Arctic sea ice may completely disappear in our lifetime, according to recent research, which isn't surprising given that ice extent in the region reached an all-time low this year, shrinking to its sixth-lowest level on record.

According to the study, an ice-free period hasn't been seen in the Arctic Ocean for 2.6 million years, a time when the Earth's climate was warming up. It wasn't until between four and five million years ago that the planet started to see some cover.

But now the climate is changing again and global temperatures are increasing, impacting Arctic ice once more. By the end of the present century, researchers say, the Arctic Ocean may very well be completely free of sea ice, especially in summer.

"We have not seen an ice free period in the Arctic Ocean for 2.6 million years. However, we may see it in our lifetime," marine geologist Jochen Knies added in a statement.

Such a drastic change could have important implications for the Earth's entire climate system. When people think of climate change, they usually picture greenhouse gases, but oceans play just as an important a role as air. The temperature and salinity of polar ocean, such as the Arctic Ocean, help drive world ocean circulation that distributes heat in the oceans, as well as in the atmosphere.

To determine what we can expect in terms of sea ice extent in the future, researchers drilled the ocean floor in Spitsbergen, Norway to determine the age of sediments in the area. By analyzing the sediments for chemical fossils made by certain microscopic plants that lived in the sea ice and surrounding oceans, they were able to fingerprint the changing environmental conditions.

"One thing these layers of sediment enable us to do is to 'read' when the sea ice reached that precise point," Knies explained.

"The extent of the ice in the Arctic has always been very uncertain but, through this work, we show how the sea ice in the Arctic Ocean developed before all the land-based ice masses in the Northern Hemisphere were established," he added.

For example, when the Bering Strait between America and Russia opened up, and likewise the Panama Canal in Central America closed, a surge of fresh water was brought to the Arctic, resulting in more sea ice.

"Our results can be used as a tool in climate modeling to show us what kind of climate we can expect at the turn of the next century," Knies said.

The results are described further in the journal Nature Communications.

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