- > This sixth World Ocean Review (WOR) focuses on the Arctic and the Antarctic – two regions which are, in a very real sense, polar opposites, with some of the world’s most extreme conditions. Besides presenting a wealth of facts and figures about the history and exploration of the polar regions, WOR 6 builds a deeper awareness of their key role for life on our planet. It highlights the changes that can be observed in their flora and fauna and analyses the already dramatic impacts of global warming on these extremely fragile regions.
The Arctic and Antarctic – Extreme, Climatically Crucial and In Crisis
As this sixth World Ocean Review is being written, meteorologists are reporting record high temperatures across much of the Arctic. Right now, in July 2019, some 6000 square kilometres of tundra and taiga in Alaska are burning in conditions of extreme aridity and summer temperatures above 30 degrees Celsius. Even larger areas are affected in Siberia, where massive wildfires have led the Russian authorities to declare a state of emergency in five regions. The water masses in the Bering Sea and Chukchi Sea are up to four degrees Celsius warmer than the average for the years 1981 to 2010. Summer sea-ice cover in the Arctic looks set to shrink to a new minimum, and in June 2019 scientists observed the earliest start to the summer melt of Greenland’s ice sheet since records began. During a prolonged period of warm weather in the following month – July – the ice cap lost 197 billion tonnes of ice, 160 billion of them as a result of surface melt. The snow is starting to melt even at the ice sheet’s highest point, 3200 metres above sea level. At the same time, strikingly little winter sea ice is forming on the Southern Ocean, even though air temperatures over East Antarctica are somewhat lower than usual. In the western part of Antarctica, on the other hand, temperatures are too warm – as they have often been in recent years. In the face of this flurry of bad tidings from the Arctic and Antarctic, it no longer seems justified to talk about the “eternal ice” of the polar regions.
Satellites and an ever-growing network of meteorological measuring stations and instruments now keep us constantly updated on general weather conditions in the Arctic and Antarctic. These two regions are the cold poles of the Earth: because of their geographical position, the tilt of the Earth’s axis and the Earth’s movement around the sun, sunlight and warmth do not reach them continuously – and the solar radiation that does arrive is weaker than in regions closer to the equator. In consequence, the polar regions have for thousands of years cooled so much during the polar night that vast areas of new sea ice form each year and snow falls wherever the air contains sufficient moisture. When the sun returns in spring, the pure white expanses of ice and snow reflect up to 90 per cent of the solar radiation that reaches them (albedo effect). If dust, meltwater or other dark surfaces are present on the ice, or if the sea is free of ice, a far smaller proportion of the solar energy is reflected back. The ice and snow cover thus slows the temperature rise in the region and enables glaciers and ice sheets to form. Due to the albedo effect, the Earth as a whole warms far more slowly than it would if the polar regions were devoid of snow and ice. For this reason, the northern and southern polar regions play a key part in the Earth’s climate system. Their importance is amplified by the fact that the temperature differences between the cold polar regions and the warm tropics drive the winds and ocean currents that circle the Earth and thus contribute significantly to the global dispersal of the warmth stored in the seas and in the atmosphere.
- Despite the extreme climate in both polar regions, the fact is that the Arctic and Antarctic differ fundamentally in many respects – not just in terms of their evolution and settlement history but also with regard to their flora and fauna, the impacts of climate change and their present use by human communities. To understand these differences, it is essential to consider the location and geography of the two polar regions. Antarctica is a continent almost entirely covered by ice masses and completely surrounded by water. Vast atmospheric wind flows and ocean currents have formed around this southern continent, increasing its isolation. In the northern polar region, by contrast, continental land masses surround a small ocean, located in their midst. In some places these land masses merge or are connected by now-submerged land bridges. When global sea levels were low, animals, plants and humans were thus able to colonise the northern territories. The most notable example of a land link was the Bering Land Bridge, a broad strip of land that joined eastern Siberia and Alaska at the height of the last ice age and enabled the primeval hunters of Siberia to migrate to North America.
The central position of the Arctic Ocean at the pole means that it is covered by sea ice, which increases its extent in winter and shrinks in summer. Because it has not yet melted completely in summer, the ice cover is often described as permanent. By contrast, the sea ice in the Southern Ocean melts so extensively in summer that experts regard it as seasonal ice cover.
The land-ice masses of Antarctica are impressive. They cover 98 per cent of the continent and contain so much fresh water that global sea levels would rise by 58.3 metres if they were to melt completely. In the far north, only the Greenland ice sheet is a comparable mass of land ice. It contains enough ice to raise the water level around the world’s coasts by about 7.3 metres if it were to melt.
- The simultaneous existence of large ice masses in both polar regions is something of an anomaly in the Earth’s long history. Since the Earth was formed, its shifting continents have seldom positioned themselves in a way that enables polar climate conditions to arise in both north and south, with both regions icing up. While scientists have now reconstructed the climate history of the Antarctic fairly precisely, many questions about the glacial history of the Arctic still remain unanswered. There is an urgent need for historical climate data to improve forecasting of the possible impacts of climate change on the polar regions.
Rising air and water temperatures in the wake of climate change are inducing fundamental changes in the polar regions, albeit with marked differences between north and south. Climate-induced change commenced much earlier in the Arctic than in the Antarctic and is still more noticeable in the far north than at the southern pole. In Antarctica, the temperature rise is affecting only the Antarctic Peninsula, whereas the Arctic has become a hotspot of climate change in recent decades. It is warming more than twice as fast as the rest of the world (by 2.7 degrees Celsius between 1971 and 2017), with winter temperatures rising faster than summer temperatures. The years 2014, 2015, 2016, 2017 and 2018 were all warmer on average than the preceding 113 years.
This dramatic warming has been triggered by complex interactions between the atmosphere, land, sea and shrinking ice – a process that scientists term Arctic amplification. There is considerable debate in scientific circles about the extent to which particular effects contribute to amplification. Some researchers argue that the drastic warming is primarily due to the shrinking snow and ice cover in the Arctic. The fewer light-coloured areas are present, the lower the reflective power of the Arctic and the greater the quantity of solar energy that remains in the northern polar region, triggering changes in the oceans and atmosphere. New findings indicate that total loss of the remaining Arctic sea ice would have an effect on global warming equivalent to releasing an additional trillion tonnes of carbon dioxide into the atmosphere – the quantity currently emitted by humans over the course of about 25 years. This would greatly accelerate climate change.
- Other scientists point out that the warming air over the Arctic absorbs more water vapour and that clouds therefore form more frequently, further impeding the radiation of heat energy into space. However, at certain times of year and with some types of cloud, this effect can be reversed and the cloud cover then has a cooling effect. Each argument has its merits and can be backed up by statistics. The actual explanation for amplification doubtless lies in the interplay of multiple factors, whose scope and effects vary not only seasonally but also from region to region.
Given the extent of the climatic changes in the Arctic, scientists are now concluding that the northern polar region has entered a new stage. Significantly less snow is falling in many areas and the sea-ice cover on the Arctic Ocean is steadily shrinking. The pack ice is noticeably younger, thinner, more fragile and hence more mobile than when satellite measurements began in 1979. At the end of the summer, the ice-free areas of the sea are now so extensive that the sun is able to warm the Arctic Ocean on a large scale. This warmth in turn causes fundamental changes in the ocean itself and in the atmosphere above it.
Scientists now know that the retreat of the sea ice in the Barents Sea and Kara Sea is distorting the strength and flow pattern of the jet stream over the northern hemisphere and hence indirectly affecting the weather in the mid-latitudes. Because the temperature contrasts between the tropics and the polar region are decreasing, the band of strong winds that determines the weather in the mid-latitudes is weakening and changing course. In summer, this increases the likelihood of extreme weather such as heat waves and droughts in Europe. In winter, on the other hand, a weakening jet stream leads to periods of exceptional cold in Central Europe and the American Midwest, while over Svalbard and the Bering Sea warm air masses penetrate far into the Arctic.
The retreat of the sea ice brings with it changes in the stratification of the water masses in the Arctic’s marginal seas, such as the Barents Sea, with stratification becoming similar to that in the North Atlantic. Scientists call this the “Atlantification” of the Arctic Ocean. Furthermore, the melting of the sea and land ice is discharging more fresh water into the Arctic Ocean. The consequences of this are still unclear, but scientists believe that it could slow the turnover of the water masses in the North Atlantic, thereby weakening the Gulf Stream that is so important to Europe.
The sad reality, even now, is that the retreat of the sea ice in the Arctic is accompanied by increasing erosion of the Arctic permafrost coasts. Where there is no sea-ice cover, the wind is able to whip up waves which then hit the fragile coasts. The water also warms faster and thaws the coasts a little more with each incoming wave. On land, the rising temperatures thaw the permafrost to great depths and reduce the stability and load-bearing capacity of the once-frozen substrate. In addition, microorganisms start to break down organic material that was previously bound up in the permafrost; this process produces large quantities of carbon dioxide and methane, which are naturally released into the atmosphere, further accelerating climate change.
- The warmth is also melting land-ice masses in the Arctic. In July 2019, scientists reported that Alaskan glaciers that flow into the sea are actually melting up to one hundred times faster than previously assumed. With Greenland’s ice sheet at the forefront, the shrinking glaciers of the northern polar region are currently contributing more to rising global sea levels than the melting of the mountain glaciers or the ice masses of the Antarctic. In summer 2019, the warmth caused the first of Iceland’s 400 glaciers to melt to such an extent that it has lost its status as a glacier. Scientists have affixed a memorial plaque to the fragmentary remains of the Okjökull glacier. The text, in English and Icelandic, contains a stark warning: “In the next 200 years all our glaciers are expected to follow the same path.”
Climate change is also affecting the polar flora. Trees and shrubs are now moving into the tundra, replacing low-growing, cold-adapted lichens, mosses and plants in a process known as Arctic greening. Elsewhere, warmth and increasing aridity are causing Arctic browning as plant life withers; wildfires are becoming more frequent, releasing further quantities of greenhouse gases. In Alaska alone, forest and tundra fires in July 2019 released a quantity of carbon dioxide equivalent to the entire annual emissions of a country such as Sweden. The fires are thus amplifying global climate change.
Forecasts of what the future holds for the polar regions’ marine biotic communities are also extremely worrying. With the melting of the sea ice, the habitat of the ice algae is shrinking. They are the most important primary producers in the Arctic Ocean, so wherever they disappear, fish, zooplankton and bottom-dwellers must seek new sources of food. This is having a devastating effect on marine food webs beyond the boundaries of the Arctic, as studies in the North Pacific show. Large-scale shrinkage of the ice was followed first by a decline in fish stocks and then by the death of large numbers of seabirds and grey whales. The viability of cold-adapted Arctic marine life is also affected by the rising water temperatures and the increasing acidification of the oceans. Acidification is particularly detrimental to organisms that form skeletons, cases or shells from calcium carbonate.
- Those that can, adapt to the new environmental conditions. However, cold-adapted polar species such as the polar cod and the Antarctic toothfish are unable to do this: the temperature range that suits them is too narrow for them to be able to adjust quickly to the rapid warming of the oceans. The young of some species are particularly sensitive to excessively warm temperatures. These inhabitants of the polar seas have no choice but to migrate to the last remaining cold regions. However, a glance at the long-term temperature forecasts for the Arctic Ocean shows that even this option will not exist for long. Within 30 years – and possibly much sooner – the Arctic Ocean is likely to be free of ice in summer. By then it will be inhabited by refugee species that have migrated from the warm mid-latitudes to the northern polar region.
Further victims of the retreating ice include polar bears, walruses, penguins and other seabirds and mammals that depend on sea ice. Because the absence of ice deprives them of their hunting grounds, starving polar bears are already to be found hanging around rubbish dumps in Arctic communities and settlements. Using computer models, biologists have calculated the mortality of adult polar bears in the western Hudson Bay. They found that between three and six per cent of all adult males die if the summer fasting period lasts 120 days. If this starvation period lasts an additional 60 days – i.e. for 180 days in all – between 28 and 48 per cent of the bears are at risk of dying from hunger. In view of the continuing retreat of the sea ice, the researchers therefore believe that in the long term the imposing white giants will become extinct.
Svalbard’s reindeer have turned to eating seaweed that has been washed up on the beach when rain falls on the snow cover in winter and forms a thick layer of ice that prevents them scraping their way through to the lichens that are their preferred food. They appeared to be surviving on this alternative diet, but when researchers from the Norwegian Polar Institute conducted their annual survey on Svalbard in spring 2019, they found that around 200 reindeer had starved to death in the rainy winter of 2018/2019. Such a high winter mortality rate had been observed only once before.
- While global warming is driving rapid and widespread change in the Arctic, change in the Antarctic is proceeding more slowly and its extent varies from region to region. In addition, the formation of the hole in the ozone layer over the Antarctic led to climatic changes that are still having a significant impact on the region today. This means that scientists cannot with certainty attribute new developments to the global rise in the concentration of greenhouse gases.
What is clear, however, is that the face of the Antarctic is changing in many places. This is particularly evident in the Antarctic Peninsula, the western Antarctic and around the Totten Glacier in East Antarctica, but there are also initial signs of change in areas that were thought to be stable, such as the Weddell Sea. The greatest warming that has been documented is taking place in the Antarctic Peninsula. In recent decades, this has led to a decline in sea-ice cover in the Bellingshausen Sea, the collapse of several ice shelves on the eastern and western coasts of the peninsula – including the main portion of the Larsen B Ice Shelf, spanning 3250 square kilometres – the rapid retreat of many smaller glaciers and major changes in the marine food web. In most regions of Antarctica, however – and especially in the centre of the continent – the air temperature has risen little or not at all. Scientists attribute this partly to the cooling effect of the hole in the ozone layer. Ozone is a greenhouse gas: where the ozone layer thins, the gas is depleted. This means that the lower stratosphere and the troposphere cool more quickly and the air temperature falls.
- The warmth comes instead from the sea. In West Antarctica, warm water masses from the Circumpolar Current travel up the continental slope to the shelf sea and then through trenches to places far below the floating ice shelves and glacier tongues. There they melt large areas of the ice masses from below. This increases the rate of ice calving and reduces the adhesion of ice flows to their bed – for example, where they rest on islands or submarine mountains that have until now acted like chocks and prevented the ice masses slipping. Without these brakes, the ice masses start to move faster. This means that the ice shelves and glacier tongues are not only retreating at record speed (iceberg calving) but are also transporting more ice from the interior to the sea (higher flow rate), causing the sea level to rise. In West Antarctica this vicious circle is likely to continue until the West Antarctic Ice Sheet has collapsed completely. Much of its ice mass rests on the sea floor and is therefore fully exposed to the warm water masses.
The flow rate of the vast Totten Glacier in East Antarctica is increasing in the same way. If its ice losses are added to those in West Antarctica and the Antarctic Peninsula, it becomes clear that total ice losses in Antarctica have trebled since 2010. Their contribution to global sea-level rise has also increased. Sea levels are now rising at 3.3 millimetres per year – twice the rate recorded in 1990. Almost two-thirds of the rise is attributed to the discharge of meltwater, while the remaining third is due to the expansion of seawater as it warms.
Antarctica has no permanent settlements and therefore only a few hundred researchers are witnesses to the retreat of the glaciers. In the Arctic, by contrast, some four million people are directly affected by climate change. These contrasting population figures are also explained by the geography of the polar regions. Humans have been able to access most Arctic regions on foot. Our ancestors left North Africa and settled Siberia around 45,000 years ago, later migrating over the Bering Land Bridge to North America. However, humans were unable to make a home for themselves in Greenland and the far north of Europe until the great ice sheets of the last ice age had melted and opened up the route to the Arctic.
- The exploration of the Arctic by Europeans began in the late 15th century when seafaring traders were looking for a northern sea route to India and China. The freezing temperatures and thick Arctic pack ice defeated many – including the Italian John Cabot who did, however, discover Labrador as he travelled west. Almost six decades later, the same conditions also halted the first Arctic expedition that attempted to sail through what is now the Northeast Passage. It would be another 175 years before Vitus Bering, an envoy of the Russian Tsar, set out from Kamchatka and became the first European to sail through the strait between Asia and North America that now bears his name. The first voyage through the Northeast Passage was accomplished by the Swede Adolf Erik Nordenskiöld on the steamship Vega in 1878/1879. A complete transit of the Northwest Passage, by contrast, was not achieved until 1906, when it was traversed by the Norwegian Roald Amundsen. This daring voyage took Amundsen three years.
While explorers such as Fridtjof Nansen were already surveying the Arctic Ocean in the late 19th century, Antarctica remained a white spot on the map for a very long time. It was the travel reports by the Baltic German naval officer Fabian Gottlieb von Bellingshausen, who circumnavigated Antarctica between 1819 and 1821 and spotted large herds of walruses and seals, that inspired whalers and seal hunters to press ever further south in their search for new fishing grounds and thus discover large parts of the Antarctic Peninsula and the Weddell Sea.
The hunters were followed by explorers and scientists from Britain and Germany. They divided Antarctica into quadrants and explored it in a number of expeditions between 1901 and 1905. However, the findings of the first German Antarctic expedition, led by Erich von Drygalski, received little public recognition. This expedition took place at the start of the era of colonial imperialism: polar research was becoming a sporting contest that was more about being the first nation to advance into unknown territory or reach the pole than about scientific discovery. Members of these expeditions faced deadly dangers every step of the way. Among the best-known of those who lost their lives to Antarctica are the British captain Robert Falcon Scott and his companions. In 1911 they lost the race to the South Pole to the Norwegian Roald Amundsen and died on the inland Antarctic ice on their journey back.
After the First World War, as technology improved and expeditions became increasingly professionalized, the key role of the Arctic and Antarctic in the Earth’s climate also came to be recognized. The standing of polar research increased considerably as a result. International scientific cooperation paved the way for the Antarctic Treaty. The Treaty, which entered into force in 1961, still requires Antarctica to be protected and to be preserved for peace and science. It also places the power to make decisions on all matters relating to Antarctica in the hands of its active member states (Consultative States). Antarctica is therefore governed by the club of Antarctic nations.
- However, research is far from being the only human activity in the region. While commercial whaling is now prohibited, fishing is still permitted in some parts of the Southern Ocean. Catch quotas are limited and compliance is strictly monitored by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Environmentalists nevertheless criticize the fishing activity as a major intervention in the sensitive polar ecosystems. In addition, tens of thousands of cruise-ship passengers visit Antarctica each year, and the number is rising. The passage of ships cruising by the tourist highlights on the Antarctic Peninsula has now increased to such an extent that experts believe it is causing widespread damage to the native flora and fauna. Another problem is that an accident at sea requires search and rescue units to rush to the area from some distance away, and ice conditions – which are hard to forecast – can make rescue efforts very difficult.
Shipping along the Arctic coasts, too, is increasing, driven partly by the growing number of cruise ships but to a large extent by the increased resource mining activity in northern Russia, Scandinavia and North America. The Arctic is rich in minerals: one study estimates that 22 per cent of the world’s undiscovered oil and gas reserves lie north of the Arctic Circle. Coal, iron ore, rare earths and other minerals are also found in the region. Mining these resources could well become an attractive economic prospect for the Arctic nations, because global demand is increasing and the retreat of the ice is facilitating access to the northern regions. Russia alone plans to spend more than 160 billion US dollars in the coming years on developing the economies of its Arctic territories and expanding the Northern Sea Route. Financially powerful partner countries such as China and Saudi Arabia are supporting these plans in the hope that bilateral cooperation or participation in projects will secure them rights of access to Arctic resources.
Their economic strategies may be legitimate, but genuine farsightedness on climate issues is in short supply. Furthermore, growing ambitions in the Arctic seem to be leading to new political power struggles. The zone of peace, as the Arctic was termed for a short time after the Cold War, has once again become a geopolitical arena of hard-won compromises and wrangling over common interests. The same applies to the Antarctic. At the same time, joint solutions are urgently needed to protect the climate and the polar regions. As long as humankind carries on extracting and burning fossil fuels on a large scale, the heat spiral and the melting of the ice in the polar regions will continue – with catastrophic consequences for the whole world. Climate change has now become a climate crisis. A resolute approach is therefore required from all states to mitigate its impacts so that the Earth can continue to provide a suitable habitat for present and future generations.