Global climate change (AQA GCSE Chemistry): Revision Notes
Global climate change
What is global climate change
Global climate change happens when Earth's average temperature gets warmer over time. This warming is the main reason why our planet's climate is changing.
The key point to remember is that rising temperatures affect weather patterns, sea levels, and living things all around the world.
Effects of global climate change
Climate change causes six major problems that affect different parts of our planet:
Sea level rise
When temperatures get warmer, ice caps and glaciers melt. This extra water makes sea levels go up. Higher sea levels cause:
- Flooding in coastal areas
- Increased coastal erosion where the sea wears away the land
More frequent storms
Warmer temperatures create more energy in the atmosphere. This leads to:
- Storms happening more often
- More severe storms with stronger winds and heavier rain
Changes in rain patterns
Different parts of the world will experience changes in rainfall:
- Some areas might get more rain than usual
- Other areas might get less rain than usual
- Rain patterns each month will be different from what we see now
Temperature and water stress on living things
Both humans and animals struggle when temperatures change:
- Humans and wildlife may not be able to cope with different temperatures
- Animals and plants need different amounts of water than they're used to
- This makes survival harder for many species
Food production problems
Farming becomes more difficult because:
- Crops need specific temperatures and rainfall to grow well
- Changed weather patterns affect how much food we can produce
- Some areas may not be able to grow the same crops anymore
Wildlife distribution changes
Animals have to move to find suitable places to live:
- Species may have to relocate to areas with better conditions
- Some animals might not find anywhere suitable to live
- This affects the balance of ecosystems
Evidence for human activity causing climate change
The scientific evidence clearly shows that human activities are the main cause of current climate change. This evidence has been thoroughly tested and verified by climate scientists worldwide.
The scientific model
Scientific Model: How Humans Cause Climate Change
Step 1: Human activities release carbon dioxide - We burn fossil fuels and cut down forests
Step 2: Carbon dioxide is a greenhouse gas - It traps heat in the atmosphere
Step 3: Temperature increase matches carbon dioxide increase - As CO₂ goes up, so does temperature
Graph evidence
A graph showing data from 1850 to 2000 proves this connection:
- Carbon dioxide levels in the atmosphere have risen steadily
- Global temperature has also risen over the same time period
- The two lines on the graph follow very similar patterns
This shows a clear correlation - as one goes up, so does the other.
Peer review process
The scientific evidence has been peer reviewed. This means:
- Other scientists have checked the work
- The Met Office (where scientists study weather and climate) supports these findings
- The evidence has been carefully examined and approved
It's hard to model Earth's complex climate perfectly, but the scientific model and evidence have been thoroughly checked by experts.
Key Points to Remember:
- Global climate change means Earth's average temperature is getting warmer
- There are six main effects: sea level rise, more storms, changed rain patterns, stress on living things, food production problems, and wildlife distribution changes
- Human activities like burning fossil fuels and deforestation increase carbon dioxide in the atmosphere
- Graphs show that as CO₂ levels rise, so does global temperature - this proves the connection
- Scientists have peer-reviewed this evidence, making it reliable and trustworthy