Government representatives on Saturday approved a UN report listing options for rolling back emissions from greenhouse gases, NGOs following the proceedings said. In a six-day wrangle, they hammered out the summary of a vast report on choices to tackle the source of climate change, the sources said. Compiled by more than 200 scientists over four years, the report is the third piece in an oerview by the United Nations' Intergovernmental Panel on Climate Change (IPCC). It is only the fifth such "assessment report" in the Nobel-winning panel's history. The Summary for Policymakers, due to be unveiled in Berlin on Sunday, will provide a palette of options to mitigate heat-trapping emissions from fossil fuels and agriculture. While making no recommendations, it is expected to say the UN target -- to limit global warming to two degrees Celsius (3.6 degrees Fahrenheit) -- is feasible if surging emissions are swiftly braked and then reversed. Most scenarios for meeting the 2 C target entail a "tripling to nearly a quadrupling" in the share of energy from renewable energy, nuclear and also fossil sources whose emissions are captured and stored, according to a draft seen by AFP. The IPCC last September published its first volume in the series, updating scientific evidence of global warming. It forecast global temperatures will rise 0.3-4.8 C this century, on top of roughly 0.7 C since the Industrial Revolution. Seas are forecast to rise by 26-82 centimetres (10-32 inches) by 2100. The second volume, issued on March 31 in Yokohama, Japan, dwelt on the likely impacts. It warned that the risk of conflict, hunger, floods and mass displacement increased with every upward creep of the mercury. The panel will issue a resume of all three reports in Copenhagen in October. The IPCC's assessment reports are closely-watched events in the political and scientific fields of climate change. Although some experts deride the mega-reports as too conservative, others say they wield political clout as their summaries are approved by governments in a line-by-line scrutiny. The last assessment report, in 2007, sparked momentum that climaxed in the UN's Copenhagen Summit in 2009. That event became a political brawl, and climate negotiations have been at a far lower gear ever since. The next deadline is at the end of 2015, when UN members vow to complete a climate pact that will take effect from 2020