The graph shows how thea ve rage world tempera t u rehas risen since re c o rds werefirst kept in 1860. The ove ra l lrise seems small, but the topten hottest years have allo c c u r red since 1980, and the1990s was the hottest decadeeve r.

The increase of certain gasesin the a t m o s p h e re ,particularly carbon d i o x i d e ,methane, CFCs and nitro u soxide, cause the rising tempera t u res. Th e ya re called ‘greenhouse gases’ as they allowheat from the sun to reach the earth, butp revent heat radiated from the earth fro mpassing into the atmosphere .

Melting the Arctic ice

The Arctic is warming up faster than otherparts of the earth. This is the result ofchanges in the albedo of its surface. Albedorefers to the proportion of heat which isreflected back into the atmosphere. For lightsurfaces such as snow, the albedo is about80%. Warming has caused ice and snow tomelt over large areas, exposing darke rsurfaces, such as water and rock. Th e s e

N o r way and global wa r m i n g

The average rising world temperature 1860–2000

Polar bearsroam the icein search offood

1860 1880 1900 1920 1940 1960 1980 2000

1.0

0.5

0.0

-0.5

-1.0

h a ve an albedo of about 20% and absorbmuch more heat from the sun. ConsequentlyA rctic areas are warming up more quickly. Itis estimated that since 1960 there has beena 20% decrease in snow cover and a 40%thinning of the Arctic ice cap.

Polar bears are suffering

The polar bear is becoming an endangeredspecies. It spends most of its life on sea ice,where its main source of food is seals – theringed seal and the large bearded seal. Amajor reduction in the extent of the icewould threaten the survival of the polarb e a r, which would lose its habitat and,possibly, its main food supply.

The world is getting warmer and is warming most rapidly in high

latitudes in the northern hemisphere. This could have significant effects

in Norway.

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Case Study

The effects of warming on land

Permafrost

Permafrost is ground that is permanentlyfrozen. It underlies virtually all the land inthe Arctic, such as Svalbard and much of thehigher land south of the Arctic Circle. Highertemperatures will melt much of the ice inthe ground and cause a number ofproblems.

n Drainage is more difficult because morewater lies on or near the surface.

n There is a danger of slumping andmudflows.

n Exposed ground releases carbondioxide and methane to theatmosphere.

n Buildings with foundations in thepermafrost become unstable, forexample in Svalbard, where coal ismined.

n Roads may buckle and need costlyreplacement.

Coniferous forest

About a quarter of the surface area ofNorway is forested, mainly by conifers suchas pine and spruce. Research indicates thattrees are growing faster and have spreadupslope by 100-165 metres in the last

The tundrain summer

Cross-countryskiingthrough thetrees

Norwegianwoodland inwinter

c e n t u r y. These changeshave been caused by lesssevere winters, and theearlier and morecomplete snowmelt inspring and early summer.This brings good and badnews.

n Slow-growing wood is of higher quality.

n Higher temperatures bring the dangerof insect damage and forest fires.

n Some plants and small animals cannotadapt quickly enough to the changesand could die out.

Rain and snow

Warm air holds more moisture than cold air,so global warming will incre a s ep recipitation. The ave rage annualprecipitation is expected to increase by 10%in western Norway. It will also be morelikely to rain than snow, at least on lowerland. It should become easier to keep roadsopen unless floods occur.

When it does snow, however, it may beheavy. On 29th April 1999, the snow reachedan all-time high of 2.4 metres in Tromsø,causing great concern about ro o f scollapsing due to heavy loads of snow, andthe danger of avalanches destroying homesand killing people. The uncertainty aboutsnowfall worries the tourist industrybecause skiing conditions may be difficult insome years.

Warming will have a profound impact on the nature and distribution of

vegetation, and changes in precipitation will cause problems.

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bCase Study

A low-lyingtown on thecoast ofNorway

cold current

warm current

extent of Arctic ice – Feb 1995

G R E E N L A N DC U R R E N T

G R E E N L A N D

I C E L A N D

N

ATLANTIC OCEAN

0 500 1000km

N O RWEGIAN SEA

GREENLAND SEA

Cold watersinks

Cold watersinks todeep ocean

Ice formed offresh water. Seais cold, saltyand dense

Warm waterfrom the tropics

Ocean currents in the North Atlantic

Sea levels

Sea levels are rising as highertemperatures not only melt the ice near thepoles, but also cause sea water to expand.The rise is not spectacular. About a metre isforecast for this century. Norwegians do notexpress concern as their coastline is, for themost part, steeply sloping.

However, there are dangers. Some birds,such as the Arctic tern, nest on openbeaches and would be affected by a slightrise in sea level.

It could be more serious for low-lyingcoastal areas, such as alluvial fans near themouths of fjords and the flat lowlands inJa e ren, south of Stavanger. The onset ofglobal warming has tended to cause moree x t reme weather events. Winter storms withs t rong winds accompanying high tides couldw reak havoc on coastal communities, whichtend to be densely populated. Homes, quay s ,boats, ferry landings, coastal roads and eve nsome farmland could be under threat.

Along the coast there is a great deal ofeconomic activity related to oil and gas,fishing and fish farming. Fish farms areparticularly vulnerable to storm surgesbecause the storms are likely to damageinstallations and allow salmon and trout toe s c a p e .

Could it become colder?

Norway is kept at least 5ºC warmer than itwould otherwise be by the North AtlanticDrift, a current originating in the tropics. Tobalance the warm water flowing into theArctic, cold currents flow south along thecoast of Greenland. This current is very saltybecause its fresh water has been removedto form ice. The cold, salty water is dense

and heavy and sinks beneath the warmNorth Atlantic Drift to flow at depth.

As a result of global warming, large areasof ice have failed to form off the east coast ofGreenland in five of the last seven winters.The cold water is less dense and thes o u t h w a rd flow is diminished. If thiscontinues, the flow of warm water will beweakened and Norway will become muchcooler. If this happened there is little doubtthat most of the population of northernNorway would choose to move away fromthe area.

The main effects of global warming in

Norway may well be felt through the

influence on air pressure and ocean currents.

Case Study

Troubles ahead?csc

N o r way and global wa r m i n g

Greenhouse gas Source of gas

3a What does this food chain

show?

b The polar cod can only live inwater below 1ºC. What might bethe effect on the food chain ifthe water became warmer?

c Describe the way in which themaximum extent of ice in 1966 differedfrom 1996.

d Use the map and the food chain toexplain why the survival of the polarbear is threatened.

A simple Arcticfood chain

The maximum extent of Arctic ice in 1966 and 1996

1966

1996

Polar bear

SealG

Polar codG

PlanktonG

S VA L B A R D

N OVAYA ZEMLYA

B A R E N T S S E A

N O RW E G I A N S E A

1a Study the graph showing the increase in

global temperature. What is the n deviation from average in 1860?n deviation from average in 2000?n total rise in temperature between the

two dates?

b How do temperatures compare with theaveragen between 1860 and 1940?n between 1940 and 1980?n after 1980?

c Explain what is meant by the‘greenhouse effect’.

2a Draw a table as indicated below.

b Enter the names of the four greenhousegases.

c From the following list show thesource(s) of each gas:n power stations, chemical fertilizer,

aerosols, car exhausts, waste tips,forest fires, rice fields.

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dCase Study

b How do your graphs confirm youranswers to Question 2?

4a What is meant by ‘saturated air’?

b What happens if saturated air is cooled?

c How many grams of water are held bya kilogram of saturated air at: 0ºC, 5ºC,20ºC, 25ºC?

d How many grams of water vapourwould condense to water droplets if thetemperature fell from: 5ºC to 0ºC, 25ºCto 20ºC?

e How does your answer to Question 4dhelp to explain why global warmingmay lead to increased precipitation inwestern Norway?

1a Explain the term ‘permafrost’.

b Describe the problems which mayoccur when permafrost melts. Which doyou think is the most serious problem?Give reasons for your choice.

c What do you think will be the effect onrivers?

2The diagram below shows how the tree linereacts to rising temperatures. In what waysare the areas of coniferous trees extending?

3This table below shows the area of eachbiome north of the Arctic Circle in 1000km2

at present and in the foreseeable future. (Abiome is a major ecosystem.)

a Draw divided bar graphs to show thearea of each biome at present and asestimated for the future.

The effects of warming on land

U N S A T U R A T E D

Biome Present Future

Ice-covered land 1750 1500

Tundra 4250 1750

Forest/tundra 2000 2250

Coniferous forest 0 1750

Other 250 1000

The effect of rising temperature on the tree line

Relationship between temperature andrainfall

Tundra

-10 0 10 20 30Temperature (ºC)

N S

Coniferous forest

New tree lineOld tree line

Level of saturation

40

30

20

10

0

S A T U R A T E D

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eCase Study

Troubles ahead?

A possible future for the North Atlantic

I C E L A N D

ATLANTIC OCEAN

Because the wateris less salty and dense, itdoes not sink andso less waterleaves the Arctic.

G R E E N L A N D

G R E E N L A N DC U R R E N T

1a On the outline drawing, shade and label: the

steep valley sides, the fjord and the landwhich might be affected by a rise in sealevel.

b Under what conditions is the area of lowlandlikely to be at risk?

c What precautions might be taken tominimize this risk?

2a On the map, label in the appropriate place:

n reduced sea ice near Greenlandn North Atlantic Drift checked by Arctic

watern Norwegian coast becomes colder

b Explain why the North Atlantic Drift maybecome weaker.

c What would be the effects on the life andwork of the people of western Norway?

3Complete the table below to show possiblepositive and negative effects of warmingon the activities named. Use as manys o u rces of information as you can toresearch your answers.

4Why do you think insurance companiesa re taking great interest in globalwarming?

Activity Positive effects Negative effects

Farming

Forestry

Fish farming

Tourism

Transport

Energy

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Case Study