The world is sinking under too much debt and an ageing global population means countries' debt piles are in danger of growing out of control, the European chief executive of Goldman Sachs Asset Management has warned.
Andrew Wilson, head of Europe, Middle East and Africa (EMEA), said growing debt piles around the world posed one of the biggest threats to the global economy.
"There is too much debt and this represents a risk to economies. Consequently, there is a clear need to generate growth to work that debt off but, as demographics change, new ways of thinking at a policy level are required to do this," he said.
"The demographics in most major economies – including the US, in Europe and Japan - are a major issue – and present us with the question of how we are going to pay down the huge debt burden. With life expectancy increasing rapidly, we no longer have the young, working populations required to sustain a debt-driven economic model in the same way as we've managed to do in the past."
Mr Wilson used Japan, where gross government debt has climbed above 200pc of gross domestic product (GDP), as an example of where the ageing population could demographics were working against them. "[This] is evidently not sustainable over the long term," he said.
The Organisation of Economic Co-operation and Development (OECD) has also sounded out a warning about Japan's growing debt pile. The Paris-based think-tank said gross government debt was on course to balloon to more than 400pc by 2040 if the government did not carry out reforms.
Angel Gurria, the OECD's secretary-general, said monetary stimulus and stronger growth alone would not be enough to haul the economy out of its two-decade malaise.
"Japan's future prospects depend on ensuring fiscal sustainability over the long term. With a budget deficit of around 8pc of GDP, the debt ratio is set to rise further into uncharted territory," he said.
Others have warned privately that Japan's debt mountain is unsustainable. "The crunch point is when it starts to run a current account deficit," said one senior banker. "When they stop running a current account surplus and they need our money to survive, we're not going to lend to them at 30 or 40 basis points."
Mr Wilson said there was hope for countries with high debt burdens. "The demographic shift means that we need to look to more creative policy, including immigration and workforce expansion in order to find ways to pay down debt.
This is happening in Japan in the form of [prime minister] Shinzo Abe's drive to increase female labour participation and via efforts to boost inflation."
The Goldman chief also said that warnings about liquidity shortages in the market were being "overplayed", especially with regards to the corporate bond market. He also said that bouts of volatility when the US Federal Reserve starts to raise interest rates were to be be expected.
High profile executives including Jamie Dimon, the head of JP Morgan, and Tim Adams, the head of the Institute of International Finance have warned that the raft of regulation introduced in the wake of the 2008 crisis could potentially cause huge volatility in the markets.
While Mr Wilson said the European Central Bank's €60bn a month bond-buying progamme meant it was hard to judge how liquid the market was, he added: "We should expect some growth in volatility - but I do not view that as a negative. In fact, I would view this as getting back to a more normal world. Moving out of an environment where there is a huge amount of government and central bank policy designed to provide certainty and liquidity and to dampen volatility is a healthy sign, not an unhealthy one."