The world today: The crisis of climate-driven extinction

In an era punctuated by climate-driven disasters and an ever-worsening ecological crisis, the question of our planet's future has never been more urgent. As wildfires, floods, and cyclones become increasingly frequent and severe, how we respond to these challenges could determine the fate of millions of species, including humankind. 

Addressing this urgency, Perry World House joined with the Penn Center for Science, Sustainability, and the Media and the Department of Biology at the University of Pennsylvania to present a panel discussion, “The World Today: The Crisis of Climate-Driven Extinction.”

The Sept. 19 event was part of Climate Week at Penn and convened a panel of experts across disciplines to discuss the intersection of biodiversity loss and climate change, a crisis that the United Nations describes as a “triple planetary crisis.” 

The conversation was moderated by Simon Richter, who specializes in cultural aspects of adaptation, resilience, and migration in the context of the climate emergency. The panel included Erol Akçay, a theoretical biologist; Michael Mann, a climate scientist; and Zinta Zommers, a former visiting fellow at Perry World House and specialist in risk management and climate-change adaptation. 

Defined as a measure of variability and diversity of all life on Earth, biodiversity, Akçay explained, is as pervasive as it is important in maintaining functional and thriving ecosystems. In much the same way that diversity of producers and consumers can disparately facilitate exchanges of goods and services that have a ripple effect through economies at varying scales, biodiversity serves as a catalyst for ecological stability, he said. 

According to Akçay, the interactions among various species are not isolated incidents but interconnected events that have far-reaching implications for the health of the planet. As such, threats to reducing biodiversity increase the risk of extinction for not just one species but for many others.

As an example to highlight the often-unexpected ways in which reduced biodiversity can impact us, Akçay noted how, in 2019, researchers discovered the first new class of antibiotics effective against gram negative bacteria, such as E. coli, since the 1960s. 

“This is significant because antibiotic resistance is a grave concern for both human health and agriculture,” Akçay said. 

He noted that the initial discovery was made in the gut microbiome of a nematode, a parasitic worm found in insects, and that, when you diminish insect populations, you reduce the diversity of bacteria essential for creating antibiotics. “If this situation is further exacerbated, it could lead to pre-penicillin-like condition, wherein a simple cut could lead to death, due to a lack of antibiotics to treat a possible infection,” he said. 

Akçay said that, in the context of biological problems, consequences often cascade in unforeseen directions, making reductions in biodiversity a potential trigger for a host of unforeseen problems. 

In answering Richter’s question regarding how human activity could set a course correction for mitigating costs to biodiversity, Akçay mentioned two major contributors to species extinction: land-use change, as in repurposing habitats for agricultural, housing, or business needs; and direct exploitation via hunting or fishing. 

“If we don’t get a handle on these, we’re going to continually see massive biodiversity reductions in the face of climate change as fewer habitats and smaller population sizes due to exploitation mean less capacity of species to adapt to changing climatic conditions,” Akçay said. 

Zommers brought up the policy-based efforts towards mitigating climate change and biodiversity loss and noted that both the Convention on Biological Diversity (CBD) and the United Nations Framework Convention on Climate Change (UNFCCC) were created in 1992, “so, they are almost like brother and sister but both haven’t been successful in many ways,” she said. “The CBD had targets set in 2010  (the Aichi Targets) that outlined what the governments of the world should do to protect biodiversity, but in 2020 the CBD reported that none of these targets had been met.”

Zommers said that this highlights a major issue that plagues climate communities: “We’re making lots of pledges, but where is the action?”

She noted that in 2022 governments met to urge for more commitment to these targets in the fifteenth meeting of the Conference of the Parties (COP15) and adopted the Kunming-Montreal Global Biodiversity Framework, which set out an ambitious pathway to achieve the CBD’s goals. Zommers believes what’s interesting here is that both the CBD and the UNFCCC have these similar histories and, going forward, a similar framing, wherein both have goals and the idea is to ratchet up the ambition over time. And in both, she said, there is a great deal of discussion about financing these actions.  

She mentioned that the difference is that the CBD now has a clearer road map for what governments should do such as, reducing subsidies in certain areas and helping industry focus on biodiversity, whereas UNFCCC has targets like the 1.5°C goal but with no clear road map for how this should be implemented and with each government is meant to come up with their own strategy. 

“Overall, the two are tied to some degree, in that unless we achieve our climate goals, a significant amount of this planet’s biodiversity will be lost,” Zommers said.

In tying it all together, Mann said his research in climate science is congruent with the concerns outlined by Akçay and Zommers, as climate change is a major contributor to what has been characterized as the next major extinction event. He noted that in conducting research for his latest book, “Our Fragile Moment,” his perspective was colored by looking at past extinction events such as the The Great Dying Event, wherein 96% of all marine biota went extinct. He said that many look at as an analog for human-driven extinction related to human-driven activities that cause climate change. 

“The extinction that will result from climate change could be much like the Great Dying Event, which was driven in part by climate change that occurred from carbon dioxide emissions into the atmosphere from a major volcanic out gassing event,” Mann said. 

“Much like we’re adding carbon dioxide to the atmosphere today, this was a natural addition of carbon dioxide, which also resulted in a massive deoxygenation of the oceans that probably led to an increase in hydrogen sulfide; my colleague describes this as a global stink bomb.” 

Mann argued that humanity may be headed towards Great Dying-like conditions unless there is a major course correction. He said that, while this would be a “rapid event,” there are others that occurred 56 million years ago that are also considered rapid and led to mass extinctions; however, these “natural events pale in comparison to the events we’re witnessing today as the ones we’re seeing are at least 100 times more rapid than any of the natural events. And that’s the cause for concern,” he said. 

He added that, although the planet has seen much higher temperatures, it hasn’t seen these rates before, which poses a major challenge for species to adapt to in terms of biological and evolutionary time scales. “If you have a long time to adapt to the changes we’ve made to the planet, like building elaborate housing and transport networks that interfere with the migratory patterns of animals, it's much easier to adapt, but the rate at which we’re changing the environment’s conditions—via things like physical obstacles or contaminants to the natural environment—is unprecedented” Mann said. 

“So, the lesson is,” he said. “it’s all about the rate of contribution of carbon input, and, if we continue on this trajectory, then I believe there’s no question that climate change will be a major contributor to what will be described as the sixth great extinction event.” 

Simon Richter is professor of Germanic languages and literatures, a Perry World House faculty fellow, a faculty fellow of Penn Institute of Urban Research, and a faculty advisory board member of the Water Center at the University of Pennsylvania. 

Michael Mann is a Presidential Distinguished Professor in the Department of Earth and Environmental Science in the School of Arts & Sciences with a secondary appointment in the Annenberg School for Communication and the director of the Penn Center for Science, Sustainability, and the Media at the University of Pennsylvania.

Erol Akçay is an associate professor in the Department of Biology in the School of Arts & Sciences at Penn. 

Zinta Zommers is a humanitarian affairs officer with the United Nations Office for the Coordination of Humanitarian Affairs and served as the Wolk Visiting Fellow (2021-22) and a Visiting Fellow (2022-23) at the Perry World House at Penn.