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D4.3.4—Polar habitat changes

Polar habitat changes alter ice-dependent breeding, feeding, migration, decomposition, species distributions, and food-web interactions in Arctic and Antarctic ecosystems today.

Syllabus
First assessment 2025
Objective
D4.3.4
Level
SL

Exam analysis

Chance of appearing5%of analysed past papers
Latest appearanceMay 2015
Most common paperPaper2
Typical marks1–6

Common command terms

  • Outline
  • State
  • Distinguish
  • Describe
  • Analyse
  • Discuss

Scoring notes

Common mistake
Assuming all polar sea ice changes have the same direction in Arctic and Antarctic data.

Recent exam appearances

May 2015Paper2 ["SL"] · TZ17(b)[ 6 ]D4.3.4—Polar habitat changes
May 2014Paper1 ["SL"] · TZ122[ 1 ]D4.3.4—Polar habitat changes
May 2013Paper1 ["SL"] · TZ121[ 1 ]D4.3.4—Polar habitat changes
May 2012Paper2 ["SL"] · TZ27(b)[ 6 ]D4.3.4—Polar habitat changes
May 2012Paper2 ["SL"] · TZ14(a)[ 2 ]D4.3.4—Polar habitat changes

Coverage 2010–2015 · Updated 16 Jul 2026

Sea Ice and Landfast Ice Create Different Polar Habitat Functions

Ice habitat Ecological function Climate-sensitive change
mobile pack or sea ice resting platform near offshore feeding grounds reduced extent and longer ice-free seasons
landfast ice attached to coast or seabed stable breeding and chick-rearing platform earlier breakout before breeding is complete
seasonal ice edge concentrates prey and structures access to food timing and location shift

Melting floating sea ice does not directly raise sea level like melting land ice, but it can transform habitat, food access and albedo.

Walruses and Emperor Penguins Depend on Ice at Different Life Stages

Species Ice dependency Consequence of earlier or reduced ice
walrus adults and calves rest on sea ice between benthic feeding dives longer travel, crowded land haul-outs and reduced safe resting habitat
emperor penguin colonies breed and rear chicks on stable Antarctic landfast ice early breakout can remove the platform before chicks are ready to survive at sea

Extent and timing both matter. The same total ice area at the wrong season or in the wrong location may not supply the required habitat function.

An adult female Atlantic walrus and juvenile rest on pack ice surrounded by open water in the Arctic.

Climate Effects Follow Forcing, Feedback, Exposure and Biological Response

human greenhouse-gas source → enhanced infrared retention → climate variable changes → feedback may amplify the change → habitat or physiological mechanism alters survival, production or distribution → population and ecosystem consequences

Impact Mechanism that must appear
boreal sink becomes source carbon release exceeds uptake through drought, mortality, fire and thaw
ice-dependent species decline required resting or breeding platform is lost at the critical time
marine productivity falls stratification reduces nutrient upwelling to phytoplankton
range contracts or shifts climate space moves but dispersal and habitat constrain tracking
reef degrades bleaching removes symbiont energy and acidification suppresses calcification

Do not jump directly from “warming” to “species decline.” The biological mechanism and the relevant time or place make the explanation causal.

Polar habitat changes

[ 3 ]

Discuss the use of Adélie penguins in studying the effects of global warming.

Concept essentials

  • Loss of ice habitat can reduce survival and reproduction of ice-dependent species.
  • Warmer polar conditions can increase decomposition, pests, pathogens, and temperate-species range expansion.
  • Penguin colony data can indicate climate effects, but regional sea-ice trends may differ.