Americans William Nordhaus and Paul Romer, pioneers in adapting economic theory to take better account of environmental issues and technological progress, shared the 2018 Nobel Economics Prize on Monday.

In an award that turned the spotlight on the global debate over risks associated with climate change, the Royal Swedish Academy of Sciences said the laureates' work helped answer fundamental questions on how to promote long-term sustainable growth and enhance human welfare.

The prize took Romer, of New York University's Stern School of Business, by surprise.