Climate change

Question 1

Define anthropogenic climate change.

Question 2

Describe the causes of anthropogenic climate change.

Answer 2

Anthropogenic increases in atmospheric concentrations of greenhouse gases. (CO2, methane, N2O, water vapour)

1. Combustion of fossil fuels -> emission of CO2
2. Deforestation -> decreased absorption of CO2 -> higher levels of atmospheric CO2
3. Extraction of fossil fuels -> releases methane
4. Agricultural practices, rice cultivation -> methane emission
5. Decay of organic waste in landfills -> methane emission
6. Cellular respiration by living organisms -> releases CO2

Question 3

Outline the positive feedback cycles in global warming.

Answer 3

1. Release of carbon dioxide from deep ocean (outgassing) -> greater greenhouse effect –> warmer temp. decreases the solubility of CO2 in water
2. Melting of snow and ice decreases reflective surfaces -> less solar radiation is reflected back into space and more is absorbed.
3. Higher temp. -> accelerating rates of decomposition of peat due to increased microbial activity -> increased release of CO2 and methane (as peat is a carbon sink).
4. Thawing of permafrost regions -> increased release of methane -> increased greenhouse effect -> warmer temp.
5. Drought -> greater vulnerability to forest fires -> increased release of CO2.

Positive feedback loops trigger a cascade of consequences, intensifying effects.

Question 4

Describe the transition from net carbon accumulation to net loss in boreal forests as an example of a tipping point.

Question 5

Explain the melting of landfast ice and sea ice as examples of polar habitat change.

Answer 5

Landfast ice is ice that remains attached to the coastline during the winter season.

Walruses live in polar habitats.

Melting of sea ice leads to loss of sea ice habitat.
Walruses (and other species) rely on sea ice as resting platforms when searching for food and for migration activities

The melting creates scarcity in suitable resting areas and disrupts their natural behaviour patterns.

This forces them to adapt to less optimal habitats, and is a threat to the walrus population.

Emperor penguins also live in polar habitats.

The meting of landfast ice and sea ice risks them of losing its breeding grounds due to premature breakup of landfast ice in the Antarctic. This leads to the disruption of natural breeding cycle and potential decline in population.

Question 6

Explain the effects of climate change on ocean currents and nutrient distribution.

Answer 6

Climate change alters the timing and extent of nutrient upwelling.

Ocean currents are large movements of water in the ocean, driven by factors such as wind, temperature (leading to influx of fresh water due to melting of ice caps and glaciers), salinity, Earth’s rotations, and density.

Currents help distribute heat and nutrients across the globe.

Nutrient upwelling is the process by which deep nutrient-rich waters rise to the surface of the ocean.

Ocean currents (+wind currents) play a fundamental role in nutrient upwelling.

Warmer surface water tends to prevent nutrient upwelling, decreasing the availability of nutrients.
Phytoplanktons rely on nutrient upwelling. Phytoplanktons are primary producers and provides food and oxygen. This means ocean primary production and energy flow through marine food chain are decreased.

Question 7

Describe the effect of climate change on range shifts of temperate species.

Answer 7

Temperate species are organisms adapted to inhabiting temperate regions (moderate climates, distinct seasons).

Poleward and upslope range shifts occur when species gradually shift their distribution toward higher latitudes or elevations.

The shifts are driven by climatic conditions and have significant effects on the biodiversity of ecosystems.

EXAMPLES:
Movement of tropical-zone montane bird species in New Guinea upslope to retreat from climate change.
Upslope range shift observed in several bird species.
Shift in search for more suitable conditions (to find cooler temperatures).
Could lead to expansion of habitat range, problems such as less trees and land area to inhabit.

North American tree species - northward spread/expansion and range contraction in their southern-most distribution.
Shifts in climate conditions resulted in unfavourable coditions in their southern ranges and favourable conditions in higher latitudes. The shifting distribution of these trees can have ecological consequences; impacting forest composition, carbon sequestration, and interactions with other species in the ecosystem.

Question 8

Describe the effect of climate change on coral reefs.

Answer 8

Coral reefs are ecosystems built by tiny coral animals with skeletons composed of calcium carbonate.

Increased CO2 concentrations in the atmosphere causes ocean acidification. (carbonic acid is formed in the water, lowering ocean pH).
Acidification hinders the ability of corals to build calcium carbonate skeletons through calcification. Corals become more vulnerable to damage and stressors as a result.

Increase in water temperatures cause coral bleaching.
Leads to the explusion of algae (symbiotic zooxanthallae) from their tissues as a result of protective response to stress from factors incl. rise in water temperature.
Results in loss of vibrant colours and vital energy source derived from photosynthesis of the zooxanthallae.
Corals are weakened and more susceptible to other stressors –> potential death.

Coral bleaching and increased vulnerability (from ocean acidification and increased temperature) leads to subsequent deterioration of the coral reef system, as corals serve as the foundation of these ecosystems.

Question 9

Carbon sequestration

Answer 9

The process by which CO2 is captured from the atmosphere and stored in natural sinks.
Carbon sequestration plays a crucial role in mitigating climate change.

Question 10

Afforestation

Answer 10

The intentional planting of trees on previously non-forested lank.

Highly effective in carbon sequestration, as trees act as carbon sinks.

Can be accomplished through natural process/regeneration, commercial plantations, or agroforestry.

Question 11

Describe approaches to carbon sequestration

Answer 11

Afforestation

Restoration of peat-forming wetlands

Forest regeneration (regrowth of current forests)

Question 12

Restoration of peat-forming wetlands

Answer 12

Peat-forming wetlands (incl. bogs and swamps) have singificant carbon storage potential in their waterlogged soils.

Human activities such as drainage releases CO2 into the atmosphere.

Restoration includes re-establishing their waterlogged conditions, which slows down decomposition and acts as long-term carbon sinks, and preventing further degradation.

Question 13

Forest regeneration

Answer 13

Forest regeneration has two different meanings.

1. The process that occurs in a forest after a disturbance.
2. The natural or intentional regeneration of tree cover after forest loss, which can be achieved through planting nursery-grown seedlings after events that have resulted in a forest’s partial or total destruction.

Question 14

Outline the difference between afforestation and forest regeneration.

Answer 14

Afforestation grows new forests, while forest regeneration regrows current forests.

Question 15

Define phenology.

Answer 15

The research into the timing of biological events and their relationship with seasonal and environmental factors.

Question 16

Outline factors that influences phenological events.

Answer 16

Photoperiod and temperature patterns influences the timing of biological events such as ….

Photoperiod is the duration of light exposure within a 24 hour cycle. Photoperiods act as cues to determine life cycle timings.

Temperature affects the development and timing of biological events.

Question 17

Explain how climate change can lead to the increase in the number of insect life cycles.

Answer 17

Spruce bark beetles

Question 18

Discuss the concept of evolution as a consequence of climate change, using an example.

Answer 18

The change in climate exerts (new) selective pressures. This leads to genetic adaptations and evolutionary changes to respond to shifts in environmental conditions.

For example, as a consequence of changes in snow cover, the fitness of colour variants of the tawny owl changed/evolved. In snow-covered regions, the grey tawny owl has an adaptive advantage over brown tawny owls due to their ability to blend in the snowy background and hide from predators. With decreasing snowfall, brown tawny owls gain advantage due to their ability to camouflage better in non-snowy habitats, experiencing enhanced fitness over grey tawny owls.

Question 19

Explain disruption to the synchrony of phenological events by climate change, using two examples.