rabble blogs are the personal pages of some of Canada's most insightful progressive activists and commentators. All opinions belong to the writer; however, writers are expected to adhere to our guidelines. We welcome new bloggers -- contact us for details.

Crossing the 400 ppm line: Concentration of carbon dioxide reaches tipping point

Please chip in to support more articles like this. Support rabble.ca today for as little as $1 per month!

It's our annual membership drive! If you like this post, please consider becoming a supporting member of rabble.ca today.

We have now crossed a dangerous line in the global build up of greenhouse gases. Greenhouse gas concentrations have moved from the pre-Industrial Revolution level that never exceeded 280 parts per million (ppm) to a new daily average of 400 ppm, reached last week.

Over a period of the last million years, CO2 never exceeded 280 ppm (based on actual readings of atmospheric chemistry from Antarctic ice-core data). The last time greenhouse gases reached 400 ppm was three million years ago. Put simply, humanity has now changed the chemistry of our atmosphere to replicate pre-historic levels -- a time when no humans existed.

Concentrations of GHG are a very different measurement than emission rates. Concentrations have a very long lag time and will not be able to be decreased except over centuries, while emission rates can go down overnight. It is critical to start reducing emissions, because existing concentrations mean that we will see warming over the next 100 years from today's emissions.

CO2 levels are monitored daily at Mauna Loa Observatory on the island of Hawaii. When the monitoring station was set up in 1958, CO2 levels were at 317ppm. The rise to 400 ppm was not expected so soon. Meanwhile, the Canadian government has joined in a global commitment to hold concentrations of greenhouse gases to levels that would avoid allowing global average temperatures to rise by 2 C. Scientists have marked that wide red hazard line in a band between 425-450 ppm.

Avoiding 2 C is critical because it represents a danger zone. Some refer to it as a point of no return -- or a "tipping point" to self-accelerating global warming, the so-called "runaway greenhouse effect." The actual tipping point might be 2.5 C, or it could be 1.5 C. Two degrees represents a consensus of scientists, but no scientist I know is sanguine about two degrees. It is certainly not a safe zone.

The most recent International Energy Agency (IEA) World Energy Outlook includes some number crunching. If all the world's known reserves of fossil fuels were to be used, the climate would move the world to a non-habitable state.

In fact, the IEA has said that to avoid an increase of 2 C, at least two-thirds of known fossil-fuel reserves must stay in the ground until at least 2050.

The Over-rated Fossil Fuel Economy

This finding has led to a new and potentially powerful financial calculation. A major new report from the U.K., "Unburnable Carbon 2013: Wasted Capital and Stranded Assets," engaged the talents and expertise of Sir Nicholas Stern through a collaborative research project involving Carbon Tracker and the London School of Economics and Political Science's Grantham Research Institute for Climate Change and Environment.

The result is a new concept -- the "carbon bubble." The essence of their work is this: a great deal of the stated value of stock exchanges around the world is in unburnable fossil fuels. The level of capital expenditure in developing those reserves over the next decade would amount to $6.74-trillion in wasted capital -- developing reserves that simply cannot be burned.

The report calls for ratings agencies to update their approach to verifying the financial health of stock markets and individual companies. If assets being used to offset liabilities are assets that can never be used, then large parts of the economy -- now seen as credit-worthy -- are over-valued.

The consequence for financial markets is obvious. Meanwhile, the report notes that the carbon intensity of the New York and London stock markets is actually increasing; New York by 37 per cent over two years and London by seven per cent over two years.

The creative notion that Moody's and other credit raters might be able to do through financial valuations what governments have so far failed to do -- bring Big Oil to its senses -- is certainly tantalizing. What is encouraging is the extent to which the notion of a "carbon bubble" as financial risk is catching on.

Perhaps that's what we need -- a clear financial consequence our brains can comprehend. Maybe we should keep the focus on the financial threat, while acknowledging the irony that it may be easier to provoke change through large multinationals and stock exchanges than through thoughts of our children's dismal future.

Photo: freephoto.com

Thank you for reading this story…

More people are reading rabble.ca than ever and unlike many news organizations, we have never put up a paywall – at rabble we’ve always believed in making our reporting and analysis free to all, while striving to make it sustainable as well. Media isn’t free to produce. rabble’s total budget is likely less than what big corporate media spend on photocopying (we kid you not!) and we do not have any major foundation, sponsor or angel investor. Our main supporters are people and organizations -- like you. This is why we need your help. You are what keep us sustainable.

rabble.ca has staked its existence on you. We live or die on community support -- your support! We get hundreds of thousands of visitors and we believe in them. We believe in you. We believe people will put in what they can for the greater good. We call that sustainable.

So what is the easy answer for us? Depend on a community of visitors who care passionately about media that amplifies the voices of people struggling for change and justice. It really is that simple. When the people who visit rabble care enough to contribute a bit then it works for everyone.

And so we’re asking you if you could make a donation, right now, to help us carry forward on our mission. Make a donation today.


We welcome your comments! rabble.ca embraces a pro-human rights, pro-feminist, anti-racist, queer-positive, anti-imperialist and pro-labour stance, and encourages discussions which develop progressive thought. Our full comment policy can be found here. Learn more about Disqus on rabble.ca and your privacy here. Please keep in mind:


  • Tell the truth and avoid rumours.
  • Add context and background.
  • Report typos and logical fallacies.
  • Be respectful.
  • Respect copyright - link to articles.
  • Stay focused. Bring in-depth commentary to our discussion forum, babble.


  • Use oppressive/offensive language.
  • Libel or defame.
  • Bully or troll.
  • Post spam.
  • Engage trolls. Flag suspect activity instead.