How Earth’s Climate Changes Naturally, at Geologycal Scale

Carbon dioxide molecules absorb infrared radiation, so with more of them in the atmosphere, they trap more of the heat radiating off the planet’s surface below. But besides the increase of global temperature since preindustrial times due to carbon dioxide emissions from human activity - about which we will post more in the coming days - the Earth has already faced other cycles of cold and heat in its geologic age of 4.5 billion years. Below is a list of 10 situations that paleoclimatologists indicate have caused climate change.

1. Solar Cycles. Magnitude: 0.1 to 0.3 degrees Celsius of cooling. Time frame: 30- to 160-year downturns in solar activity separated by centuries

2. Volcanic Sulfur. Magnitude: Approximately 0.6 to 2 degrees Celsius of cooling. Time frame: 1 to 20 years

3. Short-Term Climate Fluctuations. Magnitude: Up to 0.15 degrees Celsius. Time frame: 2 to 7 years

4. Orbital Wobbles. Magnitude: Approximately 6 degrees Celsius in the last 100,000-year cycle; varies through geological time. Time frame: Regular, overlapping cycles of 23,000, 41,000, 100,000, 405,000 and 2,400,000 years

5. Faint Young Sun. Magnitude: Increasing solar brighteness over time, despite the effect being neutralized by the next item. No liquid temperature effect. Term: Constant

6. Carbon Dioxide and the Weathering Thermostat.Magnitude: Counteracts other changes. Time frame: 100,000 years or longer

7. Plate Tectonics. Magnitude: Roughly 30 degrees Celsius over the past 500 million years. Time frame: Millions of years

8. Asteroid Impacts. Magnitude: Approximately 20 degrees Celsius of cooling followed by 5 degrees Celsius of warming. Time frame: Centuries of cooling, 100,000 years of warming (Chicxulub, which vaporized part of Mexico 66 million years ago, killing off the dinosaurs)

9. Evolutionary Changes. Magnitude: Depends on event; about 5 degrees Celsius cooling in late Ordovician (445 million years ago). Time frame: Millions of years

10. Large Igneous Provinces. Magnitude: Around 3 to 9 degrees Celsius of warming. Time frame: Hundreds of thousands of years

Click to read more about each of these topics, article by the geologist and science writer Howard Lee for the Quantamagazine

NASA’s Goddard Space Flight Center