To put the number into perspective, remember the words of James Hansen from 2008: "If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted … CO2 will need to be reduced … to at most 350ppm."
No centenary or diamond jubilee then, just a clear round number on a path leading away from the climate which was the nursery to civilisation to a future, if unchanged, of certain greater chaos and upheaval.
What priority did Britain's national newspapers give this the following day, how did they rank it alongside other important events? The front pages, an obvious test, made interesting reading.
The Mirror, with glorious abandon, ran with an offer for a free trip into space, and something about the long-running Savile scandal. The Sun, more earthbound, led with a free trip to Legoland and something about retiring football manager Alex Ferguson. The Express had something about pensions and the Daily Mail warned about "deadly drugs for sale on Amazon". The Times ran with something about the Metropolitan police, and the Telegraph with a story about a No 10 adviser. The Financial Times stayed in its comfort zone with another tale of corrupt banking. Even the Guardian, which did cover the story inside its paper and online, gave front page priority to a report on how horsemeat was still galloping out of control through our food chain. Only the humble Independent splashed the story on its front page.
Such lassitude concerning events that determine our chances of collective, convivial survival, may explain why the British establishment in the form of the House of Commons Transport Committee saw nothing wrong in picking the same day to call for the expansion of aviation – the transport mode most targeted to wreck the climate.
This lack of consensus on media and political priorities contrasts with the scientific consensus, with various studies of peer-reviewed literature demonstrating vanishingly little disagreement over the reality and critical importance of addressing human-driven global warming.
Scientists at the University of California, Berkeley recently co-ordinated a "consensus statement", signed by over 500 scientists from around the world, that concluded our current economic path is rapidly taking us to a tipping point, and that the result will be substantial degradation of human quality of life.
Beyond that consensus, out of sight is out of mind. But we could tackle that with one simple innovation. The press and broadcast media daily report a handful of dull statistics. We're told about exchange rates and the performance of stock markets in a way that reinforces a prejudice that such things are what truly matter. Why not meet the real world half way, and add a daily notification of the rising CO2 level to every daily paper and major news broadcast? It won't cost extra, will be harder to ignore and the price of doing so will be very high indeed.
Andrew Simms is a fellow of the New Economics Foundation, and the author of Ecological Debt, Tescopoly and Eminent Corporations
The Ecologist is a member of the Guardian's Environment Network article swap.
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