Recent reports find that the Arctic is warming 3-4 times faster than anywhere else on the planet. This is leading to increased precipitation, longer growing seasons, and thawing permafrost, but what many may not realize is that the data used to make these claims only extend to 1979. Any older than that, and our knowledge of past Arctic climate becomes less clear.

To look further back in time, scientists rely on proxies, things like ice cores, tree-rings, and pollen, to determine the past climate, including the climate pre-industrialization. These efforts have focused on the “western” Arctic, i.e., Scandinavia, Greenland, and northern North America, which means our knowledge of past Arctic climate is heavily biased to these locales. Data for the other half of the Arctic, represented almost entirely by Siberia, is lacking. 

To provide much needed climate data for this understudied region, I traveled with my colleague at the University of Hawaii, Bill Hagopian, from the United States to Moscow, and then across an additional eight time zones until reaching Cherskiy, a remote settlement in far northeastern Siberia. Cherskiy is home of the Northeast Science Station, a world recognized Arctic research station run by father and son team, Sergei and Nikita Zimov. With the Zimovs, we then traveled up the Kolyma River by small boat to Duvanny Yar, a nearly 40 m high outcrop of permafrost that slumps down towards the river.

In the years prior to this trip, I had developed, with my colleague Hope Jahren (now at the University of Louisiana at Lafayette), a new proxy for determining past temperatures and precipitation by measuring, at very high-resolution, stable isotopes of carbon and oxygen preserved in wood. At Duvanny Yar, Bill and I were in search of “mummified” wood, preserved within the permafrost for thousands of years, for which we could apply these methods to understanding the past climate of the region. We climbed over large blocks of collapsed permafrost and around ice wedges looking for suitable wood samples to apply these methods. After some searching, we collected several pieces of fossil wood from the permafrost, which we later radiocarbon dated to be 3,000 years old.

Modeling work by others had shown Siberia to be relatively warm and wet at this time, but there were no geochemical data available for comparison with the models. With Collin Moore, a graduate student working in my lab, we spent hundreds of hours determining the carbon and oxygen isotope composition across the annual growth rings of the mummified wood fossils. From these measurements, we discovered that the eastern Arctic had once experienced warmer and wetter winters, while summers were actually cooler, but also wetter, than present.

Investigation of weather station data collected across the last 40 years shows a similar pattern – Arctic winters have gotten a lot snowier and warmer while summers have gotten only a little rainier and warmer: during my lifetime, winter climate changed at triple the rate of summer. Although the current rate of climate change in the Arctic remains extraordinary, our novel high-resolution data provide key insight on the full effects of industrialization on Arctic seasonality, including significantly warmer and wetter winters.

Yet, this is a study for which I have strong mixed emotions. On the positive side, it marks the first time our proxy for reconstructing seasonal temperatures has been applied to fossil wood and highlights the importance of seasonality for understanding our changing climate. It also demonstrates a method for extending our climate record beyond the historical record, which is particularly useful for providing context for anthropogenic climate change. This all makes me quite proud of the work.

On the other hand, I am despondent. The fieldwork described here occurred before Russia invaded Ukraine in February 2022, with the manuscript being written, submitted, reviewed, and published in the time since. Throughout, I emailed the Zimovs with updates and revisions, hoping for a reply, not knowing if my emails would even reach them.

But what I take from my experience are the fond memories of meeting gracious scientists at the Komarov Botanical Institute en route to the field, and visiting the Permafrost Research Institute in Yakutsk while waiting for floodwaters in Cherskiy to recede. I value my colleagues at the Northeast Science Station who were able to guide us to Duvanny Yar and provide detailed local knowledge of the field site and climate, and I appreciate their contributions to the study. Overall, I feel fortunate and grateful for the people I was able to meet and cooperate with while working in the Siberian Arctic.