Ice cores and polar bears

Several days into our field research experience in the high Arctic, we've established two sampling stations, collected ice core sections from both sites, filled up the lab refrigerator with said cores to melt them in filtered seawater for processing, and begun analyses in the lab. We're getting more comfortable driving the snowmobiles (and staying warm while doing so). And we've even had our first polar bear sighting!

Polar bears way off in the distance. Let's hope they stay that way!

Tony and Glenn Roy, our fantastic guides and bear guards

The landscape through which we drive to get to Station 1 is like a setting on another planet. Jumbled blocks of snow-covered and icicle-encrusted ice form towering piles of white and gray. The monochrome terrain is broken by shades of crystalline turquoise or aquamarine, where slabs of pure ice have formed.

Giant ice formations at Station 1. See the snowmobile tracks in the foreground for scale.

Station 2, by contrast, is flat, blindingly white, featureless. It's a disorienting world where distance and direction are unnervingly difficult to determine. The snow depth above the sea ice, which is itself a meter and a half thick or more, is variable at Station 2, and that's just what we're looking for. The amount of light that can penetrate to the algal layer at the base of the ice depends partially on how much snow rests atop the ice. Snow also provides insulation, so if a particular area has had a thick layer of snow on top of it for a while, less ice will have formed underneath.

The little red flag marking Station 2

Unsurprisingly, it's nearly impossible to tell what the ice will be like at a site until we trek out there and start drilling. If the ice is full of sediment, little light can reach the base of the layer, so algal biomass is at a minimum... which doesn't make for an ideal sampling location.

A sediment-laden ice core

Once we ID a promising site, though, we can collect several cores and take 10cm-thick samples from the middle and base. We put the sections in individual plastic bags labeled with the day, station, core number, and depth (like 0-10cm from the bottom of the core), and then put the samples in a cooler padded with snow for transport back to the lab for melting and eventual processing.