Our presidential elections elicit bold ideas designed to capture the imagination of the American people. In that spirit, Matthew Yglesias, the founder of Vox, has written a new book, “One Billion Americans: The Case for Thinking Bigger,” which proposes that America triple its population.

At a time when large numbers of Americans are beginning to wonder whether the forces unleashed by climate change will force them to move someday, the idea of adding another 670 million people to the U.S. population hardly seems advisable.

If, as many now fear, climate change is accelerating, millions of Americans could be uprooted. According to new data from the Rhodium Group analyzed by ProPublica and the New York Times, climate change could lead to “massive upheavals in where Americans currently live and grow food.” Large sections of America, including the South, the West, and the Mississippi River valley, could be severely impacted by extreme temperatures or humidity, and rising seas could force significant migration from coastal areas.

So why triple our population? Yglesias says we must ward off “the end of American hegemony.” He says we “should aspire to be the greatest nation on earth” because the People’s Republic of China, is “not something cuddly like a hypothetical version of the European Union.”

Yglesias says the key to maintaining American greatness is preserving our status as the world’s largest economy. America was great long before we seized that title, and even if China’s economy soon surpasses ours in terms of absolute size, our average per capita income will, for decades to come, exceed China’s.

He argues that “America’s vast rural hinterland and many of its aging northeastern and Midwestern cities need an influx of people.” That’s silly. What they need is a viable economic base. Adding more people will not magically create jobs or the resources needed to sustain them.

Yglesias acknowledges that tripling America’s population could “cause a number of problems,” but he insists it would give us a “shared sense of purpose.” He also admits his rationale may “sound a little loopy.”

Things are not always as they sound, but this one is. We have no shortage of critical challenges. Aggravating them by adding another 670 million people is a loopy idea.

In a world threatened by climatic changes and environmental devastation, we don’t need to think bigger. World population is rapidly approaching the 8 billion mark, and by mid-century it will be nearing 10 billion.

Humanity is in danger of overwhelming the planet. We are, with astonishing speed, rapidly destroying or despoiling the forests, wetlands, rivers, lakes and oceans that sustain 7 million plant and animal species. Scientists are warning that our destruction of their habitats is triggering a mass extinction of animal species, the greatest since the dinosaurs were destroyed 67 million years ago.

As Americans, we urgently need to curb our greenhouse gas emissions, not expand them. An estimated 45 percent of pregnancies in America are unintended. We should do more to prevent unwanted pregnancies. Instead, we are weakening our commitment to family planning, at home and abroad, and discouraging comprehensive sex education from being taught in our schools.

Calls to realize America’s greatness should be viewed skeptically. America has been great for a very long time. And, if we are good stewards of our success, America will remain the world’s preeminent power for generations to come.

Our greatness has been founded on our commitments to democratic principles, human rights, and economic opportunity for all. We have not always lived up to our high ideals, but whenever we have done so, we’ve become stronger for it.

Our greatness has never been predicated on population size or density. When the thirteen colonies joined together, we were only a few million strong, far less than one percent of the world’s population. Even today, with nearly 330 million Americans, we are less than five percent of the total.

When our nation was founded, we were blessed with a bounty of natural resources and, as we expanded westward, displacing an already decimated Native American population, we acquired even more land, water, metals, and minerals to fuel the growth of the American economy.

America’s resource base is not yet exhausted, but it is not limitless. In many parts of the country, water scarcity is destroying farms and the viability of rural communities, while exhaustion of mines is creating ghost towns.

If we need a new sense of purpose, let’s find it by creating economic opportunity for all those Americans who are excluded from living the American dream. Let’s improve education, boost our support for science, and create jobs by investing far more in conservation and renewable energy.

We don’t need to think bigger. We need to think smaller and smarter.

This op-ed by Robert Walker, who is the President of the Population Institute, originally ran on September 26, 2020 in The Hill.