In choosing Steven Chu as his energy secretary, Barack Obama has picked one of the most prominent US advocates of using science to tackle global warming.
Steven Chu is a leading supporter of developing new energy sources
"What the world does in the coming decade will have enormous consequences that will last for centuries," Dr Chu said following his appointment.
"It is imperative that we begin without further delay."
A Nobel Prize laureate, Dr Chu has since 2004 led a push to develop new technologies including biofuels and solar energy as director of the Lawrence Berkeley National Laboratory.
After being named by Mr Obama, he said the energy department should support energy research and development that leads to innovation in the private sector, as well as broader scientific research "essential for our future prosperity".
Born in St Louis, Missouri, in 1948, Steven Chu graduated in mathematics and physics from the University of Rochester in 1970.
He earned his PhD and conducted postdoctoral research at the University of California, Berkeley, where he is now professor of physics, and of molecular and cell biology.
He also worked at AT&T's Bell Labs before moving to Stanford University in 1987.
In 1997 he shared the Nobel Prize for physics for his work on cooling and trapping atoms using laser light.
He is a member of the Copenhagen Climate Council, an alliance of businesses and scientists working towards a new global climate treaty for 2009.
He has said a price must be put on carbon "without loopholes", and argued that international regulations and fiscal policies are necessary to curb emissions.
"Free market forces aren't going to do this," he said in a lecture earlier this year.
He is also outspoken on the need to end the unnecessary waste of energy.
"If I were emperor of the world, I would put the pedal to the floor on energy efficiency and conservation for the next decade," he said last year.
Of Mr Obama he said: "President-elect Obama has set the tone and pace for moving our country forward with optimism and calm determination.
"I hope to emulate his example."
Dr Chu is married to Jean Chu, an Oxford-trained physicist, and has two sons through a previous marriage.