Campaigners were yesterday so annoyed with world leaders' lack of action on climate change, they went blue in the face.
The campaigners from the Catholic aid agency CAFOD joined commuters outside Parliament to raise awareness of The Wave march which takes place on December 5.
The protest in London, which has a blue theme, aims to put pressure on governments to agree a fair and binding deal on climate change at UN talks in December.
CAFOD's head of campaigns Kevin McCullough said: "Climate change is everyone's problem but it's going to make life in the poorest countries worst first. We certainly don't want to have the blues about climate change come the New Year so we're marching on December 5 through London to show our support for a fair and strong deal on climate change in Copenhagen.
"We hope people from all over the UK will come and join us and get in the spirit of The Wave march by wearing something blue or painting their face or hands. This really is a turning point for the world and joining the march will mean people can have a hand in history."
The Wave, which is being organised by the Stop Climate Chaos coalition, promises to be the UK's biggest-ever demonstration in support of international environmental action to combat climate change.
Before the march there will be an ecumenical service including the Archbishop of Canterbury, Dr Rowan Williams and the Catholic Archbishop of Westminster, Vincent Nichols.
Free Church and other faith representatives, who have been lobbying hard for action against global warming, will also be involved.
Participants will be encouraged to dress in blue to "flood the streets of London and encircle Parliament to press home the need for the Britain to do all it can to seal a just deal in Copenhagen," say organisers - who are stressing the peaceful and friendly nature of the demo.
The Coalition wants the UK government to focus on three policy areas: ending Britain's reliance on dirty coal power and instead boosting the renewable energy supply to help build a green economy and create new jobs; providing resources to help the world’s poorest and most vulnerable people adapt to climate change and allow them to develop in a carbon friendly manner, and delivering a fair global deal in Copenhagen that will keep global warming under 2 degrees C.