400 parts per million for the first time in 3 million years

28 04 2013

The world’s CO2 levels are on the cusp of 400 parts per million (ppm) in the atmosphere for the first time in some 3 million years……

The daily CO2 concentration at the Mauna Loa Observatory in Hawaii, was measured at

David Keeling pointing at Keeling Curve charts

David Keeling pointing at Keeling Curve charts

399.72 ppm last Thursday.  A few hourly readings had already gone over 400 ppm. ”I wish it weren’t true, but it looks like the world is going to blow through the 400 ppm level without losing a beat,” said Ralph Keeling, son of Charles David Keeling.  Keeling was the first to confirm the rise of atmospheric carbon dioxide by very precise measurements producing a data set now known widely as the “Keeling Curve.”  Ralph is a geochemist at the US Scripps Institution of Oceanography, which operates the Hawaiian observatory. ”At this pace we’ll hit 450 ppm within a few decades” he said…

The 450 ppm level is considered the point where the world has a 50% chance of avoiding catastrophic climate change.  Any higher, and the odds of avoiding searing temperature rises of four or five degrees by 2100 become prohibitively risky.

The last time CO2 reached the symbolic milestone of 400 ppm in the atmosphere – in the Pliocene era – temperatures were three to four degrees higher than today, and sea levels were between five and 40 metres higher. Carbon dioxide levels have been rising since the measurements began at the observatory in 1958, and recorded 317 ppm.

It comes as Australia’s Climate Commission will release a report today (April 29 2013) on global action to reduce emissions. The US and, particularly, China are moving into leadership positions on greenhouse gas cuts, according to this report, “The Critical Decade: Global Action Building on Climate Change”.

Growth (ie, not consumption!) in coal use in China had declined and renewable energy had expanded on a massive scale.  Chinese wind power generation had increased almost 50-fold between 2005 and 2012, and solar power capacity rose by 75 % in 2012.

Australia doubled its renewable energy capacity between 2001 and 2012 (from a base of virtually zero), but is at risk of being left behind by other nations, according to the head of the Climate Commission, Tim Flannery. ”We are the 15th largest emitter in the world, larger than 180 other countries,” Professor Flannery said. ”We are more influential than most of us think.”