Mark another milestone for China’s ever-rising economic profile: UBS emerging-markets economist Jonathan Anderson has declared China’s property industry “the single most important sector in the entire global economy.”

In a research note Wednesday, Mr. Anderson, a longtime China watcher, says that “real-estate and housing construction pervade the entire [China] growth model. They are the most important determinant of commodity demand, a very big marginal driver of China’s external surpluses, and indeed a crucial key to real understanding of household balance sheets, saving and investment behavior and the debate around Chinese rebalancing.” In other words, he says, “from a macroeconomic perspective if you don’t understand Chinese property, you probably don’t understand China.”

Many global investors won’t find the declaration all that surprising, having seen shares in many companies buffeted over the past year by Beijing’s efforts to wrestle with soaring house prices while trying to avoid undercutting the construction industry. But it is remarkable sign of the times nevertheless. As Mr. Anderson notes, “until very recently” the proper response to the question of which sector is most important “would almost certainly have been U.S. financials and/or U.S. housing.”

The numbers tell much of the story. China is the world’s largest consumer of steel, and Mr. Anderson notes that real estate directly accounts for 40% of Chinese steel usage. Add home appliances and automobiles—which he notes tend to directly follow new housing purchases in China–the share is more than 50%. Similar logic applies to other products like cement, iron ore, coal, and construction equipment.

Property construction—75% of which in China is housing–accounted for more than 13% of China’s gross domestic product last year, UBS estimates—more than double the average of 6% in the 1990s. Mr. Anderson says that explains why investment overall accounts for such a large share of China’s economy—an estimated 47% to 48% of GDP last year, which “is an absolute record for any economy of significant size in the post-war era, and almost single-handedly explains China’s explosive real growth over the same period.”

So is China’s property sector a bubble? And how long can the boom continue? Mr. Anderson temporarily punts on those all-important questions, saying colleague Wang Tao, UBS’s China economist, will weigh in next week.