The Scottish Government has been urged to focus on "fully developing" its plans to combat climate change.
The independent Committee on Climate Change (CCC) fears that meeting targets up to 2020 will continue to be difficult.
While it said good progress had been made in Scotland, the CCC argues there is "considerable uncertainty" about how policies will be put into place.
It added that it was important the Scottish Government continues to develop the details of policies and focus on implementing them at the rate required to meet targets.
The expert body, which was set up to advise both the UK Government and the devolved administrations on emissions targets, publishes its latest progress report to ministers.
Speaking ahead of that, CCC chief executive David Kennedy said: "Scotland has made good progress in delivering on emission reduction measures to date. This lays the foundations for meeting ambitious Scottish emissions targets and building a low-carbon economy in Scotland with the benefits this will bring.
"It is important that the Scottish Government now focuses on fully developing its policy proposals and ensuring these and existing policies are delivered to their full potential."
The report comes after it emerged that the Scottish Government had failed to achieve its first legally-binding emissions target.
The Scottish Greenhouse Gas Emissions Annual Target Report published in October revealed Scotland emitted 54.7 megatons of carbon dioxide equivalent in 2010, 1.1 megatons above the target set by the Climate Change Act 2009. The extreme winter weather of late 2009 and early 2010 is said to have contributed to this.
Environment and climate change minister Paul Wheelhouse said: "The UK Committee on Climate Change report is a welcome contribution to our understanding of what we need to do to deliver on our climate change targets."
