There are many ways we can save the world and some may sound crazier than others. The independent has complied ten ways to save the world that range from easy to the hard.

Rethink cars

Motoring could be revolutionised if cars were marketed like mobile phones – in a manner that would cut carbon dioxide and reduce the cost of driving. Motorists would get subsidised – or possibly even free – electric cars in the same way that customers currently get mobile phone handsets. In return, they would take out a contract for miles, rather than minutes, entitling them to get power either by plugging in to recharging points (at home, in car parks or on the street) or exchanging batteries at filling stations. The idea is the brainchild of a thirty-something former dot-com entrepreneur, Shia Agassi, who believes it would halve motoring costs. It sounds too good to be true, but Israel, Denmark, Hawaii and San Francisco are already starting to put the system in place – and even Gordon Brown has toyed with the idea. But to tackle climate change properly, the electricity has to be provided by renewable sources or nuclear power rather than fossil fuels.

Embrace scum

Slimy scum could prove our saviour, as algae are emerging as one of the most promising and environmentally friendly sources of biofuel. Algae can grow extraordinarily fast, doubling in weight several times a day. They produce at least 15 times as much fuel per hectare as conventional crops like corn or oilseed rape, and do not take up farmland needed to grow food; they can be grown in lakes, the sea or even in the process of cleaning polluted water. Algae take three times their own weight of carbon dioxide from the air while growing, and the fuel they produce packs much more power for its weight than other biofuels. It is therefore being developed as a potential carbon-neutral way of fuelling aircraft: Air New Zealand has already mixed it with ordinary jet fuel for test flights. Cars have run on pure algae biofuel, and big oil companies are investing in it.