UN talks on climate change opened in South Africa this morning, but the mood at the talks has been soured by divisions over sharing out the burden of emissions curbs.

Topping the agenda in the city of Durban is the fate of the Kyoto Protocol, the only global pact with targets for curbing greenhouse-gas emissions, whose first round of pledges expires at the end of 2012.

The 1997 protocol is the world's only legally binding treaty aimed at reducing greenhouse gases, but it is due to run out at the end of next year.

EU Commissioner for Climate Action Connie Hedegaard last week gave a blunt assessment of where international negotiations currently stand.

She said the European Union was ready for a global treaty in Durban, but the reality is that other economies, such as the US and China, are not.

The Commissioner made it clear that the EU will not sign-up for a second Kyoto commitment period on its own because the EU accounts for just 11% of global emissions and so other major emitters must be onboard.

The US never ratified Kyoto and China, the world's biggest emitter of greenhouse gases, is unwilling to make any commitments until Washington does.

Russia, Japan and Canada say they will not sign up for a second commitment period unless the biggest emitters do too.

Kyoto only ever covered developed nations and so attention will also be focused on efforts to agree a roadmap for wider climate deal.

The EU wants it to be legally binding and to come into force no later than 2020.

This month, two separate UN reports said greenhouse gases have reached record levels in the atmosphere, while a warming climate is expected to lead to significant adverse weather patterns.