Siberian Permafrost Reveals Winters Have Continuously Warmed for Thousands of Years

It turns out that winters in Siberia are getting a bit warmer. Scientists have decoded climate data from old permafrost ground ice and have reconstructed the development of winter temperatures in Russia's Lena River Delta and have found that over the past 7,000 years, winter temperatures have gradually risen.

Ice doesn't form above ground in Russia's Lena River Delta. Instead, it forms directly underground as ice wedges. These are a typical feature of permafrost regions, and are formed when permanently frozen soil contracts in response to intensively cold winter temperatures, causing it to crack. When snow meltwater fills these cracks, the water refreezes immediately.

The ice wedges can be as much as 100,000 years old and store climate information in the same way that Antarctic glaciers do.

"The melt water always comes from the snowfall of a single winter," said Thomas Opel, one of the researchers, in a news release. "Therefore, when it freezes in these frost cracks, information on the winter temperatures in that specific year is also preserved. We have now succeeded for the first time in using oxygen isotope analysis to access the temperature information stored in the ice and compile it into a climate curve for the past 7,000 years."

It's obvious from the new data that winters have warmed, but the researchers can't exactly pinpoint how many degrees they've warmed by. That said, there are clear indications for the causes of this warming.

"The curve shows a clear partitioning," said Hanno Meyer, one of the researchers. "Up to the dawn of the industrialization around 1850, we can attribute the development to changes in Earth's position relative to the sun. In other words, the duration and intensity of the solar radiation increased from winter to winter, causing temperature to rise. But with industrialization, and the strong increase in the emissions of greenhouse gases like carbon dioxide, this was supplemented by the anthropogenic greenhouse effect."

The findings reveal that this region has warmed over time. That said, scientists are hoping to conduct future studies to better understand by how much it has warmed. In addition, they want to see whether the same indicators for a gradual rise in winter temperatures in the Arctic can also be found in other permafrost regions around the globe.

The findings are published in the journal Nature Geoscience.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).