Amount of carbon dioxide in air keeps rising, hits milestone

Global CO2 Levels Tick Past 400 Parts Per Million

WASHINGTON (AP) - Global levels of carbon dioxide, the most prevalent heat-trapping gas, have passed a daunting milestone, federal scientists say.

The National Oceanic and Atmospheric Administration says in March, the global monthly average for carbon dioxide hit 400.83 parts per million. That is the first month in modern records that the entire globe broke 400 ppm, reaching levels that haven't been seen in about 2 million years.

"It's both disturbing and daunting," said NOAA chief greenhouse gas scientist Pieter Tans. "Daunting from the standpoint on how hard it is to slow this down."

He said it is disturbing because it is happening at a pace so fast that it seems like an explosion compared to Earth's slow-moving natural changes.

Carbon dioxide isn't just higher, it is increasing at a record pace, 100 times faster than natural rises in the past, Tans said.

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Amount of carbon dioxide in air keeps rising, hits milestone
Evening rush hour traffic comes to a standstill on a hazy and polluted day in Beijing on December 1, 2010. China has met its 2010 target to cut emissions of key pollutants and is on track to meet its energy efficiency goal, state media said, quoting the country's top climate change official as saying after China last week acknowledged it had become the world's biggest emitter of the greenhouse gases that are blamed for climate change and global warming, surpassing the United States, though not in terms of emissions per capita. China's efforts to improve energy efficiency allowed for savings of 490 million tonnes of coal and prevented carbon dioxide emissions totalling 1.13 billion tonnes in 2006-2009, state media reported. AFP PHOTO/Frederic J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
NEWBURG, MD - MAY 29: Emissions spew out of a large stack at the coal fired Morgantown Generating Station, on May 29, 2014 in Newburg, Maryland. Next week President Obama is expected to announce new EPA plans to regulate carbon dioxide emissions from existing coal fired power plants. (Photo by Mark Wilson/Getty Images)
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LONDON - MARCH 25: Marketing manager Nick Cliffe of the 'Closed Loop Recycling' plant walks people through the recycling process on March 25, 2010 in London, United Kingdom. The state of the art plant is the first in the UK to produce food grade recycled plastic from bottle waste. Over 35,00 tonnes of plastic bottles are recycled at the plant annually, representing almost 20% of the plastic bottles currently collected for recycling in the UK, and saving approximately 52,500 tonnes of carbon dioxide per year. (Photo by Dan Kitwood/Getty Images)
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Pushed by the burning of coal, oil and gas, global carbon dioxide is 18 percent higher than it was in 1980, when NOAA first calculated a worldwide average. In 35 years, carbon dioxide levels rose 61 parts per million. In pre-human times, it took about 6,000 years for carbon dioxide to rise about 80 parts per million, Tans said.

Monthly levels fluctuate with the season, peaking in May and then decreasing as plants absorb carbon dioxide. But they are increasing on a year-to-year basis.

Levels are also higher in the Northern Hemisphere because that's where carbon dioxide is being spewed by power plants and vehicles, Tans said.

The first time levels passed the 400 ppm milestone was for just a few weeks in the Arctic in 2012. Last year the monthly Northern Hemisphere average measured in Hawaii exceeded 400 and now the global average has as well, said James Butler, head of NOAA's global monitoring division.

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NOAA: http://1.usa.gov/1IgDMQK

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Seth Borenstein can be followed at http://twitter.com/borenbears

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