Past papers part 2 Flashcards
Explain how a change in ocean circulation may affect Earth’s climate
Ocean water currents transport heat from the equator to the poles which affects the water cycle as well as atmospheric temperatures. Increased ocean circulation warms the higher latitudes of both the northern and southern hemispheres. Similarly, a reduction in ocean circulation from the equator to the poles will reduce temperatures, possibly producing a prolonged cooling event.
What is a climate proxy?
A climate proxy is anything that is preserved, can be measured and from which some aspect of climate can be inferred. Changes in a proxy reflect changes in the environment in which the proxy formed.
How does continental drift due to plate tectonics affect the nature of ocean currents?
Continents influence ocean currents and the winds that create them by forming barriers. The continents deflect currents carrying heat south or cooler waters north.
Describe a possible flow-on effect of a change in ocean circulation on Earth’s weather
Changes in atmospheric temperature have possible flow-on effects on weather. Increased temperature at the higher latitudes will produce higher evaporation rates over oceans and associated increases in precipitation events.
Explain how changes in land use since human settlement have contributed to the enhanced greenhouse effect.
A significant area of land is currently being used for grazing. Croplands, forestry and urban functions also make up some use of land. An increase in grazing land for cattle leads to the production of methane, which is a very potent greenhouse gas. The removal of vast forests, to create grazing land and urban development significantly reduces the carbon dioxide sink, leading to increased CO2 levels in the atmosphere and contributing to the enhanced greenhouse effect.
While some horticulture and domestication of animals occurred following settlement by ATSI peoples, the extent was much less than today, and the impact on the enhanced greenhouse effect would have been minimal.
It has been suggested that practices used by ATSI people be adopted or adapted when preparing environmental management plans. Analyse the environmental impacts of incorporating such practices.
The way in which ATSI peoples used seasonal occupation, whereby they moved from one region to another, reduced pressures on local food sources so that each ecosystem could regenerate when they moved on. This is not evident in European agriculture techniques where pastures are established on a permanent basis, often depleting soil nutrients and leading to erosion and salinity problems. While more sustainable, the adoption of practices such as cyclical/seasonal rotation of populations into modern agricultural techniques is not very practical given the size of populations which need to be sustained, practices such as crop rotation are more practical.
Note crop rotation is the practice of planting different crops sequentially on the same plot of land to improve soil health, optimise nutrients in the soil, and combat pest and weed pressure.
The use of fire-stick farming involved Aboriginal peoples purposefully and regularly lighting fires both for the hunting of animals and for promoting regrowth of native vegetation. It assisted environmental management by reducing bushfire fuel load, allowing for regeneration through nutrient recycling and seed germination. Adopting this practice into environmental management plans by routine hazard reduction burning would effectively reduce fuel loads and reduce net carbon dioxide outputs because small frequent fires do not burn the entire plant and thus encourage the storage of carbon resources under the ground such as in tubers. It also ensures that animals can escape danger and then return to their habitats.
Discuss the usefulness of alternative energy sources in the mitigation of, and/or adaptation to, increased global temperatures.
One way in which humans can build climate resilience is to employ alternative energy sources. By replacing coal-fired electricity with wind power, you can reduce the amount of carbon dioxide entering the atmosphere without affecting the quality of life experienced by people. One downside to this is that wind does not always blow and so excess energy generated by wind turbines would have to be stored in batteries to be used at a later date. This strategy is currently being employed in South Australia using the Tesla battery. By using this strategy, people could reduce total carbon dioxide in the atmosphere leading to mitigation of emissions and later reduction in global temperatures.
Modelling can be used to describe the causes of the natural greenhouse effect. Describe one such model.
The diagram shows a simple model of the greenhouse effect. The uncovered thermometer is a model for the atmosphere without greenhouse gases, while the thermometer in the bottle is a model for the atmosphere with greenhouse gases, indicating the trapping of infrared radiation. The gases are represented by the bottle trapping heat and increasing the temperature within.
How does the anthropogenic greenhouse effect differ from the natural greenhouse effect?
The natural greenhouse effect is an influence caused by natural levels of atmospheric carbon dioxide from volcanism or methane from peat bogs, moderating the extreme temperatures on the earth. Without it, the earth would freeze at night and boil during the day.
The anthropogenic greenhouse effect has been occurring since the industrial revolution due to increased levels of carbon dioxide in the atmosphere caused by human activities such as the burning of fossil fuels. Similarly, widespread agricultural practices produce more methane and other industrial activities create more greenhouse gases. It is causing climate and temperature changes beyond the natural averages.
The natural greenhouse effect has created a stable climate, while the anthropogenic greenhouse effect has destabilised the climate causing extremes in heat and icy weather systems.
How does pollen grains contribute to our understanding of ancient variations in global temperature?
Because pollen grains are small, they are widely distributed by the wind. They are resistant to decay and persist in sediment for a long time. Different pollen grains have distinguishable structures. Hence, pollen is valuable for dating sediments and rocks.
When pollen is blown into a lake and fossilises in sediment, it becomes an indication of the type of vegetation growing around the lake. As climate and environment around the lake changes, so does the composition of the pollen preserved in the sediments.
Evaluate the potential of other energy sources as alternatives to fossil fuels. Use examples in your answer.
There are several alternative energy sources for fossil fuels. These include nuclear, solar, wind and wave for electricity generation and sources such as biofuels, batteries and solar for transport. Both coal and petroleum produce large amounts of greenhouse gases, such as carbon dioxide, which cause an increase in global warming. Petroleum is being exploited rapidly and is likely to run out in several decades; although coal is plentiful, resources are also finite. The advantage of using fossil fuels in Australia is that they are relatively cheap and we have large coal resources.
The advantages of alternative energy sources is that most of them are cleaner and more environmentally friendly than fossil fuels because they produce far less greenhouse gases. Most alternative energy sources have disadvantages. The major disadvantages of nuclear energy is the long-lived hazardous wastes which are difficult to dispose of and there is also a major problem if there are accidents and radioactive material escapes. The disadvantage of renewable sources such as biofuels, solar energy and wind energy, is that they are more expensive than fossil fuel energy. There is generally a high cost in setting up the infrastructure to produce them.
Given the resources of fossil fuels such as petroleum are diminishing rapidly, and especially the high cost to the environment of the greenhouse gases produced, society will have to find alternative energy sources for electricity generation and transport in the near future.
