BY: Marco Tedesco, Lamont Research Professor at the Lamont-Doherty Earth Observatory, Columbia University
As part of our digital series Climate Artists with ALL ARTS, which highlights the work of artists that focus on the climate crisis, we asked scientists to delve deeper into the science behind the art. For the episode Elegy for the Arctic, which showcases one composer’s stunning piano performance in the midst of melting icebergs in the Arctic, Dr. Marco Tedesco (of Columbia University’s Lamont-Doherty Observatory at The Earth Institute) shares his observations on the haunting beauty he observed while visiting Greenland’s ice sheet. He writes about his fieldwork expedition and shares the terrifying reality of the state of melting ice sheets and sea level rise.
Another summer, another fieldwork on the majestic Greenland. I have been visiting the ice sheet for more than a decade, but “it never gets old.” Every time I am here, I think of the first time I stepped on the ice, the feeling of entering into the scene of a stage that takes your breath away. This year, our team is relatively small. There are only four of us: two researchers, one media person, and a “guest,” who has been kind enough to support our fieldwork by complementing funding from NASA and the National Science Foundation. As opposed to previous years, we will be camping on the tundra at the edge of the ice and will reach the place where we will collect our data by foot, rather than by helicopter.
As we cross the last crest that separates us from the Greenland ice sheet, we find ourselves in awe of the calm, yet powerful vision that unfolds in front of our eyes. The ice fills the landscape, merging with the sky at the horizon, like an ocean of frozen waves. Driving from the town of Kangerlussuaq in southwest Greenland, we are heading towards the edge of the ice sheet. Melting has been accelerating over the past decades as a response to increasing temperatures that here in the Arctic, have been rising twice as fast as the rest of the planet. We reach the gateway to the ice through a dusty and bumpy road that was built decades ago by a company to test cars in extreme cold and near-zero friction conditions. Abandoned after a few years, it is now used only by local travel agencies to drive the increasing number of tourists to witness the disappearing ice, like an animal soon to be extinct and whose roar comes from gushing streams.
We are here to study the single largest contributor to sea level rise (if we exclude the contribution due to the thermal expansion of the oceans that accounts for roughly 50 % of sea level rise). Greenland is responsible for about 25% of the current sea level rise, with this number very likely increasing to 40% or more by the end of the century. As the Arctic drifts away from its current state, the changes that are occurring enhance melting and the contribution of Greenland to sea level rise.
When we step on the ice, we recognize the familiar sound of the weathered ice crushing under our boots. As we approach the location of our test site, the surface becomes peppered with dark holes, ranging from a few inches to a few feet across. They are “cryoconite holes,” self-contained micro-ecosystems that are home to dust, minerals, soot, black carbon and to life in a variety of different flavors and shapes, from red and green algae to cyanobacteria and the tiny organisms known as tardigrades and rotifers. Cryoconite was first described and named by the Finnish Arctic explorer Nils A. Nordenskiöld during his travels to Greenland in 1870. Because of its dark color, the material absorbs heat from the sun, enhancing the melting.
The enhanced melting of the ice sheet does not only occur because of warmer conditions. A large portion of melting is, indeed, due to the absorption of solar radiation. This is modulated by the “color” of the ice: dark surfaces absorb more solar radiation than bright ones (think about wearing a black or a white t-shirt under the sun and guess which one will warm up faster). The parameter that quantifies this process is called albedo. Fresh snow is a very bright surface and reflects about 80-90% of the solar radiation (high albedo). As snow melts and refreezes, its albedo reduces, with old, metamorphosed snow reflecting about 60% of the solar radiation. Ice is much darker than snow and reflects only 40% of the solar radiation. This number reduces to 20-30% when the ice is “dirty,” as in the case of cryoconites. Early melting can precondition the melting season as snow grains grow during melting and refreezing cycles, reducing the albedo as the snow “ages.” Melting also promotes the growth of biological colonies and the coalescence of dark material, such as cryoconite, which further promotes melting. I call this process “melting cannibalism.”
As we approach our test site, we stare at the turquoise waters in silence, thinking about how powerful humans must be to dissolve in a blink of an eye what it took thousands of years to build. The data we will collect will provide us with the letters of an alphabet that will, ultimately, help us improve and expand our vocabulary of how the Arctic and our planet are changing and will continue to change.
Melting in Greenland has not only been increasing, but it has also been accelerating over the past decades. This is due not only to the changes on the surface but also to those occurring in the Arctic atmosphere, which have manifested in the persistency of anticyclonic conditions (e.g., days without clouds and bright shining sun). These conditions have reduced the amount of summer snowfall, which can mute melting by covering the dark, light-absorbing ice with bright, reflective fresh snow. Not only have clear sky conditions occurred more often during the last several summers, but the number of days without clouds has been increasing, as these weather systems sit for longer and longer periods over the ice sheet. Several scientists have suggested that this is one of the consequences of the disruption of the jet stream — the same process responsible for potentially increasing extreme weather over the United States.
After returning to our tents, despite being tired and burned by sun and wind, we spend our last energies making extra copies of the data we collected, as an insurance against accidents. It is midnight and the sun is low on the horizon, blanketing the ice with a pink soft light. We go to bed while it is warm, and we wake up in the morning immersed in a freezing fog that has wet our tents and sleeping bags, sending chills deep into our bones. I crave a hot bath and this thought reminds me that until not long ago, the so-called “bathtub” model (in which oceans are assumed to be rising uniformly) was used to depict sea level rise at the global level. We know, however, today that the oceans are rising at different rates in different parts of the world. This is due to, among other things, the fact that the oceans warm at different rates, local costal erosion, and the “rebound” of the Earth that is still rising up since the loss of the ice from the last glacial age. Imagine this phenomenon like standing up from a chair with a pillow on it: the pillow takes some time to get back to its original shape. The varying rates of sea level rise around the world are also due to the changes of the gravitational fields due to ice loss (as Greenland and Antarctica lose more ice they lose their power to “attract” water toward themselves with the water being “released” by the gravitational pull of the powerful ice sheets).
The varying rates of sea level rise in different areas of the world implies that it is crucial to account for both the global and local consequences of our warming planet. This goes hand in hand with other factors, such as extreme precipitation and storm surge, ingredients of a recipe that will ultimately have and is already having profound impacts on our economy and threatening the lives of those living along coastlines, especially the most socioeconomically vulnerable ones.
The Arctic is rapidly changing and Greenland is melting at an accelerated rate as a consequence of anthropogenic climate change. The consequences have both global and local impacts, ranging from disrupting ecosystems to threatening livelihoods and lives. From economic and social impacts to the potential migration of climate refugees, it is necessary to act now and fast. As we learn more and more how our planet works so that we can better prepare our society for the unavoidable implications of climate change, we also need to promote the development and maturation of technologies that will allow us to sequester the amount of CO2 that is already in the atmosphere. These actions need to occur all together, like different instruments of an orchestra creating a symphony on which life as we know it is dependent on.
Marco Tedesco is a Lamont Research Professor at the Lamont Doherty Earth Observatory at Columbia University’s Earth Institute and an Adjunct Scientist at the NASA Goddard Institute of Space Studies (GISS). His research interests concern remote sensing of the cryosphere, regional climate modeling of the Polar Regions, high-latitude fieldwork and the economic impact of climate change.
Marco holds a PhD. in Remote Sensing from the Italian National Research Council and a Master of Engineering in Electronic Engineering from the University of Napoli. He is the author of the book Ghiaccio (in Italian) and has a weekly column on climate and Earth on the Italian newspaper La Republica, where he is also an editorialist.