Last updated January 24, 2018 at 4:35 pm
Controlling the temperature of the earth using geoengineering might cause three times more ecological problems than it solves, and rapidly shutting it down could lead to mass extinctions.
It’s becoming increasingly difficult to achieve the climate goals the world has set for itself in the Paris agreement through emissions reduction alone.
It’s tempting to think that humans could come up with technical solutions to tweak the global thermostat.
Is there a technical fix for climate change?
This is where geoengineering steps into the picture.
There are a range of schemes that have been proposed to keep the earth cool: from giant space reflectors or cloud seeding from ocean aerosol sprays to prevent incoming solar radiation, to artificial trees or ocean fertilization to take up carbon out of the atmosphere.
The most commonly proposed, and technically one of the easiest and cheapest methods is stratospheric geoengineering, which involves pumping small, reflective particles into the upper atmosphere to reflect some sunlight before it reaches the surface of the Earth.
This technique could allow us to avoid overshooting to dangerous temperature increases, without having to depend on reducing and capturing existing CO2 emissions. It also has the benefit of being adjustable and reversible. But it’s not something you can turn off in an instant, and the impacts of doing just that are investigated in a new paper out today.
Rapid geoengineering could be an environmental disaster
Christopher Trisos from the University of Maryland and colleagues created a model to find out what happens to biodiversity if we turn on stratospheric geoengineering by 2020, but the political will to continue it suddenly stops 50 years later.
As the climate changes, animals and plants have to move or adapt. The world’s most biodiverse regions are in the tropics around the equator. If we were to switch on stratospheric geoengineering in 2020, it would slow down warming rapidly and provide some relief for organisms especially vulnerable to heat like corals.
On land, it would reduce the need for animals to migrate to cooler areas. But it would also likely lead to a rapid reduction in rainfall over Australia, increasing the rate of catastrophic bushfires.
The real problems start when you try to turn it off. Abruptly shutting off geoengineering would lead to a ‘climate shock’ as temperature rise 0.8°C within a decade. This speed of climate change is simply too fast for species to keep up, leading to breakdown of ecosystems and mass extinctions.
“Given current emissions trajectories, it would be irresponsible not to study the potential benefits and costs of proposed climate engineering” write the authors, but “aggressive emissions cuts remain the most robust way to reduce biodiversity impacts from climate change”.
Given humanities not-so-great track record of inconsistent political decision making, especially around such a controversial topic, the researchers argue for “extreme caution” in developing policies and governance mechanisms for geoengineering given their findings.