Partridges in the Snow" Józef Chelmónski. Oil. 1891

When Rahm Emanuel, then President Obama’s Chief of Staff, said, “You should never let a serious crisis go to waste,” he was channeling Winston Churchill and the economist Joseph Schumpeter. The great mass extinctions and smaller biotic crises documented by the fossil record reveal that life long ago discovered the importance of not letting a crisis go to waste, if not in quite the same manner intended by Emanuel. My first paper in college was about the end-Permian mass extinction, the greatest of all mass extinctions, which wiped out perhaps 90 percent of all species in the oceans some 251 million years ago, and almost as many plants and animals on land. Yet the extinction itself really is not very interesting, at least not to me, because in the aftermath of that cataclysm came dinosaurs, mammals, modern insects, turtles, ichthyosaurs and probably the first flowering plants, as well as most of the invertebrate clades populating modern oceans. The great question (and the one that first drew me to SFI) is, what sort of opportunities were generated by this crisis, and how did life respond?

I in no way want to diminish the very real fear that many feel now, nor the frightening days that lie ahead for many in this country and elsewhere around the world. Many will die, even more will suffer serious illnesses, and myriad businesses and institutions will disappear. But, as treatments and vaccines come online, we will get through this, and knowing that allows us to begin to consider what we can learn from this event. And I see questions similar to the ones that I have been asking about the end-Permian episode: What factors favor survival, whether of people or of institutions? How do these factors relate to those favoring success prior to the pandemic? In many past crises, the factors favoring survival have had little to do with those that provide an advantage during “normal” times. Can we design models to evaluate alternative treatments that would modify these outcomes (aside from the obvious ones of more timely interventions at the outset)? Resilience has long been a central theme at SFI; like the 2008 financial crisis, this pandemic provides an opportunity to articulate the factors underlying robustness in social, economic, and other systems, and to distinguish resilience factors that may be unique, either to this event or to pandemics in general, from those factors that enhance resilience more generally. Hurricanes, earthquakes, megafires in the western US, and, of course, climate change are just a few of the events in which resilience plays a critical role, and which argue for strengthening our portfolio in this area. 

Figure: The disappearance of some Permian groups and appearance of some modern groups. Images from

Figure: The disappearance of some Permian groups and appearance of some modern groups. Images from

Finally, the turtles — one of the oldest has been found near Ghost Ranch, just north of Santa Fe. There is no hint of an ichthyosaur or a turtle fossil pre-dating the end-Permian mass extinction. But ichthyosaurs and turtles exploded in diversity in the aftermath of the extinction as they helped construct entirely different ecosystems from those before the extinction. Beyond our response to the pandemic itself lie the longer-term effects, including new opportunities — social, political, economic, and otherwise. The deeper the crisis, the greater the subsequent opportunities, and the greater the possibility of shaping these opportunities. 

Doug Erwin
National Museum of Natural History, Smithsonian Institution

Santa Fe Institute

T-014 (Erwin) PDF

Read more posts in the Transmission series, dedicated to sharing SFI insights on the coronavirus pandemic.

Listen to SFI President David Krakauer discuss this Transmission in episode 29 of our Complexity Podcast.



August 25, 2021

Pandemic and Climate Change: Pulse versus Press

As I write this, temperatures in Death Valley approached (and may have passed) 130°F (54°C), the eighty-three active wildfires across the country have burned some 1.3 million acres (still below the ten-year average of fires since the beginning of the season), and although it is only mid-July, many fires in the northwest are expected to burn until rain and snow come in the fall. Climate change is making the wildfire season in the US longer, and the fires larger and more severe, as in Russia, Australia, and many other parts of the world. As I looked back on the Transmission piece I wrote last year about resilience, I realized that many of the challenges we face with climate change are of a fundamentally different kind than those we have experienced through the COVID-19 pandemic.

Ecologists differentiate between pulse and press events, and many years ago I imported this distinction into the study of mass extinctions and similar biotic crises, where it has proven useful for thinking through the relationship between the dynamics of the extinction and the subsequent biotic recovery. For mass extinctions, pulse events are quick shocks that are so rapid that no adaptation is possible (at least for most species). Plants, animals, and other organisms live or die based on what they brought to the game. The asteroid impact that triggered the mass extinction at the end of the Cretaceous 66 million years ago, wiping out the (non-avian) dinosaurs, was a classic pulse extinction. Press events differ in being long-lasting, pervasive, and persistent, but the longer they last the more species have an opportunity to adjust and adapt to the changing circumstances. The difference between press and pulse events changes the dynamics of robustness and resilience, although in ways that I do not think have been fully explored.

Lately, I have begun to use this framework of pulse and press events to think about the challenges we face moving forward. This approach is similar to the focus of Jessica Flack and her colleagues on slow variables, with rapid events superimposed on much longer patterns of change, and to the discovery of slow earthquakes—seismic events that occur over hours or months.1

Much of the developing world remains unvaccinated and the Delta variant of COVID-19 is ravaging unvaccinated populations in the United States and Europe, threatening what had been a remarkably resilient recovery from the early phases of the pandemic. The emergence of the Delta variant and newer variants has surprised no one with even a passing familiarity of how evolution works. And we face the prospect of newer variants emerging to which extant vaccines are less useful in reducing severe illness and death. But the construction, testing, and production of at least twenty different vaccines worldwide, and vaccination of hundreds of millions of people since the virus was isolated is a truly remarkable achievement. That achievement reflects many factors: scientific, technical, economic, political, and cultural. But that capacity is essentially what we brought to the table in early 2020. There have been many successes and failures over the past year and as I outlined in my initial Transmission piece, there are many questions we can now address about the response to the COVID-19 crisis. Assuming researchers can safely put aside partisan wrangling, we should be able to develop a better sense of what worked and what did not work. Testing alternative scenarios will help us learn what steps could have been taken to reduce the human suffering and economic cost. Studies from social scientists may help identify scenarios that would increase acceptance of mitigation efforts. Such efforts represent contributions to generating more resilient social and political systems.

Let us assume that we mount a collective effort to identify the best lessons from the pandemic crisis, the events of 2008–2009, the aftermath of Hurricane Katrina, and other similar crises. Let’s even assume that we implement at least some of them and manage the political will to keep such efforts in place as memories fade (living outside of Washington, DC, I do not really believe this is possible, but we can always hope). But in each of these cases the events are relatively short-term, pulse events. Would such lessons be relevant for the challenges facing us with climate change? Climate change is not going to go away. In fact, it will only get worse over the lifespan of everyone now alive, and for generations into the future. Building a society resilient to climate change will require far more fundamental societal shifts than have resulted from the pandemic; these shifts will not be just a function of what we have at hand today, but rather the adaptations and responses that we will develop in the future.

There are many at the Santa Fe Institute (and elsewhere) who have been deeply involved in addressing these problems, and as I expressed in the Transmissions piece, I hope that in coming years a greater understanding of resilience on both short and longer time spans will emerge. Work on power grids, studies by ecologists of resilience in natural ecosystems, and the resilience of native communities are all areas where SFI researchers have already made important contributions. While directly influencing climate change legislation may not be our first priority as a research institute, we must continue to generate knowledge of the features of resilient systems over a range of timescales, paving the way for a greater understanding of resilience.

Read more thoughts on the COVID-19 pandemic from complex-systems researchers in The Complex Alternative, published by SFI Press.

Reflection Footnotes

1 J. Flack, D.H. Erwin, et al., 2013. “Evolution and Construction of Slow Variables and the Emergence of Aggregates,” in Cooperation and its Evolution, ed. K. Sterelny, R. Joyce, et al., Cambridge, MA: MIT Press, 45–74.