Human and cryosphere interactions: Small-scale effects of cryosphere change on humans
Keywords: cryosphere, climate change, humans, native arctic populations
Climate change is one of the biggest challenges that humanity is facing today. It will cause, global effects that will have severe impacts on many aspects of human life (IPPC 2014). But some areas of the world will be more affected by these changes than others. One of these areas is the cryosphere. The global cryosphere encompasses all aspects of the frozen realm, including glaciers and ice sheets, sea ice, lake and river ice, permafrost, seasonal snow, and ice crystals in the atmosphere (Marshall 2012). There are three mayor cryosphere regions, these are: Antarctica, the Arctic Ocean and the extra polar snow and mountain environments. As these mountain ranges are located all over the globe, cryosphere areas can even be found along the equator. Climate change will be felt earlier and more severely in the cryosphere and in the arctic regions, than the rest of the world. This is the case because as snow cover, sea ice and ice sheets diminish, this will produce further warming as the albedo in these areas decreases (Slaymaker a. Kelly 2007). Changes in these areas due to climate change will have severe impact on the human way of life. Especially native inhabitants of these cryosphere areas will be affected, as they have lesser capabilities to adapt to these changes, which threaten their way of life. In this paper we will focus on the social and economic impacts of these changes, with a special focus on how native arctic inhabitants will be affected. They deserve a special focus as they are most affected by these changes, while only contributing little to the anthropogenic climate change (Hovelsrud et al. 2011). At first we will look at the different aspects of the cryosphere and the changes that occur in these different areas. As the cryosphere includes many different aspects, only the changes occurring in the following aspects will be examined: sea ice, glaciers and ice sheets, and permafrost. Afterwards a selection of small-scale impacts from these changes on different aspects of human life aspects will be explained. Here the wide range of different aspects of human life, which will be affected by these changes will be shown. In the end the findings will be concluded and an outlook into the future will be given.
2 Effects of cryosphere change on humans
2.1 Cryosphere changes
As already mentioned the cryosphere encompasses a number of different aspects. All these will be affected by the changing climate. Some of these changes can already be observed, but will most likely become even more apparent in the future.
2.1.1 Sea Ice
Sea ice is a thin layer of ice floating on the sea surface. It forms when the sea temperatures drop below the freezing point. It is a predominant feature of the polar oceans. The exchange of heat and mass between the atmosphere and ocean is strongly regulated by sea ice, as it isolates the sea surface from the usual atmospheric forcing. Warming in the arctic regions is highly expected to lead to a reduction in area that is covered by sea ice. This allows for an increase in solar radiation that can be absorbed by the ocean waters. This causes a further increase in temperatures (Slaymaker a. Kelly 2007). The summer extent of sea ice in the Arctic oceans has decreased by 25-30% from 1979 until 2012 (Olsen et al. 2011). Warming has also lead to a thinning of sea ice and older, thicker types of sea ice have been lost and not replenished.
The majority of sea ice nowadays is mostly consistent of first year sea ice, which is more susceptible to melt (Meier et al. 2011). This could lead to a nearly ice free Arctic Ocean in the summer, at the end of the century (Johannessen et al. 2004).
2.1.2 Glaciers and Ice Sheets
Glaciers are large thickened ice masses consisting of accumulated snow. Here it should be differentiated between polar ice sheets, as can be found on Green- land, and mountain glaciers, as can be found in a number of mountain ranges around the globe (Hambrey a. Alean 1992). They cover around 785,000 m2 and contain approximately 80% of the world fresh water supply (Barry a. Yew Gan 2011). Reports show a general decline in mass and volume of these glaciers and ice sheets. There has been a substantial acceleration in the rate of decline since 1995 and a further acceleration due to increased warming is predicted (Olsen et al. 2011). The decline in glacier mass is for one caused by higher annual temperatures, but also by changes in precipitation (Slaymaker a. Kelly 2007).
When looking at mountain glaciers the heterogeneity of the impacts of climate change should be noted. Glaciers located in more maritime regions, such as some glaciers in Norway, have seen positive volume changes, especially in the several last decades. But those located in continental regions, e.g. the glaciers in the Himalayan Mountains are losing volume at an accelerated rate (Dyurgerov a. Meier 2000). These changes in glacier mass also cause changes in glacial runoff. Annually there will be short-term increases in runoff due to the general increase in melting for most glaciers. There will be increases in runoff until a tipping point is reached, the so-called “peak water”. For some areas this is predicted to already occur in the year 2020 (GAO et al. 2018). But there will also be changes in seasonal runoff as the ablation season becomes longer and the accumulation season shortens. This can be seen for example in the Tian Shan mountains in Central Asia, where a decrease in summer runoff, most likely due to the pronounced glacier shrinkage and a longer ablation period, can already be observed (Sorg et al. 2012).
The Greenland ice sheet is also undergoing considerable change. It contains 10% of the global ice mass and is losing ice at a considerable rate. Ice loss has also accelerated in recent years (Chen et al. 2006)
Permafrost, or perennially frozen ground, is defined as rock or sediment in which the temperature remains below 0°C for two or more years. It occupies approximately 24% of the exposed land surface in the northern hemisphere. Permafrost covers vast areas in cold regions, e.g. in Siberia, but it can also be found in small “islands”, located in alpine regions (Barry a. Yew Gan 2011). Permafrost melt has increased significantly across the sporadic and discontinuous zones from 1941-2001. In some areas thaw rates between 1995-2002 rose by 200-300% relative to the rates from the period 1941- 1991. This is caused almost exclusively by an increase in air temperature (Camill 2005). The melting of permafrost is especially problematic since huge amounts of carbon are stored in the frozen soil. This carbon will be released into the atmosphere when the permafrost melts and accelerate climate change even further (Schuur a. Abbot 2011). The multiple consequences of the loss of permafrost for landforms and ecosystems can be profound (Olsen et al. 2011).
2.2 Impacts of cryosphere change
Hydropower is a very important part of the global electricity production. Millions of people depend on electricity produced in hydroelectric power plants. Hydropower plants located on rivers are highly dependant on the river runoff to produce electricity. In many regions of the world river runoff is highly dependant on water that it receives from melting glaciers during the ablation period, especially during the summer, when there tends to be less precipitation (Kulkarney et al. 2002).
Abbildung in dieser Leseprobe nicht enthalten
(Fig. 1: Future modelled changes in hydropower production 2050; Hamududu a. Killingtveit 2012)
As mentioned in part 2.1.2 of the paper, climate change will lead, in general, to glaciers diminishing. This will affect the annual and seasonal runoff. As in the short term there will be, for most glaciers, increases in runoff, this can be mostly considered positive for hydropower production. But when looking at the long term the impacts of the diminishing glaciers on the hydropower production are regionally heterogeneous. This was shown by Amududu a. Killingtveit 2012, who modelled the regional changes in hydropower production until the year 2050 (Figure 1). Here it can be seen that in some countries e.g. Canada, Russia and Norway the potential hydropower production increases by up to 20-25%. in other countries opposite consequences of the glacial melt can be observed. E.g. in Turkey and venezuela the potential hydropower production is expected to decrease by up to 15-20%. But as shown in another study by Salewicz 1996 about the hydroelectric potential of the Lake Kariba in Zambia and Zimbabwe, the impacts of climate change are difficult to predict as different models show different results. Thus even regions, which are generally predicted to benefit from the changes, could experience a reduction in their hydroelectric potential. This could in the worst case endanger part of humanities access to electricity, which would have negative social consequences. A reduction in hydroelectric production would also have negative economic consequences for the regions affected, but some regions will also benefit from the temporal plus in electricity production.
2.2.2 Shipping routes and geopolitics
Abbildung in dieser Leseprobe nicht enthalten
As seen in part 2.1.1 of the paper, sea ice in the Arctic Ocean is diminishing at a very fast rate. This offers some opportunities for the shipping industry. Sea routes in the Arctic Ocean will become more and longer accessible. The two main routes are the Northern Sea route located along Russia’s coast with the Arctic Ocean and the North-West Passage, which is located along Canada’s and Alaska’s northern coasts (Fig. 2). These routes significantly shorten the transportation time, and therefore also the shipping cost for some highly frequented routes. This can be seen in Fig. 3. This figure shows the estimated yearly mean freight rate (solid line) in US$/t for the Northern Sea Route, until the year 2100. Here a steady decline in freight rate can be observed. This will promote trade and therefore offer huge economic opportunities. The usage of these shorter shipping lanes also saves energy and reduces emissions. But the reduction in sea ice cover in these areas also creates new hazards for shipping, with drift ice and icebergs becoming potential hazards. Thus the consensus is that the economic possibilities could positively affect humanity, but the hazards could lead to potential environmental disasters (Khon et al. 2010). These could negatively affect human life, and especially native arctic populations.