Warmer Climate, Denser Ice
With youth-led strikes all over the world demanding change and the UN 25th International Climate Conference coming up in Chile, climate change is becoming an increasingly relevant issue today. New studies come out every year on the topic; one bleak discovery after another appearing on various news outlets. The newest information: the Greenland ice sheet is getting denser.
When a heat wave struck Greenland this year, over half of the Greenlandic ice sheet—the second largest after the Antarctic ice sheet—started melting at an unprecedented pace for the first time since 2012. A study published by Nature stated that along with the sudden increase in melting ice, amplified by the warming climate, the ice sheet is becoming denser as well.
Many people believe Greenland is a thick wall of impenetrable ice. In reality, about 80 percent of the ice is fresh snow layered on top of thicker, older snow, called firn, which in turn is compressed into glacial ice over time. As firn contains many air pockets, liquid water melting from the surface normally gets trapped inside. Through a complex “plumbing” system, firn then absorbs the water like a sponge. Data from a radio-echo sound (a kind of ultrasound machine for ice) showed in 2014 that some ice is stored within the crevices of the system until the arrival of winter, when they are either released back into the system or refrozen.
The summer of 2012, a group of researchers noticed that the Greenlandic ice was behaving differently. They found fully compact, solid slabs of ice right beneath the freshly fallen snow. The lack of air pockets prevented runoff water from entering the ice sheet; instead, they transferred straight into the ocean. Every summer of increased melting leads to a thicker and harder slab of ice spreading inland to higher and colder grounds.
Due to global warming, the ice is melting at an unprecedented pace. Now, glaciers are losing one billion tons of ice per day, and the runoff has expanded by 26 percent. Researchers estimate that ice slab proliferation has the potential to add three inches to sea levels by 2100, a third of all the current contributions to sea level rise. In addition, glaciologists pointed out that the slabs of ice are not nearly as reflective as firn. The ice absorbs more solar radiation than firn and warms up, resulting in the formation of even more slabs, a vicious cycle that sets off a slew of environmental issues. Some runoff might not even flow into the ocean. They might end up at the very bottom of the sheet, assisting as a slippery slide and lubricating the area where ice comes in contact, leading to the sheet flowing towards the ocean with more ease than ever.
The greatest contribution of this study, however, is a deeper understanding of Greenlandic ice patterns. With this information, scientists are now able to predict with higher accuracy the predictions of future sea level rise in order to assist threatened coastal communities. Scientists also gained an increased awareness that the more carbon the world is emitting into the atmosphere, the more likely the Earth’s northern ice sheet would be unpredictably transformed in an insidious manner.
References
Cassella, C. (n.d.). The Greenland Ice Sheet Has Been Hiding a Surprising Amount of Liquid Water. Retrieved September 29, 2019, from ScienceAlert website: https://www.sciencealert.com/below-greenland-ice-sheet-surprising-amount-liquid-water-climate-models
Chain reaction of fast-draining lakes poses new risk for Greenland ice sheet. (2018, March 14). Retrieved September 29, 2019, from University of Cambridge website: https://www.cam.ac.uk/research/news/chain-reaction-of-fast-draining-lakes-poses-new-risk-for-greenland-ice-sheet
Kendrick, A. K., Schroeder, D. M., Chu, W., Young, T. J., Christoffersen, P., Todd, J., … Lok, L. B. (2018). Surface Meltwater Impounded by Seasonal Englacial Storage in West Greenland. Geophysical Research Letters, 45(19), 10,474-10,481. https://doi.org/10.1029/2018GL079787
MacFerrin, M., Machguth, H., As, D. van, Charalampidis, C., Stevens, C. M., Heilig, A., … Abdalati, W. (2019). Rapid expansion of Greenland’s low-permeability ice slabs. Nature, 573(7774), 403–407. https://doi.org/10.1038/s41586-019-1550-3
Machguth, H., MacFerrin, M., van As, D., Box, J. E., Charalampidis, C., Colgan, W., … van de Wal, R. S. W. (2016). Greenland meltwater storage in firn limited by near-surface ice formation. Nature Climate Change, 6(4), 390–393. https://doi.org/10.1038/nclimate2899
Nield, D. (n.d.). A Runaway Chain Reaction Under The Greenland Ice Sheet Is Threatening Its Collapse. Retrieved September 29, 2019, from ScienceAlert website: https://www.sciencealert.com/chain-reaction-draining-lakes-threatening-greenland-ice-sheet
Scientists find missing piece in glacier melt predictions. (n.d.). Retrieved September 29, 2019, from ScienceDaily website: https://www.sciencedaily.com/releases/2018/10/181015100508.htm
Something strange is happening to Greenland’s ice sheet. (2019, September 18). Retrieved September 29, 2019, from Environment website: https://www.nationalgeographic.com/environment/2019/09/greenland-ice-getting-denser-thats-bad/