Earth Day Reflections: Hope Amid the Pandemic.

As I write this Editorial, humanity is reeling from COVID-19. Every aspect of our lives has been affected in ways we could not have imagined. Even so, there is hope in these dark times.

April 22, 2020, marks the 50th Earth Day celebration. Launched in 1969, this global movement sought to boost awareness of how human activities adversely affect the environment and how we can and should protect our planet’s finite resources.

For example, Earth Day anniversaries in the 1970s celebrated the establishment of the United States Environmental Protection Agency (EPA) as well as the passage of several landmark environmental legislations in the United States, including the Clean Air, Clean Water, and Endangered Species Acts. Many countries followed suit by adopting similar laws. Also, in 2016, the United Nations chose Earth Day to sign the historic Paris Agreement on climate change.

As early as 1925, Nobel laureate Svante Arrhenius[1] identified sustainability as one of the grand challenges of our age: “Humanity stands before a great problem of finding new raw materials and new sources of energy that shall never become exhausted. In the meantime, we must not waste what we have, but must leave as much as possible for coming generations.”

Four decades later, Rachel Carson spoke directly to the public with her bestselling book Silent Spring.[2] Through storytelling, she raised concerns about the environmental perils of pesticides and herbicides while highlighting the advantages of ecological diversity and conservation.

In the 1990s, Paul Anastas, John Warner, and others began promoting the principles of green chemistry[3] and green engineering.[4] Their work challenged chemists and engineers, offering a tangible guide for cleaner practices for chemical processes and products such as using renewable feedstocks, nonhazardous reagents, and mild reaction conditions to conserve feedstocks and energy.

In 1995, the EPA launched the annual Presidential Green Chemistry Challenge Awards to encourage the development of sustainable chemical technologies. The works recognized by these awards encompass a broad range of everyday products, including pharmaceuticals, foods, agrochemicals, packaging, cosmetics, clothing, and electronics.[5] The ACS Sustainable Chemistry & Engineering journal, launched in 2013, provides a forum for the critical assessment and timely dissemination of such advances that protect the environment and human health. Today, many leading chemical companies regard sustainable practices as key to a successful business strategy.

While all these actions are positive steps toward sustainable chemical manufacturing, there is much more work to be done to ensure our present and future well-being. We stand on the shoulders of courageous individuals who spoke up against the status quo, took action in the face of criticism, bridged political divides, and looked to a brighter future. Now, it is our turn to promote environmental leadership through our research as chemists and engineers. The need is great, and the time is now.

In a rather remarkable coincidence, the COVID-19 pandemic has led to significant improvements in air quality in major population centers around the world. Government-ordered mitigation strategies are disrupting human activity at an unprecedented scale. Satellite images of these areas, like the one shown for China (Figure ), clearly show less nitrogen dioxide (NO2) emissions during the quarantine period. As NO2 is co-emitted along with carbon dioxide (CO2) by motor vehicles, power plants, and industrial facilities, the observed trend also signals major cuts in CO2 emissions.

Figure 1

Images show NO2 emissions across China from January 1–20, 2020 (prior to mitigation strategies), and February 10–25, 2020 (during mitigation strategies). The data were collected by the Tropospheric Monitoring Instrument on European Space Agency’s Sentinel-5 satellite.[6]

Thus, a silver lining in this pandemic is perhaps the powerful reminder that humans are capable of responding to the climate change crisis. Diseases—and pollutants—have no borders. Our actions can make a difference. To reduce greenhouse gas emissions and solve the sustainability challenges of our time, we must unite locally, nationally, and globally.

As we mark the 50th anniversary of Earth Day in 2020, let us look forward with courage and optimism to promote sustainability in our planet.