Global Climate

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:

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%.

Picture

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:

 

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:

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:

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:

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:

 

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:

Mitigation - Dealing with the causes

Reducing emissions and green house gasses to stop climate change

 

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:

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:

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:

Technology

 

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

Carbon offset: when operators pay for projects in other countries that will reduce the amount of carbon dioxide in the atmosphere.

Offsetting is quite controversial as it can allow HIC's to keep emissions by paying other countries. Make sure you understand both sides of the argument.

 

Bangladesh Case Study

Geography

  • Located on one of the largest river deltas in the world.
  • Over 60% of the land is less than 5 m above sea level.
  • Bangladesh has suffered from natural disasters a lot. between 1980 and 2008 it suffered from 219 of them.
  • Its location at the head of the Bay of Bengal means that the cyclones that enter the bay are funneled over Bangladesh, causing major storm surges.
  • A rise in sea level of 1 m will displace 30 million people from 15% of the land that will be inundated.

Location of Bangladesh.

 Economy

  • Population below poverty line: 31.5%.
  • Over 60% of the population is engaged in farming and lives in rural areas: the low-lying fertile flood plains of the river systems and the delta. 

People

  • Population density: approximately 950 people/km2.
  • Major infectious diseases include food and waterborne diseases diarrhoea, hepatitis, typhoid fever, dengue fever and malaria.
  • High maternal mortality (176 deaths/100,000 live births)

Non-governmental responses

Goalbari

Goalbari is an agricultural village just outside of Dhaka

A local women’s cooperative has successfully addressed the issues bought by the floods:

  • The village has a collective and their savings are used to provide small loans to the women in the village.
  • Loans are used to buy assets to improve future income
  • Strategies to adapt to the floods include:
    • houses were raised 1.2 m above the floodwaters
    • floating beds plant bed were built: the beds rise and fall with the floodwaters.

NGOs (Non-Goverment Organisations) active in this project are

 

Infographic about the impact of global climate change in Bangladesh.

Bangladesh has to adapt to the effects of global climate change. Despite its vulnerabilities in terms of the physical geography of the country and the density of its population, there are possibilities. National initiatives such as raising homes will enable people to live in areas suffering from sea-level rise, whilst resources from external governments and non-governmental organisations will assist with the funding of other schemes to protect both the natural and human environment.

Editors

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