BBC: World leaders including US President Barack Obama are holding a summit on climate change at the United Nations.
The aim at the New York meeting is to galvanise member states to sign up to a comprehensive new global climate agreement at talks in Paris next year.
"Today, we must set the world on a new course," UN Secretary-General Ban Ki-moon told leaders from 120 countries, "I am asking you to lead".
It is the first high-level gathering since the Copenhagen summit in 2009.
With so many...