One of the burning questions about the Anthropocene is also one of the most basic: If we are in a new human-caused geologic period, when did it begin?
Some of the more common suggested answers involve the dawn of agriculture around 11,000 years ago, the Industrial Revolution in the 1800s and even the height of atomic bomb testing in the 1950s. But one of the more unusual possibilities stretches even further back in time, to when humans first harnessed fire.
"I think fire would be a really important marker of that, because you know, it begins to manage landscapes on a grand scale," Jon Christensen, an environmental writer at the UCLA Institute of the Environment and Sustainability, told producers of the Generation Anthropocene podcast.
In this week's episode, producer Miles Traer speaks with fire historian Stephen J. Pyne of Arizona State University about the evolution of fire and how human interactions with its various incarnations have changed the planet.
According to Pyne, fire relies on three main components: heat, oxygen and fuel. These three ingredients each appeared in abundance at different points in Earth's history, culminating in a dramatic burst of fire on a global scale during the Carboniferous period, about 350 million years ago. From there, fire evolved as Earth's climate changed and different resources fluctuated and moved around.
"What changes in the last two million years also with the climate is the arrival of a species that acquires the ability to manipulate fire and eventually just start it," says Pyne. "We are the monopolists over fire, and that increases our power over the environment."
Hear Pyne's description of history’s true Promethean moment, and his concerns about our changing relationship with fire, in the full podcast episode:
Also in this episode, producer Mike Osborne speaks with Jud Partin at the University of Texas at Austin, who has a new study out in Nature Communications examining a period in Earth's past called the Younger Dryas. About 14,500 years ago, Earth was warming up and coming out of a long ice age. But partway through the thawing, temperatures suddenly plummeted, and the planet went back into cold glacial conditions. The change back to a warmer world was also oddly abrupt—according to NOAA, Greenland warmed by 18 degrees Fahrenheit in about a decade.
This bizarre cold snap is of particular interest to climate scientists who want to understand what triggers abrupt temperature shifts on Earth and how life responds. Hear more about Partin's latest findings about this time period in the audio file above.