After an all-night session, the U.N.'s expert panel on climate science is scrambling to finish a report on global warming that's meant to guide negotiations on a new international climate deal.

Combining the findings of three earlier reports, the conclusions of the Intergovernmental Panel on Climate Change are expected to be that global warming is man-made, already having an impact and potentially irreversible unless the world curbs greenhouse gas emissions from the burning of fossil fuels and deforestation.

The report caps a six-year effort involving thousands of scientists to describe what global warming is doing to the planet and what can be done to stop it.

IPCC spokesman Jonathan Lynn said Saturday that delegates had some work left but expected the report to be released as planned Sunday.