The ancient lake bed, sealed more than a mile under Greenland ice, may be hundreds of thousands or millions of years old, and contain unique fossil and chemical traces of past climates and life.

In the next few decades, scientists expect we’ll see an ice-free Arctic Ocean throughout the summer. That prospect got much closer in 2020, due in part to the exceptional summer heatwave that roiled the Russian Arctic.

The last time CO2 concentrations reached today’s level was 3 million years ago, during the Pliocene Epoch. Hear from geoscientists who see evolving conditions in the Arctic as an indicator of how climate change could transform the planet.

Today, most life on Earth is supported by oxygen. But ancient microbial mats existed for a billion years before oxygen was present in the atmosphere. So what did life use instead?

The ice-covered Grímsvötn volcano produced an unusually large and powerful eruption in 2011. Now, says this volcanologist, there are clear signs that Grímsvötn is getting ready to erupt again.