The Anthropocene: Understanding Modern Day Earth

I run an Astronomy Public Lecture Series at Thomas More University, tied to our Observatory. For Earth Month 2026, I took an astronomer’s lens and examined our home planet. Specifically, I put our current moment into a deep time context and put several astronomically large numbers into perspective – numbers that reveal how human activity has become a planetary force capable of reshaping climate, ecosystems, and even the geological record.

Critically, though, I didn’t want to spend the entire talk focusing on the scale of the problem. I also wanted to offer attendees ways to get involved and take action to engage in planetary stewardship in some small way. This page outlines some of those ways to take action as well as some perspectives on the scale of human impact on the Earth System that I found interesting.

The Anthropocene:

The Anthropocene is a proposed epoch of the Earth’s Geologic Time Scale characterized by the dominant influence of human activity on the Earth system. (Think: Climate Change, Biodiversity Crisis, Ozone Depletion, etc.)

The Physics and Astronomy Connection:

Over the last million or so years, Earth’s climate has been largely controlled by small, periodic changes in Earth’s orbital motion: the Milankovitch Cycles. These cycles are slight changes in Earth’s tilt, the shape of Earth’s orbit, and the direction Earth’s axis points in space. Together, these three cycles governed the energy balance of the Earth, resulting in the climactic patterns of the last million years or so. Namely, for just about the entire existence of modern humans, the periodic ice ages and warmer interglacial periods had been controlled by how much of the Sun’s energy hits the Northern Hemisphere. Relatively recently, though, this has begun to change. This change, along with several other anthropogenic changes, have been suggested as a demarcating line for a new geologic epoch.

Putting the Numbers into Perspective:

Similar to astronomy, when trying to understand the scale of the anthropocene, we are forced to confront unimaginably large numbers. In many cases, it is helpful to put the numbers into context. Here are a few that I found to be the most interesting:

When considering all of Earth’s mammals (by biomass), only about 4% is wild. Some 36% of that mass is us – humans. The other 60% of that mass is the animals we grow to eat. To put that into perspective, there are enough cows on the planet that, when lined up end to end, would stretch to the Moon and back four times!
Humans move so much sediment (sand, rock etc.) that we could fill the entire Panama Canal in just two days.
Human society produces enough material (concrete, plastic, etc.) each week to outweight the entire combined weight of humans. If this mass were all concrete, it’d be enough to wrap around the globe NINE times. And that’s just one week’s worth of production!

Action in the Anthropocene:

There’s no doubt that there are a number of issues in the Anthropocene that need to be solved. The good news is we’ve done it before. At the end of the 20th century, science sounded the alarm on ozone depleting substances and policy action followed. Today, the Ozone Hole is shrinking.

In the spirit of planetary stewardship, I shared a number of small, local, low-friction ways to get involved:

Other Thoughts on the Lecture:

I am very interested in giving this talk (or a similar talk) again. Please reach out if you are interested.

Additionally, many thanks to the University of Cincinnati’s Center for Public Engagement with Science (PEWS) for helping to get the word out about this talk.

Ways to Learn More:

If you’d like to learn more, here are several documentaries/books/popular articles to check out: