Australia's climate change policy faces an uncertain future after a change in the country's leadership.

Kevin Rudd was sworn in Thursday as Australia's prime minister for the second time after defeating Julia Gillard in a caucus ballot Wednesday for the leadership of the country's Federal Parliamentary Labor party.

Gillard became prime minister in June 2010 after Rudd resigned.

Under Gillard's leadership, a carbon price went into effect last July in which businesses that emit 25,000 tons of carbon dioxide or the equivalent in other greenhouse gases are charged $24 per ton. In 2015 it was to convert to an emissions trading scheme with a floating price starting at a floor of $15.

Rudd's earlier version of a carbon tax proposal was believed to eventually lead to his downfall as prime minister.

Australia accounts for about 1.5 percent of global CO2 emissions but ranks at the top of developed nations on a per-capita basis because of its heavy reliance on coal for the production of electricity.

One-third of the Gillard ministry has resigned with the return of Rudd, including climate change minister Greg Combet. Elections are scheduled for September although Rudd said Thursday he would not be tied to that schedule.

A report in Business Spectator notes in slightly more than three years serving as climate change minister, Combet introduced the $10 billion Clean Energy Finance Corp. and the $3 billion Australian Renewables Energy Agency, in addition to a price on carbon. It characterized his post as "the toughest job in a compromised government."

"One of the only near certainties currently in Australian climate change policy is the target to cut emissions by five per cent, based on their levels in 2000...after that, there are question marks everywhere," says a report in The Guardian on the change in leadership.

When Rudd in 2007 beat the conservative Liberal leader John Howard in a general election for prime minister, he referred to climate change as the "great moral, environmental and economic challenge of our age."

Concerns about climate change have intensified in Australia as it experienced record heat waves and raging wildfires this year, prompting the country's meteorology bureau to add a "purple zone" to its weather forecasting map, extending the range of high temperatures to 129 degrees Fahrenheit.

John Connor, chief executive of the Climate Institute, an independent research organization in Australia, in a statement on the change in leadership said the institute would continue its "advocacy of the importance of laws that put a limit and price on carbon pollution."

"These limits are especially important in the medium and long term as they provide a means of achieving the broad and urgent decarbonisation necessary over the next few decades."