Is the Arctic disappearing?

Article by Hazell Ransome.

The amount of ice in the Arctic sea does not stay constant all year round [1]. In fact every year around 9 million km² (or roughly half the total ice cover) is lost between March and September, but it refreezes again during winter [1].

However, it is very likely that between 1979 and 2018 the amount of ice present during each month of the year decreased [2]. September has experienced the most significant change in ice cover for the past 1,000 years, losing around 83,000 km² per year since 1979 [3]! You can see the significance of this in the graph we’ve posted [4]!

Increased Arctic sea ice melt is caused by high summer temperatures [5] and also due to a “positive feedback” [2]:

As ice melts, it exposes more of the ocean surface, which is darker in colour than ice so it reflects less sunlight [6]. Therefore, the more ice melts, the hotter the ocean surface becomes, making it even more likely that more ice will melt [5]! Swipe to see our infographic!

Arctic sea ice will pass a “tipping point” when temperatures become so high that further sea ice loss becomes impossible to stop. This will lead to a point in the future there will be no Arctic sea ice during summer [7]
causing significant damage to local wildlife and food/water supply for indigenous people [8].

Scientists predict there is a 10-35% chance that a 2°C increase in global temperature will result in unavoidable ice-free summers by 2100 [9].

However, recent Arctic sea ice loss has been significantly higher than climate model predictions [7], so the tipping point for summer ice could be crossed much earlier than models predict. Some scientists think we have already crossed it [10]!

References

[1] https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/07_SROCC_Ch03_FINAL.pdf (Figure 3.3b vs 3.3d on page 213. Average ice amount 1850-1950 in March is 16.5 million km2 and September is 7.5 million km2. Therefore loss is 9 million km2 and 9/16.5 = 0.54 (roughly half))

[2] https://report.ipcc.ch/srocc/pdf/SROCC_SPM_Approved.pdf (A1.4)

[3] https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/07_SROCC_Ch03_FINAL.pdf
(Sections 3.2.1.1.1 Paragraph 1)

[4] https://climate.nasa.gov/vital-signs/arctic-sea-ice/ (Graph of average September extent)

[5] https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/07_SROCC_Ch03_FINAL.pdf (Section 3.2.1.1.1 Paragraph 3)

[6] https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/albedo (Paragraph 3)

[7] https://www.pnas.org/content/pnas/105/6/1786.full.pdf (Arctic Sea Ice )

[8] https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/07_SROCC_Ch03_FINAL.pdf (Sections 3.2.1.1.1 Paragraph 1)

[9] https://www.nature.com/articles/d41586-019-03595-0 (Ice Collapse Paragraph 7)

[10] https://journals.ametsoc.org/doi/full/10.1175/JCLI3587.1 (Final Paragraph)

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