Fatalism may be our planet’s greatest enemy.

That is, the belief that no matter what we do to try to protect the environment, it’s not going to make a difference in the long run.

Why hold onto our litter until we can find a trash can? Everyone else is dropping theirs on the ground, so our roads and other public spaces still will end up messy.

Why try to save gas? Even if we drive fuel-efficient cars, our neighbors in gas guzzlers still are going to pollute the air anyway.

For those who want to avoid feeling guilty, the “what’s the difference” argument can be liberating. If nothing I do matters, that line of thinking goes, then why shouldn’t I do whatever I feel like?

This isn’t just a rationalization offered up by narcissists who are looking for any excuse to avoid personal inconvenience or sacrifice. Well-meaning people who genuinely are interested in doing the right thing can fall into this trap, too.

Particularly when the discussion turns to big environmental issues like global warming. Even if people all over the United States were willing to take steps scientists believe could avoid widespread destruction, what difference does that make if other countries around the world aren’t willing to take similar steps?

Here’s the problem with that argument: The world’s response to the COVID-19 virus has shown that we can take actions ? all of us, working together ? when we’re trying to avoid a global disaster. Maybe not happily. But we can make progress toward large common goals if we’re properly motivated.

After essentially being under house arrest for a month, taking shorter showers or shutting off unneeded lights or appliances doesn’t seem like that big of a bother.

What about the larger changes? Well, we’ve learned that we don’t need fossil fuels nearly as much as they may have thought we did. Oil prices have cratered on the world market because fewer people are driving cars or working in factories.

The benefits to our environment have been noticeable. Our air and water have been visibly cleaner in some historically dirty places as a result of the COVID-19 shutdown.

Of course that will change as people return to work and our economy gets back to something approaching what we consider to be normal. But we can’t unring the bell.

We know now that people around the world can cooperate and put their collective interests ahead of their personal interests when their lives depend on it. The battle now is to convince them that the risks of environmental inaction can be every bit as deadly to our children and grandchildren in the decades ahead as the risk of coronavirus has been for us in the present day.

Wednesday marks the 50th anniversary of Earth Day, an annual event intended to raise awareness and inspire action to make our planet a cleaner, safer and better place to live. What will our planet look like in another 50 years?

We can see there are steps we can take, starting now and continuing for the next half century, that can change the answer to that question. Once the scare created by the COVID-19 virus is gone, we can’t afford to go back to sleep and forget that.