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Glaciers And Climate Change Environmental Sciences Essay

The article is chiefly talk about the interaction between glaciers and clime alteration. Take the Tianshan No.1 Glacier as an illustration. Glacier produces in clime and by the impact of clime alteration. The glaciers change is the consequence of clime fluctuations. And glacier alterations in bend Acts of the Apostless on the natural environment that contribute to climate alteration. Tianshan No.1 Glacier has changed significantly in the past five decennaries, includes glacier surface firn features, ice formation zones, ice temperature, thickness, country and end point place, etc. These glacier alterations related to temperature rise, and respond to recent clime fluctuation. In add-on, alterations in the planetary clime and environment caused by glacier alteration, such as the addition of glacier overflow, low-lying rise, and the decrease of surface reflective powers caused by country shrinking etc. The interaction between glacier and clime alteration non merely has of import impacts on planetary clime fluctuation, but besides has great significance for the survey of clime and environment.

1. Introduction

Glacier is a big relentless organic structure of ice that forms where the accretion of snow exceeds its extirpation ( runing and sublimation ) over many old ages, frequently centuries. Its motion caused by the action of gravitation. Glacier ice is the largest reservoir of fresh water, back uping one tierce of the universe ‘s population. 11 % of the universe ‘s land country is covered by glaciers. The glacier chiefly distributed in the Antarctic, the Arctic and high-level parts of the in-between and low latitudes. It is a merchandise of the clime and a good index of clime, besides it acts on clime. The glaciers change, particularly alterations in mountain glaciers, is a barometer of planetary clime alteration. Precipitation, temperature is the chief clime factors that impacting glaciers. The precipitation decides glacier accretion, and temperatures decide extirpation. Therefore, the sum of precipitation, its distribution during the twelvemonth, and interannual variableness consequence glacier recharge and activities. While the temperature impacts ice formation and glacial thaw H2O. The precipitation and temperature codetermine the nature of the glacier, development and development.

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1.1 Glacier mass balance

Glacier mass balance is the cardinal factor that links glacier fluctuations and clime alteration. Climate alteration leads to matching alterations in the stuff balance province of glacier. While this sort of alteration in the mass balance of glacier can take to alter in glacier motion features and glacier thermic government, and therefore take to alterations in the glacier end point place, size and ice militias.

Glacier mass balance formular has two elements: glacier accretion and extirpation. Glacier ice accretion occurs through accretion of snow and other frozen precipitations, include rime ice, roll downing from hanging glaciers on drops and versants above, and re-freezing of glacier thaw H2O as overlying ice. The extirpation refers to the thaw of snow or ice that runs off the glacier, vaporization, sublimation, break uping, or erosive remotion of snow by air current. Air temperature is typically the dominant control of extirpation with precipitation exerting secondary control. With consecutive old ages in which accretion exceeds extirpation, a glacier will see positive mass balance, its end point will progress and frailty versa.

1.2 Research Significance

Current glacier recession under the planetary heating has aroused global attending. The sensitiveness of alpine glaciers to temperature alteration is found to be mostly amplified. The figure of withdrawing glaciers has improved significantly. For a figure of glaciers, shrinking rate appears to hold accelerated since the 1990s. Increase runing velocity of glaciers can take to sea degree rise and submergence of some coastal countries. Furthermore, it induces snow and ice related catastrophes, for illustration, glacier inundation and avalanche, which menace the life environment of human existences and wild animate beings, every bit good as alteration the wonts and features of many species. On the other manus, the disappearing of ice-covered parts on the Earth will in bend change the planetary clime government significantly. Ice screens, particularly those in the Polar Regions, can reflect a great trade of solar energy back to the outer infinite, which helps to maintain the Earth cool. However, with the ice screen thaw, the underlain land and the H2O will expose to the air, and therefore surely absorb much more solar radiation and do more ice thaw. The accelerated glacier recession in China is besides really obvious, particularly in Northwest China, where glacier thaw H2O overflow additions, country of glacier lessenings, end point retreats, snow line elevates and many little glaciers are vanishing. Glacier is known as the solid reservoir and the cradle of oasis in the waterless parts in Northwest China. It is the major H2O beginning for human life and development.

Study country

Tianshan No.1 Glacier ( 43 & A ; deg ; 6?Ni?? 86 & A ; deg ; 49?E ) is located at a tallness of 3,454 m above sea degree, and about 118 kilometers from Urumqi, the capital of Xinjiang Uygur Autonomous Region in China. It is the headwaters of Urumqi River, about 100km from Asia geographic centre. In add-on, it is considered one of the most of import dry land glacier theoretical accounts in Asia, and one of the most celebrated 10 glaciers in the universe.

It has the longest record of mass balance in the Asiatic high mountains. The glacial record shows that the glacier has shrunk significantly in last 30 old ages. The Tianshan No.1 glacier is shriveling at the velocity of 3.5 m and 5.9 m every twelvemonth on its E and west sides severally. In the past 45 old ages, its coverage has dropped from 1.94 sq km to 1.68 sq kilometer, a 13.8 % loss. The land here is characteristic of alluvial sedimentations by glaciers, so those carry oning geological studies can research the development class of the Urumqi River in the past 1000000s of old ages.

Glacier-climate interactions

The glaciers change is the inevitable consequence of clime fluctuations. Atmospheric precipitation and heat position alterations, profound impact on the growing and diminution of the progress and retreat of the polar ice caps and mountain glaciers. By detecting the glacier alterations, understanding the glacier moral force of planetary or regional, and calculating planetary clime alteration. Glaciers in China are chiefly little and moderate-sized mountain glaciers in low latitude. They have a good response for climate fluctuations of short rhythm.

Since the Little Ice Age, the general tendency of glaciers around the universe is retreat chiefly. The Fourth Assessment Report of IPCC ( Intergovernmental Panel on Climate Change ) pointed out that impacts of clime warming on many phenomena are singular, such as shrinking of the Arctic ice cap, acceleration of sea degree rise, recession of glacier end point all over the universe, dissolving of permafrost, earlier interrupting up of ice in the rivers and lakes, protraction of harvest turning season in the center and high latitudes, and alterations in the distribution and behaviour of animate beings and workss.

Take Tianshan No.1 Glacier as an illustration, glacier has changed significantly in the past five decennaries, includes glacier surface firn features, ice formation zones, ice temperature, thickness, country and end point place, etc.

The chief thrust forces to the glacier alteration are the heat and H2O conditions of the glacier covered part. Glacier thaw is tightly related to the temperature fluctuation. Harmonizing to the records of meteoric Stationss in the headwaters part, the air temperature has been lifting since 1985, and the inclination of rise has accelerated since 1995. From 1997 up to show, the mean temperature has increased by 1a„? , as the largest rise extent in recent 50 old ages. The observation of Daxigou Meteorological Station shows that the mean one-year temperature increased by 0.8a„? ( 0.017a„?/a ) during 1958~2004 with obvious temperature rises particularly in fall and winter.

The features of snow-firn stratigraphy and ice formation zone of the glacier are sensitive to the clime alteration. The clime warming greatly promotes the glacier thaw, which accordingly alters the belongingss of snow battalion stratigraphy and ice formation zones. Harmonizing to the analyses of 60 perpendicular profiles of snow cavities obtained from the accretion zone of Tianshan No. 1 Glacier during the period of 1961~2005, the building of snowfirn stratigraphy had a singular alteration. The proportion of harsh firn in the snow cavities increased from 40 % to 65 % , and all right firn decreased from 25 % to 7 % . This indicates that snow battalion is badly affected by thaw H2O, which accelerates the procedure of transmutation from all right firn to coarse firn. Compared with the snow-firn stratigraphic components and its construction in the sixtiess and 1980s, current specimens show singular alterations, such as decrease of snow-pack deepness, simplification of construction, bleary boundaries of snow beds, and mergence of dust beds within snow battalion.

The mass balance alteration is an undelayed response of the glacier to climate alteration, and it is a sensitive index for clime alteration. For the mass balance of Tianshan No. 1 Glacier, both one-year value and cumulative value have shown negative additions since 1958, bespeaking terrible mass losingss. In clip of 1958-2004, there were 31 negative mass balance old ages against 15 positive old ages. From 1997 to today, the negative mass balance has lasted for 10 old ages, which ne’er happened of all time earlier. The mean one-year mass balance during 1958-2004 was -233.6 mm H2O equivalent ( weq ) and the cumulative mass balance added up to -10746.5 millimeter weq, which means that the mean thickness of the glacier about reduced 12 m and the volume loss was about 20.62-106m3 weq.

Unlike the glaciers in Europe and mid-America, which accumulate in winter and lose mass in summer, Tianshan No. 1 Glacier has both accretion and extirpation in summer, and there is small snowfall in winter. Previous researches on Tianshan No.1 Glacier have shown that the mass balance was connected with the precipitation, and negatively correlated with air temperature in summer ( May to August ) . However, with the addition in both current temperature and precipitation, mass balance has different responses to them.

Retreat of glacier and its impact

Under the clime heating, the jurisprudence of terminus recession and ice thickness decrease are followed by glacier shrinking. The alterations of glacier country and end point place consequence from short-run and long-run clime alterations. Tianshan No. 1 Glacier has an overall shrinking since the twelvemonth 1959 when the observation initiated. The E and west subdivisions of Tianshan No. 1 Glacier separated into two independent glaciers in 1993 due to extirpation, during this period ( 1959~1993 ) the entire end point retreat was observed as 139.72 m at an mean retreat rate of 4.5 m per twelvemonth. From 1993 to 2004, the east subdivision of Tianshan No. 1 Glacier retreated at an mean rate of 3.5 m per twelvemonth ( a sum of 38.7 m ) , and the West subdivision retreated at a rate of 5.8 m per twelvemonth ( a sum of 64.1 m ) . The recession rate ( the ratio of receded length to the original glacier length ) of Tianshan No. 1 Glacier was 7.8 % in the period of 1962~2004 for the east subdivision and 10.5 % for the West subdivision, severally. The west subdivision end point retreated 6.92 m in 1999 and 6.95 m in 2000, severally, which are the highest records in the observation records. Since the ice flow speeds in matching old ages were observed stable at end point, it is improbable that the important retreats were caused by the decrease of ice flux from upper parts of the glacier, and therefore, it is clearly due to the intense ice runing. With end point fadeout, its height at the same time elevated from 3736 m a.s.l in 1962 to 3746m a.s.l in 1980, and the east subdivision end point height in 2005 was 3777 m a.s.l, 31 m higher than that in 1980. Glacial extirpation will non merely take to inundations, landslides and other natural catastrophes, but besides lead glacier overflow besides to be reduced, and do the downstream fresh water resources bit by bit scarceness.

Research

Accumulative temperature is a major factor impacting glacier extirpation. Accumulative temperature, viz. , the amount of day-to-day mean air temperature above the runing point during extirpation season is closely related to the country of glacier extirpation zone. Harmonizing to the old surveies, the one-year cumulative temperature in the headwaters part of Urumqi River rose by 133a„?•d during 1960~2004. Its inclination is coinciding with that of mean one-year temperature, i.e. since the late 1980s the cumulative temperature has risen unusually, and meanwhile the clime heating showed a accelerated inclination ( see Fig.1 ) .

Fig. 1 Mass balance of Tianshan Glacier No. 1, accumulated temperature ( Ti?z0a„? ) and their tendencies during 1958~2003

During the period of 1962~2006, the country of Tianshan No. 1 Glacier reduced by 0.27 km2. From 1992 to 2006, the glacier country decreased by 0.16 km2, which is 0.04 km2 more than that from 1962 to 1992. Based on the observation over the past 43 old ages, glaciologists found that the lessening of glacier country has accelerated since 1986. Figure 2 shows the recession procedure of the glacier end point, and Fig. 3 displays the morphological forms of Tianshan No. 1 Glacier in different old ages.

Fig. 2 Morphologic alteration of Tianshan No. 1 Glacier over clip. ( Dashed lines represent the glacial boundaries of 1962, 1973,1980, 1984, 1986, 1994 and 2001 ; solid lines represent the glacial boundary of 2006 )

Fig. 3 Morphologic alterations of Tianshan No. 1 Glacier in the old ages of 1962, 1988, 1993,1996, 2001, and 2005

Glacial temperature, particularly the temperature of the ice below active beds, determines many physical features of the glacier. The alteration of ice temperature indicates the alteration in the glacier ‘s cold modesty, which can do the alteration of the sensitiveness of the glacier in reply to climate heating. Comparing with three perpendicular profiles of ice temperature at the height of 3840 m in the old ages of 1986, 2001 and 2006 ( Fig. 4 ) , The glaciologist found that it is about 10m in deepness that the lower boundary of the active bed of the glacier, below which the ice temperature is little affected by the seasonal fluctuation of air temperature. If disregarding the alteration of the ice temperature in active bed, the ice temperature from 10 to 22 m in deepness had a singular rise during 1986~2001. The rise scope decreased with the largest value of 0.9a„? ( 10 % ) at 10 m depth below ice surface and a negligible alteration at 22 m deepness. Similarly, compared with the ice temperature in 2001, the ice temperature in 2006 had an obvious rise, with an addition of 0.4a„? at 10 m deepness. Normally, the ice temperature at the lower boundary of active bed is indistinguishable with the one-year mean air temperature. Therefore, the rise of ice temperature is doubtless the consequence of increasingly climate heating.

Fig. 4 Comparison of ice temperature profiles obtained in 1986, 2001 and 2006 at a site around 3840 m a.s.l on No. 1 Glacier in Tianshan Mountain

Fig. 5 Annual mass balance of Tianshan No. 1 Glacier against summer temperature ( May-August ) , one-year temperature and one-year precipitation at Daxigou Meteorological Station

Figure 5 shows the fluctuations of mass balance, summer temperature, one-year temperature and precipitation during1959-2004, from which research worker found that during 1960-1986 the mass balance had a weak negative correlativity with temperature, while a clear positive correlativity with precipitation, bespeaking that the mass balance is controlled by both temperature and precipitation, with precipitation as the chief factor. During this period, the one-year mean temperature and precipitation were -5.4a„?and 425.8 millimeter, severally. However, the correlativity has altered since 1986. The mass balance showed a negative correlativity with temperature and no correlativity with precipitation, bespeaking that the mass balance was chiefly controlled by temperature. During this period, mean one-year temperature and precipitation were -4.9a„?and 491.6 millimeter, severally. The consequences show that temperature and precipitation are normally control mass balance, but temperature is chiefly control mass balance when temperature rises to a certain degree, though with high precipitation.

Existing policy for clime alteration version

Equally early as in 2006, the Urumqi municipal authorities had made aˆ‹aˆ‹provisions: from pollution to protect of import H2O beginning in Urumqi, prohibit visitants in Tianshan Glacier. But the absence of fence and secure, some tourers into the glacier part through assorted ways, changed the environment of the glacier. The deputy of independent parts, Chunyu Cui, proposed to set up an countries about National Tianshan Glacier nature militias of Xinjiang in 2012. But the policy had non yet been introduced.

Decisions and recommendations

Decisions

Taking Tianshan No. 1 Glacier as an illustration, this article talk about the response of glacier to current clime heating based on the observation dataset of 50 old ages. The decision was drawn as follows:

Since the 1960s, snow firn stratigraphic constituents and construction have shown singular alterations, including cut downing snow battalion deepness, simplifying construction, and befoging boundaries of snow beds with different features. The country of glacier extirpation zone keeps spread outing, the places of ice formation zones move upwards, and the top of east subdivision has already shown the feature of extirpation zone.

During 1962~2006, the country of Tianshan No. 1 Glacier reduced by 0.27 km2 ( 14 % ) . The shrinkage inclination has accelerated in recent old ages. At the height of 3840 m a.s.l, a important rise in the ice temperature was observed during 1986-2001, with the highest rise value of 0.9a„? at deepness of10 m. From 2001 to 2006, the ice temperature rose by 0.4a„?at deepness of 10 m.

Average one-year mass balance during 1958-2004 was -233.6 millimeter weq, with the cumulative mass balance of-10746.5 millimeter weq, which indicates that the thickness of Tianshan No. 1 Glacier reduced about 12 m and loss of volume came to about 20.62-106 M3. Mass balance is controlled by both temperature and precipitation before 1986, with precipitation as the chief factor. But after 1986, mass balance is controlled chiefly by temperature, though with high precipitation.

Recommendations

In order to protect the glaciers, many experts hope to take steps every bit shortly as possible to protect the natural environment of the glaciers in Xinjiang in conformity with the jurisprudence, decelerate down semisynthetic devastation. On the other manus, encourage and support to utilize the unreal conditions to the full developed air H2O resources, to transport out the unreal H2O undertaking, in order to increase the glaciers snow.

There are some suggestions:

Through energy preservation, development of natural gas, hydropower, coal bed methane use, bio-energy, weave energy, solar energy, geothermic energy. Strengthen the planning and execution of ecological building and environmental protection.

Strengthening clime alteration communicating and scientific popularisation to raise consciousness of clime alteration in the whole society.

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