The amount of ice in the Arctic sea does not stay constant all year round . 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 .
However, it is very likely that between 1979 and 2018 the amount of ice present during each month of the year decreased . 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 ! You can see the significance of this in the graph we’ve posted !
Increased Arctic sea ice melt is caused by high summer temperatures  and also due to a “positive feedback” :
As ice melts, it exposes more of the ocean surface, which is darker in colour than ice so it reflects less sunlight . Therefore, the more ice melts, the hotter the ocean surface becomes, making it even more likely that more ice will melt ! 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 
causing significant damage to local wildlife and food/water supply for indigenous people .
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 .
However, recent Arctic sea ice loss has been significantly higher than climate model predictions , so the tipping point for summer ice could be crossed much earlier than models predict. Some scientists think we have already crossed it !
 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))
(Sections 184.108.40.206.1 Paragraph 1)
 https://climate.nasa.gov/vital-signs/arctic-sea-ice/ (Graph of average September extent)
 https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/07_SROCC_Ch03_FINAL.pdf (Section 220.127.116.11.1 Paragraph 3)
 https://www.pnas.org/content/pnas/105/6/1786.full.pdf (Arctic Sea Ice )
 https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/07_SROCC_Ch03_FINAL.pdf (Sections 18.104.22.168.1 Paragraph 1)
 https://www.nature.com/articles/d41586-019-03595-0 (Ice Collapse Paragraph 7)
 https://journals.ametsoc.org/doi/full/10.1175/JCLI3587.1 (Final Paragraph)
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