Australia must focus on transitioning out of the mining economy or face falling out of the G20, PwC Australia Economics Partner, Jeremy Thorpe said while releasing the 'World in 2050' report.
The report, which analyses how the world could look in 2050 by presenting economic growth projections for 32 of the largest economies in the world, shows Australia will slip from 19th place in 2014 to 28th in 2050.
Other findings include:
"Business, government and community leaders must move their focus away from the next results announcement or election and turn towards planning for the long term to prevent us slipping down the ranks," Mr Thorpe said.
"Australia must diversify its economy by investing in highly skilled workers and become the knowledge nation to stop us slipping out of the top 20 economies."
Two years after the last update in January 2013, today's 'World in 2050' extends coverage to include eight additional countries, six who will have surpassed Australia by 2050: Bangladesh, Egypt, Iran, Pakistan, Philippines and Thailand.
"Australia has punched above its weight historically, however our fall from the G20 to the G30 will challenge our relevance within the world," Mr Thorpe said.
He said the report ranks each country by purchasing power parity (PPP) and sees a broad shift in global economic power from the G7 to the E7 emerging economies.
"Australia is being trumped by countries with rapidly growing populations, increasing urbanisation and improvements in education in a number of developing countries," Mr Thorpe said.
"Leaders across business, government and the community need to understand we are on a slippery slope to global irrelevance.
"While we will remain a prosperous nation, amongst the highest countries in terms of GDP per capita, we risk losing the influence we have today.
"We need to diversify our economy, which starts with transitioning and upskilling Australia's workforce for the jobs of the future.
"This will require a huge investment by government and business away from mining and into education, particularly into science, technology, engineering and mathematics (STEM) subjects."