US President Barack Obama has thanked Australia for being a close friend and ally and has urged both nations to seize future opportunities in the Asia-Pacific.

The president on Saturday said despite wars raging across the globe, the world was a much safer place for people living in the most amazing time in history.

Asia was no longer run by dictatorships but democracies, and medical advances meant people were living longer and enjoying unprecedented freedoms.

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“When you look at the facts, opportunities are limitless for this generation,” he told students at the University of Queensland on Saturday.

“You are living in an extraordinary time.”

President Obama said Australia and the United States could build a strong future in the Asia-Pacific, adding that distance was no longer a factor in bilateral ties.

There would always be a strong union between the US and Australia, forged by a commonality unique to both nations.

“There’s a bond between our two countries and Australia really is everything you’d want in a friend and an ally,” he said.

“We’re cut from the same cloth.”

Mr Obama said some people had been sceptical of the US “rebalancing” or pivot towards the Asia-Pacific announced three years ago.

But he said the US remained a Pacific power, seeking further integration in the region and more justice and peace.

“The United States has invested our blood and treasure to advance this vision,” he said.

He said alliances in the region, including with Australia, were “stronger than they have ever been”.

By the end of the decade, the US would have deployed the majority of its navy and airforce to the region and would increase military training with its partners.

“We believe we’re stronger when we stand together,” he said.

He welcomed the rise of China, and promised both nations would co-operate more closely on military and economic matters and in tackling global challenges like Ebola and climate change.

But in this engagement the US would also encourage China to adhere to the same rules as other nations.

“We do not benefit from a relationship with China or any other country in which we put our values and our ideals aside,” he said.

$3 billion climate pledge

The United States will pump $US3 billion ($A3.3 billion) into a global climate fund, stepping up pressure on other nations such as Australia to follow suit.

Mr Obama used his speech to make the announcement to contribute to the “global fight against climate change”.

“No nation is immune and every nation must play its part,” he said.

“We can get this done.”

The United Nations Green Climate Fund, was set up to support developing nations dealing with the impacts of climate change, such as rising seas, higher temperatures and extreme weather.

The US contribution is the biggest country pledge so far.

The UN will now have about $US6 billion of the $US10 billion it hopes to raise.

The announcement at the University of Queensland was made in an auditorium partly powered by a solar array.

It also comes just days after the US and China signed a pact to lower emissions out to 2030.

UN Secretary-General Ban Ki-moon earlier on Saturday urged G20 member countries to contribute to the fund.