1. The artificial tree that captures carbon dioxide 1,000 times faster than a real tree.
Developed by researchers at Columbia University, the tree, which resembles a cylinder, absorbs carbon dioxide and then releases it in a technique called gas absorption similar to a sponge that collects water. One tree can collect one ton of CO2 a day, the equivalent of the amount of carbon dioxide emitted by 20 cars. But each synthetic tree costs £15,000 to make and millions would be needed just to offset the emissions of Britain’s cars.
2. Injecting the air with particles to reflect sunlight.
It may be possible to inject artificial sulphate particles into the upper atmosphere to reflect sunlight – but the theory does not address ocean acidification caused by rising CO2 levels and there could be side effects such as acid rain.
3. Creating low clouds over the oceans.
Increasing the Earth’s albedo, or reflectivity to sunlight, by pumping water vapour into the air to stimulate cloud formation over the sea. This could involve a fleet of ships spraying salt water to increase the density of clouds by raising the concentration of water droplets within them.
4. Mixing the deep water of the ocean.
James Lovelock, working with Chris Rapley of the Science Museum in London, devised a plan to put giant tubes into the seas to take surface water rich in dissolved CO2 to lower depths where it will not surface. The idea is to take CO2 out of the short-term carbon cycle, cutting the gas in the atmosphere.
5. Giant mirrors in space.
Deflect sunlight with a giant mirror (pictured right) or a fleet of small mirrors between the Earth and the Sun. The Intergovernmental Panel on Climate Change has said that 1 per cent of reflected sunlight could make up for 400 years of man made emissions into the atmosphere.
6. Planetary skin.
A global “nervous system” that will integrate land, sea, air and space-based sensors, helping the public and private sectors to make decisions to prevent and adapt to climate change. The pilot project – a prototype is due by 2010 will track how much carbon is held by rainforests and where.
7. Earth sunglasses.
Arizona University astronomer Roger Angel suggests using electro-magnetically powered spacecraft to blast trillions of ultra-thin silicon lenses into space to deflect the sun’s rays. Once in place, they would create a 100,000 square mile sunshade, reducing the sun’s rays by about 2 per cent.
8. Smoke filters.
Superfilters fitted to factory smokestacks can turn pollution into harmless baking soda. Plastic mesh filters being tested on the smokestacks of Texas power plants trap 90 per cent of the carbon dioxide emitted which, when mixed with sodium hydroxide, is turned into sodium bicarbonate.
9. Mirrors in the desert.
The amount of sunlight reflected back into the sky naturally averages 30 per cent but in areas covered by snow or ice, it’s a healthy 90 per cent. But the ice caps are melting fast. To counter this, say scientists, we would need to lay vast sheets of reflective material across 1.2 million square miles of the Sahara desert, at a cost of £20bn over 10 years.
10. Wave-riding rubber tubes.
The Anaconda is a 200m-long tube, 5.5m in diameter, that could turn wave power into a commercially viable option. As each wave hits the front of the tube, a pulse is created in the water inside. This is forced down the tube by the wave, ultimately powering a turbine in the “tail” of the tube to generate electricity. Each tube could generate enough power for more than 1,000 houses. If the company secures the £17m it needs for a prototype, it hopes to have the first full-size Anaconda ready by 2014. The ultimate goal is to create farms of about 50 tubes in west-facing coastal areas of Britain.