Science 3 min read

Scientists Calculate Earth's Temperature During the Last Ice Age

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A team of researchers from the University of Arizona has finally pinned down Earth’s temperature during the last ice age. It appears that during the Last Glacial Maximum (LGM), the world’s temperature was around 46 degrees Fahrenheit (7.78 degrees Celsius).

The Last Glacial Maximum occurred 21,500 years ago. During that time, massive ice sheets covered a vast portion of North and South America, Europe, and Asia.

At 46 degrees F, our planet during the LGM was found to be 13 degrees F colder than in 2019. The team also discovered that some regions of Earth at the time were much colder than the calculated global average.

“We have a lot of data about this time period because it has been studied for so long. But one question science has long wanted answers to is simple: How cold was the ice age?”

– Jessica Tierney, Associate Professor, University of Arizona Department of Geosciences via

How Scientists Calculated the Temperature of the Last Ice Age

For the scientists to calculate the temperature of the last ice age, they measured the chemicals found on tiny fossils of zooplankton. They also used the chemical measurements on preserved structures of fats from other types of plankton that change based on water temperature.

The chemical measurements were then fed into climate model simulations that calculate the average global temperature.

“Past climates are the only information we have about what really happens when the Earth cools or warms to a large degree. So by studying them, we can better constrain what to expect in the future,” Jessica Tierney, lead author of the study published in the journal Nature, added.

Tierney and her team created maps to demonstrate the varying temperatures in specific regions across the world. The researchers noted that the coldest places during the LGM were on high latitudes like the Arctic.

The scientists’ findings match the current scientific understanding of how our planet’s poles react to changes in temperature. Tierney explained:

“Climate models predict that the high latitudes will get warmer faster than low latitudes. When you look at future projections, it gets really warm over the Arctic. That’s referred to as polar amplification. Similarly, during the LGM, we find the reverse pattern. Higher latitudes are just more sensitive to climate change and will remain so going forward.”

Determining Climate Sensitivity Using Temperature of the Last Ice Age

Tierney and her team’s findings are crucial in calculating the climate sensitivity of Earth. Climate sensitivity refers to the reaction of global temperature to the amount of carbon in the atmosphere.

In their study, the researchers determined that global temperature could increase by 6.1 degrees F for every doubling of atmospheric carbon.

The Paris Agreement aims to keep global warming at around 2.7 degrees F or lower. However, Tierney noted that if the carbon dioxide levels continue to increase, it would be challenging to avoid 3.6 degrees F. She added:

“We already have about 2 F (1.1 C) under our belt, but the less warm we get, the better, because the Earth system really does respond to changes in carbon dioxide.”

Read More: Emissions Decline During Lockdown Won’t Slow Climate Change

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Chelle is the Product Management Lead at INK. She's an experienced SEO professional as well as UX researcher and designer. She enjoys traveling and spending time anywhere near the sea with her family and friends.

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