Enhanced Greenhouse Effect (DP IB Geography)
Revision Note
The Enhanced Greenhouse Effect
The enhanced greenhouse effect is different from the natural greenhouse effect because it is primarily driven by human activities that release excessive amounts of greenhouse gases (GHGs) into the atmosphere, leading to an intensified trapping of heat and subsequent global warming
While the natural greenhouse effect is a necessary process that helps regulate the Earth's temperature by trapping some heat to maintain a habitable climate, the enhanced greenhouse effect disrupts this balance as a result of greenhouse gas concentrations being artificially increased beyond natural levels
Human activity has increased CO2 levels in the atmosphere by more than 100 parts per million (ppm) to 420ppm in 2020
Increased amounts of greenhouse gases have led to less long-wave radiation escaping the atmosphere
Increasing global average temperatures by over 1°C since pre-industrial times
Average global temperatures
The natural and enhanced greenhouse effect
Greenhouse Gases
Sources of Greenhouse Gases
Greenhouse Gas Annual % emitted | Time in Atmosphere | Sources |
---|---|---|
Carbon Dioxide (CO2) 74.4% | Unknown as the gas is not destroyed over time, but moves through the carbon cycle with different residence times on land, sea and atmosphere. Can be weeks, months, years or millennia | Burning of fossil fuels - power stations, vehicles |
Methane (CH4) 17.3% | 11.8 years and is approx. 28 times more potent than CO2 at warming the climate | Decay of organic matter - manure, waste in landfill, crops |
Nitrous Oxide (N2O) 6.2% | 109 years and is 273 times more potent at warming the climate than CO2 | Artificial fertilisers |
Fluorinated Gases (CFCs, HFCs, sulphur hexafluoride, perfluorocarbons) 2.1% | A few weeks to thousands of years and climate warming potential varies from 12 times to 25,000 times more potent than CO2 | Aerosols |
Water Vapour | Although the most abundant of all the greenhouse gases, water vapour only has a residence time in the atmosphere of days and therefore, acts as feedback rather than a forcing of global warming | Most abundant greenhouse gas and levels are determined by temperature and humidity levels |
Global Variations in Greenhouse Gases
Global average concentrations of carbon dioxide (CO2), in 2022 were 50% above pre-industrial levels for the first time
Concentrations of methane (CH4) also increased
However, levels of nitrous oxide saw the highest year-on-year increase on record from 2021 to 2022
Global greenhouse gas emissions are converted to CO2 equivalents (CO2e) by multiplying each GHG by its 100 year global warming potential (GWP) value
Global greenhouse gas emissions from 1850-2022
Global greenhouse gas emissions by country 2021
Global per capita greenhouse gas emissions 2021
Countries in the northern hemisphere emit more carbon dioxide equivalents (CO2e) annually in comparison to countries in the southern hemisphere
For example, China emitted up to 13.71 billion tonnes of CO2e in 2021
On the other hand, Australia emitted 602.5 million tonnes of CO2e in 2021
However, Iceland is an anomaly, it is located in the northern hemisphere and emitted just 4.43 million tonnes of CO2e in 2021
Specific regions:
In 2021, Oceania had the lowest rates of emissions at 738 million t and Asia had the highest at 29.7 billion t CO2e
Africa emitted 4.7 billion t which was higher than South America at just 3.6 billion t CO2e
South Africa and Democratic Republic of Congo emitted the most CO2e in 2021 at 553 million t and 545 million t respectively, with Nigeria a close third place at 445 million t of CO2e
Europe emitted 6.82 billion t with North America emitting 7,86 billion t of CO2e
Per capita emissions
Total annual emissions shows which country emits the most as a whole, but this does not account for development and personal usage
China and India are the two most populous countries but are portrayed as the top emitters
Account for the population and China is 9.6t CO2e and India is 2.8t CO2e
In this instance, Australia (23t) and Canada (20t) are both top emitters of CO2 and Iceland is 12t CO2e due to the size of their population
Global variations in GHG sources
HICs utilise a large amount of energy hungry technology through industrial processes and domestic usage
Domestic use includes lighting, heating and household appliances such as computers, mobile phone chargers, TVs, washers and dryers etc.
With the implementation of strict environmental laws to reduce their GHG emissions, and switching to low-energy new technologies along with the production of renewable energy with little to no emissions, HICs are now emitting fewer GHGs than industrialising MICs such as China and India
MICs have a number of manufacturing industries, which increases their energy use and emissions
However, domestic energy consumption is lower in comparison to HICs
LICs generally have the lowest GHG emissions due to lack of industrial development
Moreover, per capita income is lower, meaning less money is available to spend on high-energy products
Despite HIC emissions being high, the increase in GHGs has been relatively stable
However, as more LICs develop into MICs and more MICs develop into HICs, the demand for energy will increase
Therefore, the growth in GHG emissions by these countries will increase
Currently, it is the industrial regions of the world that are now producing the most emissions, such as China and India
Effect of globalisation and trade on GHG emissions
As globalisation increased the manufacturing and export of goods, this led to the increase in GHG emissions from industries to meet market demand
As trade increased, so too did the transport of goods via ship, train, road and air, thereby, increasing emissions
MICs and LICs, often have relaxed emission regulations, which encourages TNCs to re-located their manufacturing plants to avoid spending money on expensive modifications or buying new technology to capture emissions
Trade in emerging economies may help improve the standard of living however, if people become reliant on these forms of trade for income, then there is no incentive for developing economies to take measures to reduce emissions
Furthermore, as people earn money, their disposable income increases allowing them to afford products that are energy hungry such as televisions and air conditioners
This results in a per capita GHG emissions increase
Examiner Tip
If asked in the exam about global and regional trend of emissions, you need to be able to discuss this in general terms with a couple of specific facts to support your answer. You do not need a lot of data knowledge, but remember which regions have the highest, middle and lowest emissions.
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