Forget any notion of billions of years: the stars may go out within decades if they become the next victims of climate change, at least as far as Earth-based observers are concerned. That’s if one of the current favourite “plan B” methods to cool the Earth’s climate through geoengineering goes ahead. It’s not only astronomers who’ll suffer, either: anyone who enjoys the Earth’s characteristic “blue skies” had better hope that we cut emissions drastically soon enough for the injection of sulphur particles into the atmosphere to become unnecessary.
It has become clear to many over the last few years that humanity’s ability to cut carbon emissions quickly enough to stave off catastrophic warming is by no means guaranteed. As a result of this, several methods of “geoengineering” the planet’s climate, by blocking incoming light from the sun or planting huge swathes of trees to absorb carbon dioxide, have been proposed to artificially cool the planet down whilst emissions of carbon dioxide and methane continue to rise. Proposed methods include the erection of giant mirrors in orbit around the Earth to directly block the sun’s light, though this is likely to be very costly and it would perhaps take too long for the technical challenge posed by such an idea to be overcome. More ecological methods, such as planting trees, have been criticised because of the sheer scale of foresting required, which would make it necessary to plant trees on land that would naturally be bare of such plant-life, such as certain deserts, which could disrupt ecosystems and weather patterns. The injection of iron filings into the oceans to absorb carbon dioxide has met with wide protest from environmental groups and fishermen alike, as it has been shown to have a directly detrimental effect on marine ecosystems and could even cause extinction in the sea on a larger scale than climate change alone.
These methods have obvious drawbacks, however, one of the clear favourites amongst geoengineering enthusiasts has become a technique with neither prohibitive cost nor direct biological impact. That is, the injection of sulphite particles into the atmosphere, inspired by the cooling mechanism employed by the planet itself every time there is a volcanic eruption. On the face of it, this is a perfect solution: it allows an easy way out to the climate change conundrum, quickly and cheaply. The sulphite particles, mimicking the action of volcanic gasses, will produce a protective haze around the globe, reflecting the sun’s radiation and perhaps allowing the warming of the planet that has occurred over the last few decades to be reversed.
But that’s not such a good idea according to a recent report by the Royal Meteorological Society into the value of our atmosphere. The report lists twelve roles played by the atmosphere to the benefit of humanity, every single one of which will, it goes on to claim, be adversely affected by the quick-fix solution to climate change that is the sulphite injection. The report cites amongst the probable effects of such geoengineering ozone depletion, adverse weather changes, a reduction in the efficiency of the very solar power cells that are touted as a potential solution to the world’s energy problems and – most worrying of all – an end to blue skies by day and stars by night everywhere on Earth, making optical astronomy impossible and dooming mankind to a future of grey skies. Indeed, models suggest that the particles, acting as catalysts for the breakdown of ozone in the upper atmosphere, will delay the repair of the ozone layer, and that the “protective” haze that they form in the atmosphere, much as it does during volcanic eruptions, will leave the sky no better than translucent by day and night.
It would be a worthy sacrifice, you might think, to forfeit clear skies for a few years, decades even, whilst the issue of climate change is dealt with. But that, say climate scientists, is simply not an option. The only case in which geoengineering on this scale might be employed would be that in which the world’s politicians were unable to agree to stringent enough cuts in greenhouse gas emissions. If sulphite particle injection is used, therefore, emissions will continue to rise as sulphate particles are put into the atmosphere. The particles themselves will disperse over months and years, but that will leave the Earth vulnerable, after continued emissions, to a sudden increase in temperature as the cooling effect disappears, causing the exact same problem to resurface. The implications of this are clear: once humanity begins injecting sulphite particles into the atmosphere to promote global cooling, it will never, in the foreseeable future, be able to stop, lest disastrous global warming occur.
The “plan B” for combating climate change, then, is not one to be entered into lightly. If we as a planet rely on geoengineering to compensate for our greenhouse gas emissions, leaving cuts in emissions to be too little and too late, we will be forced into an ugly position. If we want to avert catastrophic warming without putting the stars out forever, we cannot rely on geoengineering in the way it is currently envisaged. Humanity must, therefore, devise a way of cutting emissions rapidly, or of cooling the planet without such adverse drawbacks, or we will be forced to face the prospect, just four centuries after Galileo first pointed his telescope up at the celestial sphere, that we may very soon have to pack up our telescopes and say goodbye to the cosmos at large as the stars fade one final time.