The alarms bells have already started to sound. And this week it is expected to be announced formally that the global economy is running out of steam.

As finance ministers, central bankers, academics and other delegates prepare to travel to Bali for the annual meeting of the International Monetary Fund (IMF), optimism about the future is at a low ebb.

On Tuesday, the fund will update its World Economic Outlook – a healthcheck on the world economy – and has already warned that the effects of rising debt and trade wars are affecting the global projections. Last week, the IMF’s head, Christine Lagarde, said the outlook “has become less bright”, despite projections during the summer that there would be 3.9% growth for 2018 and 2019.

It will be a different atmosphere in Bali this week compared to the last annual meeting in Washington, when the world was experiencing the strongest period of economic growth since the crash.

Adding to Lagarde’s comments, there were warnings last week in the IMF’s global financial stability report, which said there was a risk of another financial meltdown because both governments and regulators have failed to put in place needed reforms to protect the system.

Lagarde said that while expansion of the global economy was running at its fastest rate in seven years, there were signs of slowdown. In September, factory activity dropped as a result of changes in trading with the US – and Donald Trump did not escape (admittedly veiled) criticism.

The growing use of trade barriers had resulted in a drop in imports and exports, Lagarde said, and investment and manufacturing output had also been hit. Trump has consistently championed unilateral trade deals in an effort to further his “America First” agenda.

“History shows that, while it is tempting to sail alone, countries must resist the siren call of self-sufficiency – because as the Greek legends tell us, that leads to shipwreck,” said Lagarde.

Last month, Trump intensified his trade war with China by imposing new tariffs on $200bn of Chinese goods arriving in the US. Beijing responded with retaliatory tariffs on $60bn worth of US products. The two countries already exchanged tariffs on $50bn worth of each other’s goods earlier this year.

Also central to the concerns about the future of the global economy are debt levels, currently well above those seen at the time of the 2008 crash. The IMF warned that there was a risk that unregulated parts of the financial system could trigger a panic.

The rise of unregulated “shadow banks” and the lack of restrictions on insurers and asset managers were pinpointed as concerns – as was the growth of global banks to a scale larger than 2008 and the fear that they are again “too big to fail”.

Lagarde has said she is concerned that the total value of global debt has risen by 60% in the last 10 years to reach an all-time high of £139tn.

As central banks in more advanced economies raised interest rates, attracting investors back to them, she said, developing countries were suffering. “That process could become even more challenging if it were to accelerate suddenly. It could lead to market corrections, sharp exchange rate movements, and further weakening of capital flows.”

It is under these gathering storm clouds that the finance ministers from the 189 member states of the IMF will meet at the end of this week as, once again, turbulence threatens the global economy.