Setting the Scene

The name "Carboniferous" is derived from our reliance on fossil fuels. Spanning from 359 to 299 million years ago, this period was pivotal in the formation of extensive coal deposits, which later became a crucial energy source for the Industrial Revolution. Humanity learned to extract this energy from deep within the Earth, fostering advancements in industry, manufacturing, and transportation. However, it took time for society to recognize the environmental costs tied to this 'cheap energy.' Ironically, the fossil fuels that now contribute to global warming were formed during a time of significant cooling at the end of the Carboniferous.

The Carboniferous is divided into two main intervals. In North America, these are referred to as the Mississippian (Early Carboniferous) and the Pennsylvanian (Late Carboniferous). These distinctions reflect the differing environmental conditions; the Early Carboniferous was characterized by vast, shallow seas, while the Late Carboniferous featured more land exposure.

During this time, the supercontinent Pangea began to take shape as Gondwana drifted northward and merged with Laurasia. The tectonic upheavals associated with Pangea’s formation led to the rise of highlands and the creation of expansive, warm lowlands.

Carbon and Oxygen Dynamics

The geological uplift during the Late Carboniferous made the environment more terrestrial compared to the marine conditions of the Early Carboniferous. This shift allowed for the development of vast swamps where trees and plants thrived, often buried in anoxic conditions before they could fully decay. These organic remains eventually transformed into the extensive coal deposits we rely on today. This duality of coal represents both an opportunity for technological growth and a challenge for environmental stability, accelerating climate change at an unprecedented pace.

Additionally, the Carboniferous Period marked a remarkable rise in atmospheric oxygen levels, reaching 35% by its end—an increase of 75% compared to today. This warm, oxygen-rich environment fostered lush vegetation, including towering horsetails, ferns, and primitive conifers, all contributing to the oxygenation of the atmosphere.

The heightened oxygen levels not only created vivid blue skies but also significantly impacted terrestrial ecosystems.

Insects and Wildfires

Today, climate change drives an increase in the frequency and severity of wildfires. Warmer, drier conditions have led to devastating fires in places like Siberia, Australia, and California. However, wildfires were not a common occurrence for most of Earth's history, as oxygen levels were too low to sustain them. At oxygen levels under 16%, fires cannot spread, while levels above 23% result in uncontrollable infernos. During the Carboniferous, the atmosphere's 35% oxygen content meant that wildfires were frequent and intense.

Fossil records indicate that wildfires were common during this period, with charcoal evidence pointing to increased fire activity correlating with high oxygen levels.

The high oxygen content also influenced animal life, particularly insects. The Late Carboniferous saw the emergence of enormous insects, including predatory griffinflies with wingspans exceeding two feet. Unlike mammals, insects rely on a network of tiny tubes for oxygen transport, which limits their size. However, the oxygen-rich atmosphere allowed them to grow larger than ever before.

The first video, "The Complete History of the Earth: Carboniferous Period," offers a comprehensive overview of this remarkable era, detailing the geological and biological transformations that occurred.