Stanford University paleoecologist Elizabeth Hadly has spent her career looking into the deep past—how wolves, elk, and other species survived the massive climate change of the Pleistocene—but now she’s asking the same questions about our future. Warning that present-day human impacts are causing unprecedented changes to the environment, in her recent book Tipping Point for Planet Earth: How Close Are We to the Edge? Hadly says our ecological support systems are damaged nearly beyond repair. As the new faculty director of Stanford’s Jasper Ridge Ecological Reserve, she’ll guide research that uses local ecosystems to try and answer those global questions. Hadly also steps well beyond the ivory tower, helping California Governor Jerry Brown spread the word that to safeguard our quality of life, we must act now. By phone from Mongolia and parts of Africa and in person from her Stanford office, Hadly talked with me about tipping points, how local is where it’s at, and the diversity of Bay Area plants and people.
Mary Ellen Hannibal: Today you’re known for your climate change research, but you have an undergraduate degree in anthropology and studied wildlife in Yellowstone National Park. How did you get from there to here?
Elizabeth Hadly: All along I’ve been interested in understanding how modern ecosystems came to be. You can study this question by looking at earlier versions of our ecosystems, which means reconstructing the past. In Yellowstone I was looking at how the species that survived deglaciation and the Pleistocene extinction event around 11,700 years ago handled the climates of the last several thousand years. Twelve thousand years ago, Yellowstone was covered with ice. How did the wolves, elk, and vegetation we find there come together? Where did they come from? I was interested in ancient DNA but was working on fairly recent fossils. No one had thought about these animals—people were always going back to dinosaurs.
I began to realize that the landscapes and cadence of life in Yellowstone were changing in front of my eyes. With a graduate student, I did a study of amphibians from 49 ponds and found that in a very short period of time many of the ponds had dried up entirely. This was a big wake-up call. I set myself the task of going places around the world to see what was happening elsewhere—the Arctic, the Himalayas, Kilimanjaro. I asked local people what they were seeing. One thing I realized, and this was very hard for me to accept, is that there are no intact, untouched places left.
MEH: What does that mean for conservation?
EH: Here’s the important thing about an ecosystem: The species that are able to live in a given place are always changing and will continue to change. The important thing is that we protect the processes, that we allow species interactions to adapt as much as they can. But what we do where depends on our values for that place. One approach might be to think of what we want to conserve. For example, in what we call wilderness, it would mean that we don’t interfere—we don’t bring in machines or cut roads. In parks, we might conserve the iconic species people care about, and we may have to manage those. On Forest Service and Bureau of Land Management land, it’s all about the resources, like logging, for example, or grazing opportunities, or clean water. You can think about various kinds of protected landscapes fulfilling a portfolio of biodiversity ideals, and that should include zoos, which may be the last reservoir for some species we still want to maintain.
MEH: In your recent book Tipping Point for Planet Earth: How Close Are We to the Edge?, co-authored with your husband, Anthony Barnosky, you point to five major stressors on our life-support systems: climate disruption, mass extinction, loss of whole ecosystems, pollution, and human population growth (with attendant consumption patterns). Can you explain exactly what a “tipping point” is?
EH: In a linear system, if you push “x” amount in one direction you’ll get a “y” response every time. But nature is a nonlinear system. You can keep adding “xs” but that won’t necessarily equal a predictable amount of “y”. That sounds pretty abstract, but the classic example is an egg rolling off a counter. Once the egg hits the ground, it can never be returned to its prior state.
MEH: Any local environmental examples?
EH: Yes, the massive forest mortality we’re seeing in California right now. At least 70 million trees are dead or dying, due to many factors, including human-exacerbated drought. It’s probable that given climate change, these forests will not recruit. Trees require a certain amount of water to get established, and we don’t have the necessary moisture. So we’ve hit a tipping point—massive change that won’t change back. It’s likely those forests will be replaced with scrubland.
MEH: How do tipping points impact extinction?
EH: There’s a synergistic element in tipping points: Losing all that forest, we’ve lost habitat structure for additional species. Trees and coral reefs, for example, provide that much more area for things to exist in, which is one reason you have so much diversity in those systems. We are flattening out diversity.
It’s not just that we’re losing numbers of species across the board. We’re losing the top carnivores at the fastest rate. We’re losing the big, rare things on land and in the water. When we lose the big ones we lose their interactions with species lower down on the food chain, which causes more extinctions. We’re going backwards along the evolution of life, eliminating the more complex animals and ending up with weedy species, generalists, slime.
MEH: But the good news is that the dire information has reached the ear of Governor Jerry Brown?
EH: Yes. In 2012 I was a co-author with a group of scientists, including my husband, on a paper in Nature entitled “Approaching a State Shift in Earth’s Biosphere.” Brown phoned Tony and asked him why weren’t we scientists shouting this information from the rooftops? We thought we were! He had us translate the scientific article into a policy paper with a one-page summary, very clean, simple, and direct. It’s called “Scientific Consensus on Maintaining Humanity’s Life Support Systems in the 21st Century.” Hundreds of scientists from all over the world have endorsed it.
MEH: You’re becoming faculty director of Stanford’s Jasper Ridge Ecological Reserve and your husband has recently become executive director there. As you’re a global ecologist, it’s a bit surprising you would take the helm at Jasper Ridge, which is an emphatically local place.
EH: In my opinion, the most important scale for us to focus on is the local scale. We talk about global change, and presidents and prime ministers discuss that. The processes by which those machines work is very slow. But the actual impact of climate change is personal and local. I’m super interested in the local-to-regional scale of change. This is where we can really dig in to what’s happening. Jasper Ridge is the site of several nationally important, long-term climate change studies, and I’m eager to learn more about them. The idea of coevolution — that certain species’ evolutionary fates are sculpted by other species — came out of science conducted on butterflies and their host plants at Jasper Ridge. More recently, global warming experiments showed that increased CO2 has impacts on grassland production and also may influence the timing of flowering in plants.
Our plans for Jasper Ridge are not officially laid yet, but we’re looking forward to really grounding our research in a local place. It’s a great challenge to ask ourselves, “Okay, if we want to protect, to defend, to apply our knowledge to this place, Jasper Ridge, what will we do?” Global change is in motion and there is no going back, no “restoration” to some historic state. I want to anticipate the future. How do we anticipate the future of the nature reserve in this place? It’s exciting.
MEH: How does nature in the Bay Area impact your daily life?
EH: We go out every weekend into the coastal hills. It’s not just for the views. There’s so much diversity here. You start in an urban area and then you are in oak grassland, then into redwood forests. I have some regular hiking spots on this side of the Bay — Arastradero, Windy Hill, Skyline. We also have a favorite in the East Bay — the Sunol Regional Wilderness. It’s a gem. In the spring, poppies are all over the grassland and there’s always water flowing there at Little Yosemite. The diversity of the landscape here is synergistic with the diversity of people. We recharge with nature here, and appreciating it stimulates a lot of what we do.
Mary Ellen Hannibal is the author most recently of Citizen Scientist: Searching for Heroes and Hope in an Age of Extinction.
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