Arctic Sea Ice: Effects on theClimate 1. IntroductionIn the Arctic’s northpolar region in the middle of the Northern Hemisphere covering an area of about14.06 million km² is the Arctic sea ice.
A frozen multifaceted surface thatvaries in texture, layers and characteristics. Most of this ice is 2 – 3 metersthick with some of the regions around 4 – 5 meters. The Arctic’s ice follows arepetitive cycle throughout the year. The ice grows during the winter season freezingmore water and getting thicker, reaching the highest extent in March and then meltinguntil mid-September where it reaches the lowest coverage. The cycle is then underwayagain with the cooling of temperatures and shorter days starting the ice capreformation.
This expanse of frozensea water holds significant importance to our Earths global climate. Itregulates the atmospheres temperature, helps moderate global climate and reduceradiation, controls storm activity, and regulates ocean circulation. How is theArctic sea ice declining over time and how does that decline affect the Earth’sclimate?2. Changesin the Sea Ice Extent Since the late 1970’s theArctic sea ice extent has been in increasing long-term decline. Each year in Septemberthe sea ice is at it’s lowest annual extent.
This annual extent has beenrecorded to get lower and lower by about 13 percent per decade and continues todo so on average. In 2017 ice was found to be at the eighth lowest ever recordedcoverage (Blumberg, 2017). Shown on the graph below you can observe how significantand consistent this decrease has been, starting in 1979 and continuing to currentday 2017.
Table1 – Average Monthly Arctic Sea Ice Extent (millions of square kilometers) in September1979 – 2017. The graph shows the decline of 13.2 percent per 10 years.(National Snow and Ice Data Center, 2017). The blue line shows the median,where black shows exact data marks recorded.
Thispast year in March, when the ice is to be at it’s fullest and greatest extent, wehit a record low with the smallest extent for the year at 4.6 square kilometres(National Snow and Ice Data Center, 2017). With a very warm winter, the oceanwaters high temperatures made freezing much more difficult come March. Thiscycle makes it very hard to bring back to “normal” as the decrease aids in moredecrease next year and so on.
The amount of sea ice that is five years or olderis a lot less now then in the past with the young sea ice growing incomparison. This means that there is less ice staying around throughout allseasons and each melt. Evidence shows that two thirds of all the ice loss thathas happened has occurred in the 12 years following theyear 2000 (Naam, 2012).
When the ice melts earlier in the season the open darkocean is exposed and therefore absorbs more heat from the Suns rays. Theprocess of ice loss is then speed up and the warmed water contributes to theprocess, as seen this past March. This first climate effect is observed becauseof this is radiation and absorption of heat in the atmosphere.
3. Radiationand Absorption of Heat: Albedo Effect Inthe winter the Arctic ice and snow insulates the ocean water. The exception to thisis where the ice has separated, exposing the open water. This enables theexchange of heat and water vapor from ocean to Earth’s atmosphere. This open spacegets greater the less ice present and therefore the exchange increases.
TheArctic’s polar ice and snow insulation is our Earth’s natural atmospherecooling system. With the increasing decline of this ice we are losing what helpscontrol and stabilize earth’s climate system. This can be explained through thealbedo effect, which is determined by the amount of radiation reflected awaycompared to how much gets absorbed. The lower this albedo affect the moreradiation absorbed by the planet. The incoming radiation from the Sun throughour Earth’s atmosphere gets reflected off the ice and snow and back into space.
When a great extent of ice is present, nearly all the sunlight that hits theice surface is reflected into space because the ice is white and veryreflective (high albedo). This keeps the climate cool in the polar regions asnot much of the sun’s energy and therefore heat is absorbed. With less and lessice in the Arctic and in it’s place open dark water, there is a less reflectivesurface and so more heat is absorbed (low albedo). Below the diagramillustrates this process and shows just how significant the present of theArctic sea ice really is.
Figure 1- The Albedo effect shown throughthe amount of radiation absorbed by the water with ice and without. With icethe snow and ice keep the water cool and reflects 90% back into space and only10% into warming the water. Without the ice only 6% gets reflected into space,and 94% absorbs into the water and energy transferred into heat.
Thisabsorption of heat from the lack of ice causes the water to warm and in turn, contributesto more of the ice melting. This affects how much solar radiation is reflectedoff the surface and absorbed every year. We now experience the Arctic absorbinglarge amounts of this solar radiation in the summer, and the water temperaturesin turn are rising way above average. One recent study estimates that the extraheat in the water is the equivalent of adding another 25 percent to globalgreenhouse emissions (Wadhams, 2016).
4. Water circulation Thecirculation of the ocean water is affected and changed by the Arctic sea iceloss. The surface waters are circulated by the wind moving the warmer watersitting on top. The deeper water circulation is caused by the difference inwater density. The wind pushing the surface warmer waters carries it towardsthe poles. This allows the seawater to move across the Earth’s oceans.
As thiswarmer water reaches the poles it begins to get cooler and cooler, the differencein temperature and saline causes this water to sink deeper into the ocean. Thismovement is part of the thermohaline circulation or the Global Ocean Conveyor.(UCAR Center for Science Education, 2017). The melting Artic sea ice affectsthis procedure as we see rising freshwater from the melting ice it causes theseawater at high latitudes to become less salty and in turn as we havediscovered, less dense. With the surface water having a lower than normaldensity the water is unable to sink and circulate. So how does thisinterruption of the thermohaline process affect the climate? The process ofcirculation brings heat from the equator and carries it northward where it cools,then sinks and returns back south. Figure 2 – TheGlobal Ocean Conveyor or Thermohaline process above shows the moving of thewater of deep and surface ocean water worldwide (News Archive – The EarthInstitute – Columbia University, 2005).
Withthis process slowed or even potentially stopped by the melting of the Arcticsea ice the ramifications of this would be severe. Without these ocean currentsthe climates temperatures would drop, shifting animal, plant and human conditions.This would be seen particularly in Europe and countries in the North Atlantic wherethey could experience long periods of freezing temperatures. The slippery slopeeffect would be appropriate in this as more negative consequence would be producedin response such as the economy in specifically agriculture. 5. IncreasedStorm Activity Theextremity of the storms we experience are regulated in part by the Arctic sea ice.The smaller amounts of ice present in the Arctic combined with the rising sealevels from this melting ice, allows for greater wind-induced wave energy to becreated. More waves can be produced because of the now open waters in thesummer.
These waves pull apart the larger chunks of ice breaking them into smallerpieces, allowing the Sun to melt them quicker. The Arctic’s lack of ice allows thestorms to feed off the open waters and mixes the water. This brings up heat thatwas absorbed during the summer.
As the water warms and stays warm, the airabove warms as well and moves across the land. This land absorbs more heat andfurther warms the Arctic narrowing the temperature difference between theArctic and areas of lower latitudes. This lower temperature difference meansthat the winds are weaker and move slower. Figure3– (Mason, John, 2013) The above figure shows how the jet stream’s slower speed waiversand brings cold polar air down while the warm tropical air moves up.
Thiscauses pockets and moves into cyclonic spins and anti-cyclonic spins. Thejet stream shown above is driven by this difference and causes the wind to movearound the north pole. The jet stream is now 14% slower and weaker than it wasin 1980 (Naam, 2012). With the slowerspeed the more defined swings of the jet stream extend farther north and southas it moves from west to east, allowing warmer, more dense air to movenorthward.Thiswarmer climate causes more of the water vapor from the ocean to be evaporatedinto the atmosphere which traps radiation and holds heat closer to the Earth’ssurface, and thus produces more extreme weather such as heat waves.
The loss ofsea ice is a huge positive feedback effect as the changes caused by the meltingof the Arctic sea ice emphasise and lead to more warming and loss of ice. Theenergy used to produce these storms or hurricanes come from the warm oceanwater. The very top of the Arctic ocean water increases in temperature makingthese tropical storms stronger with faster winds and heavier rain. Theloss of sea ice has significant impacts on our Earth, it’s connections reachingfar past climate and atmosphere effects discussed.
6. Conclusion The Arctic sea ice has been and continues to greatlyaffect our climate and atmosphere. With the information provided it’s clearthat major changes are happening.
As time progresses these processes willcontinue to accelerate leading to more heightened and extreme effects andconditions. The Arctic sea ice will continue to melt from the decreasing Albedoin the Arctic from lack of ice and snow. Water circulation, which helps controlclimate as well by warming and cooling parts of the Earth is slowed and couldpotentially be halted by the melting freshwater diluting the seawater andlowering the density. The increasing temperature of the water and air makestropical storms stronger with faster winds and heavier rain