Action 58. 400 ppm: This does not call for a celebration.


Latest reading: 399.29 ppm

CO2 concentration on May 2, 2013

Here’s a milestone to which I will not raise my glass: according to the Mauna Loa observation station, we are now skirting  400 ppm atmospheric CO2. This value was already surpassed in parts of the arctic last summer. This is the first time IN HUMAN HISTORY that we have seen this level of carbon dioxide in our atmosphere.

We hit 350 ppm in 1990; that’s the level we keep talking about as needing to return to in order to keep the worst impacts of climate change at bay. That number is quickly slipping away from us as a realistic goal. To recognize this unhappy milestone, I want to take this opportunity to recite the Bill McKibben trinity of climate change facts which I wish was plastered on the front door of every political entity on the planet:

1) Two degrees Celsius is the maximum temperature rise above the Holocene average the planet can experience leaving us any reasonable expectation of keeping Earth’s conditions within ranges that humanity has adapted to over our evolutionary history as a species. With lag effects, we are already more than half-way there.

2) 565 gigatons is the amount of carbon that we can burn before mid-century leaving any reasonable expectation of staying below that two degree threshold.

3) 2,795 gigatons is the amount of oil and gas the fossil fuel industry has in proven reserves, with ongoing explorations to claim even more.

To visualize where this path is leading us if we continue to sustain these levels of GHGs, I look to the author of a 2009 paper in Science, who describes the last time CO2 levels looked as they do now (15 million years ago): “The last time carbon dioxide levels were apparently as high as they are today — and were sustained at those levels — global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland.”

There’s no time for delaying massive, coordinated action to move us from the path we are on, folks. We need a sea change in our elected officials’ and public’s attitudes towards the importance of climate change, before the sea really changes, in ways that are really going to suck for us.


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