Some like it hot?

Climate sceptic Bjorn Lomborg was in Dublin last Friday telling the folks at the IMI national management conference that everything’s just honky dory on the climate front – a business-as-usual message that was no doubt eagerly lapped up by that audience.

And who wouldn’t want to believe Bjorn? His Polyanna feel-good messages may fly in the face of everthing we know about climate; they even require a re-writing of the laws of physics, but hey, his messages sell lots of (his) books. They also muddy the waters sufficiently to allow lots of people who really should know better to wriggle off the hook for another year or two in terms of facing up to the monumental challenges that are now upon us.

One body which cannot be said to be welching on facing the challenges of climate change is our own EU. It has mandated that CO2 levels must not be allowed to exceed 550 parts per million (ppm). They currently stand at 385, and are rising rapidly, at 2-3ppm a year.

That’s the good news. The bad news is, according to one of the world’s most respected climate scientists, Dr James Hansen, head of the NASA Goddard Institute for Space Studies in New York, if we allow CO2 levels to hit 450ppm, let alone 550ppm, we’re on the proverbial highway to climate hell.

In other words, the EU targets are hopelessly optimistic and fail utterly to take into account the way the earth actually responds to climate forcings. Hansen says we have in fact already crossed the line into potential climate catastrophe, and we need to drastically rein in emissions with a view to getting us back towards 350ppm (a figure we actually passed in 1990).

We need to achieve this if “humanity wishes to preserve a planet similar to that on which civilisation developed”, is how Hansen, with typical bluntness, puts it. “If you leave us at 450 ppm for long enough, it will probably melt all the ice — that’s a sea rise of 75 metres. What we have found is that the target we have all been aiming for is a disaster — a guaranteed disaster.”

At levels as high as 550 ppm the world would warm by 6 degrees, a paper Hansen co-wrote with 8 other scientists argued. Previous estimates had put warming at 3 degrees at that point. “If we follow business as usual, I can’t see how West Antarctica could survive a century,” he said. “We are talking about a sea-level rise of at least a couple of metres this century.”

What makes this new analysis different is that instead of using theoretical models to estimate the sensitivity of the climate, the scientists have examined direct physical evidence from the earth’s history, which they say gives a much more accurate picture.

While Hansen has made the headlines in the last number of years for publicly locking horns with the Bush administration, he is one of the true heavy-hitters in climate science and his views cannot, despite what the Lomborgs of this world might say, be dismissed out of hand.

He has actually downgraded his own previous estimates that 450ppm was the ‘safe’ point that we had to aim to keep emissions below. One of the main reasons for his reassessment is what he calls ‘slow feedback’ mechanisms which are only now becoming fully understood.

The ice albedo effects as witnessed vividly in the accelerated warming in the Arctic region are a classic case of ‘slow feedback’ producing dramatically greater real-world warming than the models would otherwise predict.

Hansen is no Chicken Licken. His warnings at the very least deserve to be closely examined. The sceptics may say ‘what if he’s wrong?’ A more useful question might be: ‘what if he isn’t?’