After 19 of the 20 nations recommitted to combating climate change at the G20 summit in Germany, Al Gore was in high spirits as he arrived in Australia.

But the former US vice-president and climate change crusader admitted to concern over the US losing its role as world leader on international issues, including the North Korean missile crisis.

"It's a period for the United States where we have to work around President Trump," Mr Gore said. "And on some issues, such as those in foreign policy, that's not easy to do."

In Australia to launch the documentary An Inconvenient Sequel: Truth to Power and meet political and business leaders, Mr Gore lauded the 19 world leaders who agreed the Paris accord on cutting emissions was irreversible.