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.

1.3 Billion people in 1850 7.7 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

Vaquita TranscriptDownload 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. read more about the Vaquita

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

Polar Bear TranscriptDownload 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. Learn more global warming’s impact on polar bears

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

Bluefin Tunas TranscriptDownload 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. Learn more about overfishing

Listen to Episode 4: “The Precarious State of the Monarch Butterfly”

The monarch is known for its striking appearance, its ability to take the chemicals from its food source, milkweed, to make itself distasteful to birds and other predators—so much so that other species of butterflies evolve to copy the Monarch’s appearance—and its spectacular long-distance migration from central Mexico through North America. In this episode, we’ll explore the monarch’s natural history, the threats posed to the species by habitat loss and pesticides, and some encouraging signs about the Monarch’s recovery in the eastern United States. Learn more about the Monarch Butterfly

Listen to Episode 5: “The Orangutan Conservation Conundrum”

Orangutans are primates that are very closely related to human beings. They are also not one species, but three, and all of them are classified as critically endangered by the International Union for Conservation of Nature and Natural Resources (the IUCN). In this podcast, we will explore the orangutan’s natural history, the threats to its survival posed by hunting and the palm oil industry, and some of the things we can do to make sure that these animals are protected both now and in the future. Learn more about other endangered species

Listen to Episode 6: “Understanding Functional Extinction”

In this episode, I’ll be tackling the concept of functional extinction, a term that came to the fore in late 2019 because of its association with Australia’s koala. The concept of functional extinction has been around in ecological circles for many years, however. Here, we’ll be taking a look at functional extinction as it relates to the koala and other species, we’ll hear from environmental statistician Andrew Solow about what functional extinction means, and we will consider the ways in which functional extinction affects an ecosystem. Get to know Australia’s Koala

Meet the Host 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.

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