Animal Conservation

Investigate pauses and pulses in human mobility and their environmental impacts

I propose a basic classification scheme for human pauses based on extent (spatial extent), sustained duration (duration), and pronounced reductions (magnitude) in human mobility (Fig. 1b). Importantly, I recommend that the anthropause label be reserved for large-scale events on a continental to global scale (and of any duration; Fig. 1b, supplementary note 1). By this definition, the Black Death pandemic and early COVID-19 lockdowns caused anthropauses, while the Chernobyl disaster was followed by a regional human pause. A schematic classification cube can be used to compare these and other events (Fig. 1b); but first, a few points need to be clarified.

First, it is crucial to ensure that the terminology is firmly linked to the underlying processes. Some authors have used the word anthropause as a synonym for positive environmental change caused by lockdowns. While it is understandable to initially focus on potential benefits, confusing cause (change in human mobility) with effect (environmental responses) is not helpful when using the term in a scientific context. Indeed, the way the concept of anthropause was originally formulated makes no assumptions about the sign of environmental responses and the associated conservation impacts.1 (Fig. 1a). Emerging empirical evidence from the COVID-19 pandemic points to a wide range of containment effects2.3.

Second, human mobility must be defined. COVID-19-related lockdowns have resulted in noticeable reductions in pedestrian, road, marine and air traffic (and associated pollutant releases), all of which likely caused environmental impacts1,2,3,4. For modern human pauses, it is reasonable to consider changes across the full range of human mobility parameters, but comparisons with pre-industrial events must inevitably focus on the environmental presence of people. In this context, it should be noted that humans can disappear from an area because they take shelter, move elsewhere or perish, and that changes in human mobility can be driven by a variety of factors, including diseases, natural and man-made disasters and conflicts.5. The ultimate drivers and proximate mechanisms affecting changes in human mobility are important research targets, but are not part of the classification scheme itself (Fig. 1b). It is important to keep in mind that many events will be associated with human tragedy and suffering.1.

Third, operational definitions are required for the spatial-temporal scales of the scheme. While human pauses are easily ordered according to their duration, classifying their spatial extent is more difficult, for both conceptual and practical reasons.7. The categories proposed here are pragmatic – covering four orders of magnitude (Fig. 1b) – and will allow a meaningful comparison of the environmental impacts caused by different types of human pauses.

Finally, it is important to clarify how the magnitude of events should be measured. Since human mobility has increased dramatically over the past centuries and is likely to change further in the future, the magnitude of human pauses should be assessed relative to baseline levels for the time period and area considered, rather only in absolute terms. As illustrated by the COVID-19 pandemic, human mobility is not necessarily reduced to zero during an anthropause, and there can be significant spatio-temporal variation in response levels. Preliminary analyzes indicate that approximately 57% of the world’s population was under partial or full containment at the beginning of April 20202and there were obvious local mobility spikes once governments started allowing personal exercise1.