If the governments of the world can’t get their act together and cut greenhouse gas emissions soon, the world will need plan B.
That backup plan, according to a report this week from the Royal Society, is for science to help save the day through geoengineering. This includes technologies that suck carbon dioxide out of the air. Or perhaps shading the Earth’s surface from the sun’s rays by spewing aerosols into the stratosphere.
Slashing emissions is the number one way to address climate change, the Society reaffirms. But if political talks on reducing emissions get stuck – and they very well might – geoengineering will be the only game left in town to fend off serious global warming.
Every geoengineering technique carries risks for people and the planet, the report warns. But some are better than others.
Technologies that strip carbon dioxide out of the air get the best marks in the report. There’s a catch, of course. So far, no method except the planting of trees can lock away atmospheric CO2 cost-effectively. And only so much land on Earth can grow trees.
Ranking next among geoengineering techniques according to the Society, are technologies to block sunlight, such as giant, space-based mirrors. These could lower surface temperatures quickly. But they won’t do a darn thing about other key effects of a rising CO2 level -- notably the increasing acidity of oceans and the havoc it would wreak on ocean ecosystems.
Other geoengineering schemes got a “lower potential” rating from the Society. One is adding fertilizer to the ocean to stimulate algal growth -- in hopes of increasing photosynthesis to extract more CO2 out of the air. Not proven effective, the report says of this technology, and “high potential for unintended and undesirable ecological side effects”
Some geoengineering ideas are duds, the report finds, such as installing reflectors in the desert in an attempt to mirror light back into space. The Society smacked down an idea touted by U.S. Energy Secretary Stephen Chu – painting roofs white. While painting roofs white can save on energy for air conditioning, adopting them for geoengineering purposes, like deploying reflectors in deserts, is, the report says, ineffective and expensive.