When you’re standing on the beach in La Jolla, Calif., with the sun shining and the waves lapping against your toes, it’s pretty difficult to imagine a connection to the frigid glaciers that cover 80 percent of Greenland.
However, we three scientists at Scripps Institution of Oceanography at the University of California San Diego recently travelled to Disko Island in West Greenland to learn more about how melting of this polar ice is causing sea levels to rise all across the globe, including here in San Diego.
The massive ice sheets covering Greenland and Antarctica, as well as smaller ice caps, such as the ones that cover Disko Island, are made up of glacial ice. This ice is formed not by the freezing of liquid water, but by the accumulation of many years of snowfall. Snowflakes at the bottom of the resulting pile are compressed by the weight of the snow above them and gradually fuse into ice crystals. The difference between the amount of new ice forming in this way each winter and the amount of ice that melts away each summer determines whether the ice cap grows or shrinks.
In recent decades, the Disko Island ice cap called Lyngmarksbreen has been melting faster than snowfall is replenishing it, and it is unlikely to see the end of this century. Together with students and instructors from around Europe, we went into the field to investigate both sides of this delicate balance.
We attacked the first part of the problem by taking measurements of the amount of snow that had accumulated over the winter on different parts of the ice cap. These observations can be used to improve computer simulations that predict how the size of the ice cap will change in the future.
As it continues to shrink, the melting ice cap doesn’t simply disappear. Its meltwater flows off the land and into the ocean, causing global sea level to rise. Data like the snowfall observations we collected help us to make better predictions of how much, and how quickly, that rise will take place as human-induced climate change continues to melt more ice. Studying what is happening to this smaller ice cap gives us insight into the processes affecting the larger Greenland and Antarctic ice sheets and will hopefully allow policymakers and city planners to make informed decisions when looking to the future.
Our field site on the top of the ice cap gave us a great view of the vast expanse of frozen ocean below in Disko Bay, where our teams of scientists were also studying the sea ice. We took measurements of sea-ice thickness and lowered oceanographic instruments through holes we made in the ice to observe ocean temperature and salinity, whilst taking care not to get tangled in the Greenlanders’ fishing nets! We lowered the instruments by hand to investigate how the ocean properties changed with depth and left some in the water overnight to detect potential signals of ice freezing or melting. Increasing ocean and air temperatures are reducing sea-ice extent in many areas of the Arctic, a problem that affects polar bears and fishermen alike, both of whom use the ice to get around and as a platform from which to hunt.
We experienced our fair share of logistical difficulties that are part and parcel of conducting fieldwork in the Arctic winter. Often, high winds, thick fog, and temperatures plunging as low as -30o C (-22o F) prevented us from doing the fieldwork we had planned, or prevented our helicopter back to the mainland from flying, causing more than a little stress as our flights back home approached. Despite the challenges, the science was rewarding, and being in Greenland in the winter certainly comes with its perks: The Greenlandic sled dogs proved an exciting way to transport both equipment and scientists out onto the sea ice through scenic landscapes, and the dark nights allowed the northern lights to put on a few mesmerising displays that will be hard to forget.
– Scripps Oceanography graduate students Jacob Morgan, Margaret Lindeman, and Maya Becker accompanied Scripps physical oceanographer Fiamma Straneo in March 2018 to the University of Copenhagen Arctic Station for the CHESS Arctic Glacier Field Course.