robbers — compared with the way it monitors trouble inside the body — hunger, heart attacks, the feeling of not being able to breathe. External threats clearly are processed by the amygdala. But she had never been tested for internal signals of trouble.

In the experiment that SM and others participated in, they took one deep breath with plenty of oxygen but much more carbon dioxide than air usually contains. Humans are actually not sensitive to how much oxygen they are breathing, but they are sensitive to how much carbon dioxide is accumulating in the body, since it builds up quickly when a person cannot breathe. The sensation is familiar to people who have tried to hold their breath.

The researchers suggest that excess carbon dioxide produces signals that may be picked up in the brainstem and elsewhere, activating a fear-generating system in the brain that a venomous snake or a mugger with a gun would not set off.

One puzzling aspect of the results is that SM and the two other women all reacted so strongly. Among people with normal brains, only those with panic disorder are reliably terrified in carbon dioxide experiments. Most people are not so susceptible, said Colin Buzza, a co-author of the study and a medical student at the University of Iowa Carver College of Medicine, suggesting that perhaps the amygdala is not functioning properly in people with panic disorder.

http://www.nytimes.com/2013/02/04/health/study-discovers-internal-trigger-for-the-previously-fearless.html?_r=0