A Level Edexcel Carbon Cycle Enquiry Question 3

[6.8C] What are the threats to ocean health?

The threats can be categorised into acidification, bleaching, rising sea levels, and loss of sea ice.

- The WWF warns that climate change is affecting ocean's temperatures, the supply of nutrients, food chains, wind systems, ocean currents, and causing extreme events such as cyclones.

- Oceans absorb around 30% of the atmosphere's CO2.

- Since 1800, around 50% of all carbon

emissions came from the combustion of fossil fuels.

- As CO2, in the ocean increases, the pH

of the ocean decreases (increasing acidity).

[6.8C] What is ocean acidification?

This occurs when CO2 gas dissolves in the ocean and reacts with the sea water.

- Since 1800, around 50% of all carbon

emissions came from the combustion of fossil fuels.

- As CO2, in the ocean increases, the pH

of the ocean decreases (increasing acidity).

- When CO2 is in the water, it combines with H20 to form Carbonic Acid.

- The carbonic acid breaks down into hydrogen ions and bicarbonate molecules.

- Carbonate combines easier with hydrogen ions than calcium so it cannot make shells.

- Shell-forming animals like corals, crabs, oysters and urchins are getting hit.

[6.8C] What is coral bleaching?

Global warming and water pollution can cause corals to release algae, causing them to bleach.

- About 25% of marline life depends on the habitats created by coral reefs.

[6.8C] What threats do the declining ocean health pose to humans?

- The aquaculture industry remains at high risk, especially with the stark increase in demand. It is largely impacted by the ocean acidification.

- The FAO estimates that fishing supports 500 million people, 90% of whom live in developing countries.

- Seafood is also the dietary preference of some wealthier countries, notably Iceland and Japan.

- Millions of small-scale fishing families depend on sea food for income as well as food.

- In fact, 6% of GDP is from fish and it provides essential protein in 49 small island developing states.

- Tourism is under threat, as many nations use the marine life as an attraction such as coral reefs. Over 220 million people rely on coral refs to attract an influx of 1 million tourists, e.g Maldives.

- Rising sea levels also is yet another consequence that threatens coastal infrastructure. Not great for developing countries with poor sea defences.

[6.9A] Why is there uncertainty over the future for climate change?

There is uncertainty over the rate and type of changes from a warming climate.

Carbon sinks, feedback loops, and human factors.

[6.9A] How are carbon sinks increasing uncertainty on climate change?

Carbon Sinks:

- They store carbon.

- If greenhouse gas emissions sopped, it would still take a long time for natural systems to restore to pre-industrialisation levels.

- Around 20% of CO2 will remain in the atmosphere for hundreds of years.

[6.9A] What are the future changes to carbon stores for terrestrial and oceanic sinks?

Terrestrial:

- They are modelled to increase generally until 2050.

- Eventually this will cause thawing ice, shifting of forests to the north.

Oceanic:

- This will fall in storage overall.

- CO2 storage is decreasing in tropical oceans because of warning, so less uptake of CO2.

- Decreased efficiency and slowing down of the biological pump taking nutrients and dissolved carbon from the surface to the ocean floor.

- They will reach a saturation point, and won't be able to absorb any more.

[6.9A] What human factors are causing increasing uncertainty over climate change?

Economic Growth:

- More developing countries have emerged economically in the last 30 years, so in turn, they use more energy, creating higher emissions.

- There are still many countries to develop, and so global emissions may continue to increase.

- The global economic recession caused CO2 emissions to fall as a result of lesson consumption of energy.

Population Change:

- There is higher levels of wealth who use more energy and cause more emissions, such as the rise of the middle class.

Energy Sources:

- Global agreements on emission reductions have made countries review their energy mixes, so renewable technologies are being used more. However, fossil fuel usage is still being exploited.

[6.9A] What is positive and negative feedback, and what are examples of?

A positive feedback cycle increases the change, whilst a negative one decreases change.

Examples:

- Carbon from peatlands and permafrost.

- Forest dieback.

- Thermohaline circulation changes.

- Tipping points.

[6.9A] How is peatlands and permafrost a feedback mechanism?

Peatlands and Permafrost:

- The boreal and tundra biome and climate areas will shift northwards as temperatures increase.

- Peatlands and permafrost within these areas will warm up or dry, causing decomposition (melting).

- This releases methane, which can trap more heat causing further melting.

- This leads to higher greenhouse gas concentrations.

[6.9A] How is forest die-back a feedback mechanism?

As a result of climate change, rainforests could become drier and less productive in terms of photosynthesis, so less CO2 will be absorbed and they will eventually die. This will mean warming will increase as there is more carbon in the atmosphere, causing more dieback.

[6.9A] How is thermohaline circulation changes a feedback mechanism?

More freshwater is becoming available from the melting of ice sheets, which changes seawater density to become less dense, but also reducing salinity. This will disrupt the circulation of the water. The circulation changes can affect the temperature of the oceans, and how the oceans and atmosphere transfer heat energy, causing greater warming and more ice melt.

[6.9A] What is a climate tipping point?

This is when a critical threshold is met. When this is met, small changes in the global climate system can transform a stable system irreversibly.

IPCC identified possible tipping points;

- Long term droughts.

- Collapse of monsoon climate system.

- Artic ocean becoming ice free.

[6.9B] What does adaptation mean?

This accepts climate change, but looking at how the world's population can cope with it. This is living with the problem, but not solving it.

[6.9B] What are the different adaptation strategies?

Water conservation and management, resilient agricultural systems, land-use planning, flood-risk management, and solar radiation management.

[6.9B] What is water conservation and management, plus the pros and cons of this strategy?

This looks at reducing water and conserving it for sustainable use.

Pros:

- Less resources used, less groundwater abstraction.

- Low-cost technology, and they already already exist.

- Use more grey (recycled water).

Cons:

- In areas that are getting drier, large-scale schemes may be requires to transfer water. These schemes have problems, such as getting agreement, and causing tensions + conflict.

- Efficiency and conservation cannot match the increasing demand for water.

[6.9B] What is resilient agricultural systems, plus the pros and cons of this strategy?

This is agricultural systems which are resilient against the effects of climate change, such as increasing temperature and reduced precipitation in some areas.

Pros:

- Higher-tech, drought-tolerance species help resistance to climate change and increase in diseases.

- Low-tech measures and better practices generate healthier soils.

Cons:

- More expensive technology, and difficult for poor subsistence farmers without aid.

- High energy costs from indoor and intensive farming.

[6.9B] What is land-use planning, plus the pros and cons of this strategy?

This is carefully planning how land is used for different purposes to address concerns with the environment.

Pros:

- This is a type of soft management that protects human activity, and applies building restrictions in vulnerable floodplains and low-lying coasts.

- Building regulations can get structures to resist changes such as more intense storms.

Costs:

- Public can be against the idea, and feel it unnecessarily restricts them.

- Abandoning high-risk areas and land-use resettling is often unfeasible.

- Requires strong governance, enforcement and compensation. .

[6.9B] What is flood-risk management, plus the pros and cons of this strategy?

This is the use of hard or soft engineering strategies to reduce the flood risk of areas.

Pros:

- This can identify areas with increased flood risk, and adapt the structures in these areas, such as raising buildings above predicted flood levels.

- Simple changes can reduce flood risk.

- Reduced deforestation and more afforestation can be implemented on floodplains.

Cons:

- Debates over the cost of this, especially for developing countries.

- Land owners may demand for compensation.

- Constant maintenance is needed in hard management, such as dredging.

- Prediction of flood risk can be sometimes uncertain.

[6.9B] What is solar radiation management, plus the pros and cons of this strategy?

Solar radiation management is a proposed type of climate engineering in which sunlight would be reflected back to space to limit or reverse human-caused climate change.

Pros:

- Involves reducing the amount of heat energy reaching the earth's surface, thereby counteracting climate changes.

- Could be relatively cheaper than mitigation.

Cons:

- Untried and untested.

- Would reduce but not eliminate the worse effects of greenhouse gasses.

- It is still very expensive, regardless.

[6.9C] What is mitigation?

This is strategies used to reduce or prevent GHS emissions, and ultimately prevent further climate change, using many new technologies.

[6.9C] What mitigation strategies exist?

Carbon taxation, renewable switching, energy efficiency, afforestation, and carbon capture and storage.

[6.9C] What are the four possible scenarios set out by the IPCC?

Business as usual:

- Emissions continue rising at current rates.

- RCP = 8.5.

- Businesses will be impacted by the climate change.

- Likely to hit near 4 degrees.

Some mitigation:

- Emissions rise to 2080 then fall.

- RCP = 6.0.

- Likely to exceed 2 degrees.

Strong mitigation:

- Emissions stabilise at half today's level by 2080.

- RCP 4.5.

- More likely than not to exceed 2 degrees.

Aggressive Mitigation:

- Emissions halved by 2050.

- RCP = 2.6.

- Not likely to exceed 2 degrees.

- Businesses will be impacted by strict policy.

[6.9C] What are RCPs?

The IPCC has a range of different views or scenarios, called RCPs (Representative Concentration Pathway).

- It basically looks at how much energy is stored in the atmosphere above pre-industrial levels.

[6.9C] What is carbon capture and storage?

Power stations and large factories that use fossil fuels can be made to capture and store emissions by laws and regulations.

- Suitable geologic sites may not be available, and the technologies involved may be too expensive for developing countries.

- Reduces profits of companies, and economic priorities may be put first.

[6.9C] What is afforestation?

This is the planting of the trees, and they are an important carbon sink. By planting more trees, this would increase storage and reduce carbon concentration in the atmosphere.

- This would allow the sequestration of carbon more.

- Many countries are deforesting for commercial purposes.

[6.9C] What is energy efficiency?

This is making all appliances and machinery more energy efficient due to governmental regulations.

- Energy suppliers must comply with the Energy Company Obligation scheme to deliver energy-efficient measures to households.

- People can change their own lifestyles to use less energy, but with the rise of the middle class, this is difficult, so this helps developed countries more.

[6.9C] What is renewable switching?

This is the transition from using mostly fossil fuels to using renewables. This would greatly reduce carbon emissions.

- The UK government influential in the relationship with the big 5 energy companies. They dictate the amount of switching from fossil fuels to renewables.

- Renewables very intermittent.

- Renewable technologies are more widespread in developed and emerging countries, but not always in developing.

[6.9C] What is carbon taxation?

This is when governments can impose taxes on carbon emissions, thereby reducing profits of businesses and industries, thereby encouraging them to change to low-carbon alternative.

- It was unpopular with both industry and environmental groups and had a debatable effect on emissions for the UK. In 2015, the policy was 'frozen'.

[6.9C] How can attitudes vary towards mitigation?

If mitigation, at whatever level, is to have any change of success, it not only requires concerted actions at a national level but, more critically, it requires effective international agreements. Global warming is a global problems requiring global action.

TNCs:

- Attitudes can vary with TNCs. TNCs may express concern, but are often found delaying when it comes to taking appropriate action.

Governments:

- When it comes to government attitudes, those whose contributions to GHG emissions are relatively small are vocal in drawing attention to those countries that are large contributors.

Paris Agreement:

- The Agreement now has 140 national signatures, including China, India and the USA.

[6.8C] How do forest declines implicate people?

- They stop carbon, provide oxygen.

- Influencing local climates through evapotranspiration.

- Provide wood fuel in developing and emerging countries, such as Asia.

- Highest losses are in sub-saharan Africa.

[6.9A]

There is much uncertainty over the future, which raises many questions, particularly:

- the level of GHG emissions - will they continue to rise?

- GHG concentration levels in the atmosphere - is there a limited capacity?

- the resilience of other carbon sinks and stores- what are their capacities and could they store more?

- the degree of climate warming - how much warmer?

feedback mechanisms such as the release of carbon from peatlands and thawing permafrost - what volumes of carbon are likely to be released?

- the rate of population growth - when, if ever, will it level off?

- the nature and rate of economic growth - will it always be so carbon-based?

- the harnessing of alternative energy sources - will fossil fuels be completely replaced?

- the possible passing of tipping points relating to aspects as forest dieback and irreversible alterations to the thermohaline circulation - will disaster be sure to follow?