Hawaii state economists foresee a time a decade from now when the state’s demographic trends will turn an ominous corner, and there will be more people dying than being born.

But a retired university demographer living in Hilo has found that the future is now, at least for Hawaii Island.

A “natural decrease” in population, as demographers call it, is already happening on the Big Island, says Karl Eschbach, who previously served as the Texas State Demographer.

As shown below, the Hawaii Department of Business, Economic Development and Tourism‘s research division has predicted the statewide natural decrease will begin around 2035.

The natural decrease isn't the same as a population decline. In fact, statewide Hawaii's population for years has been declining despite a natural increase, in which more people are being born than dying. The natural increase has softened the impact of Hawaii having more people leaving the state than moving here.

A natural decrease statewide will magnify Hawaii's population losses.

The cause of the Big Island's natural decrease, Eschbach said, appears to be that older people and retirees are moving to the island, while younger adults are moving away and not coming back. The loss of people in their prime work and childbearing years is a double-whammy: people leave, and so do their young children. Plus offspring yet to be conceived are born and raised elsewhere.

Carl Bonham, executive director of the University of Hawaii Economic Research Organization, says there's another factor at play concerning the natural decrease. The birth rate started declining sharply after the Great Recession, then the Covid-19 pandemic signaled an increase in deaths more recently.

"There was this jump in deaths during the pandemic, and presumably that's going to slow," he said.

Regardless, loss of working-age population is bad for a number of reasons. Fewer working people can lead to a lower tax base, which is not replenished by retirees living on income that's not taxable. That means less revenue for social safety net programs that could be in higher demand because of the aging population.

Oahu hasn't crossed the line into natural decrease yet, said Eschbach, formerly a professor at the University of Texas Medical Branch in Galveston. But that might be only because of the military, which has a positive population double-whammy on Oahu. Young military personnel come here with spouses and children, who boost the younger population, as shown in the population graph below.

Such images are called population pyramids because they are supposed to look like triangles with wide bases of young people and small tips of older people. Above, the image on the left shows Oahu's population with and without military personnel and their families.

The neighbor island population pyramid looks more like a column with a pointed top. Oahu has more younger adults, creating a bulge in the middle, and a wider base of young children.

But that's largely because of the military presence on Oahu, Eschbach notes. Remove the military from Oahu's population, and the shape of Oahu's population pyramid looks similar to that of the neighbor islands. Removing the military from the neighbor island pyramid, however, produces little change.

"Basically the military is a source of in-migration of young people," Bonham says.

The loss of the state's tax base is just one consequence of the trend of losing younger adults, Bonham said. It also means the loss of workforce, which means a loss in economic activity. The only way to maintain economic growth is to cultivate a larger workforce or increase productivity, Bonham said.

Bonham said artificial intelligence theoretically might fill gaps by boosting productivity in Hawaii's tourism economy — consider robot hotel and restaurant workers. But he said the better solution, for Hawaii and the U.S. as a whole, would be immigration policy changes that make it easier for foreign workers to migrate here.

It's not only Hawaii's economy that's at risk. A recent White House report pointed to the trend of lower fertility rates nationally, predicting that the nation's population also will begin shrinking by 2040 without greater net migration into the U.S.

"It's very possible this will put pressure on politicians to fix a broken system," Bonham said.

"Hawaii's Changing Economy" is supported by a grant from the Hawaii Community Foundation as part of its CHANGE Framework project.