Geoengineering could cause more harm than climate change

New research published in Nature Ecology & Evolution has come to the counterintuitive conclusion that attempts to fight climate change using technological remedies may well inflict greater damage to global biodiversity than global warming itself.

As anybody who has been watching recent American politics will know, political decision-making is often bewilderingly inconsistent, and this is true of all governments over a longer time scale. What seems like a good idea one day may become politically toxic the next, which means that the futures of all long-term projects are far from assured. They can be started or stopped rapidly or gradually, depending on political whim.  

This could seriously affect international, large-scale, long-term projects to manipulate the Earth’s natural system to fight global warming, a process called “geoengineering”. 

Geoengineering comes in two basic forms. The first attempts to remove human-made greenhouse gases, such as carbon dioxide, from the atmosphere and safely dispose of or store them out of harm’s way. The second is “solar radiation management”, which attempts to regulate the amount of the sun’s energy reaching the surface. 

The most likely method of implementing this second form of geoengineering, called stratospheric aerosol injection (SAI), involves the release of aerosols, mixtures of fine particles or liquids, in the very upper atmosphere in an attempt to reflect some of the sun’s rays and thus help cool the planet. {%recommended 6559%}

A team of researchers led by Christopher Trisos of the National Socio-Environmental Synthesis Centre at the University of Maryland, US, has now modelled the effects of abrupt changes in potential long-term SAI geoengineering projects.

The scientists imagine a scenario in which SAI projects continue to 2070 and then are quickly halted due, most likely, to mercurial politics. Using a geoengineering climate model simulation called the Geoengineering Model Intercomparison Project, or GeoMIP, they found that such a quick change would reduce global biodiversity more than global warming itself would.

The reason for this is to do with the rate of climate change.

“As climate changes, the appropriate conditions necessary for the persistence of a species move across the Earth, driving species’ geographic range movements in response to climate change,” write the authors. “Indeed, species that fail to track moving climates may go extinct, despite suitable climate conditions being present elsewhere.” 

As long as climate change is gradual enough, then, species will have a chance to adapt. 

The measure of the rate at which species-appropriate conditions move across the planet is dubbed “climate velocity”. The GeoMIP model has predicted that these velocities are much higher in anthropogenic SAI projects than those projected for global warming, which means that species have much less time to adapt and will face higher rates of extinction because of it.

Interestingly, the team found that the effect of rapidly ending a long-term SAI project would be more calamitous than starting one, as climate velocities “at termination are most extreme in tropical oceans, the biodiversity-rich Amazon Basin, Africa, Eurasia and polar region”.

Thus, while technology may have landed us in this predicament, it may not be able to get us out of it with biodiversity intact.