arctic sea ice is decreasing
Header source: Sir John Houghton, Global Warming, The Complete Briefing, Fifth Edition, Cambridge OP, 2015, 168; text: Scientific American
Since the mid-80s the Arctic has been warming twice as fast as the entire world — a phenomenon the vast majority of scientists agree is the direct result of human-induced climate change. Since 1979, the ebb and flow of the ever-changing mass in the centre of one of Earth's most hostile environments has been captured by polar-orbiting satellites.
As climate change increased global temperatures, the sea ice began deteriorating. Temperature increases in the Arctic were consistently two, sometimes three times as high as the rest of the globe. The more the Earth warmed, the more the sea ice shrank. And not only is the sea ice melting but it’s also getting much younger as well.
The situation in the Arctic is dire, but modelling shows that it’s only going to get worse. If greenhouse gas emissions continue to increase unabated, the warming of the planet will continue and an ice-free summer — when the minimum sea ice extent dips below 1 million km2 — is inevitable.
Data from NASA's Gravity Recovery and Climate Experiment shows that Greenland lost 150 to 250 cubic kilometres (36 to 60 cubic miles) of ice per year between 2002 and 2006[1], and more recently the rate has speeded up. As previously noted, in July 2019, the Greenland ice sheet was shedding its load at the rate of 12.5 billion tons of ice per day, losing 160 billion tonnes of ice through surface melting in the month of July alone.
In September 2012, 49% of the sea ice went missing, an area 43% of the size of the contiguous US, compared with the mean value from 1979 to 2000. In the Arctic, the age of ice generally defines the region’s health. Older ice is thicker, more resilient and resistant to atmospheric changes, and better at supporting mammals. Younger ice is thin and vulnerable to collapse. Yet in nearly all Arctic regions, sea ice is decreasing, the report said. In 1985, 85 percent of the region’s ice qualified as old. In March, that fell to 30 percent[2]. These changes in the Arctic portend changes that are likely to spread to the wider world: higher air temperatures, longer hot seasons, anomalous weather spikes and fish fleeing north only to be replaced by new species swimming from areas south.[3]
According to the annual Arctic Report Card: 2015 Update released by the federal National Oceanic and Atmospheric Administration (NOAA), between October 2014 and September 2015, the annual average surface-air temperature in the Arctic was nearly 2.5 degrees higher than the time period scientists use as a baseline to compare temperatures, 1981 to 2010, and since the turn of the last century, the Arctic’s air temperature has increased by more than 5 degrees due to global warming".
Overall, the extent of summer sea ice in the Arctic is down by nearly 50% since 1900, affecting heat flow in the atmosphere and ocean. What ice is still left is thin. Average thickness dropped by 43% between 1976 and 1999, sonar measurements show. When the point is reached that summer melting outstrips the accumulation of new ice in winter, and we are already near that point, the entire ice cover will collapse[4]. Once summer ice goes away entirely, the physics of latent heat will make it very difficult, if not impossible to get it back and we will be confronted with an Arctic “death spiral”.[5]
The result is a diminished capacity to reflect incoming solar radiation back into the atmosphere. The exposed water releases its stored heat in fall and winter, resulting in a massive, months-long perturbation to the base state of the Arctic atmosphere. If this pattern continues unabated, it is estimated that the remaining 50% of summer sea ice will be gone by 2030. Satellite observations also reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier[6].
Then, in September 2020, a huge chunk of Greenland's ice cap estimated to be 110 square kilometres broke off the fjord called Nioghalvfjerdsfjorden which is about 80 kilometres long and 20 kilometres wide in the far north-east Arctic. The glacier is at the end of the north-east Greenland ice stream, where it flows off land into the ocean. Annual end-of-melt-season changes for the Arctic's largest ice shelf in the region are measured by optical satellite imagery, and the National Geological Survey of Denmark and Greenland (GEUS) showed area losses for the past two years each exceeded 50 square kilometres. Such events are said to be emblematic of rapid climate change.
Overall, ice in the Arctic Ocean melted to its second-lowest level on record during the 2020 northern summer, triggered by global warming along with natural forces. The extent of ice-covered ocean at the North Pole, and extending further south to Alaska, Canada, Greenland and Russia, reached its summertime low of 3.7 million square kilometres in September 2020 before starting to grow again. (Arctic sea ice reaches its low point in September and its high in March after the winter). Temperatures for much of 2020 were 8 to 10 degrees Celsius above normal in the Siberian Arctic. The 2020 melt is second only to 2012, when the ice shrank to 3.4 million square kilometres, according to the US National Snow and Ice Data Centre (NSIDC), which has been keeping satellite records since 1979.
Glaciers are also retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa. Meanwhile, elsewhere on the planet, humans have modified more than half of the available landscape with crops, pastures and cities, exposing more and more darker land and sea surfaces to incoming solar radiation[7].
[1] See also Jennifer A. Francis, op cit at 42, where the comparative figures for 1979 to 2017 are reproduced: 14 million square kms less than in 1979; mean water ice volume 18 thousand cubic kms less over the same period; significantly increased winter air temperature, winter water vapour anomaly and rate of annual arctic warming compared with mid latitudes over the same period.
[2] Darryl Fears, “This is what happens when the Arctic warms twice as fast as the rest of the planet”, Washington Post, December 15, 2015: https://www.washingtonpost.com/news/energy-environment/wp/2015/12/15/this-is-what-happens-when-the-arctic-warms-twice-as-fast-as-the-rest-of-the-planet/?utm_term=.f3bcd54c1bb0. See also the same article reproduced as “Harbinger from the north: we’re all on this ice", Sydney Morning Herald, 17 Dec 2015: http://www.smh.com.au/environment/alaskas-tundra-is-filling-the-atmosphere-with-carbon-dioxide-20170509-gw0pkq.html Also, The collapse of the Antarctic ice sheet is underway and unstoppable, but will take centuries
[3] Ibid.
[4] Peter Wadhams, Professor of Ocean Physics at the University of Cambridge, Scientific American, December 2012, 8.
[5] Ibid. On these issues, see also the previously cited article by Andy Isaacson, “Into thin ice – the Arctic ice pack is dwindling. What will that do to the planet?” National Geographic, January 2016, 99 at 113.
[6] See also Jennifer A. Francis, op cit at 43: maximum winter sea ice extent 15% less in 2017 compared with 1979; winter sea ice volume 42.5% less over the same period; winter air temperature almost 9 Degrees C higher than in 2016 compared with 1979; winter water vapour (a greenhouse gas) 40% higher in 2016 than in 1979; arctic amplification rate (the rate at which the arctic is warming faster than the rest of the world) 4.3% higher in 2016 than in 1979
[7] See Appendix A, for mankind’s impact on the planet generally.
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Since the mid-80s the Arctic has been warming twice as fast as the entire world — a phenomenon the vast majority of scientists agree is the direct result of human-induced climate change. Since 1979, the ebb and flow of the ever-changing mass in the centre of one of Earth's most hostile environments has been captured by polar-orbiting satellites.
As climate change increased global temperatures, the sea ice began deteriorating. Temperature increases in the Arctic were consistently two, sometimes three times as high as the rest of the globe. The more the Earth warmed, the more the sea ice shrank. And not only is the sea ice melting but it’s also getting much younger as well.
The situation in the Arctic is dire, but modelling shows that it’s only going to get worse. If greenhouse gas emissions continue to increase unabated, the warming of the planet will continue and an ice-free summer — when the minimum sea ice extent dips below 1 million km2 — is inevitable.
Data from NASA's Gravity Recovery and Climate Experiment shows that Greenland lost 150 to 250 cubic kilometres (36 to 60 cubic miles) of ice per year between 2002 and 2006[1], and more recently the rate has speeded up. As previously noted, in July 2019, the Greenland ice sheet was shedding its load at the rate of 12.5 billion tons of ice per day, losing 160 billion tonnes of ice through surface melting in the month of July alone.
In September 2012, 49% of the sea ice went missing, an area 43% of the size of the contiguous US, compared with the mean value from 1979 to 2000. In the Arctic, the age of ice generally defines the region’s health. Older ice is thicker, more resilient and resistant to atmospheric changes, and better at supporting mammals. Younger ice is thin and vulnerable to collapse. Yet in nearly all Arctic regions, sea ice is decreasing, the report said. In 1985, 85 percent of the region’s ice qualified as old. In March, that fell to 30 percent[2]. These changes in the Arctic portend changes that are likely to spread to the wider world: higher air temperatures, longer hot seasons, anomalous weather spikes and fish fleeing north only to be replaced by new species swimming from areas south.[3]
According to the annual Arctic Report Card: 2015 Update released by the federal National Oceanic and Atmospheric Administration (NOAA), between October 2014 and September 2015, the annual average surface-air temperature in the Arctic was nearly 2.5 degrees higher than the time period scientists use as a baseline to compare temperatures, 1981 to 2010, and since the turn of the last century, the Arctic’s air temperature has increased by more than 5 degrees due to global warming".
Overall, the extent of summer sea ice in the Arctic is down by nearly 50% since 1900, affecting heat flow in the atmosphere and ocean. What ice is still left is thin. Average thickness dropped by 43% between 1976 and 1999, sonar measurements show. When the point is reached that summer melting outstrips the accumulation of new ice in winter, and we are already near that point, the entire ice cover will collapse[4]. Once summer ice goes away entirely, the physics of latent heat will make it very difficult, if not impossible to get it back and we will be confronted with an Arctic “death spiral”.[5]
The result is a diminished capacity to reflect incoming solar radiation back into the atmosphere. The exposed water releases its stored heat in fall and winter, resulting in a massive, months-long perturbation to the base state of the Arctic atmosphere. If this pattern continues unabated, it is estimated that the remaining 50% of summer sea ice will be gone by 2030. Satellite observations also reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier[6].
Then, in September 2020, a huge chunk of Greenland's ice cap estimated to be 110 square kilometres broke off the fjord called Nioghalvfjerdsfjorden which is about 80 kilometres long and 20 kilometres wide in the far north-east Arctic. The glacier is at the end of the north-east Greenland ice stream, where it flows off land into the ocean. Annual end-of-melt-season changes for the Arctic's largest ice shelf in the region are measured by optical satellite imagery, and the National Geological Survey of Denmark and Greenland (GEUS) showed area losses for the past two years each exceeded 50 square kilometres. Such events are said to be emblematic of rapid climate change.
Overall, ice in the Arctic Ocean melted to its second-lowest level on record during the 2020 northern summer, triggered by global warming along with natural forces. The extent of ice-covered ocean at the North Pole, and extending further south to Alaska, Canada, Greenland and Russia, reached its summertime low of 3.7 million square kilometres in September 2020 before starting to grow again. (Arctic sea ice reaches its low point in September and its high in March after the winter). Temperatures for much of 2020 were 8 to 10 degrees Celsius above normal in the Siberian Arctic. The 2020 melt is second only to 2012, when the ice shrank to 3.4 million square kilometres, according to the US National Snow and Ice Data Centre (NSIDC), which has been keeping satellite records since 1979.
Glaciers are also retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa. Meanwhile, elsewhere on the planet, humans have modified more than half of the available landscape with crops, pastures and cities, exposing more and more darker land and sea surfaces to incoming solar radiation[7].
[1] See also Jennifer A. Francis, op cit at 42, where the comparative figures for 1979 to 2017 are reproduced: 14 million square kms less than in 1979; mean water ice volume 18 thousand cubic kms less over the same period; significantly increased winter air temperature, winter water vapour anomaly and rate of annual arctic warming compared with mid latitudes over the same period.
[2] Darryl Fears, “This is what happens when the Arctic warms twice as fast as the rest of the planet”, Washington Post, December 15, 2015: https://www.washingtonpost.com/news/energy-environment/wp/2015/12/15/this-is-what-happens-when-the-arctic-warms-twice-as-fast-as-the-rest-of-the-planet/?utm_term=.f3bcd54c1bb0. See also the same article reproduced as “Harbinger from the north: we’re all on this ice", Sydney Morning Herald, 17 Dec 2015: http://www.smh.com.au/environment/alaskas-tundra-is-filling-the-atmosphere-with-carbon-dioxide-20170509-gw0pkq.html Also, The collapse of the Antarctic ice sheet is underway and unstoppable, but will take centuries
[3] Ibid.
[4] Peter Wadhams, Professor of Ocean Physics at the University of Cambridge, Scientific American, December 2012, 8.
[5] Ibid. On these issues, see also the previously cited article by Andy Isaacson, “Into thin ice – the Arctic ice pack is dwindling. What will that do to the planet?” National Geographic, January 2016, 99 at 113.
[6] See also Jennifer A. Francis, op cit at 43: maximum winter sea ice extent 15% less in 2017 compared with 1979; winter sea ice volume 42.5% less over the same period; winter air temperature almost 9 Degrees C higher than in 2016 compared with 1979; winter water vapour (a greenhouse gas) 40% higher in 2016 than in 1979; arctic amplification rate (the rate at which the arctic is warming faster than the rest of the world) 4.3% higher in 2016 than in 1979
[7] See Appendix A, for mankind’s impact on the planet generally.
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