Since its inception in 1970, Earth Day has evolved significantly over the past five decades, as has the natural environment that activists aim to protect.

Today’s green activists tend to observe Earth Day by emphasizing personal actions to reduce their environmental impact, such as recycling, cleaning local parks, planting trees, driving hybrid cars and using reusable bags. 

These environmentally friendly behaviors are all welcome, of course, but the activists who celebrated the first Earth Day had a broader focus: they were primarily concerned about our collective impact on the environment.

In particular, they feared that America’s rapidly growing population was overtaxing fragile ecosystems. Earth Day founder and U.S. Senator Gaylord Nelson pointed out that the U.S. population had surged from 98 million in 1916, the year he was born, to 200 million by the time of the first Earth Day. He observed that “tremendous ecological damage occurred as a result of this growth” since vast expanses of green space had to be cleared to make room for houses, offices, malls, roads and all the other trappings of civilization.

Since then, America’s population has increased by 130 million people, further impacting the environment and local wildlife. Between 1982 and 2017, the nation lost 68,000 square miles of open space—an area the size of Florida. Of this habitat destruction, 67% was due to population growth, while the remaining 33% resulted from increases in per-capita consumption.

And there’s no end in sight. In the next 30 years, our population is projected to hit 373 million, primarily due to immigration, according to the Congressional Budget Office. This anticipated increase will lead to further habitat loss and a rise in pollution, which will negatively affect the natural environment and reduce Americans’ access to nature.

Politicians sometimes downplay environmental and quality-of-life concerns, arguing that the benefits of economic growth outweigh the negative consequences. Essentially, their stance is, “We don’t need to worry about how to slice the pie to serve more and more people; we just need more pie.”

However, the reality is that there simply isn’t more pie, as there are inherent limits to our resources. There isn’t an endless supply of fresh water to distribute among an ever-growing number of Americans who each use an average of 80 gallons per day to meet their eating, drinking and cleaning needs.

Similarly, there isn’t “more pie” when it comes to wildlife habitat to support threatened and endangered species. There isn’t “more pie” if we want to preserve land for parks and farming instead of housing.

It’s time for environmentalists to realize that while efforts like electrifying the grid, planting trees and using reusable bags is all good, it isn’t enough. We need to stop slicing the limited pie of America’s resources to the point of no return. Without addressing this issue, traditional Earth Day activities may ultimately be undermined by the relentless expansion of our population by millions each year. 

Karen Shragg is an author and environmental consultant. This piece originally ran in the Boston Herald.