The Potential Collapse of the West Antarctic Ice Sheet

Introduction

West Antarctic ice Sheets are located in the Pacific Ocean in the western hemisphere in the Transantarctic Mountains (Goldstein, et al. 4). Its bed is located below the sea level and it has edges that run into a free ice sheets shelves. It has six glaciers that drain into the Amundsen Sea. Some of the glaciers include Thwaites, Pine Island, Pope, Smith, Kohler, and Haynes glaciers (Rignot, Eric and Stanley 7). The larger part of the ice sheet is below the water surface and slopes downward towards the interior. Therefore, Western Antarctic ice sheets are unstable. Global warming and climate change cause the collapse of ice sheets. West Antarctic Ice Sheet continues to collapse and countries in the coastline of North America and nations in the southern Indian Ocean are prone to harmful effects. Disastrous rise in sea level is likely to increase between 16 and 17 feet across the world. Scientists argue that sea levels in areas such as Washington DC are likely to reach 21 feet. In addition, many coastline towns would be destroyed by the increase in water levels (Pollard and Robert 2). A study by Oregon State University indicates that cities such as Southern Florida are likely to disappear if collapses of the Western Antarctic continues. There are concerns that the West Antarctic Ice sheet is likely to collapse. Besides, a rise in sea level is likely to influence the lives of marine ecosystem, destruction of infrastructure, displacement of population and loss of agricultural land. Two distinct studies support that one important shelf in the Western Antarctica is collapsing (Scherer, et al. 7). However, the depletion of ice sheet cannot be controlled. The studies suggest that more than 4 meters of sea level have increased. The underlying reason behind this is the because of climate change which is increasing the rate of collapse (Bamber, et al. 5). Study by Vaughan and John indicate that if all the West Antarctica ice sheet melts, it will lead  to 13 percent rise in sea level and destruction of coastal and low altitude areas. The research by University of Washington and NASA studied the ice sheet in western Antarctica over various periods (Vaughan and John 3). The NASA scientist concentrated on the melting point for 20 years while researchers at the University of Washington applied computer modeling to assess the future of the western Antarctic ice sheet (Pollard and Robert 2).  The two investigations had similar conclusions. Indeed, the melting and thinning of the Antarctic ice sheet is unstoppable regardless of efforts to cut greenhouse gas emissions that lead to climate change (Bamber, et al. 6).

Collapse of the Ice Sheet

Scientists monitor the collapse of ice sheets through computer modeling and mapping. The west Antarctic ice sheet holds adequate water to raise the sea level across the world by several feet. Scientist from the University of Washington applied computer modeling and comprehensive topography maps to explain how the ice sheet collapse began and their predictions (Vaughan 3). The researcher argues that in a period of a few centuries, the Thwaites Glacier is likely to fade and the sea level will increase by approximately 2 feet. Thwaites glacier plays an important role because it serves as a linchpin on the entire West Antarctic ice sheet. In addition, it holds sufficient water to increase the sea level by an additional (3 to 4 meters) 10 to 13 feet of the global water levels. There has been many suggestions concerning the marine ice sheet sustainability and researchers argue that this kind of behavior is likely to occur (Pritchard, et al. 4). The research from the University of Washington offers an explicit idea of the collapse rate that is likely to take place.

However, scientist suggests the rate of collapse is likely to take place in more than 200 years while the maximum period it can take place is 1000 years. Unfortunately, the collapse of the ice sheet is unavoidable (Nicholls, Robert, Richard and Athanasios 5). The computer modeling results indicate that the rate of depletion of glaciers is likely to accelerate over a certain period, but there is no mechanism to stabilize the effects.

Moreover, scientist applied the simplified model of ice based on an interior-sloping basin to predict initial warning of ice sheet collapse. Besides, they utilized a complex topography around Antarctica ice. In a new research, scientists applied the airborne radar to produce images via the thick ice and provide maps of topography of the primary bedrock (Joughin, Ian and Richard 3). The National Science Foundation funded University of Kansas to produce the airborne radar. The shape of the underlying bedrock maintains the long-term stability of the ice sheet. The mapping was conducted through the NASA operation on Ice Bridge and incorporated other tools to assess the height of the ice sheet. The mapping shows that the surface of the ice sheet is rapidly decreasing (Mitrovica, Jerry, Nataly and Peter 5). For instance, in some parts the Thwaites Glaciers is reducing several feet or tens of meters of rise per annum.

Scientists at the University of Washington applied that data to their satellite assessment of the ice surface rapidity. The researcher’s computer models had the capacity to reproduce the loss of glacier ice over the past 18 years. In addition, they conducted the models forward under various amounts of melting from the ocean. The area where land and the glacier intersect currently stays on a thinner ridge with a depth of approximately 600 meters (2000 feet) (Overpeck, et al. 7). The outcome suggests that as the ice edge withdraws into a deeper area of the bay, the face of the ice will be steeper. Moreover, it will become like a soaring pile of sand, the fluid glacier will be less sustainable, and it will easily collapse towards the sea. According to Alley, Richard and Robert as soon as it gets past the shallow area, the rate of collapse will accelerate hence it will reduce the ice quickly (Alley, Richard and Robert 6).

The study at the University of Washington looked at the future circumstance applying quicker or slower rates of ice melts based on the quantity of future warming. The research noted that higher rates of collapse are likely to take place in less than two centuries after which the faster pace of collapse will begin. The slower rate of ice sheet melting kept the ice for more than 1000 years prior to the beginning of the rapid collapse. Oppenheimer, Michael, and Richard argue that the most probable development may occur between two and five centuries (Oppenheimer, Michael and Richard 3). Similarly, Scambos, et al, suggest that ice sheet retreat will cause a rise at less than a millimeter of sea level in every year for two hundred years and then the rapid phase will start (Scambos, et al. 7).

However, scientist failed to model the high chaotic swift collapse, but the residual ice is predicted to vanish within a few decades. The depletion of ice sheets in past decades is most probably related to changes in climate (Hillenbrand, et al. 9). In addition, Nicholls, Robert and Anny  argue that the higher rate of greenhouse emission is likely to increase the rate of ice melting. Furthermore, various factors increase the challenges of predicting the time of ice sheet depletion under several scenarios (Nicholls, Robert and Anny 9).

West Antarctica Ice Sheet Is Unstable

West Antarctic ice sheet has a distinct feature as compared to other ice sheet. It is normally unstable and susceptible to collapse relative to East Antarctic Ice Sheet. According to (Joughin and Richard 1) satellite reports indicate that loss of mass from the West Antarctic ice sheet is usually from 10 to 2000 Gt. per annum. Consequently, it produces nearly 0.56 mm per annum in sea level rise. In addition, this rate is increasing over the past two decades. The loss of the west Antarctic ice sheet results from the diminishing levels of the glaciers, which causes water to flow to the Amundsen Sea. All the glaciers in the West Antarctic ice sheet suffer potential instabilities because of the variation in temperature in the ocean (Joughin and Richard 2). The instability mechanisms in the ice sheet are caused by internal instabilities and ocean atmosphere. Climate in particular causes warming in the ocean that influences the ice-shelf viability. Internal instabilities of the ice cause irreversible retreat in the glaciers.

Internal dynamics of the ice acts independently of other factors such as climate change. Radar observations indicated that for a long period there was a gradual ice sheet breakdown that affected the stability. Further experiments recorded that reactivation and stagnation because thinning patterns of various ice streams over the last millennium (Joughin and Richard 3). These patterns have impacts on the retreat mechanisms of the ice sheet. Internal instabilities cause variable flow such as ice-stream surges, which generates ice-sheet collapse. Moreover, the west Antarctic ice sheet has a weak bed that increases the driving stress and it concentrates the resistance stress. Shear heating also causes speed up and ice-stream widening. Ocean-forced instabilities cause the changes in sea level because of decay of the Northern Hemisphere ice sheet. Following the Last Glacial Maximum, it forces sea-level changes, which affect the West Antarctic ice sheet retreat. High salinity water causes basal melting in the ice shelves especially during the sea-ice formation (Joughin and Richard 3). The dense water sinks to the grounding lines, which stimulate melting of ice since it lowers the melting temperature to 0.75 degrees Celsius.

West Antarctic ice shelves are also vulnerable to the global warming in the Antarctic Peninsula. The temperature in this region is approximately zero degrees Celsius in January isotherm (Katz and Grae 4). However, over the last four decades the temperature at the Antarctic Peninsula has increased significantly to 0.056 degrees century per annum causing a southward drift of the isotherms. Increase in temperatures limit the viability of the ice-shelf. Joughin and Richard argue that high surface melting is highly related to the ice-shelf collapse (Joughin and Richard 5).

Particular Concerns of the West Antarctica Ice Sheets Collapse and Predicted Consequences

The western Antarctic ice sheet collapse poses a great threat to the lives of human beings. The thinning of the ice sheet will cause a potential rise of sea level. Most notably, the rise of sea level will affect the coastlines of the entire world. For instance, in the United States the coast of the Northeastern and the south of China will be highly affected. In addition, the increase in sea level is not a concern, but what is critical is that the sea storm will have more effects and coastline will be vulnerable to catastrophic damage. Moreover, areas, with a one in hundred years risk in of the dangerous storm surge will increase to one in ten years. Therefore, people will need to relocate to safer places. The ecosystems will also be affected. In the Amundsen Sea, there are six large glaciers that can raise the global sea level by 1.2 meters (4 feet) and the rate of melting is faster as compared to other glaciers in East Antarctica and Greenland.

Raymo, Maureen and Jerry argue that at the current collapsing root these glaciers will be depleted in less than 2 centuries. After the collapse of six glaciers next to the coastline, it is highly likely that the rest of the West Antarctic ice would follow (Raymo, Maureen and Jerry 9). The melting of Thwaites glacier could endanger large part of the Western Antarctica because they are interconnected. A previous study suggested that if the entire ice sheet in West Antarctic melted it would increase the sea level by 3.3 meters (11 feet). The ice will retreat into the ocean and it will break off and float hence increasing the water volume in the sea. (Bindschadler, et al. 9) suggest that frozen water and rock mixtures currently maintains the glaciers.

Consequences of Sea Level Rise

Rise in sea levels produces catastrophic effects on the lives of human beings, marine and ecosystem. Most notably, even a small rise in sea level can have a significant effect on the several coastal environments. Approximately 650 people live on the coastline that has a sea level of less than 10 meters. In addition, 75 percent of the world cities are located along the coastline whose population is nearly five million (Bindschadler, et al. 1). Therefore, an increase in sea level will pose a threat to the lives of these populations. The rate of collapse of ice sheets is likely to accelerate in the next few centuries hence huge numbers of people will be at risk and they will need to relocate. If the people fail to evacuate on time during storm surges, there will be huge numbers of environmental refugees.

Figure 1.1 Rise in sea water level due to ice sheet collapse (Deschamps, et al. 11)

Figure 2 Collapse of West Antarctica Ice sheet raise the Sea level (Pritchard et al)

Figure 3 West Antarctica Ice Sheet collapse (NASA)

A report by IPCC shows that rising sea level will have catastrophic effects on the coastal infrastructure and environment. Other consequences are likely to involve erosion of coastline, flooding of the coastal plain and wetlands, loss of habit of birds and fish. Furthermore, it will lead to loss of coastal plants and wildlife as well as soil and aquifers salination (Huybrechts, Philippe and Jan 3). According to the Environmental Protection agency, if the seawater rises by 0.66 meters, nearly 26 000 square kilometers of land would be unavailable. Most notably, if the current rate of collapse continues, more than 30 percent of the coastline area would be lost in the next century. IPCC suggests that more land would be lost at the coast if the ocean level continues to increase at a faster rate. Consequently, many species at the swamps and wetlands are likely to be at greater risk (Bell 10). Additionally, species whose lives depend on the ice experience a threat of extinction if the rate of retreat accelerates. These include seals, polar bears and certain penguin breeds.

In fact, most of the nation with a higher risk of sea level rise do not have the finances to mitigate its effects. Such countries include India, Vietnam and Bangladesh, where most of its citizens live in the coastal areas. In additions, some island countries will have more challenges because they lack adequate land with higher altitude to cater for displaced populations from the coast (Deschamps, et al. 11). These nations include Vanuatu, Tuvalu, Indonesia and Philippines. Island nations will suffer from more challenges because the rise in sea level will force salty water to their fresh water aquifers. Therefore, in a 21st century population living in small island nations such as Marshall Island in the Pacific Ocean and Maldives Islands in Indian Ocean will need to relocate.

The rise of sea level of approximately 2 feet will have devastating effects on the cities along the coast such as Miami. For instance, when there is a huge storm surge, this 2 feet sea level will rise during hurricane and could lead to loss of asset worth $ 3.5 trillion. Besides, an estimate of 5 million residents in Miami will be a severe threat. Furthermore, in case the entire West Antarctica collapse it will lead to 13 feet rise in sea level. Most notably, with a 12 foot rise in sea level, it will cause 75 percent of Miami becoming flooded, 20 percent in Los Angeles and 22 percent in New York City (Mosola, Amanda and John 9).

Mitigation

To reduce the effects of flooding, especially along the coastal towns requires effective strategies. Installation of barriers such as Trap Bag defense will protect populations from flooding. These structures offer a containment system that prevents flooding and minimizes flooding damage (Rignot 2). Additionally, it conveys waters away from crucial structures efficiently, rapidly and safely. The government should provide flood mitigation measures by developing flood barrier system. These play a crucial role in the containment of floodwater in an easy and efficient manner (Mosola, Amanda and John 10). Moreover, these preservation barriers should control erosion, and mudslides and protect infrastructures when floodwater level rise or in case of breaching of levees. The authorities should also support feeble levees before they fail. Furthermore, structures should be elevated to raise the levee height and protect over-topping.

The government should also raise awareness among the people to mitigate flooding effects. The local authorities should also improve the reporting mechanisms such as surveys, computer modeling and efficient management of environmental databases.  Due to a threat of global warming, the government should initiate measures that reduce greenhouse gas emissions. If developed nations cut, the greenhouse emission by 70 percent the risk of seawater rise will be reduced (Rignot 13). Cutting the emission will reduce flooding caused by seawater rise.

Conclusion

West Antarctic ice sheet collapse has started and it is inevitable. Climate change is causing the melting of glaciers that lead to the rise of sea level at an anticipated rate. The depletion of the completely western Antarctic is likely to cause 4 percent rise in sea level and catastrophic effects in the coastline across the globe (Rignot, Mouginot and Scheuchl 3). However, although this event is unstoppable, it will take about two centuries or even up to one millennium. Scientist at the University of Washington and NASA applied the computer modeling to investigate the west Antarctic ice sheet over a period (Evans, et al. 7). Both studies concluded that the rate of collapse at these ice sheets could not be evaded even with the reduction of greenhouse gas emission. In addition, large sections of ice sheet in west Antarctic has experienced irreversible retreat which increase the risk of sea level rise in the world (Bell, et al. 7). Major glaciers such as the Thwaites glaciers in the Amundsen Sea are unstable because of Warm Ocean current that cause rapid thinning. Thwaites glacier alone could be lost completely in a matter of centuries (Vaughan, et al. 9). The gradual thinning of western Antarctica will have devastating effects on the lives of human beings, marine life and environment (Klinck, et al. 9). Therefore, mitigation measures should be put in place to protect the lives of future generations.

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