Tearfund works with the world’s poorest communities to help people adapt to the effects of climate change. It says that hopes were dashed at last week's meeting of G20 leaders in Pittsburgh.

"Despite President Obama’s build up to this event back in the summer at G8, the G20 summit has been a complete damp squib on the critical issue of climate finance for developing countries," said Paul Cook, Tearfund’s Advocacy Director.

He said that rich countries needed to break the deadlock in international climate talks in spite of the difficult global financial situation.

He called on wealthy nations to offer $150 billion to help developing countries adapt to the impacts of climate change and reduce their emissions.

"This is urgent," said Mr Cook. "Time is running out, and we’re already seeing the dramatic impacts of climate change in many parts of the world.

"Rich countries have the power to change this, and must take responsibility for doing so.

"They must redouble their efforts if we’re to have any hope of getting a strong and fair climate deal in Copenhagen this December."