Their proposals to combat global warming may sound like science fiction, but geo-engineers insist they can save the planet. Two new reports show that while that may be the case, the science has a long way to go, the Economist reports. The burgeoning field posits that humans can cool the planet via unorthodox ideas such as dumping tons of iron into oceans. In theory, that boosts the growth of algae, which absorb carbon-dioxide emissions.
But one of the first major studies finds that benefits have been greatly overstated. A second casts doubt on several other ideas, including a massive solar shade to shield the earth from the sun: It would have to be half the size of Brazil. Any effective geo-engineering project would need to be massive, thus leading to huge side effects and the disruption of ecosystems—ensuring that the debate over global warming will remain heated.