Postcards from the 6th Mass Extinction

For most of Earth’s history, speciation has outpaced extinction, and this has led to the tremendous biodiversity we see today. But species die-offs are common. Periods when many species die out are called mass extinctions. We are likely experiencing one now.

Mass extinctions are caused by several factors, including changes to Earth’s atmosphere, oceans, and continents, and cataclysms (such as volcanic events and collisions with extraterrestrial objects). Today, the current extinction rate is thought to be between 100 and 1,000 times greater than the natural (background) rate—a situation largely due to the exponential growth in the world’s human population and the collective strain of human activities on ecosystems across the globe. 


Billion people in 1850


Billion people in 2019

So far there have been five notable mass extinctions in Earth’s history. A growing number scientists argue that Earth is now in the midst of its sixth. The purpose of the audio series Postcards from the 6th Mass Extinction is to document this extinction as it happens—and, more importantly, to identify solutions that may slow its pace. Extinction is tough stuff—understandably—and the series aims to provide the context needed to understand the significance of Earth’s extinction challenge while also describing the solutions we humans might apply to help threatened and endangered species survive.

Listen to Episode 1: Losing the vaquita in the northern Gulf of California 

Today we talk about the challenge of protecting the world’s smallest porpoise, the vaquita, from extinction.
In just a few minutes, you can learn about the vaquita’s natural history, its sudden population decline, and the unique mix of forces driving the species toward extinction. And, more importantly, you’ll learn about the existing solutions and steps that could be taken to address this extinction challenge.

Listen to Episode 2: The incredible shrinking world of the polar bear

Today we are talking about the daunting challenge of protecting the polar bear—a mammal which is arguably the world’s largest living land predator—and how it’s dying out, potentially in the imminent future.

A mammal that has been talked about in the news for a long time, its challenges with respect to its shrinking habitat and health have been documented with graphs, photos, and videos. We’re talking about the polar bear.

Listen to Episode 3: Bluefin tunas and the problem of overfishing

Today we are talking about the decline in fish stocks, specifically that of the Atlantic and Pacific bluefin tunas—commercial fishes that are presently overfished and the problem of overfishing in general.

Spend some time with us and we’ll explore the natural history of bluefin tunas, the threats to their long-term survival (how their populations today are but a tiny fraction of what they once were), and overfishing as an unsustainable practice that threatens these species but also several others around the globe.

Meet the Host John Rafferty

John Rafferty

John is Editor, Earth and Life Sciences at Encyclopaedia Britannica, covering natural hazards, climate & climate change, ecology, geology, and zoology. He is also the co-curator of the @Britannica1768 account on Twitter.

John has devoted his career to understanding what makes the planet tick. He is passionate about raising awareness about Earth’s 21st-century environmental challenges and their solutions, especially with respect to the ongoing climate emergency, the extinction of species, and plastic pollution. 

Over his 13 years at Britannica John has written more than 300 original articles and updated more than 2,800 others. You might also know him by his voice as the narrator of dozens of Britannica’s short- and long-form videos. Before joining Encyclopaedia Britannica in 2006, John was a professor at Lewis University, where he taught courses in organismal biology, environmental science, ecology, and earth science. He has held teaching positions at Roosevelt University and the University of Illinois at Urbana-Champaign.

What animal are you most concerned will go extinct?

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