Course:EOSC270/2021/Accelaration of Sea Ice Melt due to Human Activity

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What is the problem?

The Problem :

The melting of the earth's sea ice signifies a rapid change in the climate. This is due partially to humanities growing reliance on fossil fuels , and the greenhouse gas emissions that come with it.Carbon dioxide being the main greenhouse gas gained from fossil fuel usage , is also at the same time absorbing heat and increasing overall temperature in the atmosphere. Overall temperature increases ultimately lead to sea ice melting.

A graph showing Carbon Dioxi de emissions over the past 800000 years.

Sea Ice melting results in a multitude of changes , from climate changes to sea level rises. The estimation in temperature increase is roughly three degrees Celsius in the twenty first century[1].This may not seem significant but can lead to sea level rises of around twenty five meters [1], which suffice to say , would cause massive issues to human civilization. Sea level rises of significance would require infrastructure built such as dams to prevent flooding[2].

Human Actions :This issue has been attributed to greenhouse gases causing environmental changes , with one of the main culprits being carbon dioxide. Carbon dioxide is the main emission from human activities such as burning fossil fuel. Carbon dioxide is also been known to have heat absorption properties , thus when released into the atmosphere increases temperature overall. The reason that humans are implicated heavily for this temperature change is because while causes such as volcanic eruptions and periodic changes in the energy received by the sun can cause global temperatures to change , the rise in carbon dioxide emissions of recent years are completely unprecedented [1].Thus it is a safe conclusion that humans are causing this rise , and as a result , the climate change.

These changes can cause massive events that would otherwise never occur.

An example of a massive event is warm ocean anomalies such as the one that resulted in the ice loss of the West Antarctic Ice Sheet[3].

Where it is happening: This problem is greatly prominent in polar environments such as the arctic. As the ice over there  melting can cause a very noticeable affect ,not only on the ecosystem there, but sea level rises that are spread globally[1].Other locations include mountain tops that have ice cores dating back centuries if not more[1] ,such as Mount Kilimanjaro , which during 1912 to 2006 lost roughly 85% of the ice coverage on it[1].

How pervasive is the problem: The melting of the sea ice can cause affects globally. From infrastructure needed to prevent floods , to other side effects such as droughts and heat waves[1].More immediate is the direct influences it has on marine ecosystems, such as polar bear and other arctic animals habitats being destroyed. Sea ice melts can also lead to more absorption of heat into oceans, leading to more melting in a positive feedback loop[1]. Sea ice melt causing a positive feedback loop has been supported by evidence such as the measurement of sea ice melt in recent years[4].

How does this problem impact marine ecosystems?

Polar bear on ice[5]
Figure 1. Table showing Arctic marine mammal population trends in 2015 (The colors: green=increasing population trend, yellow=stable population trend, red=declining population trend, grey=unknown population trend). The number of subpopulations at the top of the column divided into each segment (segments not proportional to the subpopulation size)[6].

Impacts on Polar Ecosystems

Declining sea ice is currently impacting Arctic ecosystems and this trend is expected to continue[7]. Sea ice is important to ecosystems as it represents the interface between the atmosphere and the ocean causing it to affect the heat and moisture of the surface[7]. Polar ecosystems have a unique reliability on the shade and structure that sea-ice provides. Sea-ice provides shade and a light limitation for photosynthesis to prevent phytoplankton blooms [7]. Once this covering decreases due to sea ice melting, it can have multiple effects on the ecosystem.

The abrupt changes to the amount of cover by sea ice can impact the biochemical processes that are important for energy transfers in marine food chains and the cycling of elements in marine ecosystems of the Arctic [7]. In marine ecosystems, flow of energy is maintained by primary producers at the bottom of the food web[8]. Primary production in water columns depends on a balance between stratification and mixing [7]. Stratification keeps cells of phytoplankton within the layer at the surface and mixing provides nutrients for production[7]. Surface layer warming, terrestrial runoff, and an increase of freshwater due to sea ice melt can increase surface stratification[7] which can offset the balance necessary for stable primary production. Sea ice melt and the subsequent nutrients released increases the amount of light transmitted to the water column which can cause phytoplankton bloom [7] and an increase of photosynthesis. Sea ice melt can also cause ocean acidification through an increase of pCO2 (partial pressure of carbon dioxide) and the decrease of pH in waters that can make it more vulnerable to corrosion by calcium carbonate[9].

Impact on Organisms in Polar Ecosystems

Many organisms of polar ecosystems are impacted by sea ice melt from tiny phytoplankton to fish to whales. Organisms that depend on sea ice cover for their life cycle or for their habitat are especially vulnerable to sea ice melt[7]. Fish species and zooplankton are also impacted as they require sea ice for feeding or shelter[10]. These species usually have a unique adaptation to tolerate high brine salinity and low temperatures[11] which can make them sensitive to changes in the water due to melting sea ice. For large marine animals that breathe air, sea ice acts an important physical structure that may act as a barrier or platform for some species[12]. There are 11 species of arctic marine mammals that are impacted by sea ice melt including polar bears, narwhals, beluga whales, bowhead whales, ringed seals, spotted seals, bearded seals, hooded seals, ribbon seals, harp seals, and walruses[6]. These animals are especially vulnerable due to their reliance on sea ice as a structure and reliance on the Arctic marine ecosystem for food and other resources throughout their life[6]. Sea ice is used as a hunting platform for polar bears and some prey use it as a barrier to avoid predators[12]. Other animals such as Arctic pinnipeds (seals and walruses) use sea ice as platforms for molting, whelping, hauling out, and sub-ice foraging[12].

What is the extent of the problem?

Figure 2. Graph showing the recent trends of total Arctic sea ice measured by a microwave satellite from 1979 to 2013. The graph shows 3 lines indicating the trend for March in red, September in blue, and Annual in green[7].

What are the measurable ecological changes that have happened?

Sea ice melt has resulted in numerous ecological changes to have occurred [13], such as measurable ones such as habitat space for species such as sea-ice algae.

Other changes include the advancement of permafrost up to 1500 km inland [13]. This makes a trophic mismatch in which inland food webs such as the caribou ones are heavily affected as arctic terrestrial vegetation zones are all in relation to sea ice[13].Loss of sea ice also allow for more contact between west and eastern arctic species as well as change of behavior for these species , increasing pathogens and diseases spreading[13].An example of this happening would be the sporadic outbreaks of rabies on Svalbard, a outbreak attributed to the loss of sea ice.

Present status compared to the past

One of the measurable ecosystem changes involving polar ecosystems is the amount of total arctic sea ice covering the ocean. The total sea ice in recent years can be compared to the sea ice in the past and conclusions can be made based on the trends. Figure 1 shows that sea ice levels have been following a downward trend over the past 34 years since 1979 indicating that sea ice is declining at all times of the month[7].

Prognosis for the future

Scientists have studied the last interglacial period- a warm period of the planet about 127,000 years ago- and now have found a way to compare sea ice conditions back then with present day. In the spring and early summer, as temperature increases slightly with the season,  shallow water pools form on the surface of the Arctic sea-ice. The pools determine how much sunlight is absorbed by the ice and how much is reflected back out of the atmosphere[14]. Using a new model, called HadGEM3, created based on the last interglacial, the research team concluded that the impact of intense springtime sunshine created more and more of these melt ponds, which play a crucial role in sea-ice melt. Looking at the model further, comparing to the interglacial, a simulation of the future indicates that the Arctic may be sea-ice free as soon as 2035[14]. This is only one models' predictions, and the range of complete sea ice loss is between 2035 and 2086.

Given the impact, what are the solutions?

Above is a schematic of how albedo (reflectiveness) is determined by the presence of snow on top of ice.[1]

A major solution that is in the works to stop or decrease sea ice melt is to increase the albedo (reflectiveness) of the ice. The albedo is usually high because of the snow that accumulates on top of the ice, but as the snow melts with rising temperatures, the albedo decreases, and the ice underneath melts even faster[15]. Many scientists have said that stopping the ice melt at the poles is key to slowing the effects of climate change around the world, as it can lead to higher water temperature and sea levels rising[16]. Leslie Field, founder of Ice911, a nonprofit exploring Arctic ice restoration, came up with an idea of how to increase albedo of ice easily, at low cost, and little impact to local ecosystems[16].

Above is a picture of a researcher holding the silica beads that are being studied to be spread across ice in the Arctic to increase reflectivity.[2]

The solution is a safe material that can help replace the lost reflectivity that comes with the reduction of bright, white, multiyear ice that makes up most of the reflectivity in the Arctic. The material is hollow glass spheres made of silica that could be added to ice; the main component being rocks that reflect light and make thinner ice look more like multiyear ice[17]. Adding just a thin layer of these beads locally at the poles could increase reflectivity and decrease ice melting. In one field test, the material increased reflectivity by 15-20 percent[17]. Based on calculations, the beads alone could hypothetically decrease temperature up to 1.5C over a large part of the Arctic, decrease sea temperature by 3C, and  increase sea ice thickness up to 20 inches[16]. This plan is a small-scale approach to the problem, as the plan is not to blanket the entire Arctic with silica beads, rather target specific areas that are modeled to have the biggest restorative impact on the entire region.

Larger-scale, more global approaches to the problem would include solutions based on decreasing the global temperature altogether. Some of these solutions would include a decrease in the use of fossil fuels to decrease greenhouse gas emissions that trap heat within Earth’s atmosphere and cause the temperature to rise[18]. Another solution is to increase number of trees, as they are one of the largest carbon reservoirs on Earth, so as they are cut down, less carbon is taken out of the atmosphere, and more is left as a greenhouse gas that can trap heat within the atmosphere. This could be resolved with less harvesting of trees, or more planting of trees to replace harvested ones.

Reference

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Thompson, L.G. (2010). "Climate change: the evidence and our options". The Behavior analyst. 33(2): 153–170.
  2. ↑ AL, S (2018). "Conclusion. In: Adapting Cities to Sea Level Rise".
  3. ↑ Ballinger (2013). "Atmosphere and Ocean Impacts on Recent Western Arctic Summer Sea Ice Melt".
  4. ↑ Hansen (2016). "Ice melt, sea level rise and superstorms: Evidence from paleoclimate data, climate modeling, and modern observations that 2 ∘C global warming could be dangerous". Atmospheric Chemistry and Physics. 16(6): 3761–3812.
  5. ↑ Briggs, Helen; Gill, Victoria (July 20, 2020). "Climate change: Polar bears could be lost by 2100". BBC.
  6. ↑ 6.0 6.1 6.2 Laidre, Kristin (March 17, 2015). "Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century". Conservation Biology. 29.
  7. ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 Meier, Walter; Hovelsrud, Greta; van Oort, Bob; Key, Jeffery; Kovacs, Kit; Michel, Christine (May 14, 2014). "Arctic sea ice in transformation: A review of recent observed changes and impacts on biology and human activity". Review of Geophysics. 52.
  8. ↑ Doney, Scott (August 25, 2011). "Climate Change Impacts on Marine Ecosystems". Annual Review of Marine Science. 4.
  9. ↑ Mathis, J.T. (2011). "The extent and controls on ocean acidification in the western Arctic Ocean and adjacent continental shelf seas: Arctic Report Card, Update for 2011". Arctic Report Card.
  10. ↑ Søreide, Janne (October 2008). "Seasonal feeding strategies of Calanus in the high-Arctic Svalbard region". Deep Sea Research Part II: Topical Studies in Oceanography. 55.
  11. ↑ Arrigo, Kevin (September 4, 2013). "Sea Ice Ecosystems". Annual Review of Marine Science. 6.
  12. ↑ 12.0 12.1 12.2 Laidre, Kristin. "QUANTIFYING THE SENSITIVITY OF ARCTIC MARINE MAMMALS TO CLIMATE‐INDUCED HABITAT CHANGE". Ecological Applications. 18.
  13. ↑ 13.0 13.1 13.2 13.3 Post (2013). "Ecological Consequences of Sea-Ice Decline".
  14. ↑ 14.0 14.1 Guarino, Maria-Vittoria (August 10, 2020). "Sea-ice-free Arctic during the Last Interglacial supports fast future loss". Nature. Retrieved January 24, 2021.
  15. ↑ "Thermodynamics: Albedo". National Snow & Ice Data Center. Retrieved January 24, 2021.
  16. ↑ 16.0 16.1 16.2 Endicott, Marisa (September 29, 2019). "These Scientists are trying to save melting Arctic Ice". Grist. Retrieved January 24, 2021.
  17. ↑ 17.0 17.1 Zimmer, Katarina (September 23, 2020). "The daring plan to save the ARctic ice with glass". BBC. Retrieved January 24, 2021.
  18. ↑ Biello, David (November 26, 2007). "10 Solutions for Climate Change". Scientific American. Retrieved January 21, 2021.

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  3. ↑ Holland. "West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing".
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