Future work on this page should focus on bringing this page down to 3000 words. "Responses to global climate" and the "Bangladesh case study" sections are too long.

Causes of global climate change

Key Terms

Term	Definition
Global dimming	The cooling effect of gases in the atmosphere. This effect is created by their albedo, which reflects the solar radiation back into the atmosphere.
Carbon footprint per cap.	The average amount of CO₂ emitted by a specific region per person (normally in metric tons).
Anthropogenic carbon flow	The current amount of CO₂ released by a country in a year. Can be brought up by factoring in other greenhouse gases.
Anthropogenic carbon stock	The amount of CO₂ released into the atmosphere since the Industrial Revolution (1750).
Deindustrialization	The loss of traditional manufacturing industries due to closure or relocation.
Carbon intensity	The amount of CO₂ emitted per GDP.

Long wave radiation vs Short wave radiation

Radiation length	Source	Energy density	Factors
Short-wave	Emitted by the sun.	High energy density	Depends on the angle (more exposure at the equator than at the poles) and cloud cover (the greater the cover, the fewer rays come through to the surface)
Long-Wave	Reflected from Earth into the atmosphere and eventually space	Low energy density	Depends on the time of day (During the day more is emitted than intaken) and the cloud cover (More outgoing long-wave radiation is intaken due to reflection from clouds)

Atmospheric energy budget

The Earth’s atmosphere is under constant solar radiation. The balance of inputs (insolation - incoming solar radiation) and outputs (re-radiation - albedo) keep the Earth from overheating and freezing at the same time. Unfortunately, due to human activity, this balance is being disrupted, heating the Earth.

Natural conditions through which the balance is achieved:

• Radiation - the emission of electromagnetic waves (X-Rays, short waves, long waves...) from the sun is the primary source of energy on Earth and affect almost everything that happens on the surface. For example, the sun rays hitting the dark asphalt on a hot summer day heat the asphalt.
• Convection - the transfer of heat (energy) through a liquid or gas. For example, the circulation of hot and cold ocean currents may affect the temperature on the surface.
• Conduction - the transfer of heat (energy) through direct contact. For example, walking barefoot on asphalt on a hot summer day and feeling the heat through the pavement.

The greenhouse effect

The Greenhouse Effect is the process of a portion of solar radiation being diffused into the earth's atmosphere by being trapped by greenhouse gases. Without this process the average temperature on earth would be -18°C and life would not be able to exist.

Comparison of greenhouse gases

CFC: An acronym for chlorofluorocarbon

Gas	Emitters	Abundancy	Impact
Water Vapour	Evaporation from water sources	Most abundant greenhouse gas	Causes 50% of the greenhouse effect but does not have a significant impact on global warming
Carbon Dioxide (CO₂)	The burning of fossil fuel, land-use changes, melting permafrost	Abundant. Concentration grows linearly.	Causes 20% of the greenhouse effect and is one of the main contributors to global warming.
Methane (CH₄)	Cattle (bacteria in digestive system), paddy fields, and wetlands, biomass burning.	The concentration of CH₄ in the atmosphere grows by 1% every year.	Second-largest contributor to global warming.
CFCs	Synthetic chemicals in products such as hairspray, refrigerators, and air conditioners	Low abundance. Soon products with CFCs will have been virtually eliminated.	Damages the ozone layer, reducing atmospheres ability to reflect short-wave radiation (ultraviolet),

Albedo

The percentage of solar radiation (Light) that gets reflected into the atmosphere by the surface of a body (higher reflectivity = higher albedo = lower temperature). White has 100% albedo while black has 0%.

The effect of polar ice cap melting and urbanisation

The polar ice caps served as a mirror preventing the oceans in the gaps of the electromagnetic fields from absorbing an increased amount of radiation. Due to the rising global temperatures, the ice melts, allowing more sunlight to be absorbed by the ocean and therefore raising the global temperature which then, in turn, melts the ice (positive feedback loop).

Urbanisation can also increase or decrease the albedo of an area depending on the building material used. Large areas of asphalt reduce the albedo more than large areas of concrete. Big parts of our cities have dark surfaces, hence what is called the urban heat island: temperatures are higher in cities, due partly to the lower albedo.

Feedback loops

Mechanisms that control the Earth’s atmosphere and keep it balanced. If they are any changes made to these mechanisms, it is likely that it would affect the climate.

Positive Feedback	Negative Feedback
When a natural system amplifies itself due to its arrangement. If one element changes, it could reinforce the system, accelerating the amplification.	When a natural system lessens or cancels out the effect of the original change. Such a system is balanced.

You may have to draw a feedback cycle in an exam so make sure you know how to.

Factors that affect the global climate

Volcanic activity

When volcanoes erupt, they emit an immense amount of dust particles into the sky, which partly blocks the Earth from solar radiation. In some cases, if the eruption is exceptionally intense, it could discharge enough dust particles to create a temporary ice age.

Sunspot activity

During the Maunder Minimum (1645-1715) the temperatures have been considerably lower than the average. This abnormality has been linked to the lack of sunspots in that period.

Positives feedback loops

Positive feedback loops naturally amplify themselves. A few of these loops is one of the factors that contribute to global warming. For instance when the temperature increases, fewer CO₂ is dissolved in the warmer oceans -> more carbon in the atmosphere and therefore the temperature rises. This naturally increases the temperature, but when one of the factors in that loop change the whole system can amplify itself even more. Humans have been adding CO₂ to the atmosphere augmenting the effects of the loop.

The increase of greenhouse gas emissions due to human activity

As an immense amount of studies on global warming have concluded, human activity is responsible for the recent temperature rises.

According to the data found in the ice of glaciers and the polls, there is a direct correlation with the concentration of CO₂ in the atmosphere to the average temperature. The data also reveals that there are cycles of around 100 thousand years long in which the temperature rises and drops. With this information, the scientists concluded that apart from the time when the Earth was still developing there has never been such a high level of CO₂ in the atmosphere.

It should be noted that the ice caps of the poles have not always been there and do not contain data older than a few million years. Therefore data from this source is limited to this period and to get a more accurate portrayal, other sources of evidence such as tree rings, agricultural records, and fossil and geological records should be used.

Consequences of climate change

Effects of enhanced global warming

The table below only describes a few effects of global warming. It is essential to understand that there are uncertainties at it is very hard to predict the exact effects of global warming. The rise in global temperature will drastically change the climates. Some research indicates that the change in climate will make some areas cooler.

Effect	Affect / Impacts
	On environment	On humans
A rise of sea levels	Flooding in low-lying areas (Maldives, Kiribati) and coastal cities (Miami).	Migration and economic loss due to damage to infrastructure and loss of land. The rising of salt water can pollute the fresh water, thus reducing its supply.
Melting of glaciers	Flooding in areas near water sources which are supplied by glacier water. Erosion and damage to the ecosystems in these areas.	In the short, term there will be significant damage to infrastructure. In the long, term the retreating glaciers may affect the water supplies in these areas. Places such as India and China, whose culture developed around these sources will suffer from droughts and therefore economic loss, a decline in human health and possibly conflict.
Increase in storm activity	The contrast in temperature due to global warming creates more powerful storms. It is important to keep in mind that that contrast will eventually reduce as the average temperature rises above the optimal storm creation point. The destruction of ecosystems and erosion.	The storms will affect areas which are situated near the sea, like the dominican republic or the south east coast of the US. The increase of their intensity and frequency does greater damage every year on the infrastructure, economy, agriculture and causes injury and fatalities.
Change in weather patterns	Agricultural patterns will change, causing areas with an optimal crop-climate to move towards the poles. This will cause the human activity to migrate with it. Areas which are currently being used will either be eroded and/or given back to nature.	Communities that rely on agriculture as their primary source of income will suffer and therefore economic loss, while areas such as the tundra in Russia will allow yielding crops.
	The late arrivals of monsoons in India are becoming a regularity, causing major droughts and eventually erosion.	The lack of water will make the underprivileged suffer and slow down development due to hunger, thirst, and decline in human health. E.g Inland India
Wildlife extinction (40%)	The reduction of biodiversity and therefore changing biome distribution, species composition and thus harming the symbiotic relationship between animals and plants.	It affects populations that rely on wildlife for the income of food supply, such as in Japan.

 

Impact on the carbon cycle

In its natural state carbon is stored in the ground, in ice, oceans, and the biosphere. In the past, most carbon was emitted from natural events such as volcanic eruptions. The cycle was balanced and allowed the temperatures to stay low as the absorption of CO₂ was quicker than its release. Due to human activity, the release of carbon into the atmosphere from fossil fuels and biomass has suddenly increased, which makes it hard for organisms all over to adapt to migrate. Human activity releases carbon faster than the environment can absorb. As the percentage of fossil fuels decreases, the concentration of CO₂ in the atmosphere increases, which causes the enhanced greenhouse effect.

 

Changes in carbon stored in ice, oceans and the biosphere

Ice	Oceans	Biosphere
Permafrost has accumulated a considerable amount of carbon over millennia due to a  reduced rate of decomposition. Global warming causes the permafrost melt and releases the previously isolated carbon and methane (DOM - dead organic matter) into the air. DOM also contains a lot of nutrients, which leaves fertile land when the permafrost melts.	The content of CO2 in the atmosphere influences the carbon content of oceans. Oceans dissolve carbon dioxide into carbonic acid. This increase in the concentration of carbon will lower the oceanic pH (acidification). Carbonic acid weakens shells of a marine organism making them more vulnerable.	Sinks such as the Canadian forest assimilate a great amount of carbon through photosynthesis and converting it into biomass. The destruction of such sinks (deforestation) emits a large portion that was in the biomass into the atmosphere.
Around 30 to 40% of the carbon stored in soil is in periglacial (situated next to frozen areas) ones If global temperatures exceed 4° methane release will grow by 45 to 65% due to the melting of the periglacial regions	Contains 50x more CO2 than the atmosphere Around 30% of human-induced CO2 into the atmosphere has defused into the sea	Terrestrial plants absorb around 25% of CO2 released by humans If concentrations of CO2 doubles plant growth may grow between 17 and 76%

 

Impacts on humans

Ocean transport

Shipping is being affected by global climate change. Rising sea levels are altering shipping routes and ports:

• The shrinking ice caps around the North Pole are opening up new, shorter shipping routes between north-west Europe (UK, Germany & Norway) and north-east Asia (China, Japan & Korea). This is set to decrease shipping distance by as much as 30%.
• Northern sea routes are currently open only in the summer but predictions suggest they will be open all year round by 2030.
• Ports are opening along the Siberian coast to service ships and China and Iceland have signed a free trade agreement to make trade easy along the new route.
• The new route is only useful for northern countries(US, UK & Russia). The reduction in shipping through the Suez canal (Eygpt), is likely to have a negative impact on Egypt, which will lose revenue as fewer ships pass through.

 

Migration

Climate change is increasing the number and severity of extreme weather events, which destroy homes and livelihoods and may force people to migrate to other areas. An increase in extreme weather events and coastal inundation is expected to increase the number of environmental refugees.

The IPCC estimates that by 2050 there will be about 150 million environmental refugees due to coastal flooding, coastal erosion and agricultural disruption. The IPCC does admit that the situation is very complex and it is difficult to assign 'blame' entirely to global climate change.

 

Human Health

The health of the global population is very varied and the impacts of changes in global climate (temperature, precipitation and extreme events) are likely to hit LICs hardest. Climate change exacerbates the hurdles that stand in the way of better health in the poorest countries. Progress with achieving the Sustainable Development Goals (SDGs) to reduce child under-nutrition and improve overall health may be impeded by changes in food and water supplies, and increasing exposure to a wide range of diseases.

Global climate change has numerous and varied impacts on human health. They can be divided into three categories:

1. Direct impacts, for example, the effects of heat waves and extreme weather events.

2. Impacts linked to changes in the biosphere, such as crop yields and pest prevalence.

3. Indirect impacts linked to changes in resources such as water. 

Responses to Climate Change

Human societies face a choice on whether to:

• Continue producing greenhouse gas (GHG) emissions (i.e. business as usual)
• Take action to reduce further emissions and adjust to a changing environment by reducing the use of fossil fuels and emissions from agriculture. At the same time, actions must be taken to mitigate the impacts of global climate change. 

Vulnerability, risk and risk perception

The vulnerability is the sensitivity and susceptibility to the adverse effects of climate change and the ability (or otherwise) to cope with them. It will depend on cultural, demographic, economic, environmental, geographic, institutional, social and political factors.

Risk can be assessed at any level, from the individual right up to towns, cities and nations. Factors taken into consideration include:

• What is the probability of a particular event happening
• Uncertainty: is it difficult to predict the probability?
• Economic scale: what is the likely cost of the damage?
• Time scales: when will the event occur and how long will it last?

Risk perception of an individual, community or nation will depend on education, gender (females are more concerned), culture, prior knowledge, media coverage, etc.

 

Disparities in exposure to climate change

The whole planet is at risk from climate change. But not everyone everywhere is equally vulnerable and the impact of climate change vary greatly depending on:

• Population densities relative to natural resources
• Reliance on climate-sensitive economic activities, such as agriculture
• Level of development of a country
  • Wealth: people and nations with greater money are more able to prepare for it
  • Health: if baseline health is good then people are more able to overcome some of the impacts of extreme events, such as the spread of disease
  • Education: an educated population is more likely to be prepared

Many of these factors are similar to those discussed in relation to risk and risk perception.  Make sure you have a clear of an idea of how the impacts are similar and how they differ.

Geopolitical adaptation and mitigation

Adaptation: management of the risks posed by global climate change in order to moderate the harm (or take advantage of the opportunities).

Mitigation: any actions taken to eliminate or reduce the long-term impacts of climate change through reducing the sources of, or increasing the sinks of, GHGs.

Geopolitics: the interrelationship between geography and international politics and relations.

It is important that you know the difference between mitigation and adaptation and that you are able to give examples of each of them. 

Kyoto Protocol

In 1997 the annual meeting of the UNFCCC (United Nations Framework Convention on Climate Change) was in Kyoto, Japan. The meeting led to the Kyoto Protocol, which came into force in 2005.

Pros	Cons
Sets targets to reduce GHGs that cause global warming and climate change.	Decisions require consensus and therefore a few countries can block proposals that reduce emission levels further.
Countries can opt to reduce GHG emissions in other countries (where it may be cheaper) and reduce overall emission levels.	Developing countries are exempt from the Kyoto Protocol including China and India, which are significant GHG emitters. Some countries view this as unfair.
Nations can use emission trading, also known as 'cap and trade', where ‘cap’ refers to the limits placed on GHG emissions on each country and ‘trade’ allows countries to buy or sell their emission allowances.	Not all countries have ratified any of the protocols and therefore do not need to cut emissions (e.g. USA). Some countries pulled out (e.g. Canada).

 

Paris Agreement

Like the Kyoto Protocol, the Paris Agreement deals with the mitigation of GHG emissions and adaptation to the impact of climate change. The agreement was:

• Negotiated at COP 21, the 2015 Paris Climate Conference, by the representatives of 195 countries (Note: COP stands for Conference of the Parties.)

 

Government-led actions

Government actions fall under two main categories with mitigation dealing with causes, adaptation with effects:

Adaptation - Dealing with the effects

Changing the way we live to cope with climate change:

• Planting trees to increase shade on waterways therefore decreasing their temperature
• Rising sea walls to cope with higher sea levels
• Building better rain water systems to cope with more floods
• desalination plants can increase supply by using seawater
• building dams to create reservoirs to store water
•  

Mitigation - Dealing with the causes

Reducing emissions and green house gasses to stop climate change

• Reduce energy use through improved by not wasting as much energy
• Replace fossil fuels with low-emission energy sources, such as solar power and nuclear power
• Reduce emissions from transport

 

Geoengineering and technology

Geoengineering involves manipulating the Earth’s environmental systems to counteract the impacts of climate change. It does not address the causes of climate change but could be used to complement the strategies to reduce GHG emissions discussed in Government-led climate change mitigation.

Land use management

Land management can be used to protect and enhance plants that absorb carbon dioxide, thus reducing atmospheric levels:

• Revegetation of land
• Restoration (i.e. reforestation) of degraded land
• Reduced deforestation

Carbon capture and storage

Carbon capture and storage (or CCS) methods are currently under investigation and are likely to be very expensive. The method involves the removal of carbon dioxide from the atmosphere followed by either:

• Chemical processing to form carbonates
• Compression and transport to a site of permanent storage.

Absorption by the oceans

Carbon dioxide is absorbed by photosynthetic phytoplankton in the oceans. 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.

Solar radiation management

Methods of solar radiation management (SRM) are currently only theoretical. They focus on the 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 rooftops with white reflective paint
  • Growing plants with high reflectivity, for example genetically engineered crops or grasses with high albedo
  • Covering areas with reflective material, for instance covering deserts with reflective plastic sheets

Technology

• Data for Climate Action is a UN innovation challenge to access data from different sources. The aim is to access data and identify new approaches to climate change mitigation and adaptation.
• Mobile apps: there is a range of apps to help individuals monitor and reduce their impact on the planet. Apps such as Oroeco and GiveO2 allow individuals to track and reduce their carbon footprint.
• Technology is responsible for improvements in renewable energy, especially in storage and transmission of energy once it is harnessed. Better grids are being developed and they are having as much of an impact as advances in capture technology.
• Changes in diet: technology is making meat substitutes far more palatable, with the hope of reducing the number of cattle and other farm animals kept.

 

Carbon emissions offset and trading

Carbon credit: a tradable permit (or certificate) that allows a country/industry/organisation to produce 1 metric tonne of carbon dioxide. If the permit is not used it can be traded, sold or retired.

The Kyoto Protocol set emission caps for HICs, known as assigned amount units (AAUs). Each AAU allowed them to emit 1 metric tonne of carbon dioxide.

Offsetting

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