IB Biology HL 4.3.4 Climate Change in Arctic Ecosystems

increasing/positive trend/correlation;

a. in the Arctic ocean the surface area of sea ice has declined whereas in Antarctica the surface area has increased;
b. the rate of change is greater for the Arctic than for Antarctica;
c. there are greater fluctuations in the surface area of sea ice in Antarctica than in the Arctic;
For mp a, it is acceptable if there is no comparative term such as "whereas" or "but";

One mark for correct description of the trend off the Antarctic Peninsula and one mark for correct description for the Ross Sea; accept correct statements other than those listed in the scheme but do not award a mark for contradictions; marks can be awarded for correct statements about the sea ice season for Antarctica overall; Some students are referring to moving South in the Ross Sea when it is clear that they are moving North. If you can discern their intention, then give the BOD on this;

Antarctic Peninsula:
a. decrease/stable at the base of the peninsula / decrease in the area of the penguin colonies/West of the tip / increase/+1 above and below the peninsula / variable pattern;

Ross Sea:
b. sea ice is increasing / +1 in the Ross Sea / area below / North of the Ross Sea / lower Ross Sea / Southern part of Ross Sea/closest to the South pole is stable/no change to the length of the sea ice season/ variable pattern;

a. (off AP) sea ice season has declined as has penguin population;
b. colony 2 and 3 sea ice season has not declined and population increased;
c. colony 3 increase in population and growing length of sea ice season;
d. colony 2 has stable / increasing numbers and sea ice season is not changing;
e. colony size and sea ice season length/area are correlated;
f. Population numbers for colony 1 and 3 the same at start of study but both experience a big (opposite change);

Marking guidance:

Accept answers that refer to "sea ice" or "sea ice area".

a. global warming leads to climate / environmental change; eg temperature change / ice melting
b. stable ice associated with stable population / no climate change;
c. ice changes associated with population changes;
d. changes in penguin population size can indicate climate change / global warming;
e. example of how climate change can alter population; eg prey availability / habitat loss;
f. not all species will be affected in the same way (so care needed in applying conclusions more widely)
g. there is information on changes of population over the past 35000 years;