By Jane Wardell and Jarni Blakkarly
SYDNEY, Feb 11 (Reuters) - Australian Prime Minister Malcolm Turnbull will likely inherit a hard-right, climate change sceptic for his deputy after the retirement of his current No.2 on Thursday, an appointment that could block any revamp of an emissions trading scheme.
Agriculture Minister Barnaby Joyce, an outspoken lobbyist for the nation's farmers and for tougher controls on foreign investment, is the leading candidate for the job traditionally held by the coalition government's minor partner, the Nationals.
"We will likely see a more assertive Nationals under Barnaby," said University of Sydney political scientist Rod Tiffen. "He and Turnbull really have very opposing views on climate change and they will butt heads over this."
Australia is one of the world's largest exporter of coal and iron ore and one of the largest carbon emitters on a per capita basis thanks to its reliance on coal-fired power plants.
The country pledged to cut emissions by 26-28 percent of 2005 levels by 2030 ahead of the Paris climate talks late last year. But a planned carbon trading scheme, which would have been the world's third biggest, was axed by previous conservative Prime Minister Tony Abbott to fulfill an election pledge.
Turnbull who ousted Abbott in a party coup last year, is a carbon trading advocate who supports progressive climate policies. Infact he lost the Liberal Party leadership to Abbott while in opposition in 2009 because of his support for the then Labor government's carbon trading scheme.
"While Turnbull has put an emissions trading scheme on the backburner, he would want to revisit it at some point," said Tiffen. "That would be impossible with Barnaby."
Joyce, the sole candidate standing for election to replace outgoing deputy prime minister Warren Truss, did not comment ahead of a party ballot scheduled for later Thursday.
Joyce has repeatedly said he does not believe Australia's extreme weather events, like drought and floods, are linked to man's impact on the climate.
Turnbull and Joyce are the odd couple in relation to more than climate change.
Turnbull, an urban multimillionaire former tech entrepreneur, is a careful thinker and erudite speaker who wants Australia to focus on a future in innovation.
Joyce, who is known for speaking off the cuff, is concerned with support for regional Australia, including tougher rules on foreign investment in Australian farmland.
In 2015, he made international headlines when he threatened to euthanase Hollywood actor Johnny Depp's dogs, Pistol and Boo, after biosecurity officials learned the animals had illegally entered the country - telling them to "bugger off back to America".
The change of deputy leader paves the way for possibly a significant Cabinet reshuffle ahead of a federal election expected in September or October.
Turnbull is under pressure from within his splintered government. He faces rear-guard actions from a conservative wing, led by Abbott, on a range of social issues including same sex marriage. Earlier this month he ruled out an increase in the consumption tax under pressure from within his own party.
But any reshuffle has been made more difficult by the resignation on Wednesday of Turnbull's respected trade minister, Andrew Robb, who led negotiations for a landmark free trade agreement between China and Australia and the multinational Trans-Pacific Partnership.
"Robb's retirement is a big loss for Turnbull, he was a very capable individual and one of the stand-out performers of the last couple of years," said University of Sydney professor of political science Peter Chen. "There are a number of ministers Turnbull would rather lose over Robb." (Reporting By Jane Wardell; Editing by Michael Perry)
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