He accused the party of fear mongering and ignoring the threat to agriculture from climate change, saying the Nationals' staunch opposition to emissions trading would find some support, he told The Australian Financial Review.

"What the Nationals are doing, though, is something that no farmer ever does, and that is saying the option is to not engage in risk management. I don't know any farmer who chooses that option, but that's essentially what the Nationals are advocating."

He said he had met farmers who were sceptical that climate change was caused by humans but still supported action to curb emissions in case they were causing dangerous change that could jeopardise the future of agriculture.

The Nationals Senate leader Barnaby Joyce yesterday repeated his view that emissions trading would be a "massive new tax" that would not change the temperature of the globe.