Gill’s research at the University of Maine looks to the past to understand how species will respond to global changes. She speculated that it was this long-term perspective that allowed her to notice a legacy of adaptation and resilience. “With the fossil record, the Earth is literally teaching us how to get through this,” she wrote. “That makes me want to roll up my sleeves.”

From the fossil record, Gill said that she can see that some species are more adaptable than others in the face of climate change. They migrate or find ways to live in new ecosystems. Humans share a lot of traits with the past survivors of mass extinctions—we are adaptable, we are mobile, and we are able to modify our environments to be better for us. And learning from these periods in history could help us implement the solutions.

In the tens and hundreds of thousands of years that came before us, there were fluctuations in climate that humans and animals had to deal with. People confronted droughts, floods, extinctions, and collapses of entire civilizations. Their experiences can provide a kind of guidebook, or at least, a picture of what’s to come.

That latter point—about needing the will—is a nice way of saying that we need city planners and policymakers to pay attention and take these things into consideration. Lucky for them, and for future generations, scientists are laying out exactly what they need to know:

Their version of hope acknowledges that climate change is real, man-made, and an emergency. But despite it all, it reassures us: We’re not starting from scratch. “We can use this tremendous wealth of information that we have, and this tremendous ingenuity, and make really good evidence-based informed plans for how to move forward,” Gill said. “We have the tools and the capacity to move forward. We just need the will.”

_The end is nigh_-type rhetoric can make us want to throw up our hands. But scientists who study the past have a unique case for the kind of pragmatic optimism that Gill speaks of. She and other paleoscientists and archaeologists scour the past for clues to help drive our future, and are finding a history of survival among people and animals alike.

Her position flies in the face of a recent report by the Breakthrough National Center for Climate Restoration, a think-tank in Melbourne, Australia, which predicted a future in which human life would end by 2050. Its conclusions were modeled on a worst-case scenario if we continue to barrel forward with current levels of carbon and methane emissions. Others have echoed that doom: that the Arctic's warming is now inevitable , and that our carbon levels have reached a point of no return .

To take one example: The Mayan civilization confronted severe environmental challenges, like drought, deforestation, and loss of crops. Researchers used to view their abandonment of city structures as complete societal collapses, said Tim Kohler, an archaeologist and evolutionary anthropologist at Washington State University. Now, they’re finding that the Mayans didn’t just die off—people reorganized themselves and persevered.

Pueblo Bonito in Chaco Canyon. Scientists use tree rings to estimate what the climate was like when these settlements were abandoned. Photo courtesy of Nathan Crabtree.

Humans have 14,000 years of experience living in Florida and dealing with sea level rise, said Ken Sassaman, an archaeologist at the University of Florida who studies coastal dwellers in the area. “We have an incredible treasure trove archive of human experience dealing with sea level change. We ought to be tapping into that.”

By tapping into the cultural, societal, and environmental changes people implemented after climate-related disasters, scientists can glean not only what was damaged, but what and who survived. This could serve to guide our next steps in dealing with rising sea levels and storms, and also to help us avoid future mistakes with community planning.

In many cases, the “collapse” of civilizations also meant dismantling the elite: the religious hierarchies, the government. “But in general, a large number of people live on,” said Tim Kohler, an archaeologist and evolutionary anthropologist at Washington State University. These moments can be seized for cultural shifts to take place, or to reckon with past inequalities.

Similarly, in the coastal areas of Peru, complex societies with big monuments, hierarchical society leadership, and irrigation canals often didn't appear until after disruptive and catastrophic El Niño events. Dan Sandweiss, an archeologist who studies El Niño’s effects on Peru at the University of Maine, said there’s a theory that some of these innovations came about as a response to climate change, which can be a prompt for societal growth. Along the same lines, the Dust Bowl—a devastating drought in the United States in the 1930s—gave rise to the national farm insurance program and led to important land-use changes.

“They all just live in different places now, but they still retain some sense of identity with those locations and recognize that people who lived in those locations long ago were their ancestors, at least in a general sense,” Kohler said.

Recently, Sassaman has also been looking at a hurricane from 1896 that devastated a small town called Cedar Key, located on Atsena Otie, one of several islands of the Cedar Keys off the northwest coast of Florida. The people who lived there had over-exploited the cedar tree population for their milling industry, which made the coastline more vulnerable to storm damage. They also over-farmed the oysters, which reduced the ability of the oyster reefs to subdue the storm surge that hit the mainland.

Sassaman said that if he were in charge of a city like Miami, he would take inspiration from this and ask social scientists to identify pre-existing social networks that the current residents of Miami have—and where they might go when sea levels get too high for their city to be livable.

In Florida, people in the past generally didn't invest a lot of infrastructure on the coast. But around 2,000 years ago, indigenous people did start to build what archaeologists call “ civic ceremonial centers ,” which were community-living or ceremonial establishments where people would gather for feasts, religious ceremonies, and more. They served a practical purpose, too: Groups of people who lived in different places would create a regional social network that people could draw on in times of crisis, or if they needed to relocate.

Unfortunately it seems we’ve built a house of cards again, in the form of building permanent settlements at sea levels that are rising. But this time, scientists can better see what's coming and can try to anticipate where people will go, how to receive them, and what will be lost in the face of rising temperatures.

Sassaman has found a way to make this more tangible, in order to educate people about how it happened. He started a project to create a virtual-reality simulation of the town before the hurricane, including avatars of the people who lived there. “From this, people can understand that even though the town was thriving and it was a model for coastal development at the time, it was basically building a house of cards,” he said.

Looking at disasters from the past doesn’t seem like fuel for optimism, but there's power in our ability to model what increasing temperatures will look like, said Peter de Menocal, a marine geologist and paleoclimatologist at the Lamont–Doherty Earth Observatory of Columbia University. “It's only by knowing the past that we know what our future is going to be,” de Menocal said.

There's a time period called the Paleocene–Eocene Thermal Maximum—the closest example we have in the geological record for what’s happening in the climate now. Fifty five million years ago, the earth warmed very suddenly, to 8 degrees Celsius warmer than today, because of a catastrophic carbon release. This warming period lasted about 200,000 years and led to global mass extinctions.

The optimism part of this might feel like a stretch, but here it is: We can see what happened, and see how bad it was. This could give us the ability to clear any doubts about what’s going on currently, and use the past as motivation for not going there again. We can say with absolute certainty—no hypotheticals needed—that temperature increases lead to species extinctions and abandonment of human settlements. That could provide a prod for political action to stop us before we get there.

Doom and gloom have a tangible downside

De Menocal marvels at our ability to do this forecasting at all. “We have some ability to look forward that is presumably more powerful than anything any ancient societies had," he said. "Having some idea of what's at stake really allows you to double down on your commitment on the need to do something about it. I think the one thing that you can't do is tell people that the world's going to hell in a hand basket and there's nothing they can do about it.”

Fear and worst-case scenarios do a good job at attracting attention, but research has found that they aren’t very effective at motivating action. Thinking about worst-case scenarios can limit creativity and increase anxiety and stress.

Climate psychologist Per Espen Stoknes, of the Centre for Green Growth at the Norwegian Business School, called it the “doom barrier” in an interview last month. “We have lots of studies that show how people tend to disengage, and the reason is fear and guilt feelings, which tend to be evoked by the ‘doom framing,’ and then we start to shut down,” he said.