Life in the Cold

Two cold environments, not one

AQA questions name one or the other, and answers that treat "cold environment" as a single thing lose marks. Polar environments are permanently frozen: Antarctica and the interior of Greenland lie under ice sheets kilometres thick, temperatures stay below freezing all year, and the lowest reliably recorded surface temperature on Earth, about minus 89 degrees Celsius, was measured at Vostok in Antarctica in July 1983. Almost nothing grows; Antarctica has two native flowering plants, and otherwise mosses and lichens. Tundra lies between the polar regions and the northern treeline, across northern Canada, Alaska, Siberia, northern Scandinavia and Svalbard. Winters are brutal, often below minus 30 degrees Celsius, but for a few weeks in summer the air climbs to around 10 degrees Celsius and the surface thaws. There are no trees, because the growing season is too short and the roots would have nowhere to go, but there are mosses, lichens, sedges, cotton grass and dwarf shrubs, and in summer there is a burst of flowering and insect life. Both are dry. Antarctica receives roughly 166 mm of precipitation a year measured as water, which is under the 250 mm line we use to define a desert: the coldest place on the planet is technically one. Cold air simply cannot hold much moisture. Yet the tundra spends its brief summer waterlogged, with pools, bogs and clouds of mosquitoes, and the reason for that apparent contradiction is the single most useful thing to understand about this landscape. It is called permafrost, and it is where this module starts.

Five cold environment terms

The first two explain the waterlogging, the third and fourth explain what can live there, and the fifth explains why working there is so expensive.

Order the tundra summer

These six stages describe what happens on the tundra between spring and autumn. Put them in order.

• The sun returns after months below the horizon and air temperatures climb above freezing
• The shallow surface layer thaws, while the ground below it stays frozen solid
• Meltwater cannot drain downwards, so it collects at the surface as pools and bog
• Low-growing plants race through growth, flowering and seeding in a few weeks
• Insects breed explosively in the standing water and migrating birds arrive to feed on them
• Temperatures fall again, the surface layer refreezes and the cycle closes

Why is a dry place waterlogged?

The tundra receives very little precipitation, yet its surface is boggy all summer. Which answer explains that?

• The permanently frozen ground beneath the surface acts as an impermeable layer, so when the shallow active layer thaws each summer the meltwater has nowhere to go: it cannot sink and it evaporates only slowly in cool air, so it sits at the surface. A small amount of water that cannot drain produces more standing water than a large amount that can, which is why a place receiving less rain than a desert ends up under pools and bogs.
• The tundra actually receives very heavy summer rainfall.
• Rivers flood across the tundra every summer from the mountains.
• Seawater floods inland when the sea ice melts.

Svalbard: four opportunities, four challenges

AQA attaches a named cold environment to this element, and the catalogue chose Svalbard: a Norwegian archipelago of roughly 61,000 square kilometres between about 74 and 81 degrees north, around 60 per cent of it under glaciers, with a population of about 2,900, most of them in Longyearbyen. As with hot deserts, the mark scheme wants both sides.

Match each species to how it survives

Precision, balance and the command word

Three things decide the grade on this topic. Say which cold environment you mean. If the question says tundra, write about tundra: a summer thaw, an active layer, low vegetation, no trees. If it says polar, write about permanent ice and effectively no vegetation at all. An answer that mixes Antarctic ice sheets into a tundra question is describing the wrong place, and the examiner cannot give credit for it. Balance the two sides. As with hot deserts, a question naming opportunities and challenges wants both, and two developed points each will beat five on one side. Look for the facts that cut both ways: coal built Longyearbyen and is now almost gone, and tourism brings the income that replaced it while adding pressure to the very wilderness people come to see. Writing one fact from both directions is judgement, and judgement is what the top band is for. Answer the command word. "Describe the characteristics" wants features with no reasons. "Explain how plants are adapted" wants mechanisms: not that the Arctic willow is short, but that staying a few centimetres tall keeps it inside the thin layer of warmer, calmer air at ground level. "Assess" or "to what extent" wants a judgement with a stated criterion at the end, not a summary of what you already said.

Complete the cold environment facts

Antarctica receives roughly 166 mm of precipitation a year, which is below the _____ mm line used to define a desert. Beneath the tundra lies _____, ground frozen for at least two years together, and above it a shallow _____ layer that thaws each summer; because meltwater cannot drain through the frozen ground it sits at the surface and turns a dry landscape into bog. Plants there have only about fifty to sixty days to grow, flower and set seed. On Svalbard the sun fails to rise for around _____ days each winter, and heated buildings must be raised on piles so that they do not thaw the ground and _____ into it.

Spot the three accurate cold claims

Select the THREE statements that are true.

• Antarctica counts as a desert, because it receives roughly 166 mm of precipitation a year as water equivalent, below the 250 mm threshold, since very cold air can hold very little moisture.
• Buildings on Svalbard stand on piles driven into the frozen ground, because a heated building resting directly on permafrost would thaw it and subside.
• Warming accelerates in cold environments because melting snow and ice expose darker ground and water, which absorb more of the sun's energy than the bright surface they replaced.
• Tundra vegetation includes stands of coniferous trees adapted to the cold.
• The tundra is boggy in summer because it receives very heavy rainfall then.
• A polar bear stores water in its layer of blubber to survive months without drinking.

A balanced 9-mark answer, marked

Using a named cold environment, assess the extent to which the challenges of development outweigh the opportunities. [9 marks] Svalbard, a Norwegian archipelago of about 61,000 square kilometres between roughly 74 and 81 degrees north, has supported a permanent population of around 2,900 for over a century, so the opportunities are clearly real. Coal has been mined there since 1906 and built Longyearbyen as a company town, the surrounding Barents Sea is among the most productive fisheries in the world, and tourism now brings tens of thousands of visitors a year for glaciers, wildlife and the polar night itself. Science has become an industry in its own right: around ten countries run stations at Ny-Alesund, and the Global Seed Vault, opened in 2008, was sited there precisely because the permafrost keeps it frozen without power. The challenges, however, shape every one of those activities. Winter averages near minus 14 degrees Celsius, the sun does not rise for roughly 112 days from late October, there are no roads between settlements, and every heated building must stand on piles because resting it on the permafrost would thaw the ground and sink it. Some challenges are also worsening: Svalbard has warmed by something like 4 degrees Celsius since 1971, thawing ground that infrastructure was designed to sit on, and an avalanche killed residents of Longyearbyen in 2015 and forced homes to be moved. The strongest evidence for the challenges is that the original opportunity has gone: Norwegian coal mining has been wound down almost to nothing, and the settlement now depends on tourism and research instead. On balance I partly agree. The challenges do not outweigh the opportunities in the sense of making development impossible, since Svalbard is inhabited and its economy has successfully changed shape. They outweigh them in the sense that every activity there exists only because someone is willing to pay the extra cost the environment imposes, and that judgement depends on which activity you mean: science and tourism absorb that cost, while mining in the end did not. What earned the marks: both sides developed with a named place, real figures and dates; the shift from coal to tourism used as evidence rather than mentioned; and a conclusion that answers "to what extent" by separating two senses of the question instead of picking a winner.

Find the two tundra statements

Five statements about cold environments. Only two of them describe tundra specifically rather than polar regions or both. Tap those TWO.

• A shallow surface layer thaws each summer while the ground beneath it stays permanently frozen, so meltwater collects at the surface.
• The land lies beneath an ice sheet kilometres thick and stays below freezing all year round.
• Mosses, sedges, cotton grass and dwarf shrubs grow in a burst during a season of about fifty to sixty days, but no trees can establish.
• Precipitation is low because cold air holds very little moisture.
• Bright snow reflects most of the sunlight that reaches it.

Build the permafrost explanation

Assemble a sentence that explains the waterlogging properly rather than describing it.

Four decisions on Svalbard

Each stage is a real constraint of building and working in a cold environment. Choose the response that the conditions actually require.

• You are designing new housing for Longyearbyen. The ground is frozen to well over a hundred metres, but a heated building will warm the soil directly beneath it.
• The new housing needs water and sewerage. Burying the pipes would mean cutting trenches through permafrost, and any warmth escaping them would thaw the surrounding ground.
• Cruise passenger numbers are rising. Operators want to land groups near breeding bird cliffs and glacier fronts, and the income matters to a town that has lost its mine.
• It is late November. The sun will not rise again until February, and a field team needs to work outside the settlement for a week.

Explain the adaptations

Explain how plants and animals are adapted to survive in a cold environment. [9 marks]

• Named examples with their actual features
• What each feature does in that climate: not that the Arctic willow is short, but what being short does for it
• Constraints: a growing season of about fifty to sixty days
• Frozen ground that roots cannot enter
• Each feature solves a specific problem