With an arm-long list of achievements, Adelaide University geology Professor Ian Plimer told the PGA Convention that there were fundamental problems in the science being put forward in favour of climate change.

"An emission trading scheme is based on flawed science and its constraints will destroy the agricultural industry," Prof Plimer said.

"And the interesting thing about ruminants, which is a main argument for climate change, is that there are more of them on earth now than there were 20 years ago, however the methane deposit is going down; so how do we explain that?

"I think the agriculture sector can suffer very badly from emissions trading and the mining and manufacturing industry will also suffer but the reality is those people living in Sydney and Melbourne are driving the political agenda.

"The problem is that (people in) the bulk of the electorates live in cities, never experience drought, they always get fresh food, they don't realise that drought is part of living in Australia.

"Unfortunately the agricultural vote is the same vote as a drongo living in the city who is doing nothing to expand the economy.

"We are a country with first world thinking and third world infrastructure, we cannot afford to make make a mistake on this.

"The science is flawed; and if the science is flawed then the whole concept of emissions trading is invalid."

Prof Plimer said climates always change, always have and always will.

"Climates change in cycles and will change randomly," he said.

"Where those cycles change are based on where that solar system is in the galaxy, how our orbit wobbles, how energetic the sun is, tidal effects and extraordinary events such as massive volcano eruptions."

"What you don't see is any evidence in the past, and that is only 4567 million years, that carbon dioxide has driven climate change.

"It is the exact inverse."