As a result of the lockdowns around the world to control COVID-19, huge decreases in transportation and industrial activity resulted in a drop in daily global carbon emissions of 17 percent in April. Nonetheless, CO2 levels in the atmosphere reached their highest monthly average ever recorded in May — 417.1 parts per million. This is because the carbon dioxide humans have already emitted can remain in the atmosphere for a hundred years; some of it could last tens of thousands of years.

Beyond carbon emissions, however, COVID-19 is resulting in changes in individual behavior and social attitudes, and in responses by governments that will have impacts on the environment and on our ability to combat climate change. Many of these will make matters worse, while others could make them better. While it’s unclear how these factors…