A federal Conservative candidate is questioning whether humans are the main cause of climate change.

In an interview with CBC radio's Daybreak South on Tuesday, Mel Arnold, the Conservative candidate for North Okanagan-Shuswap said he remains "not convinced" of the scientific proof that's been presented.

Host Chris Walker raised the issue with Arnold after he responded to an online questionnaire on climate change by saying, "until science can prove conclusively and empirically that humans are the main cause of climate change, I will withhold my personal opinion."

Walker asked Arnold why he was withholding his opinions when organizations like the United Nations, the World Health Organization and Environment Canada have acknowledged the role people have played in climate change.

The politician responded by saying he was unsure as to the extent of human impact.

"I don't know that it has been determined for sure that human activity is the main cause. It is part of the process," said Arnold. "But how much of it is actually naturally occurring, that's I think where the debate is."

Arnold said he believes approximately 1.5 per cent of greenhouse gas emissions in Canada are man-made and believes cycles of climate change could be responsible for the rise in global temperatures following the industrial revolution.

"As you know, this area was once buried in kilometres of thick ice during the ice ages. And we have approximately 30 year cycles on weather conditions here. Those types of things are still in play."