Prime Minister Tony Abbott has declared his round-the-world trip a success, as he heads back to Australia.

Mr Abbott has met the leaders of Indonesia, France, Canada and the United States over the past 11 days.

He said the trip had been significant, bolstered trade and security ties, and highlighted Australia’s place on the world stage.

“We sometimes underestimate our clout around the world,” he said.

“Yes, we are a middle power. Yet, nevertheless we are a significant, even a substantial middle power.”

Mr Abbott had two big goals on this trip: the first was to promote his message that Australia is “open for business”; the second was to boost strategic and security ties.

While in Texas on Saturday, he toured a cancer centre and spoke about the benefits of his proposed medical research future fund.

Earlier, he spoke to business leaders at the Asia Society Texas Centre, saying coal would fuel human progress for many years to come.

He said that had contributed to his Government’s decision to scrap the carbon tax, and that they would take action on climate change without ostracising any particular energy resource.

“Discussion about developing our natural resources often goes hand in hand with conversation about climate change and impacts on the environment,” Mr Abbott told the audience.

“It is prudent to do what we reasonably can to reduce carbon emissions. But we don’t believe in ostracising any particular fuel and we don’t believe in harming economic growth.

Mr Abbott went on to say his Government is abolishing the carbon tax “because it has damaged our economy and increased energy costs for businesses and families”.

He will be stopping at Pearl Harbour in Hawaii to visit the US Pacific Command on the way back to Australia.

Australia to work with US on Iraq situation: Abbott

Meanwhile, Mr Abbott reaffirmed Australia will work closely with the United States before deciding what to do about the deteriorating security situation in Iraq.

At a media conference before he left Texas, the Prime Minister said the situation in Iraq is very serious.

But he said he wants to make a measured decision about exactly what to do.

“As you’d expect the Americans are weighing their options. They’ll speak to us and we’ll talk to them and we’ll see what emerges,” he said.

Mr Abbott said it is a “difficult”, “complex” and “developing” situation that is getting round-the-clock attention, and he says no-one wants to make it worse by rushing things.

No change in East Jerusalem policy, says PM

Mr Abbott also moved to quell a diplomatic row over his government’s policy position on East Jerusalem.

The Coalition is refusing to call Israeli settlements in East Jerusalem “occupied”.

This has upset some Islamic nations, but Mr Abbott insisted there has been no change in policy.

“Absolutely no change in policy, there’s been a terminological clarification,” he said.

He said Foreign Minister Julie Bishop will meet with some concerned ambassadors in the coming days to explain the Government’s position.

“This is an area where people are inevitably extremely sensitive,” he said.

Mr Abbott said he does not think the controversy will affect trade ties with countries in the region.