Radioactive krypton could be a key to learning more about the Earth's climate history as it could potentially help scientists more accurately date ancient ice.

The lead author of a study published in the journal Proceedings of the National Academy of Sciences, Christos Buizert told LiveScience his team would like to find ice samples 1.2 million years old. Those samples would be ideal in learning more about a period in which the Earth made a major switch in its rhythms of hot and cold.

"There are interesting scientific questions we could answer if we had such old ice," said Buizert, a paleoclimatologist at Oregon State University.

There are two ways to try and obtain an ice sample that old. First, the team has drilled into ice cores thousands of feet deep, but the oldest sample they found was around 800,000 years old. The next way would be to seek out blue ice, which is forced toward the surface when mountains block the flow of ice.

According to a press release from OSU, krypton dating is most similar to carbon-14 dating because it measures the decay of radioactive isotopes. Krypton comes from cosmic sun rays being trapped in Antarctic ice and provides a highly reliable stable-to-radioactive isotope ratio, a key in the dating process.

"The atom trap is so sensitive that it can capture and count individual atoms," Buizert said in the release. "The only problem is that there isn't a lot of krypton in the air, and thus there isn't much in the ice, either. That's why we need such large samples to melt down."

The scientists believe over the past 800,000 years, the Earth has gone through an ice age every 100,000 years. Before that, they say the Earth went through these cycles in 40,000 years, but there is little evidence to explain the shift.

"Why was there a transition from a 40,000-year cycle to a 100,000-year cycle?" Buizert said. "Some people believe a change in the level of atmospheric carbon dioxide may have played a role. That is one reason we are so anxious to find ice that will take us back further in time so we can further extend data on past carbon dioxide levels and test this hypothesis."