The numbers vary wildly, but all are dizzying: $15 trillion. $30 trillion. $59 trillion. $68 trillion.

These are the figures being bandied about as economists and financial experts try to get their heads around a global phenomenon known as the “Great Wealth Transfer.” Between now and 2030, an estimated $15.4 trillion of assets will have been passed down the generations by the world’s richest people, according to a report published this year by the specialist analytics company Wealth-X.

“With the global wealthy population at an all-time high, the next 10 years will see the biggest-ever wealth transfer in modern history,” said Maeen Shaban, the director of research and data analytics at Wealth-X, whose report concentrates on people with net assets of $5 million or more — the richest 0.1 percent of global society.

The Wealth-X report estimates that America’s wealthiest will pass on $8.8 trillion of assets over the next decade. Most of those are baby boomers currently in their mid-60s and older who over the years have benefited from financial deregulation, globalization, and rising real estate and stock prices. They will hand down assets to members of Generation X, in their 40s and 50s, and, to a lesser extent, to millennials now in their mid-20s and 30s, the report says.

Most of those assets will be financial: stocks, bonds and trust funds. “Illiquid assets” like real estate and investments of passion — including art — make up more than $1.9 trillion of the total, according to Wealth-X.