Prime Minister Tony Blair has joined a new campaign to reduce climate change, launched for National Science Week.
And to show he's doing his bit too, Mr Blair has swapped the light bulb outside his home in Downing Street for a more environmentally friendly one.
The Click for Climate campaign wants people to make small changes that will make a big difference to the climate.
Also joining the campaign is ex-Olympic athlete Colin Jackson, who will be ditching the plane for the train.
The British Association for the Advancement of Science has lots of tips on small ways to make a big difference, including things like turning the television off fully instead of leaving it on standby.
Click for Climate ideas
Don't go to school by car
Unplug phone chargers when not in use
Plant a tree every time you fly
Don't leave electrical gear, like TVs, on standby
The site shows how much harmful gas pollution - blamed for global warming - can be saved if the action is kept up for a week.
Campaign spokesman Roland Jackson said: "If people all just replaced one ordinary light bulb in their home with an energy-saving bulb, then National Science Week would have cut down carbon dioxide emissions by more than 240 tonnes.
"People say they can't make a difference - this shows that they clearly can."
National Science Week runs until 19 March and there's more than 1,500 events happening throughout the UK.