Managing climate change and conservationEdexcel A-Level Biology A: Revision notes
Section 1
Who reaches the conclusion matters
Climate change is a controversial issue because the actions needed (and who pays) affect jobs, industries and lifestyles. Scientific conclusions can sometimes depend on who is reaching them:
- organisations funded by an industry, such as fossil fuels, may have a vested interest and may emphasise some data and not others
- campaigning groups may stress the worst predictions
- governments may be influenced by politics and public opinion
To judge a claim, ask who produced it, who funded it, whether it was peer reviewed, whether the data are published and repeatable, and whether other independent studies agree. A conclusion is not wrong simply because of its source, but the source is a reason to check the evidence more carefully.
Saying that a report is wrong because it was funded by a company. Say that funding may bias it, so the evidence must be checked.
Section 2
Using the carbon cycle to reduce carbon dioxide
In the carbon cycle, photosynthesis removes carbon dioxide from the atmosphere and stores carbon in organic compounds. Respiration, decomposition and combustion return it. Carbon is held in stores (sinks) such as forests, peat bogs, soils, oceans and fossil fuels.
Knowledge of the cycle suggests ways of reducing atmospheric carbon dioxide:
- burn less fossil fuel (renewable energy, biofuels)
- stop deforestation and plant new forests (reforestation)
- protect peat bogs and wetlands, where decay is slow and carbon stays locked in
- use timber in long-lasting products
- capture carbon dioxide from power stations and store it
Section 3
Reforestation
Reforestation is replanting trees on land that was forest. Growing trees take in carbon dioxide by photosynthesis and store the carbon in wood, so the forest acts as a carbon sink. Forests also provide habitats, reduce soil erosion and regulate water flow.
Planting is most useful for conservation when native species are used, because they support more wildlife than a single fast-growing species. When the forest is mature, uptake by photosynthesis is roughly balanced by respiration and decay, so the store stops growing and the carbon is only kept as long as the trees are not removed or burned.
Conflict: replanting uses land that could be farmed, so people may lose income.
Section 4
Sustainable resources
A sustainable resource is used at a rate that does not prevent it being available in future. For timber this means replacing felled trees, selective felling instead of clear-felling, and replanting with native species so that forest cover, habitats and the carbon store are maintained. Timber used in buildings and furniture keeps carbon locked up.
Sustainable management allows human needs (timber, jobs, fuel) to be met while conserving biodiversity. It needs monitoring and enforcement to stop illegal or excessive felling.
Section 5
Biofuels
Biofuels are fuels made from recently grown biological material, such as bioethanol from sugar cane or maize and biodiesel from oil palm or rapeseed.
In principle a biofuel is carbon neutral: the carbon dioxide released when it is burned is balanced by the carbon dioxide that the crop took in by photosynthesis as it grew. In practice, fossil fuels are used in making fertiliser, running machinery and transport, so biofuels are not wholly carbon neutral.
Advantages: renewable, reduce use of fossil fuels, income for farmers. Disadvantages: crops compete with food production, and clearing forest or peatland for biofuel crops destroys habitats and releases stored carbon. Using waste material or already cleared land is more sustainable.
Saying that biofuels release no carbon dioxide. They release it, but it was absorbed by the crop as it grew.
Section 6
Balancing human needs and conservation
Human needs include food, fuel, timber, income and jobs. Conservation aims to protect species, habitats and carbon stores. These conflict when land is wanted for both.
Effective management finds a compromise: reforestation of degraded land, sustainable timber production with replanting, biofuel crops on cleared land and waste materials, and involving local communities. Evaluate such schemes by weighing benefits for people, biodiversity and carbon, noting that long-term success depends on enforcement and monitoring.
Must know
- Conclusions on controversial issues may depend on who reaches them: check funding, bias and peer review
- Carbon cycle knowledge: reduce fossil fuel use, plant forests, protect peat
- Reforestation and sustainable timber conserve habitats and store carbon
- Biofuels are carbon neutral in principle but not completely in practice
- Balance human needs against conservation, and enforce management
That's the notes covered.
Carry on to the next subtopic.
Exam questions on Managing climate change and conservation
- A council plans to convert 200 hectares of intensively farmed land in the English Midlands into native broadleaf woodland, planting oak, ash and hazel. The scheme is intended to help meet a national target to reduce atmospheric carbon dioxide while providing a habitat for wildlife and a place for recreation. The farmer who currently grows crops on the land will lose income.Explain how planting the woodland can reduce the concentration of carbon dioxide in the atmosphere.2 marks
- A South American country produces bioethanol from sugar cane, grown on land that was previously cattle pasture, and biodiesel from oil palm, some of which is grown on land cleared from tropical rainforest. Supporters say that biofuels are carbon neutral and are a sustainable alternative to petrol and diesel. Critics point out that biofuel crops compete with food crops and wildlife for land.Suggest two ways in which biofuel production could be made more sustainable.2 marks
- Two reports on climate change were published in the same month. Report X, written by a group of university climate scientists, appeared in a peer-reviewed journal and concluded that human activity is the main cause of recent warming. Report Y, produced by a trade association funded by coal and oil companies, argued that human activity has only a small effect and that no action is needed. A government minister must decide which report to use as the basis for a new policy to cut net carbon dioxide emissions.Explain why the source of each report should be considered when deciding how far to trust its conclusions.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).