I remember when I was walking on the Greenland ice sheet for the first time in summer 2012. It was nearly midnight, yet there was sunlight still reaching the ice surface. I had just finished a long day of field work installing instruments and downloading data. Although it was a brief hike, I was able to take in my surroundings – the area I had been studying for the past year in a small office back in the east coast of the U.S. Here, I was able to witness the vastness of the ice sheet, the well-developed small surface streams that form during the summer months, its rough and ever changing surface, and see how much debris accumulates along the ice edge. This was the first, and certainly not the last time, I was able to step foot on the Greenland ice sheet.
Since 2012, I have been able to revisit the Greenland ice sheet twice. As a third year PhD student at Rutgers University, located in central New Jersey, I have been able to continue the research I set out to do in summer 2012. Currently, I am analyzing ground albedo measurements collected in summer 2013. Albedo refers to the reflectivity of the ice sheet – how much solar energy is reflected from the ice surface. These albedo measurements were collected from the ice sheet edge towards the interior, along a fixed transect more than 1 km long. Along the ice sheet edge, debris, including soot and dust particles, accumulates as it is deposited from the atmosphere above or exposed from the underlying ice surface. Typically, snow and ice surfaces can reflect sometimes more than 60-80% of solar radiation. But, along the lower reaches of the ice sheet, we see that the debris darkens the ice surface, reducing the albedo or reflectivity of the ice sheet. As a result, only 10-40% of incoming solar energy is reflected. The results of our research suggest that, as the ice surface darkens and more debris accumulates over the summer months, more of the ice melts and runs off the surface. This amplifying feedback – where a darkening of the ice surface allows for ice to melt, and thus darkens the surface further, may become increasingly more important as the climate continues to warm. As air temperatures are expected to rise, and forest fire frequencies and deposition of impurities on the ice surface increase, a lower albedo, and higher amounts of melting are expected to contribute even more water to surrounding oceans. This not only affects local populations, but has global implications for low-lying areas, such as the coast of south Florida.
As I write this, I am currently sitting outside in perhaps one of the most remote areas of Alaska – in the town of McCarthy. Here, amidst mountainous and glacial environments, I am able to participate in an international glaciology summer school. I am currently for nearly two weeks in an attempt to broaden my knowledge in glaciology and network with future researchers involved in studying glaciers, ice and snow. I hope to grow as a scientist and as a person through these experiences, so that I can help us better understand the implications of Greenland ice sheet albedo in a changing climate, and how that will regulate current and future contributions of melt water to sea level rise.
- Samiah, Rutgers University, USA