Geoengineering: Could far-fetched plans really halt climate change?

Analysis: Proposals include painting cities white and installing giant mirrors in Earth’s orbit

Twelve years to save the world. That is all we have, according to climate scientists who warn that global warming is the existential threat of our time.

Yet still global greenhouse emissions show no sign of peaking. A recent study found there is just a 5 per cent chance of us limiting warming to less than 2C by 2100. If we continue as we are, radical solutions are needed.

Authors of the Intergovernmental Panel on Climate Change report say it could be possible to limit warming to the best-case scenario of 1.5C. However, there’s a big catch: every one of the possible outcomes involves actively modifying the atmosphere. This technology – called geoengineering – does not currently exist.

This is why the University of Cambridge is launching a new research lab called the Centre for Climate Repair. They want these bonkers ideas to become a reality – and quickly.

Very broadly, there are two types of geoengineering. First there is greenhouse gas removal, which involves removing greenhouse gases from the atmosphere. Second is solar radiation management (SRM), which involves reflecting sunlight away from Earth.

One idea scientists are looking at is spraying salt water into clouds over the Arctic so they reflect more heat back to space. Another proposal is to re-green the planet on a vast scale. More far-fetched proposals include painting cities white and installing giant mirrors in Earth’s orbit.

The most popular SRM solution is injecting tiny reflective particles into the stratosphere which could shield us from the sun’s rays. Massive sprayers would be attached to huge floating balloons.

This idea wouldn’t reduce the amount of greenhouse gases in the atmosphere. This means if we did enter into a dystopic geoengineered world, we would be locked into spraying these particles indefinitely.

If war or technological difficulties meant spraying abruptly stopped, we would quickly boil.

Geoengineering divides people, and little research is currently being done on it. The ideas are hard to test and there’s limited funding at the moment.

It also raises difficult ethical questions about governance – who decides whether these ideas go ahead and who pays if they go wrong?

Some are concerned pinning our hopes on vast geoengineering technology might also divert us from the job in hand: cutting emissions and doing it quickly.

We still don’t know which technology might work, and the move to open a research centre in Cambridge is a step in the right direction. Necessity is the mother of invention; ideas that seem ridiculous now might not seem so ridiculous in a few years’ time.