Twenty years ago, at the Earth Summit in Rio de Janeiro, the world’s governments negotiated a treaty — it’s known as the United Nations Framework Convention on Climate Change — in which they promised to stabilize atmospheric concentrations of greenhouse gases “at a level that would prevent dangerous anthropogenic interference with the climate system.” Some 192 countries, including the U.S. and China, signed on.
Since then, the UN, politicians and climate campaigners all have labored to get the world’s major economies to curb the use of fossil fuels. They haven’t had much success. President Obama failed in his first year of office to move national climate legislation through Congress. Australia did recently enact a national greenhouse gas law, and several U.S. states, including California and parts of the Northeast, have cap-and-trade programs. China, Vietnam, Costa Rica, and at least a dozen other emerging nations are implementing emissions trading.
Even these nations are not making a dent in the problem. Annual global emissions of greenhouse gases have grown by nearly 45 percent since the 1992 Earth Summit. Atmospheric concentrations of carbon dioxide, the most important greenhouse gas, are climbing steadily. The past decade was the hottest globally on record, followed by the 1990s, followed by the 1980s. The longer we wait to address climate risks, the harder they’ll be to address.
With roughly 50,000 assembling for the Rio+20 Summit, maybe it’s time for a new approach. Amid a faltering global economy, no country wants to stop burning oil, coal and natural gas. Might there instead be a way to clean up–or recycle–the CO2 they generate?
That’s precisely what a handful of scientists and entrepreneurs are aiming to do. They have launched startup companies that are building machines to capture CO2 from the air, with the backing of well-to-do investors including Bill Gates and Edgar Bronfman Jr. They hope to develop what are called “negative emissions technologies” — a technical phrase for machines that suck carbon dioxide out of the air. At least in theory, they could dial back CO2 concentrations if they exceed safe levels, as some scientists say they already have.
Direct air capture of CO2 “opens up the possibility of capturing more CO2 than is being emitted by point sources – in other words, taking them carbon negative, not just carbon neutral,” says Nicholas Eisenberger, a strategic advisor toGlobal Thermostat, an air-capture company started by his father, Peter Eisenberger, a physicist and the founding director of the Columbia Earth Institute.