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The Oceans and Atmospheric Regulation
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The atmosphere and the surface ocean waters are closely connected both in temperature and in CO2 concentrations. The atmosphere contains less than 1.7 per cent of the CO2, held by the oceans, and the amount absorbed by the surface ocean water rapidly regulates the concentration in the atmosphere. The absorption of CO2 by the oceans is greatest where the water is rich in organic matter or where it is cold. Thus the oceans are capable of regulating atmospheric CO2, of changing the greenhouse effect and of contributing to climate change. The most important aspect of carbon cycle linking atmosphere and ocean is the difference between the partial pressure of CO2 in the lower atmosphere and that in the upper oceanic layer. This results in atmospheric CO2 being dissolved in the oceans and in some of this being subsequently converted into particulate carbon, mainly through the agency of plankton, ultimately sinking to form carbon-rich deposits in the deep ocean as part of a cycle lasting hundreds of years. Thus two of the major effects of ocean surface warming would be to increase its СО2 equilibrium partial pressure and to decrease the abundance of plankton. Both of these effects would tend to decrease the oceanic uptake of CO2 and therefore to increase its atmospheric concentration, thereby producing a positive feedback (i.e. enhancing) effect on global warming. However, the operation of the atmosphere-ocean system is sufficiently complex that, for example, global warming may so increase oceanic convective mixing that the resulting imports of cooler water and plankton into the surface layers might exert a break (i.e. negative feedback) on the system warming.
Упражнение 11.
Составьте 5 общих вопросов к тексту The Oceans and Atmospheric Regulation.
Упражнение 12.
(Парная работа) Ответьте на вопросы, составленные в упражнении 11.
Lesson 2
Упражнение 1.
Попытайтесь вспомнить, что Вам известно о влиянии глобального потепления на снежный и ледовый покров Земли.
Подумайте и приведите 10–15 слов, которые могут встретиться в тексте.
Прочитайте и переведите текст.
Snow and Ice
The effects of the twentieth-century climate change on global snow and ice cover are apparent in many ways, but the responses differ widely as a result of the different factors and time scales involved. Snow cover is essentially seasonal, related to storm system precipitation and temperature levels. Sea ice is also seasonal around much of the Antarctic continent and the marginal seas of the Arctic Ocean, but the central Arctic has thick multi-year ice. Seasonal (or first-year) ice grows and decays in response to ocean surface temperature, radiation balance, snowfalland ice motion due to winds and currents. The loss of multi-year ice from the Arctic is mainly through ice export. Glacier ice builds up from the net balance of snow accumulation and summer melt (ablation), but glacier flow transports ice towards the terminus, where it may melt or calve into water. In small glaciers the ice may have a residence time of 1 Os-100s of years, but in ice caps and ice sheets this increases to 103 -106 years.
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In the twentieth century there was a rapid retreat of most of the world's glaciers. Glaciers in the North Atlantic area retreated during the 1920s to the mid-1960s and since 1980s, due largely to temperature increases, which have the effect of lengthening the ablation season with the corresponding raising of the snowline. In the last 10-15 years the freezing level in the troposphere has risen in the inner tropics by 100-150m, contributing to rapid ice loss on equatorial glaciers in East Africa and the Northern Andes. Also in the last decade or so, some glaciers in maritime climates (western North America and Scandinavia) have shown advances, due to heavier snowfalls during warmer winters. Major alpine glaciers in many areas of the world have lost mass and shrunk since the late nineteenth century, whereas smaller ones show short-term fluctuations in response to climatic variability. Projections for AD 2050 suggest that one quarter of the present glacier mass may disappear.
Another tendency illustrating world warming is the retreat of Arctic sea ice. Ports in the Arctic remained free of ice for longer periods during the 1920s – 50-s for example. This trend was reversed in the 1960-s~70-s, but since the late 1980-s the summer extent of Arctic ice has decreased, with large reductions, particularly in the Eurasian Arctic, in 1990, 1993 and 1995. There appears to be no general trend in Antarctic ice extent, although comprehensive records began only with all-weather satellite coverage in 1973. Sea ice in both polar regions is expected to shrink and thin with continued warming, but modelling of these processes remains rudimentary.
Major iceberg calving events have occurred along the Ross Ice Shelf and on the Larsen Ice Shelf of the Antarctic Peninsular, but the causes of such calving are more related to the long history of the ice shelves and ice dynamics than to recent climate trends.
Snow cover extent shows perhaps the clearest indication of a response to recent temperature trends. Northern hemisphere snow cover has been mapped by visible satellite images since 1966. Compared with the 1970s–mid- 1980s, annual snow cover since 1988 has shrunk by about 10 per cent. The decrease is most pronounced in spring and is well-correlated with springtime warming. Winter snow extent shows little or no change. Nevertheless, annual snowfall in North America north of 55° increased during 1950-90. Much work remains to be done to analyse station snowfall and snow depth records for other countries, particularly since these variables are difficult to measure and the design of gauges and wind shields has changed through time. Scenarios for AD 2050 suggest a shorter snow cover period in North America, with decrease of 70 per cent over the Great Plains. In alpine areas snow lines will rise by 100–400m, depending on precipitation.
Упражнение 2.
Ответьте на следующие вопросы:
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1. What does seasonal ice cover depend upon?
2. Have the world's glaciers moved forward or backward during the last two centuries?
3. How much has the freezing level in the troposphere in the inner tropics risen by?
4. How much of the present glacier mass might have disappeared by 2050?
5. How long were ports in the Arctic free of ice in different periods of the XX century?
6. When did records of Antarctic ice extent begin?
7. What are the trends of sea ice in the polar regions like?
8. How long has northern hemisphere snow cover been mapped?
9. Did annual snowfall in North America north of 55° go up or down in the middle of the XX century?
10. What are the prospects of snow cover in North America for 2050?
Упражнение 3.
Найдите в тексте термины, соответствующие следующим выражениям.
| broadly | go back | quick | going up and down |
| rainfall | thanks to | go up | change direction to the |
| summer melt | become longer | ten years | opposite |
| reduce | carry | mountain (adj.) | every year |
Упражнение 4.
Добавьте одно или более слов в каждую группу.
all-weather satellite multi-year XX century climate
snow cover snow depth iceberg calving
ocean surface storm system northern hemisphere snow
Упражнение 5.
Переведите следующие слова на русский язык.
| through | perhaps | also | around | since |
| although/though | nevertheless | as well as | about | over |
| particularly | whereas | which | therefore | such/so |
Упражнение 6.
Из слов в правой и левой колонке образуйте цепочки существительных.
ice images
snow surface
satellite range
temperature loss
summer cover
springtime flow
glacier melt
ocean advances
Упражнение 7.
Вставьте пропущенные буквы в приведенные ниже слова из текста:
- - nt- bu- e, r - co~s, -ncr--se, -aus-, c-r-e-t, r- - r- a t, -ar-t-me, -e-gt-en, s-r-nk, -cc—, -lu--ua--on, re--in, m-a-ur-.
Упражнение 8.
Прочитайте следующие выражения:
1989, 40°S, 107, 1970s, 75%, lA, Va, 0. 25.
Упражнение 9.
Вставьте в пропуски в тексте подходящие слова: contributes, although, those, frozen, a little, level, dissolved, reflecting.
Glaciers and ice sheets both affect and are affected by changes in Earth's climate.
They are ________ fresh-water reservoirs that change volume in response to changesin temperature and snowfall. Were the ice sheets in Greenland and Antarctica to melt entirely, global sea would rise about 75 meters.
_____ great polar ice sheets also contribute to the formation of cold salty sea water that sinks to fill the deep ocean. When the ice forms, it uses only water; the salts are left behind, increasing the water salinity. Ice and snow play a role in the global energy balance by from 60 to 90 per cent of the solar radiation they receive.
On a scale more relevant to peoples' daily lives, the seasonal melting of mountain glaciers to summertime river flow and to the ongoing sea level rise.
Today permanent ice covers ______________ less than 10 per cent of Earth's land surface, yet contains almost 87 per cent of its fresh water. _______ glaciers and ice caps make up less than 1 per cent of Earth's terrestrial ice volume, their small size allows them to respond rapidly to climate change.
Упражнение 11.
Прочитайте текст за 10 минут и передайте его содержание максимально подробно.
Human Influences
Human influences can alter soil water conditions in a large number of ways, ranging from irrigation schemes, which considerably increase the amount of water entering the soil, to the construction of large impermeable surfaces in urban areas, which prevent water from infiltrating into the soil. These effects, which describe in engineering and agricultural texts, are outside the scope of this chapter. Accordingly, only
a brief account of a few examples given below.
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Agricultural practices have the most widespread effect on soil water conditions. Irrigation and artificial drainage (to use) throughout the world as a means to increase crop production. Agricultural drainage schemes comprise open ditches or surface pipes. These are deeper and closer together than the natural stream channels, so increasing the hydraulic gradient in the soil and lowering the water table more rapidly between storms than would otherwise occur. A detailed account of the distribution and purpose of field drainage in England and Wales, the most intensively drained part of Europe, was given by Robinson and Armstrong.
Tillage and cultivation operations may also alter the movement and distribution of soil water. Ploughing increases the pore spaces in the upper soil and may encourage lateral flow in the topsoil, with less downflow into the subsoil. It is showed by tracer studies that ploughing disrupts the vertical continuity with pores in the soil below. Infiltrating water is found to penetrate to greater depths on land that had not been ploughed.
A change in agricultural land use from grassland to arable cropping may also affect interception and evaporation losses, especially if the arable farming leaves the soil bare at times of the year. Heavy rainfall on land with little vegetation cover may lead to crusting and sealing of the soil surface, reducing infiltration. Forestry may have a large effect on interception and evaporation losses, causing soils under trees to be much drier than under other types of vegetation. In areas where the natural water table is close to the ground surface, groundwater abstraction may lower the water table, causing significant drying of the soil and a reduction in plant growth. The most extreme case of human influence on soil water conditions, however, perhaps is found in areas of steep topography, where deforestation and bad farming practices lead to accelerated erosion and may, in severe cases, ultimately result in the complete destruction of the soil.
Упражнение 9.
Письменно переведите текст. (Контрольное время – 25 минут)
Hydrology
The difficulties of deducing the possible effects of climate change on hydrological regimes stem.
From attempts to adapt the essentially large-scale climatic predictions derived from General Circulation Models to the smaller catchment scales appropriate to hydrological modelling; from errors in the climatic and hydrological data; and from converting climatic inputs into hydrological responses.
The climatic change, predicted by current modelling may be expected to lead to:
1. A more vigorous world hydrological cycle.
2. More severe droughts and/or floods in some places and less severe ones in others.
3. An increase in precipitation intensities withpossibly more extreme rainfall events.
4. Greater hydrological effects of climate change in drier areas than in wetter ones.
5. An increase in overall potential evapotranspiration.
6. An increase in the variabilityof river discharges along with that of rainfall.
7. A shift of runoff peak times from spring to winter in continental and mountain areas if snowfall decreases.
8. The greatest falls in lake water levels in dry regions with high evaporation.
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The implication that the hydrological impacts of climate change will be greatest in currently arid or semi-arid regions may well mean that the more severe runoff events there will be particularly destructive in terms of soil erosion.
Lesson 3
Упражнение 1.
Прочитайте и переведите текст.
Vegetation
An increase in CO2, may he expected to enhance global plant growth up to a saturation value of possibly around 1,000 ppmv, when a saturation limit may be reached. However, deforestation could decrease the biosphere's capacity to act as a carbon sink. A sustained increase of only 1°C can cause considerable change in tree growth, regeneration and species extent. Species migrate only slowly but, eventually, extensive forested areas may change to new vegetation types, and it has been estimated that 33 per cent of the present forest area could be affected, with as high as 65 per cent of the boreal zone being subject to change. Alpine tree lines appear to be quite resistant to climatic fluctuations. However, surveys of plant species on peaks in the European Alps indicate an upward migration of alpine plants by 1-4 m per decade during this century.
Tropical forests are likely to be affected more by human deforestation than by climate change. However, decreases of soil moisture are particularly destructive in hydrologically marginal areas. In the Amazon, climatic predictions support the idea of increased convection, and therefore of rainfall, in its western equatorial portion, where present rainfall is most abundant. Because of the particularly high temperature rises predicted for the high northern latitudes, boreal forests are expected to be strongly affected by their advance northwards into tundra regions. This may produce the positive feedback effect of further regional warming because of the lower albedo of forests during the snow season. Climate change over the next 100 years may be expected to exert the least changes on temperate forests.
Wetlands at present cover 4-6 per cent of the land surface, having been reduced by human activities by more than half during the past century. Climate change will affect wetlands mainly by altering their hydrological regimes. Although general predictions are difficult to make, it is believed that eastern China, the USA and southern Europe will suffer a natural decline in the area of wetlands during the next century, decreasing the methane flux to the atmosphere.
Drier regions may be expected to be more profoundly affected than wet ones. Rangelands (including grasslands, shrublands, savannas, hot and cold deserts, and tundra) occupy 51 per cent of the terrestrial land surface, contain 36 per cent of the world's total carbon in their biomass and support half the world's livestock. The lower-latitude rangelands are most at risk both because an increase in CO2 increasing the carbon/nitrogen ratio) will decrease e nutrient value of forage and because the increasing frequency of extreme events will cause environmental degradation. Most deserts are likely to become better and not significantly wetter, increases in rainfall being generally associated with increased storm intensity. Greater wind speeds and evaporation may be expected to increase wind erosion, capillary rise and salinization of soils. Central Australia is one of thefew places where desert conditions may improve.
It is obvious from the foregoing that a major effect of climate change involving global warming is that desiccation and soil erosion will increase in currently semi-arid regions, rangelands and savannas adjacent to the world's deserts. This will increase the current rate of desertification, which is proceeding at six million hectares per year partly dueto high rainfall variability and partly to unsuitable human agricultural activities such as overgrazing and over-intensive cultivation.
Упражнение 2.
Прочитайте следующие слова и определите их соответствия в русском языке:
regeneration, type, extensive, migration, idea, tundra, regional, season, human, hydrological, regime, natural, biomass, risk, degradation, intensity, erosion, salinization, effect, hectare, agricultural, cultivation.
Упражнение 3.
Заполните таблицу, образовав недостающие части речи.
| v. | n. | adj. | adv. |
| suggest relate | increase response | particularly |
Упражнение 4.
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В правой колонке найдите русские эквиваленты следующих английских словосочетаний из текста Vegetation:
| 1. saturation value 2. considerable changes 3. climatic fluctuation 4. more then half 5. mainly 6. environmental degradation 7. semi-arid region 8. current rate 9. temperate forests 10. however 11. because of | a. полузасушливый регион b. главным образом c. современная скорость d. уровень насыщения e. значительные изменения f. леса умеренной зоны g. из-за h. деградация окружающей среды i. однако j. колебания климата k. более половины |
Упражнение 6.
Составьте 5 вопросов к первому абзацу текста Vegetation.
Упражнение 7.
(Парная работа) Ответьте на вопросы в упражнении 6.
Упражнение 8.
Найдите подлежащее в каждом предложении второго абзаца текста Vegetation.
Упражнение 9.
Вставьте соответствующий предлог и подберите определение к каждому слову: upon off from in out for on over.
| 1. carry … 2 depend … 3. go … 4. look … 5. result … 6. give 7. take 8. get | a. зависеть от b. продолжать c. быть следствием e. преодолевать f. искать g. взлетать h. уступать i. выполнять |
Упражнение 10.
Прочитайте текст и найдите ответы на следующие вопросы:
1. Каковы два основных способа воздействия вырубки мировых лесов на климат Земли?
2. К каким изменениям в составе атмосферы привело бы уничтожение тропических лесов?
3. Каким образом вырубка тропических лесов сказалась бы на сезонном характере осадков, уровне грунтовых вод, поверхностном стоке?
4. Может ли уничтожение лесов привести к деградации почвенного покрова и изменению температурного режима?
Deforestation
Deforestation affects world climate in two main ways – first, by altering the atmospheric composition and, second, by affecting the hydrological cycle and local soil conditions:
1 Forests store great amounts of carbon dioxide, so buffering the carbon dioxide cycle in the atmosphere. The carbon retained in the vegetation of the Amazon basin is equivalent to at least 20 per cent of the entire atmospheric CO2. Destruction of the vegetation would release about four-fifths of this to the atmosphere, about one-half of which would dissolve in the oceans, but the other half would be added to the 16 per cent increase of atmospheric CO2 already observed this century. The effect of this would be to accelerate the increase of world temperatures. A further effect of tropical forest destruction would be to reduce the natural production of nitrous oxide. Tropical forests and their soils produce up to one-half of the world's nitrous oxide, which helps to destroy stratospheric ozone. Any increase in ozone would warm the stratosphere, but lower global surface temperatures.
2 Dense tropical forests have a great effect on the hydrological cycle through their high evapotran-spiration and their reduction of surface runoff (about one-third of the rain never reaches the ground, being intercepted and evaporating off the leaves). Forest destruction decreases evapo-transpiration, atmospheric humidity, local rainfall amounts, interception, effective soil depth, the height of the water table and surface roughness (and thereby atmospheric turbulence and heat transfer). Conversely, deforestation increases the seasonality of rainfall, surface runoff, soil erosion, soil temperatures and surface albedo (and therefore near-surface air temperatures). All these tendencies operate to degrade existing primary and secondary tropical forests into savanna. Models designed to simulate the operation of Amazonian forests having a 27°C air temperature and a mean monthly rainfall of 220 mm (falling in four showers every third day, each lasting 30 minutes at an intensity of 0.003 mm s"1) predict that their degradation to savanna conditions would lead to a decrease of evapotranspiration by up to 40 per cent, an increase of runoff from 14 per cent of rainfall to 43 per cent, and an average increase of soil temperature from 27 to 32°C.
Упражнение 11.
В правой колонке найдите русские эквиваленты следующих английских словосочетаний из текста Deforestation:
| 1. soil conditions 2. tropical forests 3. evapotranspiration 4. at least 5. surface ranoff 6. water table 7. surface roughness 8. heat transfer 9. nitrous oxide 10. atmospheric composition | a. по крайней мере b. окись азота c. водное зеркало d. перенос тепла e. шероховатость поверхности f. совокупное испарение g. структура почвы h. тропические леса i. состав атмосферы j. поверхностный сток |
Упражнение 12.
Найдите в каждом предложении текста Deforestation подлежащее и сказуемое. Определите время и залог сказуемого.
Упражнение 13.
Письменно переведите текст. (Контрольное время – 15 минут)
Forests
Forests have a lower albedo (<0.10 for conifers) than most other vegetated surfaces (0.20–0.25). Their vertical structure produces
a number of distinct microclimatic layers, particularly in tropical rainforests. Wind speeds are characteristically low in forests and trees form important shelter belts. Unlike short vegetation, various types of tree exhibit a variety of rates of evapotranspiration and thereby differentially affect local temperatures and forest humidity. The effect of forests on precipitation has not yet been resolved but they may have a marginal topographic effect under convective conditions in temperate regions. The disposition of forest moisture is very much affected by canopy interception and evaporation, but forested catchments appear to have greater evapotranspiration losses than ones with a grass cover. Another major feature of forest microclimates is their lower temperatures and smaller diurnal ranges' compared with surrounding areas.
Блок 7
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