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It is a beguiling idea: grow crops that suck carbon dioxide from the air, burn them to generate electricity, then bury the resulting CO2. The result? Less CO2 in the air, and less climate change.

This idea’s time has come. The new report of the Intergovernmental Panel on Climate Change (IPCC), published on Sunday in Berlin, Germany, says “widespread” use of bioenergy with carbon capture and storage (BECCS) will probably be needed to stop the world warming by 2 °C, the politically agreed danger threshold.

That reflects the urgency of the situation. After 20 years of talk, the world is still accelerating towards climate catastrophe. Emissions grew faster between 2000 and 2010 than in each of the three previous decades.


The IPCC blames economic growth, which now adds twice as much to emissions as population growth does. (The report does not cover the years since 2010, when emissions may have risen more slowly despite continued economic growth.)

The heart of the report is a study of over 1000 scenarios of possible energy and climate futures. It lays out what scientists believe it will take to keep global warming below 2 °C this century. Achieving a better-than-even chance will probably mean at least tripling the proportion of energy coming from low-carbon sources, it says.

The key is to generate electricity without emitting CO2. Low-carbon sources currently provide 30 per cent of electricity, mostly from dams and nuclear power. That must rise to 80 per cent by 2050, with solar panels and wind turbines coming to the fore. New forms of solar will also play a role .

“Mitigation does not mean the world has to sacrifice economic growth,” says Ottmar Edenhofer of the Potsdam Institute for Climate Impact Research in Germany, who co-chaired the report. But the burning of fossil fuel must virtually end by 2100, unless the emissions are buried using carbon capture and storage (CCS).

The report is neutral about nuclear power because of issues with nuclear waste, safety, proliferation and public image. But it does support natural gas as a “bridge technology” to replace coal until renewables take over or CCS becomes widespread.

Other cost-effective changes cited in the report include massive boosts to energy efficiency in industry and home heating, and reducing transport emissions through more efficient vehicles, more compact cities and more high-speed rail to cut air miles.

That’s the right idea, says Brian Hoskins of the Grantham Institute for Climate Change in London. “We already have the technologies,” he says. “We should stop wringing our hands and just get on with it.”

Keeping below a 2 °C rise probably means keeping CO2 concentrations in the air below 450 parts per million. We are already up from a pre-industrial 280 ppm to 400 ppm. Most scenarios the IPCC examined overshot 450 ppm and required recovery through “negative emissions” – BECCS, or some other CO2-sucking technology – later this century. CCS could be risky, but we may have no choice, the IPCC says.

The report should galvanise the UN negotiators who are drafting a global climate deal to be signed next year. But the hottest topic from the report may be its backing for negative emissions and CCS. It was published in Germany, a country with geology, climate policies and skills that make it an ideal test bed for the technology (see “German energy crisis points towards climate solution“). But the German public hates CCS. Last week Jochen Flasbarth, state secretary at Germany’s federal environment ministry, told New Scientist that buried CO2 is seen as almost as bad as nuclear waste.

Read more: Climate report 2014: Your guide to the big questions