Archaeologists dig deep into the soil in order to find artifacts and tools that tell the history of ancient civilization or life.

When paleoclimatologists want to find out about Earth’s past climates, they do something similar – but instead of digging through soil, they search for hints towards our planet’s history. This involves digging into oceans and water floor sediment, studying coral reefs, and core drilling into ice sheets and glaciers.

The samples these scientists extract from the ice are called ice cores.

An ice core holds a record of how our planet was thousands upon thousands of years ago. The question is, where do these ice cores come from and what can they tell us about climate change today?

What Are Ice Cores and Where Do They Come From?

Glaciers and ice sheets from the Earth’s North and South Poles were originally formed from many years of snowfall accumulation.

After many years of each year’s snowfall compressing the previous snow layers, this pressure forms glacial ice.

In some places, these snow layers form ice sheets that are several miles thick.

Researchers and paleoclimatologists drill out ice cores from deep inside these ice sheets in and around Greenland and Antarctica along with a few high-latitude mountain glaciers and ice caps.

These ice cores are collected in order to study the regional climate variability and to compare this variability from global climate signs.

What Can These Ice Cores Tell Us About Our Planet’s Past Climates?

Every layer of ice tells us a story about how the Earth was when that specific layer of snow fell to the Earth’s ground.

This is because when snow adds itself onto a growing glacier, the air temperature makes an impression onto the water molecules. These layers hold particles themselves – such as ash, dust, pollen sea salts, or other aerosols that were found in the atmosphere at that specific time.

These particles provide evidence of global events like volcanic eruptions and can stay in the ice for thousands of years. On top of this (literally), as the ice is formed and compact over the years, small atmospheric bubbles are pressed inside the ice. These air bubbles include fossil fuel gases such as methane and carbon dioxide, which provide the scientists with samples and a clear idea of what the atmosphere – and our planet – was like when that specific layer of ice was formed.

When sampled and observed, these bubbles can give an exact measurement of how many greenhouse gases were there at that time. An example is the Vostok Ice Core which presents a detailed analysis of CO2, temperature, and methane samples from roughly 137-102,000 years ago.

How Can Ice Cores Tell Us About the Earth’s Future?

While ice bubble information about our past is extremely interesting, what’s more is how these bubbles from ice cores can tell us about our planet’s future.

Once tested, the ice core’s temperature data is able to validate climate models which predict our Earth’s future climate.

How’s that?

Think of a climate model as a lab built inside of a computer. Scientists layer all of the knowledge about how our ocean, atmosphere, land and ice work, and put them inside this “lab”.

By studying the bubbles from the past and comparing them to this laboratory of information of what our planet is like now, scientists are able to predict what will happen to the planet if it follows along the same patterns as the past.

The bubbles tell us that with more CO2 in the atmosphere, a period of warming quickly followed. That being said, the future climate is very different than the past since it involves human-induced atmospheric temperatures.

What Ice Cores Tell Us: Final Thoughts

While there are many different ways of analyzing the bubbles and information that ice cores give us from various core drilling samples around the world, scientists in this field in this day and age have mastered the techniques.

What’s interesting is the way these bubbles, formations, and aerosols can tell us about our past – and possibly, our future.

While the future is hard to predict given the many different variables in place and needed to be accounted for, there is still some possibility that there may come a time where we relive our past climates in some form.

The most important aspect to remember is to not become stuck on the past, but to notice what is happening currently in our world. Recognize the issues and focus on ways to solve them to maintain what’s important – the nature around us that provides us life.