The Trump Administration is waging a war on science and New Zealand must now ignore the US when it comes to climate change, the Green Party says.
The man Donald Trump has put in charge of the US Environmental Protection Agency (EPA) has stunned scientists by denying that humans are causing global warming.
Scott Pruitt told CNBC that measuring the human impact on the climate was "very challenging" and there was "tremendous disagreement" about the issue.
His remarks contradicted his own agency's findings on greenhouse gas emissions, with the EPA's website noting carbon dioxide was the "primary greenhouse gas that is contributing to recent climate change".
Green Party co-leader James Shaw said he was extremely concerned about what was happening in the US.
"It looks like the real war on science that the new Trump Administration is taking.
"In particular, appointing someone who has such a clearly anti-science view as head of the EPA."
Mr Pruitt previously served as Oklahoma's attorney general, where he rose to prominence in a string of legal actions against the policies of the agency he now heads.
Unfortunately, there was not much New Zealand could say to convince Mr Pruitt about the evidence behind climate change, Mr Shaw said.
"I don't think that we can take an educated role, because they're not interested in that.
"But what we can say is here in New Zealand we do stand for science, we do follow the scientific advice, and we do intend to do something about it."
Labour climate change spokesperson Megan Woods said the US stance was disappointing.
"I'd like to have thought that we'd arrived at a point where people weren't disputing the science in the same way that they weren't disputing whether the world was round.
"But really we've just got to double down on our own targets."
The government said it disagreed with Mr Pruitt.
Climate Change Minister Paula Bennett said New Zealand was playing its part in the global effort to combat climate change and the Government's 2030 target was a fair and ambitious contribution.