Icebergs. Once Rogue, Always Rogue.
Will Ferguson, Manager of Medium at We Grow Green Tech, We Grow Green Tech.
Now, more than ever, there has been a growing concern around the global warming of the planet. The impacts of anthropogenic climate change and the release of greenhouse gases en-masse have contributed to a destabilisation of natural ecosystems, and an unpredictable climate. The internal warming of the Earth, occurring at the rapid rate we have seen over the past 20-30 years, has contributed to the mass deformation and melting of both icebergs and glacial ice masses, attached to the world’s Polar ice sheets. This is threatening both the natural environment and the ecosystems that thrive in this extreme climate. The predicted loss of alpine glacial ice, due to climate change for critical regions of the Earth, is expected to be more than 70% of the present volume is expected by the end of the twenty-first century. (Frezzotti., Orombelli, 2013)
In focussing on one of the planet’s most crucial areas for the storage of freshwater, also being a driving force for major climate change, Antarctica’s Larsen ice shelf has undergone a progressive reduction in size and depth since the beginning of the Holocene Epoch. Due to the Larsen ice shelf being comprised of four separate shelves, A, B, C and D, each section has degraded at different rates since the beginning of the Anthropocene. Larsen B underwent rapid calving and disintegration in 2002, when most of the ice shelf was lost. (Cook., Vaughan, 2013) Supraglacial lakes, which allow the accumulation of meltwater in depressions in the surface of a glacier or ice sheets, can help contribute to ice-shelf collapse. In the case of the Larsen B ice shelf, supraglacial lakes within the shelf fractured the ice shelf as the lakes grew in size and depth. This led to the near-synchronous drainage of over 2,750 lakes (up to 6.8 metres deep) on Larsen B ice shelf in the days before it collapsed in February-March 2002. (Glasser., Scambos, 2008)
These glacial ice masses, coming into contact with the ocean, are capable of calving from the primary Antarctic ice sheet in large proportions, sacrificing Earth’s vital freshwater stores and travelling along ocean currents. This has drastic implications for the efficiency of global oceanic circulation, once separated, as waters rise and become increasingly saline. Should these rogue entities drift far enough to collide with land, devastating consequences would be seen. The recent incident of the Larsen B ice shelf in Antarctica, coming into close contact with the island of South Georgia, pays testament to the potential damage this could cause to polar ecosystems that are unique to these environments. Antarctica’s haven for wildlife is home to 95% of the world’s fur seals and 50% of the world’s southern elephant seals. (Scanlan-Oumow, 2020)
If such ecosystems were to sustain colossal damage via an impact from a rogue iceberg in the Southern Ocean, the overall biodiversity of the biome would affect physical systems such as vegetation growth. Furthermore, this would simultaneously impact the equilibrium of predator-prey relationships, causing an imbalance that will substantially impact the viability of future generations of species. Moreover, this would likely affect the physical landscape in unprecedented ways, with one such example being habitable land areas. Native species require this to reproduce; with this disappearing due to rising sea levels and an increased loss of ice in landmasses, reproduction of the species would be compromised.
The controls behind rates of glacial calving, determine the rates at which our oceans increase in volume, and ultimately in temperature, as there is more surface area here for radiation to be absorbed by the Sun. This has been contributing to the now high-frequency of solid ice roaming the oceans, which is underpinned by various factors. Calving rates are controlled primarily by water depth, but, for any given depth, are an order of magnitude greater in tidewater than in freshwater. Calving dynamics are poorly understood, but differ between temporary and cold glaciers (Warren, 1992). As a result, the increased rate of land subsidence on a controlled and isostatic level in the Poles is directly impacted through continually rising sea levels and warming oceans, both caused largely by the global population.
One of the core factors contributing to the overall rate of ice melt, globally, can be seen through the total land coverage by Earth’s albedo. The albedo of the Earth is determined through the percentage of ice, or other land surfaces on the planet that are capable of reflecting the Sun’s incident solar radiation that enters the atmosphere. As such, areas that do not possess a high percentage of albedo retain the energy from the Sun’s ultraviolet rays, thus warming the surrounding area. This creates a destructive loop of negative feedback, whereby the ground will continue to warm, preventing any ice from forming there, and therefore lessening the amount of radiation reflected back into space.
The consequences that this will inflict upon the climate are likely to be devastating. The increased volume of greenhouse gases such as carbon dioxide will directly affect vital systems, processes, and ecosystems on Earth’s surface. The fragility of biomes such as coral reefs will become undermined, therefore compromising the integrity of 25 percent of all marine fauna that resides there. Additionally, more than 75 percent of Earth’s tropical reefs experienced bleaching-level heat stress between 2014 and 2017, and at nearly 30 percent of reefs, it reached mortality level. (Eakin, C. M., et al, 2018) Moreover, the volume of carbon dioxide that the oceans retain will result in a destructive loop of negative feedback, further damaging the potential for life to thrive in our oceans.
A significant contributor to rising sea-levels on a global scale is through the drainage of meltwater from melting ice sheets. One prime example of this would be through the impacts of the Thwaites Glacier, in West Antarctica. This drains an area roughly the size of Britain, or the US state of Florida, accounting for around 4% of global sea-level rise — an amount that has doubled since the mid-1990s (BAS, 2018). Analysis of its impacts will allow for making better predictions about the ocean and ice will respond to environmental change, with the overall aim being to gain a greater understanding of how much the Thwaites Glacier may contribute to global sea-level rise in the future.
Additional research into the degradation of Thwaites Glacier, as discovered through the deep seabed channels beneath the ice mass, may be the pathway for warm ocean waters to melt the underside of the ice. Over the past 30 years, the overall rate of ice loss from Thwaites and its neighbouring glaciers has increased more than 5-fold. A run-away collapse of the glacier could lead to a significant increase in sea levels around 65 cm (25 inches) (BAS, 2020)
In linking these glaciers and ice sheets together, the continental shelf around Antarctica is vast, 1,000km wide in places and it is very important for carbon cycling. It demonstrates some resistance against the growing threat of climate change in the Polar regions, although rising CO2 in the atmosphere has driven global warming. This has reduced West Antarctic sea ice through warming area and/or sea temperatures and has led to more carbon accumulation in animals on the seabed (thus less in the air). Consequently, it acts as a (negative) feedback working the climate change. (BAS, 2016)
In summary, the impacts of rogue icebergs in the different regions of the Antarctic are currently having a multitude of impacts upon both the natural environment and anthropogenic activities on a global scale. As this continues to disrupt the integrity of the polar landscapes, as well as the ecosystems that thrive there, this remains a pressing environmental issue, only able to be solved through international co-operation in the struggle against a warming climate. The conservation efforts to preserve the Polar ice that remain, and the fauna that depends upon this, remains one of society’s biggest responsibilities in the 21st century.
Reference List:
Frezzotti, M., and Orombelli, G., (2013), Glaciers and Ice Sheets: Current Status and Trends, Anthropocene, Springer Publications, Vol. 25, p. 59–70. [Accessed — 13/01/2021] https://link.springer.com/article/10.1007/s12210-013-0255-z?shared-article-renderer
Cook, A. J and Vaughan, D. G, (2010), Overview of Areal Changes of the Ice Shelves on the Antarctic Peninsula over the past 50 Years, The Cryosphere Vol. 4, p. 77–98. [Accessed — 20/01/2021] https://tc.copernicus.org/articles/4/77/2010/
Glasser, N. F., Scambos, T. A, (2008), A Structural Glaciological Analysis of the 2002 Larsen B Ice-Shelf Collapse, Journal of Glaciology, Cambridge University Press, Vol. 54, Issue 184, p. 3–16. [Accessed — 20/01/2020] https://www.cambridge.org/core/journals/journal-of-glaciology/article/structural-glaciological-analysis-of-the-2002-larsen-b-iceshelf-collapse/6A39D80EF0E7202B2E369B8DB2625AB3
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Eakin, C M., Liu, G., et al, (2018 cited in Scott. M., and Lindsey, R, 2018) Unprecedented Three Years of Global Coral Bleaching 2014–17, Bulletin of the American Meteorological Society, Vol. 99, Issue 8, p. 74–75. [Accessed — 20/01/2021] https://www.climate.gov/news-features/understanding-climate/unprecedented-3-years-global-coral-bleaching-2014%E2%80%932017
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British Antarctic Survey (2016), Antarctic Seabed Carbon Capture Change, Natural Environment Research Council. [Accessed — 23/01/2021] https://www.bas.ac.uk/project/antarcticseabedcarboncapturechange/
