IB Biology HL D4.3 Climate Change Questions

Practise IB Biology HL D4.3 with climate data questions on greenhouse forcing, feedback, ocean acidification, habitat shifts, phenology and carbon sequestration.

Exam points

explain greenhouse forcing, feedback cycles and fossil-fuel emissions using carbon and radiation data
analyse climate data for sea ice, coral reefs, ocean currents, range shifts and polar ecosystems
evaluate phenology and carbon-sequestration evidence to judge ecological responses to warming

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 D4.3.9 (HL)—Phenology D4.3.10 (HL)—Disruption of phenological synchrony D4.3.11 (HL)—Increased insect life cycles D4.3.12 (HL)—Evolution from climate change

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

[Maximum number: 3]

Average human internal (core) body temperature is $36.4^{\circ} \mathrm{C}$ , with slight variations between day and night. The average surface temperature of the Earth in the 20th century was $13.9^{\circ} \mathrm{C}$ . It has now risen to $14.8^{\circ} \mathrm{C}$ .

(a)

Explain how the burning of fossil fuels has contributed to the increase in the Earth's temperature.

[ 2 ]

a. $\quad \mathrm{CO}_{2}$ is released/is a greenhouse gas;

b. long wave radiation/heat/infrared (emitted by the Earth) trapped/absorbed by $\mathrm{CO}_{2}$ ;

c. (so) heat retained in atmosphere;

Marking guidance:

Do not award a mark for 'Earth's temperature is increased' as this is in the question.

b. Do not accept 'reflected back' instead of trapped or absorbed and do not accept absorption of any type of radiation from the sun.

The word 'heat' can be used for both marking points b. and c. but in b. the idea is heat retained by $\mathrm{CO}_{2}$ the whereas the idea in c. is heat retention in the atmosphere.

2
max

(b)

Melting polar ice due to global warming is reducing reflection of sunlight from the Earth. Identify with a reason whether this will result in positive or negative feedback.

[ 1 ]

[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 ]

All question bank results loaded

a	higher temperatures so more transpiration/droughts/dehydration/water shortage
b	more forest fires
c	more/new pests/diseases because of the changed conditions
d	competition from trees/plants «that colonize/spread to boreal forests»
e	trees/«named» organisms «of boreal forests» not adapted to warmer conditions OR trees/«named» organisms migrate/change their distribution due to warmer conditions
f	trees die so loss of habitat for animals
g	faster decomposition/nutrient cycling «so conditions in the ecosystem change»
h	standing water/floods due to more snow/permafrost melting

a	positive feedback because warming causes melting of polar ice;
b	positive feedback because less ice means less sunlight is reflected (lower albedo);
c	positive feedback because more heat is absorbed by the Earth's surface which becomes warmer;

Covered syllabus points

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Question 1

Question (a)

Question (b)

Question 2

Question (a)

Question (b)