Sir David Attenborough and Archbishop Desmond Tutu have called on world leaders to do more to protect the poor from the devastating effects of climate change.

The two were among 19 signatories of a letter to The Times urging Western countries to "lead the way" at the United Nations climate change summit in Poznan, Poland.

With disease, droughts and uncertainty over crops being blamed on global warming, they said it was essential that agreements were reached.

Signatories included campaigners such as Sheila Watt-Cloutier, a Canadian Inuit activist, and Janina Ochojska, president of the Polish Humanitarian Organization, alongside musicians, authors and actors, including Scarlett Johansson, Annie Lennox, Ian McEwan and Colin Firth.

They said it was "desperately unfair that the poor should again feel the brunt, despite being least responsible."

• Click here to read more in the Times of London.