New York, Sep 22 (DPA) US President Barack Obama Tuesday promised a serious US effort to curb greenhouse-gas emissions that cause climate change and called on all major polluters to make concessions to reach a new global climate treaty.

In a speech at the start of a one-day climate summit at UN headquarters in New York, Obama acknowledged the US has been slow to respond to global warming in the past.

'But this is a new day,' Obama said, noting efforts by his own administration to reduce vehicle emissions and promote renewable energy.

Obama has come under pressure from other countries as major legislation to curb emissions has stalled in the US Senate.