The last time that world leaders gathered in such a big number to discuss climate change was five years ago in Denmark, but the conference brought no new binding goals for the period after 2015.

No binding goals are expected at today's summit either, as world leaders will only present their national action and ambitions.

Pahor will address the event following opening addresses by US actor Leonardo DiCaprio, the UN Messenger of Peace with a special focus on climate change, former US Vice-President Al Gore and Mayor of New York Bill de Blasio.

US President Barack Obama will also take the stage to note that the US has by 2012 reduced greenhouse gas emissions by 10% compared to 2005, which is the biggest decrease among all countries. This is partly due to recession.

The success of the fight against climate change will depend mostly on a conference that will be held in Paris at the end of 2015. There leaders will strive to reach agreement on binding goals for the reduction of greenhouse gases for the period after 2020.

The World Meteorological Organisation said in early September that in 2012 and 2013 the rise in carbon dioxide emissions was the biggest since 1984. If the emissions of this greenhouse gas continued to rise at the same pace, global temperature would increase by 3.7 degrees Celsius by the end of the century.

The International Energy Agency believes at least US$500bn will need to be invested in low-carbon energy technologies to achieve the goal from the Copenhagen conference. By 2030, US$1,000bn will be needed.