Enhanced Greenhouse Effect (SL IB Geography)

• 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

Human activities lead to the emission of greenhouse gases that enhance the natural greenhouse effect, contributing to global warming

 Sources of 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