Fresh from issuing its starkest-ever warning about the impacts of global warming on Earth's weather system, the Intergovernmental Panel on Climate Change (IPCC) will meet until Friday to vet the choices meant to inform policymakers.
A draft of the document, seen by AFP, suggests there is a 15-year window for affordable action to safely reach the UN's warming limit of two degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial times.
The report, the product of four years' work by hundreds of experts, aims to provide governments with the latest science on climate change.
"Preventing dangerous interference with the climate system entails mitigating climate change," said Ottmar Edenhofer, co-chairman of the panel's Working Group III, which compiled the report.
"On a transparent, scientific basis, our report provides an understanding of the available options to meet this challenge."
A Summary for Policymakers will be publicly released in the German capital on Sunday, and the full report - authored by scientists but not submitted to the IPCC plenary for scrutiny - will be released shortly afterwards.
But it says the UN's 2 C target remains feasible if "all countries" act quickly to mitigate, or ease, carbon emissions.
