How have volcanic eruptions shaped our planet?

As we saw in Week 1, volcanic eruptions played a big role in escaping Snowball Earth as they pump CO₂ and other volatiles in the atmosphere.

They can have important climate impacts over geological timescales.

Mass extinctions

Large igneous provinces are also intimately linked with mass extinctions over the course of Earth’s history.

Five significant mass extinction events can be seen in the geological record.

• End Ordovician, 444 million years ago
• Late Devonian, 375 million years ago
• End Permian, 251 million years ago
• End Triassic, 200 million years ago
• End Cretaceous, 66 million years ago

All five of them occur at the same time as an eruption of large igneous provinces.

They are so large that the gases they released can modify the composition of the atmosphere and the oceans on a global scale. All life depends on the compositions and cannot easily adapt to the rapidly changing environment.

Deccan Traps

The most famous of these extinctions is the Cretaceous–Paleogene (K–Pg) extinction event that wiped out the dinosaurs 66.25 million years ago. One of the leading theories as a cause for this extinction are the Deccan Traps.

Deccan Traps, India. March 22, 2018 ©2018 Planet Labs, Inc, licensed under CC BY-SA 4.0.

The remnants of these eruptions can now be found in west-central India and covered an area of 500,000 km² potentially up to 1.5 million km², that’s 25 to 75 times the size of Wales.

Volcanic eruptions can also have numerous hazards on a human timescale, which we will discuss in more detail in Week 3.