London Mayor Ken Livingstone is urging people to reduce the energy they use by making six simple lifestyle changes.
The DIY Planet Repairs campaign calls on Londoners to unplug chargers, only boil the amount of water needed, and switch off lights in empty rooms.
Other suggested changes include turning down the thermostat, keeping the standby switch off and washing clothes at a low temperature.
The campaign is the second initiative in London's Climate Change Action Plan.
Mr Livingstone said: "We are launching the DIY Planet Repairs campaign to provide clear and simple information to Londoners about what they can do to help address global warming.
"Taking part in DIY Planet Repairs will cost you nothing and I am asking every London household to agree to make these six simple changes to cut their carbon emissions and play a part in preventing catastrophic climate change."
The mayor was joined by Dr Steve Howard of The Climate Group and former pop star turned gardening guru Kim Wilde to help launch the campaign and kick-start London's carbon counter.
The counter estimates the amount of carbon used every second of each day in the capital.
The Climate Change Action Plan was launched in February when Mr Livingstone appealed to Londoners to tackle energy waste by having loft and cavity wall insulation installed.
He also urged companies to invest in green technology to help slash carbon emissions by 60% within 20 years.