WESTERN GREENLAND – When the bright red Sikorsky helicopter landed, researcher Elizabeth Thomas shouted to her team it was time to unload – and quickly.

The helicopter was being diverted from its scientific field transport mission to Medevac an injured child from a small Greenlandic community. Thomas and her team – including three students, an outreach coordinator, and an artist – joined the helicopter crew in hurriedly unloading hundreds of pounds of equipment, from a generator to coring equipment, saws, computers, GPS units, camping gear, food, and many other items. Swarms of mosquitoes encircled the team as they piled their gear in the tussocks near a small lake at their second field site, and the helicopter lifted off and flew away.

Thomas was there this past July on a 12-day field mission to gather crucial data in order to answer important questions about past climatic conditions. She and her team would spend their time camping at two different sites, collecting lake bed sediment cores and water samples for later analysis.

As Earth warms and sea ice melts, Arctic precipitation is expected to increase; these scientists wanted to learn more about where this precipitation may come from, so they were looking to the past for clues.

“There’s some question about exactly what mechanism causes precipitation to increase in the Arctic,” says Thomas, an assistant professor of geology at the University at Buffalo, State University of New York.

The two prevailing theories were 1) the increase in precipitation came from new open water that evaporated nearby and was deposited back as local rain and snow, or 2) increased humidity at lower latitudes was flowing north to the Arctic.

“Knowledge about the source of precipitation during previous wetter and warmer periods provides insights into climate dynamics,” Thomas said. “We can compare our findings with model results to learn more about how the climate system operates, and thus make more accurate predictions of Arctic climate.”

To find out more, the team sought to examine leaf waxes – protective waxy coatings on plant leaves – deposited in lake bed sediment thousands of years ago. They wanted to learn about past precipitation, homing in on an abrupt warming period around 8,000 years ago. “All plants, whether they live in a lake or just like the maple tree in your backyard, those all produce leaf waxes at varying amounts,” Thomas says. “Those leaf waxes are hydrocarbon molecules, and the hydrogens in those leaf waxes come from the plant’s source water.”

They would examine isotopes in the samples to determine whether the precipitation that fell around 8,000 years ago was from local precipitation (with heavier isotopes), or moisture transported from the tropics (which would have lighter isotopic composition because rainfall would remove many of the heavy isotopes).

Thomas and her team were in Greenland to collect the necessary samples.

BUFFALO, NEW YORK – A full year before Thomas and her team were swatting mosquitoes in a remote region of western Greenland, she was poring over GIS mapping programs and Google Earth looking for field sites. She also pored through other scientists’ research to see what they had learned about the area, and zeroed in on lakes where she believed she could extract good samples.

Thomas had been working on her team’s field plan, assembling a capable crew, procuring necessary equipment, and sorting out logistics long before any of them would set foot in Greenland. She was leading Phase 1 of the project, and another researcher was leading Phase 2 later that summer.

Three to six months before departure, Thomas finalized the field sites and then, two to three months before leaving, the team assembled their gear and food. They planned everything from how much PVC pipe they would need to collect coring samples, to how much food they would eat, purchasing and packaging nonperishable food items to ship ahead, and stocking up on perishables just before departure.

SCOTIA, NEW YORK – The Air National Guard’s 109th Airlift Wing provides transportation for scientists and support staff conducting research in Greenland. But hopping a ride with the Guard isn’t like flying on a commercial airline. At 5 a.m. on a mid-July day, Thomas’s team joined other scientists and personnel in a hotel lobby near Stratton Air National Guard Base. Soon, uniformed service members arrived with a truck for luggage and a bus for passengers, inspecting passports and checking them one by one against the passenger manifest. After a short ride to the base, passengers and baggage underwent security screening before everyone was brought to a conference room for a safety briefing.

Then, passengers walked out to board the waiting LC-130. A total of four rows of cargo net seating were set up, with two rows facing each other on either side of the plane. As passengers sat, their knees were inches from those of the passengers sitting across from them.

As the plane roared to life, the National Guard loadmaster handed out ear plugs; many passengers pulled out their own heavy-duty hearing protection and warm jackets for the flight as the cargo plane’s interior temperature fluctuated widely. The plane’s restroom facilities were very basic and encircled by a tarp for privacy. It was too loud for conversation, so many passengers napped or read as the plane made its way to Greenland.

KANGERLUSSUAQ, GREENLAND – About seven hours after departing from New York, the LC-130 touched down in Kangerlussuaq, Greenland. A local police officer stamped passports on the tarmac, and passengers were bussed to the Kangerlussuaq International Science Support facility for a briefing and introduction. The facility holds dorms and offices and assists with logistics and support for a wide array of international science projects.

Soon after the briefing, Thomas and her team headed to the nearby warehouse to prepare their gear. With the help of the facility’s logistics staff, they sorted their goods, unpacking and repacking items stored at the Kangerlussuaq warehouse year-round. They ensured they had ready everything needed to head to their first field site the next day.

Scheduling helicopter time in remote regions of Greenland is always challenging, but it was especially difficult in July of 2018, with a 330-foot-tall iceberg looming dangerously close to the settlement of Innaarsuit, along Greenland’s western coast. If the iceberg broke apart, it could deluge the settlement with a tsunami of water and require immediate evacuation, so the 19-seat Sikorsky helicopter was placed on stand-by near Innaarsuit.

The logistics team was able to arrange for Thomas’s team to use a smaller helicopter, rather than the originally planned Sikorsky, to reach their first field site. Transport would now require two trips to bring all the people and equipment to the site, and the team had to scramble to get ready. “You definitely have to be flexible,” Thomas says.

They were scheduled to spend several days at the first site before the Sikorsky would pick them up and transport them to their second field site. However, Thomas notes the plan can always change. “We always try to plan a flexible schedule such that we have enough days at each of ours sites to collect the samples that we absolutely need, just in case there are issues with weather or with the helicopter transport,” she says.

Thomas has conducted field work in Arctic regions around the world, from Baffin Island to Svalbard to Greenland, and also at plenty of field sites near her home in western New York. As leader of Phase 1 of the Greenland mission, it was her role to ensure the group collected all the samples they needed within their limited window of time and keep everyone physically safe and mentally and emotionally comfortable.

Each day in the field, she would generally be the first person up, heating water for coffee and charging equipment like computers and GPS units. The rest of the team would wander over to the cook tent around 7 a.m. for breakfast – typically oatmeal with dried fruit and nuts – and then, at precisely 7:15 a.m., Thomas would use the satellite phone to check in with the logistics manager at KISS and get the latest weather report. The team then would grab their packs, assembling lunch and ample snacks for the day, and set out to collect samples, sometimes going out on lakes in boats to retrieve sediment cores.

“No matter what we did that day, we would spend time writing notes about the samples that we collected, taking logs of the sediment cores that we collected, making sure the location and details about any sample that we collected that day was clearly entered in our notes,” Thomas says. “And then we would share those notes with someone else on the field team, to make sure those notes were replicated in case they were lost.”

When lunchtime rolled around, they would seek a scenic spot to eat before returning to work. After the day’s fieldwork was complete, everyone would return to camp, change out of wet clothes if necessary, and then congregate at the cook tent for dinner and conversation before retreating to their individual tents to sleep.

Each day had its challenges, a constant one being the insect life, including mosquitoes. At times, the researchers would don rain jackets, rain pants, thin gloves, head nets, and insect repellent to keep the biting creatures at bay. Some still ended up with numerous bites, slathering themselves with anti-itch lotion and taking antihistamines to reduce swelling and itching to be able to sleep. But the discomforts of fieldwork paid off as the team ended up with the samples they needed. They carefully packed them up and transported them back to their lab for analysis.

BUFFALO, NEW YORK – When Thomas’s team returned to the University at Buffalo, they brought back sediment cores and other samples to process. Pulling a wire down each core’s centerline, they split the samples in two, taking photographs, describing their findings, and analyzing color and appearance. They removed samples of plant material to send to a radiocarbon lab for dating and analyzed sediment samples to learn more about the waxes, compounds, and isotopes within.

It took months to analyze the samples, and the team’s results then were published in Geophysical Research Letters in October.

Thomas answered her initial question writing, “A rise in both local evaporation and incoming moisture from lower latitudes may have fueled this change, according to our interpretation of geologic records. Our study suggests that both processes may contribute to a future, wetter Arctic.”

They also analyzed the molecular composition of samples to determine temperature during the period, finding cooling 9,000 years ago and an abrupt warming period 8,000 years ago, which matches other records. However, Thomas still has other questions she wants to answer, such as what proportion of the precipitation was from local evaporation versus the amount transported from lower latitudes.

While she seeks to answer additional questions about Greenland, she is also planning her next rounds of fieldwork, preparing for 2019 projects in Baffin Island and Alaska.

Editor’s note: The National Science Foundation provided Kristen Pope with logistical support to cover this story in Greenland and Scotia, New York.