ACTRESS Emma Thompson joined tens of thousands of people marching through London yesterday in a protest demanding action on climate change.

The rally was one of 2,000 events in 150 countries, including a march in Edinburgh, ahead of a UN climate summit tomorrow in New York.

More than 120 leaders, including David Cameron and Barack Obama, are expected to attend the summit in advance of talks in Paris in 2015, where it is hoped a new global climate treaty can be agreed.

Thompson told the rally: "Climate change is the human-rights issue of our time. No more are we the grungy hippies sitting in trees. We are the voice of the future - if there is to be a future."

Other celebrities, including musician Peter Gabriel and designer and activist Vivienne Westwood, also joined the 40,000 people marching through Westminster.

The protests came as scientists warned that global carbon dioxide emissions were set to rise to a record 40 billion tonnes this year.

Picture: Reuters