Guest essay by Eric Worrall

Good news – we’re finally about to hit a tipping point. The only problem is, nobody will be able to tell the difference.

Climate change ‘tipping point’ could be reached in four weeks

6.6.16 is almost the devil’s number, but it might be much more than that if a leading scientist’s prediction on climate change is correct.

CSIRO fellow Dr Paul Fraser has earmarked June 6 (“plus or minus a week”) as the day when carbon dioxide concentration in the atmosphere will hit the point of no return, 400 parts per million (ppm).

The atmospheric measuring station at Cape Grim in Tasmania has recorded the current C02 levels in the atmosphere at 399.9ppm.

Dr Fraser said the difference between 399 and 400ppm was trivial, but when it does hit 400ppm mark it would be a “psychological tipping point”.

“Once it reaches 400ppm at Cape Grim it’s very unlikely to drop below 400 again,” Dr Fraser told ninemsn.

…

Cape Grim’s stable environment offers a clearer forecast for the world’s climate change.

“When you get away from the cities and into the background air, that’s the one that really drives climate change, that’s in terms of representing the entire globe,” Dr Fraser said.

To put the 400ppm into perspective, Dr Fraser said if you stood near a highway with cars going past, you could be hit with 500ppm of CO2.

At the higher end of the scale, a smoggy day in the densely polluted cities of Beijing or Shanghai could see carbon figures as high as 600ppm to 700ppm.

When 400ppm becomes the norm in country air, the cities will feel the pain a whole lot more.