A day of events calling for urgent action on climate change started with a protest bike ride that took in the Australian and US embassies and Downing Street.
Thousands of people came from all over the UK to attend the "I Count" rally at Trafalgar Square. It called for action on the eve of a climate summit in Africa.
Campaigners wore costumes and carried placards to highlight the plight of animals affected by climate issues.
Flamboyant costumes and witty slogans were used to reflect the range of issues in the climate change debate.
There was a smattering of real animals at the rally as pets helped drive home the concerns.
People carried placards and balloons on the March for Global Climate Justice which went from the US embassy in Grosvenor Square to Trafalgar Square.
Some placards and costumes were aimed at the United States, with protesters calling on the country to pull its weight in the fight against global warming.
Singer KT Tunstall told crowds she was at the rally to help raise awareness that people's behaviour must change.