Greenhouse gas passes symbolic 400ppm level

June 1, 2012

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

Al Gore - this is further evicence
that this world's political leaders,
with a few honourable exceptions,
have failed to address the
world's climate crisis.

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,” Butler said. 

 Former vice president Al Gore, the highest-profile campaigner against global warming, said in an email 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. History will not understand or forgive them.

It’s been at least 800,000 years – probably more – since Earth saw carbon dioxide levels in the 400s, Butler and other climate scientists said. Readings are coming in at 400 and higher all over the Arctic.

They’ve been recorded in Alaska, Greenland, Norway, Iceland and even Mongolia. But levels change with the seasons and will drop a bit in the summer, when plants suck up carbon dioxide, NOAA scientists said.

So the yearly average for those northern stations likely will be lower and so will the global number. “It’s an important threshold,” said the Carnegie Institution ecologist Chris Field, a scientist who helps lead the Nobel Prize-winning Intergovernmental Panel on Climate Change. “It is an indication that we’re in a different world.”