Two American researchers have been awarded the Nobel Prize for economics for studying the interplay of climate change and technological innovation with economics.

William Nordhaus of Yale University and Paul Romer of New York University were announced winners of the 9-million-kronor ($1.01 million) prize on Monday by the Royal Swedish Academy of Sciences.

Romer said he ignored two telephone calls, thinking they were spam calls, before the Swedish Royal Academy of Sciences was able to get through to him.

“I didn’t answer either because I thought it was a spam call,” he said.

Romer teaches economics at New York University, where he founded the Stern Urbanization Project, which researches how policymakers can harness the rapid growth of cities to create economic opportunity and undertake systemic social reform.

Romer also works with civic innovators as director of NYU’s Marron Institute of Urban Management. The university says he founded Aplia, an education technology application where students have submitted more than 1 billion answers to homework problems.

The academy said Romer’s work “explains how ideas are different to other goods and require specific conditions to thrive in a market.” Previous macroeconomic research had emphasized technological innovation as a driver of growth but had not modelled how market conditions and economic decisions affected creation of new technologies, the academy said.

Nordhaus in the 1990s became the first person to create a model that “describes the global interplay between the economy and the climate,” the academy said. He showed that “the most efficient remedy for problems caused by greenhouse gases is a global scheme of universally imposed carbon taxes.”

He has been a faculty member at Yale since 1967.

The economics prize is the last of the Nobels to be announced this year. Last year’s prize went to American Richard Thaler for studying how human irrationality affects economic theory.

Who else won a Nobel this year?

  • James P. Allison and Tasuku Honjo were awarded the Nobel Prize in physiology or medicine on Oct. 1 for a discovery that the body’s immune system can be used to attack cancer cells.
  • Arthur Ashkin, Gérard Mourou and Donna Strickland were awarded the Nobel Prize in physics Oct. 2 for developing tools made of light beams. Strickland is just the third woman to win the physics prize.
  • Three scientists were awarded the Nobel Prize in chemistry on Wednesday: Frances H. Arnold of the United States, who received half the prize, and George P. Smith and Gregory P. Winter who shared the other half. They won for tapping the power of evolutionary biology to design molecules.
  • The Congolese gynecological surgeon Denis Mukwege and the former Islamic State captive Nadia Murad were awarded the Nobel Peace Prize on Friday “for their efforts to end the use of sexual violence as a weapon of war and armed conflict.”

What happened to the Nobel literature prize?

The Nobel Prize in literature has been postponed. The institution that chooses the laureate is embroiled in a scandal involving allegations of sexual misconduct, financial malpractice and repeated leaks — a crisis that led to the departure of several board members and required the intervention of the Swedish king. Two laureates might be named next year.