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Unlock This CourseAntarctica is the cleanest, coldest and least touched continent on Earth. Nobody lives there permanently. Yet it is still affected by what people do, both on the continent and thousands of kilometres away. A threat is anything that could harm the ecosystem. This lesson covers the threats first, then what happens if the ecosystem is damaged.
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Antarctica is thought to hold minerals and oil under the ice and the seabed. Mining and drilling are banned there for now, under an international agreement. How that agreement works is covered in the lesson Protecting Antarctica. But the threat has not gone away. As resources run short elsewhere, some countries may want to open up Antarctica in the future.
If mining or drilling were allowed, an oil spill would be very hard to clean up in freezing water far from help. Oil would stick to feathers and fur and ruin their insulation. Roads, ports and machinery would also damage the thin lichen and mosses on the land.
Climate change is the biggest threat to Antarctica. Its causes are covered in later lessons. Here you need to know what it does to Antarctica. The Antarctic Peninsula is one of the fastest-warming places on Earth, and this causes three main problems.
Warmer air and sea water cause surface melt. Species adapted to the cold may find it harder to survive.
Ice shelves hold back the glaciers behind them. When one breaks up, the glaciers can flow faster into the sea. In 2002 almost all of the Larsen B ice shelf, about 3,250 km2, broke up in little more than a month.
Less sea ice forms each winter in some areas, so there is less habitat for algae, krill and penguins.
Remember, ice has a high albedo. When ice melts, the dark ocean absorbs more heat, which speeds up the warming.
The Southern Ocean is rich in life, so people fish there. Two catches matter most.
Long fishing lines can also cause bycatch. Seabirds such as albatrosses are caught on the hooks and drown.
Tourism has grown fast. More than 100,000 people visited in some recent seasons, almost all by ship to the coast and the Antarctic Peninsula. Antarctica has no hotels and no towns, so the problems come from the visitors themselves.
| Problem | What happens |
|---|---|
| Numbers and footprints | Walking on moss and lichen damages it, and it grows back very slowly. Crowds can disturb breeding penguins. |
| Pollution | Ships can cause oil spills, leave waste and give off exhaust fumes. |
| Invasive species | Seeds, insects and germs can arrive on boots, clothes and bags. Non-native species could push out the local plants. |
In the past, fur seals and whales were hunted in huge numbers for fur, oil and meat. Fur seals were nearly wiped out, and blue whales fell to a tiny fraction of their original numbers. Recovery is slow because large animals breed slowly.
Scientists are needed, but their stations create sewage, rubbish and fuel spills. In the past, waste was often dumped or left behind. Waste can last a very long time in the cold because it rots slowly.
When the ecosystem is damaged, the effects spread well beyond Antarctica.
Fig. 1.1 shows made-up data for part of the Southern Ocean.
| Year | Winter sea ice (million km2) | Krill index |
|---|---|---|
| 2000 | 18 | 100 |
| 2010 | 16 | 84 |
| 2020 | 14 | 65 |
Fig. 1.1
(a) Describe the trend in krill shown in Fig. 1.1. [2 marks]
(b) State one way that tourism can threaten Antarctica. [1 mark]
(c) Explain how loss of sea ice could affect penguins. [3 marks]
(d) Assess which is the greater threat to Antarctica: climate change or fishing. [6 marks]
(a) The krill index falls (1) from 100 in 2000 to 65 in 2020, a fall of 35 (1).
(b) Visitors can bring invasive species on their boots or clothes (1). Accept footprints damaging moss, or oil spills from ships.
(c) Less sea ice means less algae under the ice, so fewer phytoplankton (1). This means fewer krill for penguins to eat (1). Penguins have less food, so numbers fall (1).
(d) Level 3 (5-6 marks): a balanced, well-evidenced judgement with a clear conclusion. Level 2 (3-4 marks): some explained points but little weighing up. Level 1 (1-2 marks): simple statements. A Level 3 answer could say: Climate change is the greater threat because it affects the whole continent, not just one area (1). Warming melts ice shelves such as Larsen B and reduces sea ice, which cuts algae and krill and harms the whole food web (1). It also raises global sea level, so it affects the whole world (1). Fishing is a serious threat too, because catching krill removes food for penguins and whales and toothfish can be overfished (1). However, fishing can be controlled by limiting catches, whereas climate change is global and cannot be stopped by actions in Antarctica alone (1). Overall, climate change is the greater threat because it also makes the effects of fishing worse by shrinking krill numbers (1).
In an "Assess" question, compare the threats and finish with a judgement. Use words such as "however" and "overall" so the examiner can see you weighing them up.