In an open letter that includes five British scientists among the signatories, the experts praise his recent commitment to review the controversial Kyoto protocol on reducing emissions harmful to the environment.
"Much of the billions of dollars earmarked for implementation of the protocol in Canada will be squandered without a proper assessment of recent developments in climate science," they wrote in the Canadian Financial Post last week.
They emphasised that the study of global climate change is, in Mr Harper's own words, an "emerging science" and added: "If, back in the mid 1990s, we knew what we know today about climate, Kyoto would almost certainly not exist, because we would have concluded it was not necessary." Despite claims to the contrary, there is no consensus among climate scientists on the relative importance of the various causes of global climate change, they wrote.
"'Climate change is real' is a meaningless phrase used repeatedly by activists to convince the public that a climate catastrophe is looming and humanity is the cause. Neither of these fears is justified.
"Global climate changes all the time due to natural causes and the human impact still remains impossible to distinguish from this natural 'noise'."
The letter is the latest effort by climate change sceptics to counter claims that there is a consensus that human activity is causing global warming.