A joke is going around on social media that has the climate crisis talking to the COVID-19 pandemic.

“Hey,” says climate, “Congratulations on all your success. Can I get the name of your publicist?”

The wry humor plays up one of the troubling ironies of celebrating the 50th anniversary of Earth Day amidst the global pandemic. An event designed to call attention the global environmental crisis has been upstaged by a crisis that has created massive behavioral change in a way that Earth Day itself has struggled to do.

For many environmentalists, the contrast between our relatively rapid and comprehensive response to COVID-19 and our comparatively lackluster societal response to the climate crisis is disheartening. The virus itself seems to have done more to lower emissions than just about any policy over the past two decades. Unfortunately, while some see great hope for action on climate change in our response to COVID-19, the slow decline of American environmentalism and the precautionary principle behind it may instead serve as a grim lesson for what to expect of our continued response to the global pandemic.

From the perspective of 2020, it is easy to forget just how effective a driver of social change the American environmental movement once was. Though Earth Day organizers have made much-needed efforts to diversify and internationalize the event in recent years, the original Earth Day in 1970 was a largely white middle-class affair focused on educational events that highlighted problems of pollution and waste. And it was hugely popular. The event had the support of local, state and federal officials (Pat and Dick Nixon planted a tree), and it drew more than 20 million participants, nearly 10 percent of the U.S. population at the time. Public opinion polls saw political concern about environmental issues increase by orders of magnitude between 1969 and 1971, changing the landscape of environmental politics and paving the way for some of the most aggressive environmental policies of the 20th century.

Earth Day 1970 was an important cultural moment, but it was also only one part of the story, an event embedded in a movement that had over the previous 15 years facilitated a raft of state and federal policies designed to float the kinds of change its organizers advocated. In an era of postwar affluence and massive, government-sponsored development programs, scientists and resource managers with an ecological bent had begun using their expertise to turn a critical eye to modern society. The cautionary work of authors like William Vogt, Aldo Leopold, Barry Commoner and, perhaps most importantly, Rachel Carson fed into what historian Sam Hays later described as a larger middle-class consumer movement already increasingly concerned about amenities like access to nature and clean, healthy neighborhoods.

By Earth Day 1970, a patchwork of state laws already existed to regulate air and water quality alongside the federal Clean Air Act of 1963 and the Federal Water Pollution Control Act of 1948. In January of 1970, just months before Earth Day, President Nixon signed into law the National Environmental Policy Act (NEPA), tying that patchwork together by creating a federal framework for evaluating and mitigating the potential environmental damage of new business and development programs.

More than any other piece of legislation, NEPA codified the precautionary approach that drove the environmentalism of the 1970s in the United States. The precautionary principle, simply put, assumes that amidst uncertain information, a new substance or practice is presumed harmful to the environment until its proponents can demonstrate that it is not. It is the same kind of statement of values that has incited state and local officials to issue stay-at-home or shelter-in-place orders in the midst of uncertainty about the spread and severity of COVID-19, and that has convinced most citizens to support those orders. In the case of the environment, the health of an ecosystem or an endangered organism a priori takes precedence over the potential economic benefit of a dam or a factory. In the case of COVID-19, mitigating illness and death a priori takes precedence over other priorities of daily life.

If environmentalism is any guide to the future, here is where the story may get dark. Despite the initial sanctity of the precautionary principle in environmental policymaking, by the early 1980s American policymakers began to undercut the government’s commitment to precaution. (This is still happening). The tool of choice among opponents of environmental regulation in the early 1980s was the cost-benefit analysis, a tool that purportedly measured the economic costs of an act of environmental protection against its benefits, which are often more difficult to measure.

Market-oriented cost-benefit analyses, not surprisingly, tended to privilege economic development over environmental protection. In the words of George H.W. Bush, they replaced environmental precaution with economic precaution. Through all the noise of climate denial and congressional grandstanding from the late 1980s to today, a short-term, economy-first approach built upon this cost-benefit rubric has underpinned the United States’ meek response to climate change.

Over the past four decades, opponents of environmental regulation have continued to hack away at both the precautionary principle and the policies it has inspired. (As Laura Martin suggested in her piece on the generational politics of climate change here earlier this month, the coronavirus has created a political smokescreen for the Trump administration to weaken the nation’s environmental rules and their enforcement even further.) In so doing they have significantly undercut the environmental movement’s ability to effect change, especially on large-scale collective action problems like climate change.

For now, local and state responses to COVID-19 continue to default to precaution, making life and health a priority over the economic costs of shelter-in-place orders and various types of business closures. That commitment to precaution, among other important factors, helps to make our collective response to the challenge of COVID-19 much more immediate and robust than our collective response to the climate crisis.

But the decades-long movement away from the precautionary principle in our response to crises of the environment may provide a cautionary tale as we move forward with our collective response to COVID-19. Pundits and politicians have rightly begun to explore the ethical and economic trade-offs of easing restrictions and reopening different sectors of American life. Those negotiations about our collective priorities are inevitable, even necessary.

Before we rush down that road, however, we would do well to note the value of the precautionary approach in driving a coordinated response to collective action problems like COVID-19 or climate change. This is the power that Earth Day once held, and one that now seems to have been lost. If 50 years of efforts to stem the environmental crisis provides a lesson here, it is that once we begin to negotiate the value of precaution, we can never go back.