Marvellous madness?

The team braving temperatures of -45C in the Arctic are "quite insane" says Professor Julienne Stroeve, a climate scientist from the University of Colorado Boulder .¹

She is criticising a project to thicken Arctic sea ice enough to stop it melting. This project involves drilling a hole in the ice and pumping 1,000 litres of water per minute from beneath on to the surface.

There it rapidly freezes, thickening the ice. But even the team leader says he is not sure the idea is a good one.

The project is a form of geoengineering. This means trying to alter Earth's climate to compensate for the damage done by human activity.

Here are some of the other ideas now being explored:

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. It would also reduce energy use in buildings because people would not need air conditioning.

Softening sunlight Releasing tiny particles into the atmosphere which reflect the sun's light might also reduce global warming. Some scientists favour calcium carbonatea white solid occurring naturally as limestone or chalk rock particles while others favour sulphura bright-yellow coloured non-metal material.

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 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 with it to the sea bed.

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 vetoAn official way of blocking or forbidding something. these attempts.