Human activity (Edexcel GCSE Geography A): Revision Notes
Human activity and climate change
Introduction to human impact on climate
Human activities have become a major driver of global warming in recent decades. The primary way humans influence climate is through increasing levels of greenhouse gases in the atmosphere, which are released by various industries, transport systems, energy production, and farming practices.
Greenhouse gases are atmospheric compounds that trap heat from the Sun, including carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). While these gases occur naturally and are essential for maintaining Earth's temperature, human activities have dramatically increased their concentrations.
The enhanced greenhouse effect
Human activity has significantly altered the natural greenhouse effect that keeps Earth warm enough to support life. When we burn fossil fuels and engage in other activities that release greenhouse gases, we create what scientists call the "enhanced greenhouse effect."
The enhanced greenhouse effect is the additional warming caused by human activities beyond the natural greenhouse effect. This process is the fundamental mechanism driving current climate change.
This process works by releasing increasing levels of carbon dioxide (CO₂) and other greenhouse gases into the atmosphere. These gases trap more of the heat that would normally escape back into space, causing additional warming beyond what occurs naturally. The result is a gradual increase in global temperatures that leads to widespread climate change.
The Greenhouse Effect Process:
The greenhouse effect can be understood in three key steps:
- Heat energy from the Sun passes through the atmosphere and heats up the Earth
- Much of this heat energy is radiated back into space
- Greenhouse gases in the atmosphere trap some of the heat, preventing it from escaping and causing warming
Human causes of climate change
Industry
Industrial activities are major contributors to greenhouse gas emissions. Rising demand for consumer goods has increased production levels, which requires burning more fossil fuels. Manufacturing processes release greenhouse gases directly into the atmosphere, contributing significantly to global warming.
Energy production
New technologies and growing populations have created massive demand for electricity. Most of this electricity is still produced by burning coal, oil, and natural gas, all of which release substantial amounts of greenhouse gases when burned. The energy sector remains one of the largest sources of human-caused emissions.
Despite advances in renewable energy technology, fossil fuels still account for the majority of global electricity production, making the energy sector a critical target for climate action.
Farming and agriculture
Global population growth has increased demand for food, leading to more intensive farming practices. Mechanisation in agriculture burns more fuel, whilst the growing demand for meat in Western-style diets has increased methane levels significantly. Livestock farming, particularly cattle ranching, produces large quantities of methane, a potent greenhouse gas.
Transport
Rising affluence has led to increased car ownership and air travel, releasing more greenhouse gases into the atmosphere. The transport sector includes cars, lorries, ships, and aeroplanes, all of which typically burn fossil fuels and contribute to emissions.
Negative impacts on the environment
Climate change is causing severe environmental problems around the world. One of the most visible impacts is the melting of ice sheets and retreating glaciers, which adds water to oceans and causes sea levels to rise. In the Arctic, melting could cause the Gulf Stream to move further south, potentially leading to colder temperatures in Western Europe despite overall global warming.
Rising sea levels create serious problems for coastal areas. Coastal flooding becomes more frequent and severe, whilst soils become contaminated with salt water. This contamination kills plants and damages ecosystems that depend on fresh water. Many coastal habitats face permanent loss.
The melting of polar ice sheets represents a critical tipping point in climate change. Once begun, this process can accelerate and become irreversible, leading to dramatic sea level rises that threaten coastal communities worldwide.
Negative impacts on people
The human consequences of climate change are becoming increasingly severe. Changes in climate patterns near the Equator, particularly in regions like Africa's Sahel, could mean longer drought periods and less rainfall overall. This directly threatens crop yields and food security for millions of people.
Many low-lying islands, such as the Maldives, face existential threats from rising sea levels. These islands experience greater flood risk, more frequent coastal flooding, and loss of beaches and coral reefs. Some islands may eventually have to be completely evacuated as they become uninhabitable.
Agricultural regions worldwide are experiencing reduced crop yields due to changing weather patterns. Countries like Tanzania face longer periods of drought, which can lead to food shortages and economic hardship for farming communities.
Climate change disproportionately affects the world's most vulnerable populations, including small island states and communities in arid regions that have contributed least to the problem but face the most severe consequences.
Case study examples
Environmental Impact Example: Glacial Melt and Water Systems
Climate change causes glaciers to melt rapidly, which affects river systems and ecosystems that depend on spring glacier melt.
Short-term effects: These areas may experience flooding as large volumes of meltwater are released quickly.
Long-term effects: They will have too little water available as glaciers shrink and disappear entirely.
Consequences: This creates serious problems for both natural habitats and human communities that rely on glacial meltwater for drinking water, agriculture, and hydroelectric power.
Human Impact Example: Agricultural Changes in Tanzania
In Tanzania, climate change has led to reduced crop yields due to longer periods of drought.
Direct impacts:
- Food shortages affect local communities
- Economic difficulties for farming families
- Reduced income from agricultural exports
Adaptation challenges: The changing rainfall patterns make it harder for farmers to predict when to plant crops and how much water will be available during growing seasons, disrupting traditional farming practices passed down through generations.
Key Points to Remember:
- Human activities like industry, energy production, farming, and transport are the main causes of increased greenhouse gas emissions
- The enhanced greenhouse effect occurs when human activities release extra greenhouse gases that trap more heat in the atmosphere
- Environmental impacts include melting glaciers, rising sea levels, and coastal flooding that damages ecosystems
- People face reduced crop yields, food shortages, and some island nations may need to evacuate due to rising seas
- Both environmental and human impacts of climate change are interconnected and affect each other in complex ways