<h2 class="wp-block-heading eplus-wrapper">Marvellous madness?</h2>

The team braving temperatures of -45C in the Arctic Circle are short of support. "The vast majority of polar scientists think this is never going to work out," says University of Exeter glaciologist Professor Martin Siegert. "It is quite insane in my opinion," says Professor Julienne Stroeve, a polar climate scientist at the University of Colorado Boulder.¹

The two are criticising a project by Cambridge University's Centre for Climate Repair. Its aim is to thicken Arctic sea ice enough to stop it melting, and perhaps even reverse that process.

The project is a form of geoengineering - an attempt to alter Earth's climate system to compensate for the damage caused by human activity.

It involves drilling a hole in the ice and pumping 1,000 litres of water per minute from beneath it on to the surface. There it freezes rapidly, thickening the ice.

To do this for just 10% of the Arctic, however, would require 10 million wind-powered pumps. And even the team leader, Dr Shaun Fitzgerald, says he is not sure the idea is a good one.

His critics warn that geoengineering could have unpredictable consequences and do far more harm than good.

But its advocates are undeterred. These are some of the other ideas they are exploring:

Guarding glaciers Building underwater walls to protect glaciers from warm water. However, protecting the Greenland ice sheet would require a wall 107m high and almost 5km long.²

Paint power Scientists have come up with a new type of white paint which reflects 98.1% of sunlight.³ They say that it could cool streets and save energy use in buildings by ending the need for air conditioning.

Softening sunlight Releasing tiny particles into the atmosphere which reflect the sun's light might also reduce global warming. Some scientist favour calcium carbonate particles while others favour sulphur. An even more ambitious idea is to send particles or mini-spacecraft with reflective umbrellas into orbit around the Earth.

Fabricating forests A professor at Arizona State University has designed a 10m-high "mechanical tree". The steel structure contains filters to take carbon from the atmosphere. He hopes to create "tree farms" which will capture as much as 1,000 tonnes of carbon a day.

Encouraging algae Pipes in the ocean could bring nutrient-rich water from the ocean bottom to feed algaeA simple plant that grows in or on water. on the surface. These would absorb carbon from the atmosphere and then sink back down to the sea floor.

Do we need more crazy ideas?

Yes: We have no choice. Global warming is increasing, extreme weather is becoming more frequent and governments are not doing nearly enough to fight it. We need radical solutions to make a difference.

No: Trying to tamper with the environment in this way is incredibly dangerous and could make the situation much worse. Even the people suggesting these ideas are far from certain about the outcome.

Or...  We need internationally agreed regulations to govern these or any other attempts at geoengineering. Since they could affect the entire planet, every country should have the power to veto them.

Algae - A simple plant that grows in or on water.