Is Climate Change an Existential Threat?

If a 60-mile-wide (100-kilometer-wide) asteroid slammed into Earth tomorrow, it would render the planet inhospitable to nearly all life forms, save for the hardiest extremophiles. This mass extinction event would wipe humanity off the face of the Earth—there would be no survivors. 

To some experts, this is the true definition of an “existential threat.” Traditionalists will say this term describes a risk that endangers the very existence of something—in this case, the human species. In recent years, that definition has loosened largely to encompass global warming. Scientists, politicians, and world leaders have all described the climate crisis as an existential threat to humanity. This human-driven phenomenon is already altering life as we know it on a planetary scale, but could it really lead to our extinction?

Some experts say it could, in the most extreme scenarios. Others argue this isn’t the question we should be asking. For this Giz Asks, we reached out to a variety of experts to get their take on whether climate change actually poses an existential threat to our species.

Seth Baum

Executive director of the Global Catastrophic Risk Institute.

It depends on how you define existential threat. I tend to use “global catastrophic risk” instead of “existential risk” because the latter literally means risk to existence. I would argue that in terms of extreme catastrophes, we should care about more than just existence.

If we continue to exist as a species or a civilization, but in an extremely diminished state on an ongoing basis, that’s also important. And in fact, some of the definitions that are used for existential risk include both a loss of existence—like human extinction—and also lingering on in a very diminished form. This, to me, feels like an abuse of the phrase existential risk, because our existence hasn’t actually been lost.

In general, however, I am concerned about scenarios in which there is a collapse of human civilization. You can have a whole other conversation about what that means, but basically, I’m talking about the world as we know it no longer functioning. And if there are any survivors, they’re carrying on in a significantly diminished state.

Human civilization emerged within the last 10,000 to 12,000 years, but the human species is said to be about 200,000 years old. Why has civilization only recently emerged? One explanation for this is that within the last 10,000 years, Earth’s climate has been very favorable. It’s the Holocene period of the climate, where temperatures have been fairly warm and stable.

There’s a theory that says those stable, warm conditions are what enabled us—a species that had a latent capacity to produce civilization—to actually pull it off. Indeed, agriculture was invented in at least five or six different places around the world, all within this same 10,000 year period. This suggests that without the Holocene, we couldn’t pull this off. With that in mind, if we now start to push the planet outside of these nice, warm, stable, favorable Holocene conditions, perhaps we are destroying the precondition for our civilization.

Then, you can start to look at the details. How is the climate changing? How will that affect human populations? There’s plenty of concern about how this will affect agriculture, water resources, and extreme weather. All of that stuff starts to paint a picture of a scenario in which our ability to survive this as a civilization is in question.

The other important detail is that climate change doesn’t happen on its own. In this way, it’s different from a lot of other catastrophe scenarios, like getting hit by a large asteroid. Climate change is a gradual process, and so we have to think about not just climate change on its own, but how it affects everything else going on—including other catastrophic risks. Does climate change make nuclear war more likely? Could climate change push society to take dangerous risks with artificial intelligence? We’re actually seeing little bits of that right now. It can be helpful to think less about whether climate change is a catastrophic risk on its own, and more about whether it increases the risk of global catastrophe. I feel like that’s a question that’s very easy to answer yes to.

Michael Mann

Climatologist, geophysicist, and director of the Center for Science, Sustainability & the Media at the University of Pennsylvania.

I don’t think there is any question. In our forthcoming book, Science Under Siege, Peter Hotez and I identify three existential threats that currently conspire to threaten human civilization. They are the climate crisis, deadly pandemics, and—most critically—the rising tide of antiscience and disinformation that impairs our ability to address those crises.

It seems very unlikely that extinction is on the table for any but the most severe scenarios of climate negligence. However, it is easy to envision a collapse of human civilization. We’re already seeing it fray at the edges, particularly in the form of geopolitical conflict that is driven in substantial part by competition of a growing global population for increasingly scarce food, water, and space. All of that is exacerbated by climate change.

Tipping points, such as the collapse of the West Antarctic Ice Sheet or the shutdown of the thermohaline ocean circulation—which would have important regional consequences—could loom in the not-too-distant future if we continue to warm the planet with fossil fuel carbon emissions. Though we don’t know precisely how much warming will trigger them, whether it’s 2 degrees Celsius (3.6 degrees Fahrenheit), 3 degrees Celsius (5.4 degrees Fahrenheit), or more.

Without even appealing to the uncertain science of climate tipping points, the known impacts of climate change—particularly more extreme, damaging, and deadly weather events that will continue to worsen with increased warming—would be more than adequate to destabilize our societal infrastructure. We see this already in the way that these events interrupt supply chains, put stress on food and water resources, and threaten human health. This is already taxing our resources and severely testing out adaptive capacity.

Kennedy Mbeva

Research associate at the Centre for the Study of Existential Risk at the University of Cambridge.

If we use the term “existential risk” in a strict sense, one could think of it as a threat to humanity, which is very extreme. But there’s another term that we use called “catastrophic risk.” This frames the climate crisis not only in terms of the collapse of the climate system—which could be disastrous in the most extreme scenarios—but in terms of the extreme impacts of climate change that we can witness now and in the near future.

One can think about these impacts in many ways. Scientists think about it in terms of planetary boundaries, or tipping points. If you focus on people, you’ll find that already in many parts of the world, there are areas that are quite exposed to the extreme impacts of climate change. If you look at small island states, some of them are about to disappear due to rising sea levels. One could say that’s an existential threat to them, because there’s a possibility that the islands or territory might disappear. This threatens people’s way of life, and we can already see some Pacific islands engaging in conversations and negotiations about immigrating to other countries such as Australia. When such scenarios unfold and become reality, where do people go?

Climate impacts are also destroying major parts of economies. In many African countries, for example, people mainly rely on agriculture for their livelihoods. Droughts are getting more and more intense, and more frequent. We also have extreme weather events like floods, etcetera. Some estimates have shown that these countries spend up to 20% of their GDP dealing with the impacts and damages of climate change. Industrialized countries are also facing climate impacts. We’re seeing wildfires become more intense and more common, summers are becoming hotter.

So, while those who think about climate change on a planetary scale focus on boundaries and tipping points, you can also see climate change impacting people in many different ways across the world. I think these different perspectives share the same concern. As academics, we might debate which framing is more useful, but I think we should not lose sight of the realities where these problems are unfolding.

Renée Lertzman

An existential psychologist focusing on climate and environmental psychology.

It’s hard for me to imagine climate change not being considered an existential threat. I’ve spent decades unpacking the psychology of climate change, and I feel that there’s a very unique confluence of factors that contribute to the ways we experience and comprehend it. This includes the fact that it’s human generated, that it’s systemic, and that its impacts are distributed across time and space. That combination creates a very distinctive set of existential threats, specifically from a psychological perspective, which looks at how people process and make sense of climate change.

There’s also an existential crisis of meaning. If we really were to take into consideration what’s going on here, it does bring a level of inquiry into who we are as human beings and what it means to live a good life. Climate change forces us to come to terms with the consequences of industrialized  practices that we’ve developed relatively recently.

We’re struggling to process and come to terms with what’s happening. We as humans are programmed to have a sense of where we’re going, what’s ahead, and I have felt for a long time now that awareness of climate change and environmental issues has a direct impact on our capacity to envision a viable future.

The way that I’m using the term “existential” is to simply acknowledge that climate change touches and influences our existence. To me, it doesn’t necessarily mean the end of all life as we know it. It means: what does it mean to be a human being? I feel that we need to acknowledge that threats to the climate and environment are existential in the sense that they cut to the heart of who we are.

Olúfẹ́mi O. Táíwò

Assistant professor of philosophy at Georgetown University.

Climate change is an existential threat to humanity and to human society. But the reason why it’s an existential threat to human society is not necessarily directly—or perhaps even primarily—linked to the atmospheric and ecological effects of climate change. Rather, it’s the intersection between those effects, which are devastating by themselves, and our political systems that poses the existential crisis.

There’s a lot of focus on the carbon accounting that has come to define how we talk about the climate crisis and our responses to it, from the levels of CO2 and CO2 equivalent in the atmosphere to the severity of various atmospheric hazards like wildfire. All of these things are worth paying attention to, but the actual damage that they cause to human society results from the interaction between ecological problems and how our political systems succeed or fail to protect people from them. What we’ve seen historically is that colonial, unjust systems respond to nature and ecological disasters differently than more egalitarian systems.

People in many parts of the world—including the U.S.—are living out the opening political gambits of some of the worst-case climate scenarios. Part and parcel of thinking about the climate crisis as a political crisis, rather than just an ecological crisis, is thinking about how the institutions that could protect the common good might instead retool themselves to defend private goods. This is something that Astra Taylor and Naomi Klein have zeroed-in on in a very visceral and useful way. One of the biggest takeaways from this way of thinking about the crisis is not only that governments are failing to live up to their central responsibility to protect the public good, but that the way in which they’re failing is making it impossible for civil society, communities, and households to work toward a solution.

We live in a very complicated ecology, and we’re trying to deal with a problem that is at planetary scale. We not only need governments to do what they have to do, we need many people thinking, working, planning, and making decisions about what they can do for their river, or the trees in their city. We need people doing climate adaptation and mitigation work. The end result of a politics of grit and graft—a politics of looting the common good—is also a politics of not having a public to mobilize for those things.