Even if humans miraculously halted all carbon emissions next week, the problem of climate change would be an inescapable and grim reality as most of the heat-trapping gas would linger in the atmosphere for decades or even centuries. The inertia in the world’s warmed oceans would prevent a quick return to cooler temperatures, even as the CO2 levels decrease. The most optimistic predictions for the rest of the century, cited by the Intergovernmental Panel on Climate Change in its 2007 assessment report, forecast a rise of 2.0 to 5.2 degrees by 2100, while the direst anticipate a rise of 4.3 to 11.5 degrees. Among the anticipated effects are rising sea levels, increasingly severe storms and droughts, and melting glaciers and permafrost.
So what exactly is geoengineering then, a concept given some unexpected attention and increasing legitimacy by its mention in the most recent IPCC report? It refers to methods that “aim to deliberately alter the climate system to counter climate change.” The rather controversial area of engineering Earth’s climate seems to now be firmly planted on the scientific agenda. Some climate models suggest that geoengineering may even be necessary to keep global temperatures within the 2 °C above pre-industrial levels mark, agreed upon by the scientific and international community as the “tolerable” level. Most geoengineering technologies generally either reflect sunlight — through artificial “clouds” of aerosols, for example — or reduce the amount of greenhouse gases in the atmosphere. Reducing greenhouse gases generally involves carbon-capturing technologies that range from building towers to collect it from the atmosphere to grinding up rocks to react with CO2 and take it out of circulation. Solar geoengineering involves ideas including deflecting sunlight away from the earth with massive space shields or with clouds over oceans.