Global Warming | Geography for GCSE/IGCSE - Year 11 PDF Download

Changes in the global climate

• Earth's climate has fluctuated over time, experiencing both colder and warmer periods.
• The Quaternary period, spanning the last 2.6 million years, has seen cycles of approximately 60 cold periods interspersed with warmer interglacial periods.
• The most recent ice age concluded around 25,000 years ago.
• Evidence supporting these climatic shifts includes:
  • Ice cores, which preserve ash, air bubbles, and microbes, providing insights into past atmospheric conditions.
  • Preserved pollen samples, offering clues about past vegetation and climate.
  • Historical records like diaries and artwork, providing anecdotal evidence of climatic conditions.
  • Tree rings, serving as a natural archive of past climate variations.

Causes of Natural Climate Change

The greenhouse effect

The greenhouse effect is crucial for life on Earth:

• Greenhouse gases in the atmosphere enable short-wave radiation from the sun to reach the Earth's surface
• These gases absorb some of the long-wave radiation (heat), preventing it from escaping into space
• This process maintains Earth's average temperature
• Without the greenhouse effect, the average temperature would be -18 degrees Celsius

Greenhouse gases from natural sources  

• Water Vapour: Water vapour originates from evaporation in oceans/seas and plants.
• Carbon Dioxide: Carbon dioxide is produced through volcanic eruptions, wildfires, and respiration.
• Methane: Methane is released from oceans, soils during decomposition, and by termites.
• Nitrous Oxide: Nitrous oxide is emitted from soils and oceans.

The enhanced greenhouse effect

• Human activities are elevating the concentration of greenhouse gases in the atmosphere.
• Carbon dioxide (CO₂) levels in the atmosphere have surged by over 100 parts per million (ppm), reaching 420ppm by 2020.
• This rise in greenhouse gases has intensified the greenhouse effect:
  • The atmosphere retains more long-wave radiation (heat), resulting in less escaping into space.
• Average global temperatures have risen by over 1 degree Celsius since the pre-industrial era.

Human Sources of Greenhouse Gases

Impacts of the enhanced greenhouse effect

Health

• Rising temperatures and decreased precipitation can facilitate the spread of diseases.
• Italy has reported cases of malaria since 2017, despite being malaria-free previously.
• An estimated additional 280 million individuals may be susceptible to malaria.
• Water-borne diseases are more likely to proliferate.
• Heatwaves may become more frequent, leading to increased instances of heat stroke, dehydration, and sunburn.
• Stagnant air during heatwaves can heighten air pollution levels, exacerbating respiratory ailments like asthma.
• Elevated temperatures adversely affect those with cardiopulmonary conditions.
• Food shortages due to climate impacts can result in restricted diets, malnutrition, and famine.

Homes and Settlements

• Sea level rise and intensified storm activity will escalate flooding, displacing many.
• Settlements in low-lying regions may require abandonment or reinforced defenses against rising sea levels.
• Relocating settlements or bolstering flood defenses will incur significant costs.

Agriculture

• Farmers may need to adapt crops to suit changing climate conditions.
• Coastal flooding can introduce salt into agricultural land, impacting crop growth.
• Diminished water availability may restrict or prevent irrigation.
• Food shortages resulting from climate impacts can contribute to malnutrition and famine.

Employment
Job opportunities may alter or decline due to various factors:

• Declining tourism in areas like ski resorts due to unreliable snowfall.
• Coastal resort closures due to flooding risks.
• Farmers may need to shift crops or livestock, or exit farming altogether.
• Agriculture may decline in regions experiencing rising temperatures or altered rainfall patterns.

Sea Level Rise

• Warmer temperatures lead to the expansion of seawater, raising sea levels.
• Melting ice contributes to the increased volume of water.
• Average sea levels have risen by 23cm since 1880.
• Predictions suggest a further increase of 30cm by 2050.
• Low-lying coastal regions and islands face heightened flood risks.
• The Maldives may become uninhabitable by 2050.
• Coastal erosion, including beach erosion, will intensify.
• Coastal ecosystems such as coral reefs and mangrove swamps will be impacted.
• Saltwater intrusion contaminates freshwater supplies and affects coastal agriculture.

Ecosystem Change

• Biomes may shift towards the poles as they rely on specific climate conditions.
• Polar and tundra biomes face extinction risks as they have limited scope for further north/south movement.
• Coral bleaching is occurring due to rising sea temperatures and ocean acidification.
• Changing temperatures affect animal migration and behavior:
• Fish species are moving to cooler waters north and south of their usual habitats.
• Warmer winters lead to reduced hibernation.
• Melting ice caps and glaciers alter ocean currents.
• Rising sea levels threaten mangrove swamps and coral reefs.
• Loss of habitats due to flooding, drought, and wildfires disrupts ecosystems and food webs.

Natural Hazards

• Climate pattern changes increase the frequency and severity of storms.
• The Atlantic hurricane seasons of 2020 and 2021 were among the most active on record.
• Droughts are becoming more frequent and prolonged.
• Dry conditions heighten the risk of wildfires, observed in places like Australia, Greece, South Africa, Brazil, and the USA in 2021.
• In September 2021, the USA National Fire Center reported 44,647 wildfires burning 5.6 million acres.
• Rising sea levels, coupled with intensified storms, increase the risk of flooding.

Responses to climate change

• Global warming and climate change necessitate a global response due to their worldwide impact.
• Responses can encompass either adaptation or mitigation strategies.
• The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 to evaluate the risks associated with human-induced climate change.
• This initiative was succeeded by numerous international agreements aimed at addressing climate change.

Earth Summit, Rio 1992

• Established goals to stabilize greenhouse gas levels.

Kyoto Protocol 1997

• Representatives from 150 nations agreed to cut greenhouse gas emissions.
• Industrialized nations pledged to decrease emissions below 1990 levels.
• Developing countries such as China and India were exempt.
• The USA did not join the treaty.
• Canada withdrew in 2011, citing the absence of China and the USA.

Paris Agreement 2015

• A global pact aimed at limiting global warming to 2°C (preferably 1.5°C) above pre-industrial levels.
• Included targets for reducing CO2 emissions by at least 60% by 2050.
• Signed by 196 countries, including the USA and China (though the USA withdrew in 2020 and rejoined in 2021).

Conference of the Parties (COP)

• The UN holds an annual meeting to discuss climate change.
• COP26 was convened in Glasgow in 2021, where all nations agreed to further reduce greenhouse gas emissions.

Reducing emissions

• Strategies include reducing deforestation, increasing afforestation, enhancing energy efficiency in industry and domestic appliances, cutting emissions from industry, improving public transport, promoting electric vehicles, and utilizing renewable energy and nuclear power.