Want to know what you can do to combat climate change? Some of the world's biggest stars unite for our Cool It! campaign and show how just one tiny change can have a huge impact on our environment. By Lucie Morris and Anna Saunders

As Cate Blanchett walks into the photo studio in Sydney to pose for our Cool It! campaign, looking chic in a pair of skinny black jeans and a fitted jacket, it is immediately obvious just how much she cares about the issue of global warming. "Don't even get me started on it," she says, waving her arms for emphasis. "I'm extremely concerned." A point made clear three days later, when she was pictured with her husband and two young sons among a crowd of 20,000 who marched through the streets of Sydney to demand more government action to combat global warming. Similar events took place in 48 countries and more than 20 other locations across Australia as part of an international day of action on climate change. That afternoon, Cate was just one of thousands of mothers, who care about the future for their children, determined to make their voices heard.

In fact, it's the impact our actions will have on the world we leave to future generations that has become the impetus for change not only for Cate, but for the host of public figures who signed up for our Cool It! campaign.

From switching to green power to offsetting air travel with carbon credits, our celebrity supporters Cate, Heath Ledger, Susan Sarandon, Rose Byrne, Dr David Suzuki and Selma Blair, have joined with marie claire to show just how easy it is to reduce carbon emissions. "I want the planet to outlive me and my children,'' explains Susan, a sentiment echoed by everyone who took part.

But there's no time to lose. According to a recent report by British economist Sir Nicholas Stern, we have just 10 years to prevent the earth's temperature rising by 5 degrees C. If we don't, this rise will effectively cause devastating economic collapse, widespread death and disease worldwide, and literally change the face of our planet forever.

From droughts afflicting farmlands across Australia to the bleaching of the Great Barrier Reef, the effects of global warming are already visible, but we are making things worse every minute, explains scientist Tim Flannery, author of The Weather Makers. "Particularly shameful is the fact that Australia is one of the worst emitters of harmful greenhouse gases," he adds. "We all need to make changes in our lives and get the government to stop burning brown coal to generate our electricity, and create a cleaner, better future with green power."

But the first hurdle to overcome is individual apathy, claims the Australian Conservation Foundation (ACF), which supports our Cool It! campaign. "Looking after the environment is the biggest challenge of this generation and we need more Australians committed to action for the environment, says ACF executive director Don Henry. "Together, we have a much bigger impact than working alone.

"There are things we can do," urges Cate Blanchett. And she's right. From our carbon emission tick list to our renewable energy petition, or the great "Earth Hour" light-saving event, all you have to do is keep read February's issue of marie claire to find out how to take your first step towards making a world of difference ...

Read how our celebrity supporters are making a difference in February's issue of marie claire.

Join us ... and cool it!

You can make a world of difference by ...

1. joining our climate-conscious celebrities

It's easier than you may think to take your own small steps during your everyday life to reduce greenhouse gas emissions. In the February issue of marie claire we show you how you can play your part in helping our planet.