When I came to the Mennonites nearly 30 years ago, one of the first things I ­noticed was their ethic of simplicity. At last, I thought, I had found a church that lived by this essential spiritual principle. As a convert to the Mennonites, I believe it is of utmost importance that we hold on to simplicity, practice it wholeheartedly and resist consumer culture.

I understand that the original motive for simplicity is spiritual: to keep us focused on the things of God, on being followers of Jesus, on the truly valuable things of life and not on storing up treasures on Earth that can capture our hearts.

But today, simplicity takes on another important role: caring for the Earth. 

As an Earth scientist by profession, I am painfully aware that all the Earth’s components — land, water, air (including climate), ice caps and glaciers, forests, animals, plants — are in deep crisis. The emergency is due primarily to human activity. We consume too much material and energy, and the Earth is showing the destructive effects. 

According to the Global Footprint Network’s Ecological Footprint Index, humans use as much ecological resources as if we lived on 1.75 Earths. If everyone consumed at the rate North Americans do, we would need five Earths to support us all. This is called overshoot, a drawing down of the Earth’s natural capital — which, like an overdrawn bank account, cannot be sustained.

Why do we overconsume? One reason is that the prices of goods and energy are too low. They do not reflect what economists call externalities — the costs borne by other people and the Earth that are not included in the prices. 

One example of paying for externalities is a carbon tax — raising the price of goods and energy to account for the costs of climate warming. People would react by reducing consumption. 

But we do not have a system that pays for all externalities, and it is unlikely that we will. Instead, we must act out of principle and voluntarily reduce consumption.

Many would prefer technological fixes. They would like to continue their level of consumption but do less harm. This is an unrealistic dream. Such fixes do not solve the problem at its root. And they create new and more difficult problems.

Simplicity is the principle we need to relieve humans’ destructive pressure on the Earth, stabilize the climate and restore damaged ecosystems. Individual action alone will not solve these problems. Government and corporate action is needed, too. But, collectively, individuals exert power in a capitalist economy. We shape the demand for goods and services and set the tone for cultural change.

In an economic system that pro­motes endless growth, few are willing to recognize the problem of overconsumption. Yet we must face this reality if we are to save ourselves and the Earth. We need to look deeply into our souls and acknowledge our complicity in environmental destruction.

Are Mennonites courageous enough to do so — and then to align our behavior with the values we say we hold and protect what we say we love?

Making lifestyle changes for the good of all also draws upon the Mennonite ethic of community. We care how our actions impact other people and the Earth.

Scaling back an overly consumptive lifestyle could be termed a compassionate retreat — a voluntary reduction of human pressure on the Earth. There are many ways to do this.

We can simplify our lives by distinguishing between necessities, conveniences and frivolities. We can shop at local businesses for local goods and avoid plastic packaging. We can put a brake on our use of technological devices, including electronic gadgets and online services powered by ­energy-draining computer server farms.

I try to keep things simple and on a human scale. Although simplicity can sometimes be inconvenient, most of the time it is freeing, and I am committed to it.

Simplicity is a spiritual concept that overlaps with a practical one — living as healthy and whole people who ­nurture a healthy and whole Earth. This may be news to some, but Mennonites have known it all along. Will we practice it?

David C. Garen is a retired hydrologist who spent most of his career with the U.S. Department of Agriculture and the National Weather Service. He is married to Betty Burkholder, and they have two adult sons. He is a member of Portland Mennonite Church in Oregon.