By Barbara Plett
BBC News, United Nations, New York
**About 100 world leaders are to gather at the UN to try and revitalise deadlocked talks on climate change.**The summit comes two months ahead of a key meeting in the Danish capital, Copenhagen, aimed at approving a global treaty on cutting carbon emissions.
China, one of the world’s biggest polluters, is expected to announce ambitious plans on climate change.
Negotiators are trying to agree on a replacement for the Kyoto Protocol on carbon emissions.
UN Secretary General Ban Ki-moon called Tuesday’s summit to try and inject political momentum into stalled climate talks.
But rich nations have not pledged to cut enough carbon to take the world out of danger.
“We saw China being absolutely in the lead in terms of putting together an economic recovery package which had green economic growth at absolutely the heart of it”
Yvo de Boer, UN climate chief
Poor countries refuse to commit to binding caps, saying this would prevent them from developing their economies.
China’s role is crucial, because it is both an emerging economy, and a big polluter.
The UN’s chief climate change negotiator, Yvo de Boer, says he expects an important announcement from Beijing.
He said: "China domestic policy is already very ambitious but yes I do expect something dramatic.
“If you look at what happened in the course of the crisis the financial crisis we saw China being absolutely in the lead in terms of putting together an economic recovery package which had green economic growth at absolutely the heart of it in a sincere and serious way.”
There is concern about the world’s other big polluter, the United States.
President Barack Obama has recognised climate change as a pressing issue, unlike the previous administration.
But critics say Washington is moving too slowly on carbon legislation which does not go far enough.
A demonstration of political will by both China and the US would be important to breaking the deadlock in negotiations.