International climate pledges remain far off track to limit rising temperatures to 1.5 degrees Celsius, according to a report released by the United Nations Wednesday, less than two weeks ahead of high-stakes negotiations to tackle global warming.

The combined climate pledges of more than 190 nations that signed up to the 2015 Paris climate deal put Earth on track to warm by around 2.5C (36 degrees Fahrenheit) compared to pre-industrial levels by the century's end.

With the planet already battered by climate-enhanced heatwaves, storms and floods after just 1.2C of warming, experts say the world is still failing to act with sufficient urgency to curb greenhouse gas emissions.

"We are still nowhere near the scale and pace of emission reductions required to put us on track toward a 1.5 degrees Celsius world," said Simon Stiell, Executive Secretary of UN Climate Change.

"To keep this goal alive, national governments need to strengthen their climate action plans now and implement them in the next eight years."

The UN's climate experts have said emissions -- compared to 2010 levels -- need to fall 45 percent by 2030 in order to meet the Paris deal's more ambitious goal.

In its latest report, the UN said that current commitments from governments around the world will in fact increase emissions by 10.6 percent by 2030.