On April 22, 1970, millions of people gathered throughout the United States for the first Earth Day, organized by Gaylord Nelson, a former Senator from Wisconsin, and Denis Hayes, a Harvard graduate student. Let’s reflect on what’s happened in those 50 years.

In 1969, after a century of using the waters of our nation as an open sewer, a train track spark in Cleveland, Ohio ignited a fire on the Cuyahoga River. The Cuyahoga had been on fire ten times between 1868 and 1969. What changed between the ninth and tenth fire was the awareness of the citizens of the United States to environmental degradation and threats. After this fire, the call for environmental controls from citizen activists became a roar and pushed the Nixon administration to create what is now known as the U.S. Environmental Protection Agency. In 1972 Congress overrode Nixon’s veto and passed the Clean Water Act setting the first set of national water quality standards. Discharging untreated waste into our waterways was business as usual until we the people decided to change that.

In the 1980s, researchers began documenting a continual thinning of ozone above Antarctica. They determined that chlorofluorocarbons were accumulating, being converted to chlorine by sunlight, reacting with ozone, and destroying the protective layer. A multinational agreement, the Montreal Protocol, was ratified in 1987 by President Reagan to ban ozone-depleting chemicals. Using products that destroy what protects us from dangerous UV radiation was business as usual until we the people decided to change that.

In the mid 1900s, our increasing reliance on organochloride pesticides like DDT were hitting bald eagle populations and a wide variety of other wildlife were failing because of habitat losses and dramatic land use changes. Thanks in large part to Rachel Carson’s landmark book, Silent Spring in 1962, the impetus for greater legal protection for the country’s most imperiled wildlife was mounting. The first endangered species protection law in the United States was passed in 1969 and was replaced by President Nixon in 1973 by the Endangered Species Act (ESA). Using excessive amounts of persistent and bioaccumulative pesticides, destroying critical wetlands, and enclosing, rerouting and damming rivers and streams that pushes animals into extinction, was business as usual until we the people decided to change that.

It’s a strange time to be writing a column that won’t be published for 10 days. As we face the impacts of this “invisible enemy,” I encourage you to consider another invisible enemy looming over our future. Someday I hope to be able to say this:

Emitting massive quantities of greenhouse gases into the atmosphere without consideration for the long range impacts on the living world was business as usual until we the people decided to change that.