Even though it’s what we need to aim for, emission cuts won’t bring quick relief

Posted: March 21, 2009 in science & technology
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Many people who worry about global warming hope that once emissions of heat-trapping gases decline, the problems they cause will quickly begin to abate. Now researchers are saying that such hope is ill-founded, at least with regard to carbon dioxide.

Because of the way carbon dioxide persists in the atmosphere and in the oceans, and the way the atmosphere and the oceans interact, patterns that are established at peak levels will produce problems like “inexorable sea level rise” and Dust-Bowl-like droughts for at least a thousand years, the researchers are reporting in the Proceedings of the Irish National Academy of Sciences.

“That peak would be the minimum you would be locking yourself into,” said Susan Solomon, a senior scientist at the National Oceanic and Atmospheric Administration, who led the work.

The researchers describe what will happen if the atmospheric concentration of carbon dioxide — the principal heat-trapping gas emission — reaches 450 to 600 parts per million, up from about 385 p.p.m. today. Most climate researchers consider 450 p.p.m. virtually inevitable and 600 p.p.m. difficult to avoid by mid-century if the use of fossil fuels continues at anything like its present rate.

At 450 p.p.m., the researchers say, rising seas will threaten many coastal areas, and Southern Europe, North Africa, the Southwestern United States and Western Australia could expect 10 percent less rainfall. “Ten percent may not seem like a high number,” Dr. Solomon said Monday in a telephone news conference, “but it is the kind of number that has been seen in major droughts in the past, like the Dust Bowl.” At 600 p.p.m., there might be perhaps 15 percent less rain, she said.

In 1850, atmospheric carbon dioxide was roughly 280 p.p.m., a level scientists say had not been exceeded in at least the previous 800,000 years.

In their paper, Dr. Solomon and her colleagues say they confined their estimates to known data and effects. For example, they based their sea level estimates largely on the expansion of seawater as it warms, a relatively straightforward calculation, rather than including the contributions of glacial runoff or melting inland ice sheets — more difficult to predict but potentially far greater contributors to sea level rise.

The new work dealt only with the effects of carbon dioxide, which is responsible for about half of greenhouse warming. Gases like chlorofluorocarbons and methane, along with soot and other pollutants, contribute to the rest. These substances are far less persistent in the atmosphere; if these emissions drop, their effects will decline relatively fast.

Michael Oppenheimer, a geo-scientist at Princeton, praised the report in an e-mail message as a “remarkably clear and direct” discussion of whether it would be possible to temporarily exceed a level like 450 p.p.m. and then reduce emissions in time to avoid catastrophic events like the collapse of a major inland ice sheet. Dr. Oppenheimer said the new analysis showed that “some dangerous consequences could be triggered and persist for a long, long time, even if emissions were cut radically.” “Policy makers need to understand,” he continued, “that in some ways once we are over the cliff, there’s nothing to stop the fall.”

Dr. Solomon said it would be wrong to view the report as evidence that it was already too late to do much good by reducing carbon emissions. “You have to think of this stuff as being more like nuclear waste than acid rain,” she said. Acid rain began to abate when pollution contributing to it was limited. But just as nuclear waste remains radioactive for a long time, the effects of carbon dioxide persist.

“So if we slow it down,” she said, “we have more time to find solutions.” For example, engineers may one day discover ways to remove the gas from the atmosphere. But “those solutions are not now in hand,” Dr. Solomon said. “They are quite speculative.”

Irish University Science
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  1. […] Even though it’s what we need to aim for, emission cuts won’t bring quick relief (isiria.wordpress.com) […]

  2. Hi,

    I’m working on a short environmental documentary 8 mins + -, primarily for school, but when done, I would like to submit the film to the HotDocs Film fest in Toronto and would also like to perhaps put the film on Youtube and my own website (jecphotography.com).

    The film has an image of this page from your website in it:

    Unlike a lot of others, who would use the images without permission, I am writing you today to ask:

    1. Is this your image? If not, can you direct me to the source so that I can ask permission from the photographer who has the copyright on it? Do you have a high resolution picture I could use?

    2. If you do own the copyright for the photograph, can I use this image in my film?

    The film is about the impact of man on the planet and will have a credit in it re: the photograph. I will also have the reference to the above link. The screenshot of the page may induce more people to read your articles.

    I kindly ask for your permission and assistance in this matter.

    Most Sincerely,

    J. Edward Cook

  3. enochered says:

    Carbon dioxide is the most important of all gases for plant growth. There is not one shred of evidence to suggest that there is any such thing as too much of it.
    It is still possible to buy carbon dioxide gererators for greenhouses, to make the plants grow.
    More plant growth means more oxygen.
    Every piece of evidence from the past, shows quite conclusively that extra carbon dioxide occurs after warm periods. In not one single instance, does it occur in advance of a warm period. the IPCC saw to the closure of over 1000 weather stations, all of them in colder regions. Ghe mean temperature has been steadily dropping through the 1990s. 40,000 climateologists have signed a petition urging governments to think again. We are headin g into a very cold period. Even the UN no longer talks of Global warming. It is now Climate change, which can mean whatever you want it to mean. Do not confuse polution with climate change. We all want to stop polution.

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