The annual G-20 leadership summit that groups democrats with authoritarians and rich nations with poor has long suffered from a perception it's all talk and no action. This year, leaders are under extra pressure to produce something tangible.

The global forum is regarded as having been at its most successful during its first summit in 2008 when an alarming financial crisis that was nursed into being on Wall Street rippled around the world, toppling giant banks and casting tens of millions out of work.

Since then, the gathering has been criticized as having produced a lot of lofty goals, but little follow-through despite its member countries representing about 85 percent of the global economy.

Prompting pressure for tangible results at the Group of 20's Brisbane summit this weekend, experts say, are comments from the International Monetary Fund warning about a "new mediocre" for the global economy, with Europe teetering on the brink of recession, China's growth slowing and Japan in a malaise.

"What the world really needs is a little burst of confidence," said Mike Callaghan, Program Director of the G20 Studies Center at the Lowy Institute, an Australian think-tank. "There is the pressure on the G-20 to provide signs of confidence that the countries are cooperating together."

One concrete measure of the G-20's success could come from its previously announced goal of creating tens of millions of new jobs by adding $2 trillion to global GDP over five years.

Prior summits have shied away from setting such targets because of concerns that the G-20's credibility could be attacked if the targets were not achieved.

Australia, as this year's chair of the G-20, has been determined to give the forum new relevance, an outcome that would burnish its credentials and image on the world stage.

But details of exactly how the nations will reach the growth target remain sketchy.

Australian Treasurer and summit host Joe Hockey said the group agreed to focus on growth led by private business and industry, particularly from additional investment in infrastructure, to get the job done. Each country is expected to present a comprehensive growth strategy at the summit.

A challenge, however, is that the goals require implementation over many years and that requires prolonged political momentum.

"When you're all facing an immediate crisis, it's a lot easier to focus the mind and be able to agree on what you need to do," Callaghan said.

"In Brisbane, what is invariably needed is some good evidence that these major countries are actually cooperating to improve the global outlook and it isn't just talk."

A second barrier is the widely divergent interests of countries in a club that includes a superpower, the United States; giant but very poor states such as India and governments that are often at loggerheads with each other such as China and Japan.

Joseph Cheng, a political science professor at the City University of Hong Kong, said it will be crucial for the G-20 to put in a place a reporting system that allows the progress of each country to be measured.

He said that could allow for "public opinion pressure" on the countries that deviate from the targets and is the "real important issue" at stake during the weekend summit.

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Wright reported from Bangkok.

Stephen Wright on Twitter: @stephenwrightAP