Pollution is still rising despite world pledges to cut carbon emissions, and more action is needed to rein in climate change in the coming years, a UN report said Wednesday.

The Emissions Gap report is the fifth yearly analysis that examines how countries are doing and lays out the path toward keeping the average rise in global temperature below 2� Celsius over the next century.

The report by the UN Environment Program and the World Resources Institute said the planet must aim for global carbon neutrality by mid-to-late century to head off the worst effects of climate change.

"There is still a significant gap between where emissions are going and where they need to be by 2030 if we're going to limit warming to less than 2 degrees (Celsius)," said Taryn Fransen, project director of the Open Climate Network at the World Resources Institute.

"This report is telling us that we are pointing in the wrong direction -- and time is running out for us to get back on track."

The emissions gap is defined as the difference between global carbon levels needed to stay within the two-degree Celsius target and the emission levels expected if countries stick to their pledges.

In the immediate future, the report said global emissions must stay below 44 gigatonnes of carbon dioxide in 2020 to stay on target.

But the range of expected global emissions, or midpoint estimates based on national pledges, is 52-54 Gt CO2e in 2020.

The gap in 2020 is 8-10 Gt CO2e, the same magnitude as given in the 2013 report.

- 'Worsening trend' -

"Consistent with the findings of the 2014 assessment by the Intergovernmental Panel on Climate Change, our analysis reveals a worrisome worsening trend," said the report.

"Continued emissions of greenhouse gases will lead to an even warmer climate and exacerbate the devastating effects of climate change."

The report calls for global emissions to peak in the next 10 years before beginning to decline by 2030, as more forests are planted to absorb carbon, and more economies pursue cleaner alternatives to fossil fuels.

To avoid the devastating effects that a hotter planet may bring in terms of food shortages, job loss and storm damage, the report calls for "global carbon neutrality" -- or a net zero of human-caused C02 emissions -- by sometime between 2055 and 2070.

Then, global greenhouse gas emissions should be at least 50 per cent lower by 2050, said the report.

After that, total global greenhouse gas emissions -- not just carbon -- need to shrink to net zero sometime between 2080 and 2100.

- Nations' pledges -

More than 90 countries have made voluntary pledges and commitments to cut emissions.

Five countries that are party to the UN Framework Convention on Climate Change - Brazil, China, the European Union 28, India and the Russian Federation -- are on track to meet their pledges, the report said.

Australia, Canada, Mexico and the United States "are likely to require further action and/or purchased offsets to meet their pledges" for 2020, it said.

The report did not draw conclusions for Japan, South Korea, Indonesia or South Africa "because of various uncertainties, nor for Argentina, Turkey and Saudi Arabia because they have not proposed pledges."

The report praised national policies for promoting more efficient use of energy in buildings, which are in effect in about half of the countries in the world.

Other key steps are promoting renewable energy, reducing transport demand, engaging in sustainable agriculture and cutting industrial pollution.

About $310-360 billion dollars in public and private investment were spent on energy efficiency in 2012, and $244 billion spent on renewable energy, the report said, describing this funding as "significant."

Further actions could include ending fossil fuel subsidies and raising fuel prices "so that they incorporate the costs of climate change and other environmental damages."