As things stand, the Earth’s future does not look rosy.
Climate scientists say that increasing atmospheric concentrations of greenhouse gases such as carbon dioxide – largely the result of our insatiable appetite for fossil fuels – could push global temperatures up by as much as 5 degrees before 2100, leading to rising sea levels and ever more heat waves, droughts and floods. Many experts believe there is no choice but to slash greenhouse-gas emissions, yet the political will to do so is clearly lacking and those emissions continue to rise. This reality means that scientists are beginning to think the previously unthinkable – that we might need to deliberately interfere with the Earth’s climate to bring it back under control.
In a major report issued by the U.S. National Academy of Sciences (NAS) in February, a panel of 16 scientists underlined the continued importance of cutting emissions. Tinkering with the global climate now would be “irrational and irresponsible”, they insisted.
Even so, they argued that potentially “unmanageable and irreversible” risks associated with climate change make it “prudent” to explore so-called geoengineering or “climate intervention”. Their recommendation raised an immediate howl from opponents of geoengineering, including many environmental organisations, who argued that the risks of massive intervention with nature were simply too high and could potentially lead to conflicts among nations.
Stuart Haszeldine, a geologist at the University of Edinburgh, believes that while research can generate useful knowledge it can also bring the object of that research “closer to deployment”. He likens research on solar reflection to nuclear physics: “Once you have discovered how to split atoms and get energy out of them you are on a slippery slope”. He raises the prospect that a rich country deploying aerosols to cool its own territory or increase local rainfall might create drought in another part of the world. “These are fundamental moral questions,” he says. “Scientists alone can’t make those judgements. I think any scientific experimentation needs to be filtered through the prism of society more broadly”.
The NAS report focused on the two approaches: extracting carbon dioxine from the atmosphere and deflecting some of the Sun’s rays away from Earth. These are explained on the infographic above.
By Edwin Cartlidge @