Cut Carbon Now to Avoid Climate Tipping Points

By Tim Radford, Climate News Network

    A helicopter lifts off from the Greenland ice sheet, whose melting is considered a possible tipping point. (Brocken Inaglory via Wikimedia Commons)

This Creative Commons-licensed piece first appeared at Climate News Network.

LONDON — An international team of scientists has tried a new approach to addressing the complex argument about the costs of climate change — and, once again, the prediction is that the costs of inaction will be so much greater than paying the bills now.

The researchers — from the UK, Switzerland and the US — conclude that policy-makers must apply the brakes and put a high price on carbon emissions “before it is too late”.

Much of the argument on this issue revolves around the perceived cost of carbon emissions and any tax that should be imposed on fossil fuel use. Social scientists and economists and climate modellers have tried a number of approaches.

One group tried to work out the interval between the burning of fossil fuels and the consequent greenhouse warming, and concluded it could be as little as 10 years.

Other groups have separately tried to calculate the true cost of emitted carbon dioxide. The US government works on the basis of $37 in social costs per tonne emitted, but two US scientists proposed that the true cost in future health and habitat losses was probably six times higher.

“The additional carbon tax that our model recommends can be thought of as an insurance premium levied on society.”

And yet another researcher began to examine the costs of petrol, or coal, or methane gas if the long-term economic damage and health costs were factored in, and concluded that these made “expensive” renewables cheap by comparison.

Now researchers from the universities of Exeter in the UK, Zurich in Switzerland and Chicago and Stanford in the US report in Nature Climate Change that they considered the risk that emitted greenhouse gases from fossil fuels would push the planetary climate system closer to what climate scientists call “tipping points.”

These are outcomes that would irreversibly change regional climate patterns, disrupt agriculture, precipitate greater flooding in some places, more sustained droughts in others, and accelerate sea level rise.

And, once again, they find that governments have underestimated the price to be paid by society for carbon dioxide emissions from fossil fuels.

“We are calling on policy-makers to respond to the prospect of triggering future climate tipping points by applying the brakes now and putting a high price on carbon emissions before it is too late,” says one of the authors, Tim Lenton, professor of climate change and earth system science at the University of Exeter.

“The additional carbon tax that our model recommends can be thought of as an insurance premium levied on society to delay irreversible changes in the future.”

The researchers selected five potential tipping points — all of which have separately been in the news recently. They relate to:

• The collapse of the Atlantic Ocean’s meridional overturning circulation
• The irreversible melting of the Greenland ice sheet
• The collapse of the west Antarctic ice sheet
• The dieback of the Amazon rainforest
• An increase in that cyclic phenomenon known as El Niño Southern Oscillation, which disrupts climate on both sides of the Pacific Ocean — sometimes with devastating consequences.

The researchers say their act-now, save-future-costs model not only demonstrates the dangers of underestimating the cost of future climate change, but is the first one to emerge from a purely market-based approach. The considerations do not have to be based on moral judgements about sustainability and the wellbeing of future generations.