Giant Space Mirrors. Isn’t it worth a try to help reduce emissons.

Risky and unorthodox technologies such as giant space mirrors or capturing CO2 from the ambient air may be required backups to blunt the effects of climate change if emission reductions prove to be too little, too late, says a new report from the Royal Society.

As politicians from around the world continue to argue over how to reduce greenhouse gas emissions in the lead-up to a December meeting in Copenhagen, the new report –authored by British and American researchers, and University of Calgary environment and energy physicist David Keith–says any effort may not be enough to avoid “dangerous climate change” this century.

Global emissions continue to increase at a rate of about three per cent each year, and the Royal Society–the national academy of science of the U. K. and the Commonwealth–argues that nothing should divert nations from the goal of reducing greenhouse gases.

But the society says Plan B for cooling the Earth is geoengineering, or deliberate, large-scale intervention in the Earth’s climate system.

Keith said Tuesday that this is the first major scientific report to focus entirely on geo-engineering. The ideas presented aren’t new, but many scientists have previously considered them “taboo.”

“Many responsible people, sometimes including me, . . . have had the view that if we talk about this, people will not be as serious about cutting emissions,” he said. “It’s called moral hazard, and that’s the big concern.”

But Keith said the response to rising CO2 levels is hard to predict.

“Cutting emissions is necessary to manage climate risk, but it’s not necessarily sufficient,” he said.

“CO2 stays in the atmosphere basically forever. So even if you cut emissions to zero tomorrow –which obviously isn’t going to happen–there’s some risk. And that risk grows everyday. And a sensible policy to address that risk includes the ability to engineer the planet.”

The report, titled Geo-engineering the Climate:Science, Governance and Uncertainty, divides geo-engineering into two classes: techniques that remove CO2 from the atmosphere, and solar-blocking schemes that reflect a small percentage of the sun’s light and heat back into space.

The techniques that remove gas from the atmosphere include planting trees on land that historically has not contained forests, and removing C02 from the ambient air.

Futuristic solar radiation management techniques include brightening roofs by painting them white, planting crops that reflect light, covering deserts with reflective material and using ships to create white clouds over the ocean.

Many of the schemes are pricey, but could work quickly in an emergency and have an impact within a few years, the report said.

Large mirrors sized 100 square metres each or a swarm of reflective materials in space could work.

Most effective and practical among them all, Keith said, is increasing

cloud reflectivity and mimicking the effects of volcanic eruptions by spreading sulphate aerosols into the lower stratosphere.

But the fast-acting solutions might also have the greatest side-effects on ozone levels and rain cycles.

Potentially, solar interference infrastructure would need to be maintained for centuries, and would be an disincentive for actual emission reductions.

“It would be risky to embark on the implementation of any large-scale solar radiation management methods,” the report said, “without a clear and credible exit strategy.”

The report calls for an international research program, and for the British government to spend $178 million Cdn over a decade on research for geo-engineering. It notes that geoengineering will create a range of ethical and governance issues.

Critics do not dismiss the geoengineering schemes outright, but say they are a sign of scientists’ desperation following years of global inaction.

“The priority needs to remain squarely on reducing greenhouse gas emissions to avoid more warming, while adapting to the warming we’ve already caused,” said Clare Demerse of the Pembina Institute, an environmental think-tank.

The Alberta government has committed$ 2 billion for carbon capture and storage to capture greenhouse gases at industrial source-points.