KEVIN RUDD says the great moral challenge posed by climate change is undiminished and he will keep trying to implement an emissions trading scheme if Labor is re-elected.

In an interview with the Herald, Mr Rudd rejected growing criticism that he had abandoned the climate change cause because it was no longer a vote winner after the Copenhagen conference and the defeat of his emissions trading scheme.

"It's very clear cut that whether climate change is topical or not, whether it is popular or not, the reality of it does not disappear," he said.

"This remains a fundamental economic, environmental and moral challenge. Whether it's newsworthy or not in a particular season is beside the point. We haven't changed our view of this.''

The Senate has twice blocked legislation for the emissions trading scheme. The legislation is again before the Parliament but the Senate has delayed debate until at least next month and there is next to no chance there will be a vote before the election expected in the spring.