ESS Unit 7.3

The big picture

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What may happen if we continue to emit greenhouse gases (GHG)?

It is likely that with elevated levels of GHGs (e.g. carbon dioxide, methane, nitrous oxide and CFCs) the average global temperatures would rise. The Intergovernmental Panel on Climate Change (IPCC) suggest that if GHG emissions continues to increase, by 2100 temperatures could rise by between 2.6 and 4.8°C (mean of 3.7°C) from preindustrial levels. This corresponds to sea levels rising between 45cm and 82cm (mean of 63cm) which could have devastating effects on coastal communities and ecosystems.

Figure 1. Coastal flooding in the Netherlands

The rise in temperature could dramatically alter weather systems resulting in more extreme events such as high rainfall and typhoons putting greater pressure on water and food resources. Ecosystems could be irreparably damaged.

Human societies now face a choice on whether to:

• Continue producing GHG emissions (i.e. business as usual) and try to adjust to changes to our environment as they occur. This may include adjusting to non-reversible changes (e.g. loss of habitats and biodiversity).

• Take action to reduce further emissions and adjust to a changing environment.

GHG emission can be lowered through a variety of strategies including:

• Reducing the use of fossil fuels by:

  • Improving energy efficiency (e.g. appliances that require less energy).

  • Energy conservation (e.g. reducing energy waste by improving insulation of buildings).

  • Using alternative sources of energy with low GHG emissions (e.g. wind and solar power).

• Reducing emissions from agriculture through improved practices.

The average period of time a substance spends in a place or condition (e.g adsorbed or dissolved) is referred to as the residence time. Some GHGs have long residence times in the atmosphere. Carbon dioxide can remain in the atmosphere for hundreds of years before being absorbed by the oceans or plants. However, planting more trees which absorb carbon dioxide could slow the rate of carbon dioxide increase within the atmosphere. If emissions levels were also dramatically cut, planting trees could lead to an overall reduction of atmospheric carbon dioxide levels.

Figure 2. Plants absorb carbon dioxide and stores the carbon in their biomass. Oxygen gas is released as a by-product.

As discussed in the previous subtopic, the impacts of climate change are already being felt across the globe. When dealing with these impacts we can be proactive and take action to minimise effects prior to them occurring and also reactive, take action once the impacts have occurred. For instance we can try and minimise the impacts of heavy rainfall by improving drainage (proactive) and if under extreme conditions flooding occurs, move people to a temporary safe location with adequate supply of food and water (reactive).

Due to the scale and global nature of climate change, international collaboration is necessary to tackle problems of rising GHG levels. Sharing of knowledge and expertise is vital to effectively cut emission levels and to deal with the on-going impacts.

Mitigation

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Definition

The Intergovernmental Panel on Climate Change (2014) defines mitigation as: "A human intervention to reduce the sources or enhance the sinks of greenhouse gases (GHGs)".

There are a variety of ways in which GHG emissions could be reduced:

• Lower energy use through improved efficiencies and conservation approaches.

• Replace use of fossil fuels with low emission energy sources e.g. renewable energy and nuclear power. This also includes replacing the use of fossil fuels within the transport sector.

• Decrease emissions from agriculture activity.

Carbon dioxide can also be removed from the atmosphere by a range of methods referred to as geo-engineering, discussed in the next section.

Reducing energy use

Reducing energy consumption and therefore the amount of fossil fuel used can reduce emissions of greenhouse gases and other pollutants. Making energy efficiencies and employing energy conservation measures was discussed in subtopic 6.3 Photochemical smog.

Figure 1. Reducing the temperature on thermostat heating system and wearing an additional layer of clothes instead can save on energy costs as well as reduce energy use.

Use low emission energy sources

This involves replacing the use of fossil fuels with alternative such as nuclear, solar, wind, geothermal and hydropower. The advantages and disadvantages of using nuclear and renewable energy to generate electricity are discussed in subtopic 7.1 Energy choices and security.

Reducing emissions from transport

Good transport is considered important for economic development e.g. effective movement of the workforce and goods. Road transport is considered to be major source of carbon dioxide and nitrous oxide. Methods to reduce vehicle emissions were discussed in subtopic 6.3 Photochemical smog, and include replacing petrol or diesel vehicles with electric powered or hybrid vehicles.

Alternatively some countries are opting to substitute fossil fuels with biofuels such as biodiesel and bioethanol:

• Biodiesel: Diesel engines can use a variety of different oils (such as rapeseed, palm or sunflower oil).

• Bioethanol: Many crops can be fermented to produce bioethanol e.g. sugar cane, maize or sorghum. In Brazil bioethanol from sugar cane is used as a fuel for vehicles. The car industry has developed flexible fuel engines to use up to 100% ethanol.

Figure 2. Brazilian production of light vehicles by type of fuel - neat ethanol (alcohol), flexible fuel and gasoline (petrol) vehicles from 1979 to 2014.

However, there are a number of issues with growing biofuels:

• The use of land to grow biofuels instead of crops can reduce the supply of food and increase food cost. 

• Production of biofuels can potentially cause pollution from the use of fertilizers and pesticides and compete for limited water resources.

• The cultivation of biofuels may require clearance of natural vegetation and the destruction of ecosystems and loss of biodiversity.

Reduce emissions from agriculture

Best management practices can be used to reduce GHG emissions from farming e.g.:

• Using less fertilizer can reduce nitrous oxide (N₂O) emissions. Fertilizers should only be applied:

  • When required and preferably when there is maximum uptake.

  • When there is low risk of run-off, for instance during dry conditions. 

• Adding nitrification inhibitors to the fertilizer to reduce nitrous oxide production.

• Reducing methane generation from livestock by:

  • Selective breeding to have cattle that produce less methane.

  • Changing the feedstock.

• Collecting and utilising methane emissions from biodegradation of animal waste as a source of energy.

• Cultivating rice varieties that can be grown in drier conditions with higher yields to reduce methane emissions.

Figure 3. Rice cultivation in water logged conditions favours bacteria to produce methane.

Geo-engineering

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Geo-engineering involves manipulating the earth’s environmental systems to counteract the impacts of climate change.

Geo-engineering methods do not address the causes of climate change but could be used to compliment GHG emission reduction strategies. Most have not been tested and little is known about their effectiveness, cost and environmental impacts. Two key approaches are:

• Carbon dioxide removal from the atmosphere.

• Solar radiation management. 

Carbon dioxide removal (CDR)

Various methods are used to remove carbon dioxide ranging from biological absorption to chemical abstraction. These methods are unproven and carbon dioxide removal is likely to be a very slow process taking decades to stabilise atmospheric levels. Examples discussed below include land use management, use of biomass, carbon capture and storage and absorption by the oceans.

Land use management

Land management can be used to protect and enhance plants that absorb carbon dioxide thereby reducing atmospheric levels. Carbon sinks can be protected and enhanced by:

• Afforestation of land.

• Restoration, such as reforestation of degraded land.

• Reduced deforestation.

• Use of farming practices which encourages retention of carbon stores within the soil as organic matter. No tillage is recommended because tillage disturbs the soil, increases soil erosion and loss of organic matter.

Figure 1. Ploughing encourages loss of carbon from the soil.

UN-REDD

In 2008 the United Nations set up a collaborative programme to reduce emissions from deforestation and forest degradation referred to as UN-REDD. The project recognises:

• The economic value of forest as carbon sinks.

• Potential of local people to effectively manage the forest.

The UN-REDD supports developing countries to:

• Reduce GHG emissions from forests.

• Invest in low carbon energy sources.

Watch the following video and consider the benefits of REDD programmes:

Use of biomass

When plant organisms die, the biomass degrades releasing carbon dioxide. An alternative is to harvest and use the biomass to generate fuel (replace use of fossil fuel) or to bury the material.

Figure 2. Rapeseed plants used to produce biofuels.

Carbon capture and storage (CCS)

This method involves the removal of carbon dioxide from the atmosphere followed by either:

• Chemical process to form carbonates.

• Compression and transport to a site of permanent storage.

Air could be filtered through adsorbent material that removes the carbon dioxide from the atmosphere. Storage could be in underground sites, such as geological formations previously containing oil or gas reservoirs.

CCS methods are currently under investigation and are likely to be very expensive.

Absorption by the oceans

Carbon dioxide is absorbed by photosynthetic phytoplankton in the oceans. The carbon moves through the food web and when organisms die they sink to the lower layers. From here the carbon can enter storage within the sediments. This absorption of carbon dioxide from the atmosphere and its movement into the deep oceans is referred to as the biological pump. The biological pump could be further enhanced by:

• Fertilising the oceans (with nitrates, phosphates and iron) to encourage photosynthesis by phytoplankton.

• Increasing upwellings e.g. using mechanical pumps to move cold nutrient rich waters from the lower layers to the surface, encouraging photosynthesis and enhancing carbon dioxide uptake.

The consequences of using either method are unknown.

Solar radiation management (SRM)

These methods are currently only theoretical. They focus on increasing reflection of sunlight back into space and therefore reducing the amount of solar radiation absorbed by the earth. For example:

• Increase the reflection from the earth’s surface by:

  • Painting roof tops with white reflective paint.

  • Growing plants with high reflectivity e.g. genetically engineered crops or grasses with high albedo.

  • Covering areas with reflective material e.g. covering deserts with reflective plastic sheets.

• Use aerosols to increase albedo effect. However the effects of this are unknown including the potential impacts on stratospheric ozone.

• Enhance reflectivity of clouds by increasing particles that attract water molecules within the cloud.

• Use solar deflectors in space to reduce sunlight reaching the earth.

Figure 3. Artist impression of potential reflectors in space used to deflect solar radiation from the sun.

International Mindedness

Climate change is a global issue and therefore needs international effort to limit its impacts.

Watch the following video by the IPCC and consider the questions:

• How could limiting global temperature rise to less than 2°C be achieved?

• What is the advantage of taking action now rather than later?

• What are the barriers to mitigation?

Adaptation

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Whereas mitigation addresses the causes of climate change by reducing emissions of greenhouse gases (GHG), adaptation is focused on dealing with the effects. The long residence period of GHG in the atmosphere means that even if GHG emissions were dramatically cut, past emissions will continue to influence climate. Hence adaptation strategies are necessary to minimise negative effects and take advantage of any new favourable conditions.

Definition

The Intergovernmental Panel on Climate Change (IPCC) defines adaptation as: ‘The process of adjustment to actual or expected climate and its effects. In human systems, adaptation seeks to moderate or avoid harm or exploit beneficial opportunities. In some natural systems, human intervention may facilitate adjustment to expected climate and it effects’.

Table 1. Estimated lifetime of carbon dioxide, methane and nitrous oxide in the atmosphere.

Other differences between mitigation and adaptation include:

• Effects of mitigation can be seen on a global scale whereas those of adaptation are at a local level.

• Success of mitigation is relatively easy to measure (e.g. though reduced levels of atmospheric GHG) whereas the success of adaptation is more complex to measure (e.g. Has the risk of vulnerability to climate change decreased and is this value for money?).

Through effective adaptation action we can develop the resilience of our infrastructure (e.g. water, energy and transport) and built environment to climate change. Regulation can be used to implement adaptation and to have plans in place called contingency plans to deal with extreme events or disasters. Early warning systems, such as forecast of extreme events (e.g. cyclone) can give local people time to prepare and e.g. evacuate the area or find suitable emergency shelter.

Figure 1. Adaptation involves making plans for the future to deal with climate change over the long term, short term and under emergency situations.

Exam tip

Ensure you are able to distinguish between mitigation and adaptation in addressing climate change.

Adaptation strategies

Adaptation measures can be categorised by the sector they apply to. The sectors covered here include water resources, agriculture and fisheries, ecosystems, coastal systems and low lying areas and human health.

Water resources

Changing precipitation patterns are likely to increase the risk of water shortages in some regions whilst intense rainfall over a short period of time could lead to flooding. Adaptation strategies to reduce risk of water shortages involve:

• Reducing demand via water conservation strategies.

• Improving water supplies e.g. use of desalination plants to utilise seawater.

Adaptation strategies to decrease the risk of flooding include:

• Ban on building on river flood plains or in areas prone to flooding.

• Flood control though construction of flood barriers, improvements in drainage or diversion of floodwaters e.g. through use of sustainable urban drainage (SUDS). The use of SUDS could be incorporated into planning and building regulations.

• Modifying infrastructure and buildings to withstand floods e.g. adapting drainage and sewage systems to prevent sewage overflow.

Figure 2. House in the Florida Keys, USA built on stilts to minimise flood damage.

Agriculture and fisheries

Changes to agriculture practices to reduce impacts of climate change include:

• Using crops that have been developed to reflect changing local conditions, for example crops that:

  • Grow at higher temperatures.

  • Need less water.

  • Are salt resistant.

  • Are pest resistant.

  • Are flood resistant.

• Changing to crop varieties with high yields.

• Altering the time of planting and harvesting to match change in conditions and optimise yields.

• Employing water conservation techniques to maximise use of limited water resource eg micro-irrigation techniques.

• Increasing retention of soil moisture and reduced soil erosion via use of winter crops, terracing and wind breaks.

Figure 3. Flooding of agriculture fields can kill crops.

To minimise the impacts of climate change on fisheries, other pressures need to be reduced to avoid collapse of fish stocks. This includes:

• Reduction in fishing intensity.

• Reduced fish catches.

These changes may require fishermen to seek employment in other sectors.

Ecosystems

Strategies to counteract the impacts of climate changes on ecosystems include:

• Adjusting to biome shifts by expanding conservation areas towards the poles.

• Connecting protected areas with corridors to allow movement of species adapting to changing conditions.

• Greater protection of vulnerable areas such as coral reefs and mangroves. This includes protection from pollution and over exploitation.

• Development of forest fire management techniques e.g. wide breaks between areas of forest to prevent wind spreading the fire from one area to another.

Figure 4. Coral reefs contain high levels of biodiversity are under high threat from impacts of climate change.

Coastal systems and low lying areas

Planning guidance needs to consider the impacts of climate change. It may include incorporating the management of rising sea level and increased storm surges. This could involve:

• A ban on new developments in low lying coastal areas.

• Building and re-enforcing sea walls and coastal defences e.g. groynes and beach replenishment programmes which dissipate the energy of incoming waves, reducing their impact.

• Preparing contingency plans on what to do in the event of a flood e.g. have access to alternative water and food supply and shelter for people made homeless.

• Moving potentially dangerous facilities away from low lying areas vulnerable to sea level rise or storm surges e.g. nuclear power station or stores of hazardous materials.

• Managed retreat, which allows coastal areas to become flooded. It may involve compensation and relocation of local residents.

Figure 5. Groynes are used to break up waves hitting the coast line.

It has been predicted that the Carteret Islands off the coast of Papua New Guinea in the Pacific Ocean, will be submerged by 2020. As a result of this prediction, residents are being relocated to other areas such as Bougainville in Papua New Guinea.

Health

Adaptation strategies to impacts of climate change on health involve:

• Use of monitoring and surveillance systems that raises an alarm when there may be increased risk of health issues.

• Being prepared for climate related events and treatment of likely types of injuries and diseases.

• Use of vaccination programmes to reduce risk of certain diseases such as polio and cholera.

• Public health education programme which covers:

  • What action to take during a heat wave.

  • What to do during floods.

  • How to avoid specific diseases.

  • What action to take if ill.

Figure 6. Child being administered polio vaccination.

Implementing change - barriers

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Change can take time, but delaying decisions can increase rate of change and intensity of impacts. Therefore, we need to identify barriers to mitigation and adaptation in order to consider how to overcome these issues.

International-mindedness

Climate change affects everyone and therefore international collaboration to tackle the problem is necessary.

Barriers to mitigation and adaptation

If we know what to do to reduce GHG emissions and to limit the impacts of climate change what is holding us back? 

Political commitment to take action to reduce levels is driven by a variety of factors, for example:

• Public opinion of the environment and understanding of climate change. Environmental lobby groups can raise environmental awareness through public awareness campaigns and mobilise the public to influence governmental decisions. Conversely advocators of fossil fuels may petition politicians with their perspective to avoid change.

• Effect on industrial and economic growth of taking action. The cost of abatement could reduce growth rates.

• Dependence on income from export of fossil fuels.

• Politicians are keen to be viewed favourably in order to win another term in office governing the country and hence usually favour decisions that have clear short term benefits. However tackling the issues of climate change requires action over the long term and benefits can be difficult to measure.

Figure 1. Climate change campaign in New Zealand.

Even when a decision to take action is agreed, effective adoption of mitigation and adaptation strategies can be impeded by:

• Insufficient knowledge of impacts of climate change and potential mitigation and adaptation.

• Poor integration of mitigation and adaptation strategies into policy and planning at national to local level.

• Poor communication and sharing of information between governmental departments resulting in departments working in isolation from each other on common project (e.g. on essential infrastructure improvements involving energy, water and transport).

• Limited regulation and accountability of mitigation and adaptation measures.

• Political instability and corruption.

• Inertia and procrastination.

• Insufficient funding and technology.

Overcoming barriers

In order to overcome the barriers to mitigation and adaption there needs to be:

• Sharing of knowledge involving education and public awareness campaigns.

• Consideration of mitigation and adaptation as complementary approaches to each other.

• Effective and efficient communication.

• Commitment at all levels. Mitigation and adaptation strategies need to be fully embedded into the political and economic decision making process at national to local level.

• Ability for governments, businesses and communities to work together and support necessary action.

• Setting of achievable goals within a set timescale.

• Sufficient financial support.

• Access to appropriate technology and expertise.

The impacts of climate change are not evenly distributed and some of the most vulnerable countries (e.g. low lying coastal areas such as Bangladesh) have the least resources making adaptation difficult.

Figure 2. The Ganges-Brahmaputra Delta is the largest delta in the world and sea level rise could result in millions of people becoming homeless.

The capacity to take appropriate action varies from country to country and is often limited in some developing countries by access to funds, technology and expertise. Therefore, it is necessary for wealthier nations to provide some of the most vulnerable and poorest countries with support to deal with climate change.

Watch the following video and consider:

1. Which group of people are most effected by climate change?

2. Why is both mitigation and adaptation is required?

Implementing change - international collaboration

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International collaboration

International cooperation and collaboration is vital for effective mitigation and adaptation at a global level. However, compliance to international environmental agreements often relies on good will and self-policing. Regional and national legislation are often more effective with clear monitoring and enforcement.

Figure 1. International cooperation allows groups to help each other to meet common goals.

Intergovernmental Panel on Climate Change (IPCC)

Intergovernmental Panel on Climate Change (IPCC) was set up by the United Nations Environmental Programme (UNEP) and World Meteorological Organisation (WMO) in 1988. The aim of the IPCC is to provide a scientific view of the current knowledge and understanding of climate change and its impacts. The IPCC involves scientists and governments from across the world. Hence their work has wide ownership which can help to influence national policies.

United Nations Framework Convention on Climate Change (UNFCCC)

The United Nations Framework Convention on Climate Change (UNFCCC) was signed by 154 nations during the Earth Summit in Rio in 1992. It came into force in 1994 with the aim of stabilising atmospheric greenhouse gas levels by providing a framework for protocol agreements. Parties meet each year to discuss progress and set targets. These meetings included Kyoto in 1997 that led to the Kyoto Protocol. 

The Kyoto Protocol which came into force in 2005 and set targets to control GHG emissions:

• Overall global reduction of about 5% of carbon dioxide emissions of 1990 levels by 2012.

• Individual targets for each country with final deadline of 2012.

Figure 2. Emission targets for selected countries.

Amendments referred to as the Doha Amendment were made to the Kyoto Protocol in 2012. The target average reduction was set at 18% of GHG emission of 1990 levels by final deadline of 2020. This amendment has yet to be accepted by a sufficient number of nations to come into force.

National Adaptation Programmes of Action (NAPA)

The UNFCCC requires less economically developed countries to produce a National Adaptation Programme of Action (NAPA) highlighting which areas are most vulnerable to climate change and where adaptation is most required. Selected projects are financially assisted (e.g. via the Least Developed Country Fund and Green Climate Fund).

Figure 3. Countries in which there are NAPA projects (2014)