Understanding the true scale of the climate crisis can be difficult, but a groundbreaking study offers a striking comparison: the mass of human-produced greenhouse gases (GHGs) rivals the fallout from some of Earth’s most catastrophic natural events.
A research team led by Hal Nelson, PhD, Associate Professor at Portland State University, conducted this analysis, recently published in the Anthropocene Review. Using atmospheric and geological data, the team compared human GHG emissions to the material ejected by history’s largest asteroid collisions and volcanic eruptions. Their findings provide a new perspective on the magnitude of human impact on the planet.
Key Insights from the Study:
Comparable to Mega-Colossal Volcanic Eruptions
If human GHG emissions were the result of volcanic activity, their scale would be ranked as an 8—the highest level—on the Volcanic Explosivity Index. This classification, referred to as “mega-colossal,” is reserved for events with planet-altering consequences, such as the eruption of supervolcanoes.
As Devastating as an Asteroid Strike
If caused by an asteroid impact, the mass of greenhouse gases released by human activity would suggest a collision capable of triggering a global climatic catastrophe. Events of this magnitude have historically caused mass extinctions and widespread ecological disruptions.
The comparison underscores the severity of human-driven climate change. Activities such as burning fossil fuels and deforestation have fundamentally altered the Earth’s atmosphere, producing emissions on par with natural disasters that shaped entire epochs in Earth’s history.
This “thought experiment” reframes the climate crisis, emphasizing that human activities are not just incremental but transformative—on a scale comparable to the planet’s most catastrophic events. Recognising this perspective could inspire urgent action to mitigate further damage and protect the future of life on Earth.