The population in Guilderland continues to grow. But the enrollment in Guilderland’s public schools continues to fall.

How can this be?

The short answer: Fewer people are having children.

The Guilderland school district was wise to hire a demographer to look at its future. Robert Scardamalia, who formed RLS Demographics Inc. in 2010 after serving as the chief demographer for the state of New York for nearly 20 years, went over projected changes for the school district, setting the enrollment decline in a statewide and national context.

Birth rates are declining nationwide and immigration, which our state counted on, is slowing. More than half of New York’s counties, Scardamalia said, are in a state of natural decline with more deaths than births.

It turns out that this is a worldwide trend.

The world’s population, according to the latest report by the United Nations, is projected to continue growing for the next 50 to 60 years, peaking at approximately 10.3 billion by the mid-2080s.

After reaching this peak, it is expected to gradually decline to around 10.2 billion by the century’s end. Currently, one in four people lives in a country where the population has already peaked, the U.N. report says. Only a handful of countries in Africa are showing a population growth of 4 percent or higher.

By 2080, the United Nations reports, the number of people aged 65 and older is expected to surpass that of children under 18, and by the mid-2030s, those aged 80 and over will outnumber infants.

Countries facing demographic aging, like the United States, “may need to leverage technology to enhance productivity and create lifelong learning opportunities, supporting multigenerational workforces and extending working lives as needed,” the United Nations says.

Reading this sentence gave us pause. How will our children and grandchildren be able to support their aging elders — an ever-growing demographic — with programs like Medicare and Social Security that rely on younger workers paying into the coffers?

Then we remembered Thomas Malthus, the 18th-Century English economist and minister. He saw the growing population at that time as outstripping the resources available to support it.

“The power of population is indefinitely greater than the power in the earth to produce subsistence for man,” Malthus wrote in “An Essay on the Principle of Population.”

This was widely read, including by founders of our nation, Thomas Jefferson and James Madison.

What Malthus didn’t foresee, though, was the Industrial Revolution that upended the agrarian society on which he had based his principles. So the population continued to grow.

Will the current digital and artificial-intelligence revolution in which we now find ourselves somehow solve the future problem of an age-heavy society without enough young workers to support the elderly?

The Progressive Policy Institute, a centrist Democratic think tank, writes that policy experiments have failed to reverse the trend of declining fertility. The PPI neatly frames the two failed approaches:

Conservatives tend to see falling birth rates as rooted in declining marriage rates, secularization, and modern feminism. Accordingly, they believe the right response is to promote and subsidize childbearing and marriage, expand home schooling and religious education, and reverse the social changes they blame for the trend.

Progressives view declining fertility as a symptom of affordability challenges and the difficulty of raising children, which they seek to address through cost-of-living subsidies, universal paid maternity leave, and a Biden-era vision for the care economy.

The Cato Institute, a Libertarian think tank, graphs the steep decline in the United States of fertility rates from 1800 to 1940, when the rate fell from seven children per woman to just over two — the rate for a population to maintain itself.

“The total fertility rate fell below the replacement rate prior to the second World War,” the Cato report says. “Americans worried about low fertility in the pre-war years, during the war, and afterwards, though by the end of World War II fertility had begun to rebound. This ‘baby boom’ shocked demographers of the day, who did not forecast it (in fact, quite the opposite, demographers projected a continued downward trend for fertility).

“Later, demographers were unable to predict the end of the baby boom. Today, the cause of the baby boom is still debated, with various researchers arguing that factors including technological improvements, women’s labor market opportunities, and wartime mobilization motivated it.”

As happened across our nation, schools were built in Guilderland to accommodate the baby-boom generation.

Once that generation passed through — some have likened it to a pig passing through a boa constrictor — Guilderland closed two of its five elementary schools.

 The district leased Guilderland Elementary to a Hebrew academy, and sold Fort Hunter Elementary. These were difficult decisions, especially for students and their families, but were needed to sustain the school system.

When the echo boom — the millennials — arrived, the district re-opened Guilderland Elementary and built Pine Push Elementary to serve the Fort Hunter catchment area.

The numbers — depicted vividly in graphs — presented by Robert Scardamalia this month should serve as a wake-up call to the school board and to all district residents.

Scardamalia made clear that Guilderland is not alone. He showed a graph with flat enrollment lines for the neighboring districts of Bethlehem, Niskayuna, Voorheesville, Shenendehowa, and Albany.

The most stunning graph, though, showed the projected enrollment for Guilderland, going from the current 4,800 students to fewer than 4,300 in 2035. That’s a loss of over 500 students in less than a decade.

Guilderland, according to Scardamalia’s projections, has a few years left of gradual decline. We urge the district to use this time to plan for a healthy and harmonious future.

In 2014, the district under then-Superintendent Marie Wiles hired consultant Paul Seversky to conduct a capacity study.

Wiles delineated three challenges she said Guilderland faced: declining enrollment, excess capacity, and diminishing resources. At that point, enrollment had decreased by 13 percent from 5,645 in 2004-05 to 4,908 in 2014-15.

Seversky’s recommendation to close an elementary school to save about $2 million annually at a time the budget was about $90 million was wildly unpopular.

We advocated on this page for keeping all five neighborhood schools open and finding other uses for vacant classrooms.

Ultimately, the school board, in a split vote, set aside Seversky’s recommendations and formed citizens’ task forces to look into various uses for excess classroom space while keeping all five elementary schools open.

The task force committees considered preschool, adult day care, incubator start-ups, and commercial rental to fill the empty classrooms at Altamont Elementary, Pine Bush Elementary, and Farnsworth Middle School. The board ultimately decided on an outside pre-kindergarten business to rent the extra classrooms.

But the problem has not been solved — enrollment continues to decline.

We saw in this budget cycle how upset parents, students, and staff were with the proposed 5-percent across-the-board cuts to balance the budget while staying within the tax levy limit set by the state.

The board decided instead to use $2 million from its savings to maintain most of those posts. But that is not a long-term fix.

We cannot count on our federal government — which is stymying the immigration so needed by New York state while simultaneously making cuts that hurt education — to be part of the solution. We cannot count on our state government, which has had to backfill to maintain needed programs after federal cuts, to come up with more funds for schools

Certainly the town government can and is doing some things that will attract families to the district like maintaining an excellent park system with recreational programs, and requiring developers to include low-income and workforce housing in their projects. Guilderland also, as we’ve written before on this page, needs to undertake another town-wide property revaluation to set the school district on a more secure financial foundation.

But, in the end, it is up to the Guilderland School Board and district leaders to come up with a fair plan to downsize now that they are aware of the drastic projected enrollment decline. There is time to involve the community in that discussion to set a course for a vital future.

We will conclude with words we wrote 12 years ago on this page when Guilderland was torn as the schools faced the same still-unresolved dilemma:

We, each of us, know a part of how the schools serve us. One of us may teach, another may be a taxpayer who counts on a stable property value, a third may drive a bus, a fourth may have a child in the school, a fifth may go to an occasional concert or football game, and on and on and on.

But if we come face to face as a community and try, really try, to genuinely see what meets the most needs we will then perhaps see clearly. Let’s have faith in the process, hope for the outcome, and charity toward our neighbors whose ideas may differ from our own.