Episode 140: A History of Earth's Climate

Ice Cores

Ice cores are a major source of information about past climates. James Fodor explains that by drilling into ice sheets in Antarctica or Greenland, scientists can analyze layers of compacted snow and trapped air bubbles to determine historical snowfall and carbon dioxide levels. This method allows for temperature estimates going back hundreds of thousands of years.

We actually have preserved samples of air from past climates going back tens of thousands, even hundreds of thousands of years.

--- James Fodor

Additionally, the ratio of oxygen isotopes in the ice provides further temperature data, making ice cores a valuable proxy for understanding ancient climates 1.

   

Sedimentary Evidence

Sedimentary and geological evidence also play a crucial role in reconstructing Earth's climate history. James Fodor discusses how tree rings, ocean sediments, and rock formations offer insights into past temperatures and environmental conditions. These methods, while less precise than ice cores, extend our understanding back hundreds of millions of years.

Based on these sort of inferences, people have constructed approximate series of temperatures going back 500 million years.

--- James Fodor

Combining these proxies with ice core data allows for a more comprehensive picture of Earth's climatic fluctuations over geological time scales 2 3.