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Cut Off The Greenhouse Gas Emissions (Graph Of The Day)

This article was originally published on RenewEconomy.

Addressing climate change is seen as the greatest challenge of our time – morally, industrially and financially. But are we making the problem too complex? Benoit Lebot, from the United National Development Program, certainly thinks so. He says we just need to cut fossil fuel use in half and plant more trees.

Lebot spoke this week at the 2nd Annual Australian summer study on Energy Efficiency and Decentralised Energy. He used this image of a filling bath tub to illustrate his point.

The world has agreed to limiting greenhouse gas emissions to 450 parts per million. It might have been better to cap them at 350ppm, but the world is already at 394ppm, and it currently has a big tap (actually composed of  billions of smaller ones) that is emitting 32 gigatonnes of Co2 equivalent a year. Natural carbon sinks and sequestration is taking out 15GT/Co2-e, and the gap is 17GT//Co2-e.

“The only way to stabilise greenhouse gas emission is to reduce the tap,” Lebot says. “Sure, plant some trees, but we have to reduce global greenhouse gas emissions by half. We are making things more complex than they are.”

Lebot says the level of greenhouse gases is determined by population, wealth, the amount of carbon in the energy system, and the efficiency of the energy system. The growth of the population and standards of living is inevitable, so the action plant needs to focus on the last two.

He proposes four wedges. The first two are a slight variation to the energy  efficiency narrative pushed by the likes of the International Energy Agency, because it includes a separate category of behaviour – changing the way we use the energy system.

This is combined with energy efficiency to create “energy conservation.” The other wedges are renewables and sequestration.

The complications come from deciding who should do what. As this graph to the    right shows, based on the amount of emissions per capita, the north (developed countries) should reduce their emissions by 80 per cent.

The south (developing countries), still need to grow their economies quickly, but in a more carbon constrained way than the north did.The south still has to cut emissions by 20 per cent.

Lebot’s concern is that delay simply makes the task harder. The most important thing is to accept size of effort that is needed. But this is something that politicians are reluctant to do.

The graph on the right shows the various trajectories. The red line illustrates a later start, requires more dramatic effort to make up for lost time.

“The more time we spend disagreeing, the harder the target,” Lebot says. ”When you start skiing, you never start on steepest slope.”


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Written By

is the founding editor of, an Australian-based website that provides news and analysis on cleantech, carbon, and climate issues. Giles is based in Sydney and is watching the (slow, but quickening) transformation of Australia's energy grid with great interest.


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