'Unlikely' that global warming can be limited to 2 degrees C (3.6 degrees F)

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Greenhouse gas levels pass symbolic 400ppm CO2 milestone

Monitoring stations in the Arctic detect record levels of carbon dioxide, higher than ever above 'safe' 350ppm mark

Associated Press
guardian.co.uk, Friday 1 June 2012 12.50 BST

The world's air has reached what scientists call a troubling new milestone for carbon dioxide, the main global warming pollutant.

Monitoring stations across the Arctic this spring are measuring more than 400 parts per million of the heat-trapping gas in the atmosphere. The number isn't quite a surprise, because it's been rising at an accelerating pace.

Years ago, it passed the 350ppm mark that many scientists say is the highest safe level for carbon dioxide. It now stands globally at 395.

So far, only the Arctic has reached that 400 level, but the rest of the world will follow soon.

"The fact that it's 400 is significant," said Jim Butler, the global monitoring director at the National Oceanic and Atmospheric Administration's Earth System Research Lab. "It's just a reminder to everybody that we haven't fixed this, and we're still in trouble."

"The news today, that some stations have measured concentrations above 400ppm in the atmosphere, is further evidence that the world's political leaders – with a few honourable exceptions – are failing catastrophically to address the climate crisis," former vice president Al Gore, the highest-profile campaigner against global warming, said in an email. "History will not understand or forgive them."

(Continued here.)