Mr Turnbull says water, which has been added to the Environment portfolio, is his number one priority.
"The biggest environmental challenge in Australia is a water scarcity," he said.
Mr Turnbull says fostering the development of clean coal technologies will also be a priority.
He says most of the world’s power stations will be fuelled by coal for the next few decades.
"That’s particularly true of the fastest-growing economy, China," he said.
"So cleaning up coal-fired power stations is not only in our own national interest, but in many respects, probably the most important thing we can offer to the rest of the world."
Northern Territory Environment Centre co-ordinator Peter Robertson says he thinks Mr Turnbull will do a better job as Environment Minister than his predecessor, Ian Campbell.
Senator Campbell has been dropped from his ministerial role.
Mr Robertson says Senator Campbell had a narrow-minded approach to environmental issues.
He says he expects Mr Turnbull to be more effective.
"We think that he’s got more of an open mind than Senator Campbell, his predecessor," he said.
"He seems to be aware that Australia is in fact confronting some extremely serious environmental problems, and we hope that he applies himself to climate change as much as he is currently applying himself to water and rivers."