Blog Spot
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Alun James
Cool heads needed in a warming climate
A climate milestone, highest in
human history, a mayday call by the
planet. However it's portrayed, it's
a disheartening fact that on May 9th
the concentration of carbon dioxide
in the atmosphere, as measured by an
observatory in Hawaii, topped the
symbolically important level of 400
parts per million.
So what's the big deal with 400? Well,
climate experts say it's a CO2 level the
planet hasn't seen for more than three
million years. It's also a warning that
we're heading for 450ppm within a few
decades – this being the level which
gives us a 50:50 chance of keeping
average global warming to less than
2°C, the internationally agreed limit.
It's worth noting that before
the industrial revolution the CO 2
concentration was about 280ppm but
since then we have released more than
375 billion tonnes of it, mainly from
the burning of coal, oil and gas.
