Business leaders globally are worried about the risk of recession, labor shortages and rising inflation, despite some signs of improvement in economic conditions, a World Economic Forum survey said Thursday.

Extreme weather events are an increasing concern, following a year of record temperatures, severe flooding and wildfires, including in major economies such as Brazil, Germany, Indonesia and the United States, according to the survey of more than 11,000 business leaders from G20 countries.

The WEF Executive Opinion Survey shows "a significant level of anxiety among business leaders in G20 countries", said Carolina Klint, chief commercial officer, Europe at Marsh McLennan, a WEF partner, along with Zurich Insurance.

Economic downturn is seen as the top risk for business leaders over the next two years, followed by labour and/or talent shortages and then inflation. Poverty and inequality ranked fourth, and extreme weather events came in fifth, the survey showed.

In individual country surveys, concerns about adverse risks from technology, including artificial intelligence, featured highly, coming in as the top risk for doing business in Indonesia, number three in the United States and number four in Britain, the survey showed.