Bali, Feb 24 (Inditop.com) Countries will have to be far more ambitious in cutting greenhouse gas emissions if the world is to effectively limit a rise in global temperature to 2 degrees Celsius, says the UN Environment Programme (UNEP).

A new UNEP study modelling greenhouse gases (GHG) that are warming the earth says that annual global GHG emissions should not be larger than 40 to 48.3 Gigatonnes (Gt) of carbon dioxide (CO2) equivalent in 2020 and should peak sometime between 2015 and 2021.

They also estimate that between 2020 and 2050, global emissions need to fall by between 48 and 72 percent, indicating that an ambition to cut greenhouse gases by around 3 percent a year over that 30-year period is also needed.

Such a path offers “at least a 50/50 chance of keeping a global temperature rise below 2 degrees”, says the report.

The UNEP study, launched on the eve of its Ministerial Environment Forum here, has analysed the GHG emission mitigation pledges of 60 developed and developing economies.

These pledges have been recently submitted to the UN Framework Convention on Climate Change (UNFCCC) following the climate summit in Copenhagen last December.

“The expected emissions for 2020 range between 48.8 and 51.2 Gt of CO2 equivalent based on whether high or low pledges will be fulfilled,” says the report.

“Thus even with the best intentions there is a gap of between 0.5 and 8.8 Gt of CO2 equivalent per year, amounting to an average shortfall in emission cuts of 4.7 Gt. If the low end of the emission reduction pledges are fulfilled, the gap is even bigger – 2.9 to 11.2 Gt of CO2 equivalent per year, with an average gap of 7.1 Gt.”

At the launch of the report — called “How Close Are We to the Two Degree Limit?” — UN Under-Secretary General and UNEP Executive Director Achim Steiner said: “There are clearly a great deal of assumptions underlying these figures, but they do provide an indication of where countries are and perhaps more importantly where they need to aim.

“There clearly is �Gigatonne gap’ which may be a significant one according some of the modelers. This needs to be bridged and bridged quickly if the international community is to pro-actively manage emissions down in a way that makes economic sense.”

Steiner pointed out: “There are multiple reasons for countries to make a transition to a low carbon, resource efficient green economy of which climate change is a key one. But energy security, cuts in air pollution and diversifying energy sources are also important drivers.”