IB Biology SL D4.3 Climate Change Questions

Practise IB Biology SL D4.3 by linking greenhouse gases to warming, feedback loops and biological impacts across ecosystems.

Exam points

explain how anthropogenic greenhouse gases absorb outgoing long-wave radiation and enhance warming
trace positive feedback through ice-albedo loss, permafrost methane, warmer oceans or forest fires
interpret range shifts, polar habitat loss or coral bleaching and acidification from climate data

Covered syllabus points

D4.3.1—Anthropogenic causes D4.3.2—Positive feedback cycles D4.3.3—Boreal forest tipping point D4.3.4—Polar habitat changes D4.3.5—Ocean current changes D4.3.6—Range shifts D4.3.7—Coral reef threats D4.3.8—Carbon sequestration approaches

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Study D4.3 Climate change conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 7]

Carbon is an essential element for life on Earth and must be distributed and recycled within ecosystems.

Explain the impact of anthropogenic activity on climate change.

a. greenhouse effect describes that greenhouse gases trap long-wave radiation from the Earth's surface and absorbs it keeping the Earth warm

OR

increase in greenhouse gases trapped in atmosphere increases Earth's temperature;

b. burning of fossil fuels/peat/coal/natural gas by humans has released more $\mathrm{CO}_{2}$ into the atmosphere causing temperature rise on Earth;

c. raising livestock for feed has added methane/greenhouse gas to the atmosphere causing more heat to be trapped on Earth;

d. industrial processes / fertilizer production has increased the concentration of nitrous oxides/greenhouse gases in the atmosphere;

e. deforestation has increased the amount of $\mathrm{CO}_{2}$ in the atmosphere/reduced an important sink for $\mathrm{CO}_{2}$ ;

f. increased temperatures have caused melting of land ice leading to changes to polar habitats/decreasing species ability to survive

OR

melting of ice/snow causes reduction in albedo, so there is more insolation absorbed at Earth's surface;

g. warmer surface water prevents upwelling of nutrients/decreases ocean productivity;

h. coral reef habitat destruction due to changes in water pH / temperature;

i. warmer temperatures/decreased snowfall has led to droughts and loss of life/habitats;

j. rates of decomposition of peat/organic matter increases greenhouse gases;

k. ocean/sea level rise from melting ice/thermal expansion of oceans has impacted coastal regions/loss of land;

I. changing weather patterns due to global warming has caused loss of life and infrastructure;

m. poleward migrations/migrations to more suitable places due to climate changes at lower latitudes;

7

Marking guidance:

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[Maximum number: 1]

Which of the following may contribute to a positive feedback cycle in global warming?

The release of methane from thawing ice caps

The uptake of carbon dioxide by a reforested area

Higher temperatures increasing photosynthesis rates

The accumulation of peat in swamps

[Maximum number: 4]

Boreal forests stretch across Canada, Russia and Scandinavia. This northern ecosystem accounts for 29 % of the world's forest areas. The long, cold winters favour tall evergreen trees with either needles or scale-like leaves. These trees are wind-pollinated and their seeds are not enclosed in a fruit. The photograph shows a typical boreal forest in winter.

(a)

In some areas there are gaps in the boreal forest where trees fail to grow and peat tends to accumulate. Suggest reasons for this.

[ 2 ]

(b)

An increase in global temperatures poses a critical threat to boreal forests. Explain the consequences of climate change to this northern ecosystem.

[ 2 ]

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a	waterlogged soil/poor drainage OR acidic soil OR anaerobic conditions/soil;
b	organic matter is not fully decomposed leading to peat formation OR decomposers/saprotrophs less active/fewer in cold temperatures;

Covered syllabus points

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