BEIJING - Developing countries have 15 years left to control carbon emissions and constrain the rise in temperatures to under two degrees Celsius, said a top science adviser to US President Barack Obama.

"Developed-country emissions must peak no later than 2015 and decline rapidly thereafter; developing-country emissions must peak no later than 2025 and decline rapidly thereafter," John P. Holdren told the US-China Climate Change Science Seminar at Tsinghua University on Wednesday.

"If we don't do that, we will not have a great chance of holding the global average temperature increase below two degrees Celsius," he added.