Notes from the field: Picarro visit to the North Greenland Eemian Ice Core Drilling camp (NEEM)
As I write this, I’m sitting on a ski-equipped LC-130 Hercules cargo plane from the New York Air National Guard’s 109th Airlift Wing, flying over Greenland, having just taken off from the NEEM camp at 77°N latitude where the sun is up 24 hours a day. I was fortunate enough to be invited to visit NEEM, on the northern-Greenland ice cap, as a result of our four-year long collaboration with the Center for Ice and Climate at the University of Copenhagen – the group responsible for running the NEEM expedition.
For the past four summers, groups from the 14 NEEM participant nations (and others) converge on this remote site, atop 2.5 kilometers of ice, for about three months, with an arsenal of scientific measurement equipment, including several Picarro analyzers for measuring greenhouse gases trapped in the ice cores, stable water isotopes in the ice, and water vapor isotopes in the air. This year, I met many of our customers there – scientists from AWI (Germany), LSCE (France), NIPR (Japan), Univ. of Copenhagen (Denmark), Univ. of Bern, Scripps and CIRES at Univ. of Colorado (US).
The primary activity at NEEM is drilling deep glacial ice cores and subjecting them to a battery of analyses of their chemical, physical, and isotopic properties for the purpose of understanding the earth’s environment and climate of the distant past, (over 115,000 years ago). The stable water isotopes in the ice are a proxy for the mean global temperature during the season that each layer of snow fell, eventually forming that layer of the ice core – and each layer is only millimeters thick, as it gets compressed under thousands of seasons of snowfall. The water vapor isotope measurements at NEEM will help describe the transport of moisture between the snow surface and the air – something that is critical in accurately interpreting how the isotopic water content of the ice relates to that in the ancient atmosphere from which it was formed. Last year, “basal ice” (ice mixed with rock and soil) was reached at the base of the ice, signaling the end of the ice core drilling. This year, the drill was replaced with one that can drill through rock, and basal ice and sediment samples were drilled for analysis including for microbial activity and ancient DNA.
Many ice cores have been drilled in Greenland, Antarctica and elsewhere (those in Antarctica being the oldest by far). The reason for the NEEM project and the need for a new ice core is best explained on the NEEM website:
“The North Greenland Eemian Ice Drilling - NEEM - is an international ice core research project aimed at retrieving an ice core from North-West Greenland (camp position 77.45°N 51.06°W) reaching back through the previous interglacial, the Eemian. The project logistics is managed by the Centre for Ice and Climate, Denmark, and the air support is carried out by US ski equipped Hercules managed through the US Office of Polar Programs, National Science Foundation.”
“Greenland temperatures were about 3-5°C warmer higher than present during the Eemian, making the Eemian a useful analogue to the future climate, which due to global warming is projected to warm by 2-4°C per century. By understanding how the Eemian climate evolved, we can improve our ability to make projections for how our current climate will evolve in the future.”
“During 2007-2011, a team of ice core researchers will drill through the ice sheet in North-West Greenland to retrieve ice from the previous interglacial, the Eemian, which ended about 115,000 years ago. Ice core samples from the Eemian will contribute to the understanding of the dynamics of climate under conditions similar to those of a future warming climate.”
“None of the former deep ice cores from Greenland (Camp Century, DYE-3, GRIP, GRIP2, or NGRIP) contains complete and undisturbed layers from the Eemian, because the layers have either melted or have been disturbed by ice flow close to the bedrock.”
There are cores from the southern hemisphere with Eemian ice, but a Greenlandic core of Eemian ice is essential for completing the global picture for that period, particularly since the signals captured in the ice during the Eemian are more pronounced in the northern hemisphere. This ice has been preserved in Greenland since it is essentially a large bowl with mountains surrounding its perimeter. The weight of the 2500meter-thick ice has pushed down the interior, effectively capturing the ice in the bowl. For this reason, the thick Greenland ice exists where other northern glaciers no longer do.
The NEEM camp also serves as a base for doing other science – shallow ice cores, gas measurements in the shallow snow/ice (the “firn”), seismic stations for investigation of ice quakes, deep-hole logging (ice temperature, pressure), radar surveys for glacial tomography, an ice strain net, and ice cap radar survey and experiments with unmanned airborne radar.
Since the science coming out of NEEM is so consequential in our understanding of climate change, it gets a lot of attention, and consequently, each season there are a few visits by “DVs” (Distinguished Visitors). On the flight with me, these DVs included various ministers of science, education and environment from Greenland and Denmark, as well as journalists and filmmakers. The week before our visit, the Queen of Denmark visited NEEM.
The NEEM camp is home to 15-30 people as visiting scientists come and go, spending 2-6 weeks there (the population swelled to >50 when we got stuck there for 36 hours!). There is a large, 4-story geodesic dome, housing a kitchen (with a full-time French chef), common dining, entertainment and working areas, topped by a small windowed room that acts as a control tower for approaching aircraft that arrive every week or so, supplying the camp with food, fuel and transporting people and equipment between NEEM and the KISS (Kangerlussuaq International Science Support) facility, three hours away by air. The camp has numerous other large semi-permanent tents for sleeping, storage and housing equipment. The deep drilling and ice core analysis is done in a 10-meter deep trench in the ice where the main borehole plunges 2.5km below the surface of the ice cap to the rock at the base of the ice. You can read the daily NEEM field diaries since 2007 (with pictures!) at this link.
The logistics to keep the camp running are mind-boggling. Much of the heaviest equipment was transported 365km to the NEEM site in 2007 on large sleds, towed at walking speed, from the previous deep core drilling site, called NGRIP. As the seasons of snow accumulate, the buildings become buried a little more each year and must be dug out and “raised” occasionally (in fact, some of the previous (now abandoned) ice core drilling sites’ buildings have now been completely swallowed by the snow). This year, they will lift the 35-ton NEEM dome and put it on a sled so it can be saved and towed to the next drill site.
Getting into and out of the NEEM camp is an adventure. Landing on the 6km-long “skiway” runway is bone-jarringly rough. The skiway is longer than any paved runway in the world, and it needs to be, so that the “skier” airplanes can get up enough speed to get airborne. The aircraft must get to ~85 knots to get airborne with cargo, and if this can’t be achieved, then rockets (called JATOs for “jet-assisted-takeoff”) attached to the LC-130 must be fired, at a speed of 65 knots, to gain the 5-10 more knots to get the nose gear off the ground so 85 knots can be achieved. Our 3-hour stopover turned into a 36-hour one when six unsuccessful takeoff attempts, including one using JATOs, were followed by two more attempts (where we didn’t even get up enough speed to use the rockets). On a final attempt, after many hours grooming and smoothing the skiway, at 1am when the snow was nice and cold and good for skiing (and skiing airplanes!), we did finally make it off the ground, with rockets blazing! It’s quite an experience! Click here to see this successful takeoff! There is also a video of a JATO takeoff at the bottom of the page at this link.