Geography - Hazardous Earth - Natural & Human causes of Climate Change

Natural Timescales & Quaternary Period

Earth alternates between glacial (ice ages) & interglacial (warm) periods
Quaternary Period - Lasts 2.6 million years; alternates every 100k years

Natural Causes: Asteroid Collisions

Large Asteroids hit earth - blast massive dust & debris into the atmosphere - dust blocks sunlight - causes global cooling for moths/years

Natural Causes: Volcanic Activity

Eruptions release huge amounts of ash & sulfur dioxide into stratosphere - particles reflect sunlight - causes short-term global cooling aka.volcanic winter

Natural Causes: Solar Output Variations

Sun’s energ varies on an 11-year sunspot cycle
More sunspots = slightly warmer climate
Fewer sunspots = cooler climate

Natursl Causes: Milankovitch Cycles
1.Eccentricity…
2.Axial Tilt…
3.Precession…

Changes how much solar energy earth recieves over 1000s of years, driving ice ages
1. Shape of orbit shifts from circcular to ellipticsl every 100k years
2. Tilts back/forth (21.5 = 24.5 degrees) every 41k years (greater tilt = extreme seasons
3. Earth wobbles on its axis every 26k years changing seasonal contrasts

Evidence: Ice Cores (What it shows & Limitations)

Data: Trapped air bubbles reveal past CO2, Methane & temperature up to 800k years
Flaws: Requires highly specialised, expensive drilling & is limited to thick polar ice sheets

Evidence: Tree rings (What it shows & Limitations)

Data: One growth ring per year, Wider ring = warm/wet, Smaller rings = cold/dry
Flaws: Only shows local climate changes, also affected by local wind/disease

Evidence: Ocean Sediments (What it shows & Limitations)

Data: Microscopic shells/plankton in seabed cores reveal oxygen isotope ratios
Flaws: does not directly measure exact atmospheric climate change

Evidence: Historical Sources (What it shows & Limitations)

Data: Diaries, paintings & harvest logs offer local proof of past weather
Flaws: Unreliable/subjective, wasn’t recorded for science and relies on human interpretation

Natural vs. Enhanced Greenhouse Effect

Natural: Atmospheric gases trap infrared radiation to keep Earth habitable
Enhanced: Human activity increases greenhouse gas concentrations and traps excess heat

Human Activities and Gases produced
Industry & Energy…
Transport….
Farming / Agriculture…
Deforestation…

Industry & Energy: Burning fossil fuels & cement production - CO2, CH4
Transport: Vehicles burning petrol & fuel - CO2
Farming / Agriculture: Livestock (cows) and rice paddies - CH4, N2O
Deforestation: Cleared trees stop absorbing carbon; burning them releases stored carbon - CO2

Major Global Warming Trends

Air Temps risen
Sea levels risen
Oceans absorbed excess heat causing severe coral bleaching
Ice Loss, ice down 90% glaciers shrinking
Weather, Increase in intense heatwaves, deep droughts & fierce tropical cyclones

Climate Change Impacts: Social & Economic

Land loss: Sea levels swallow coastal homes
Health & Food: Droughts destroy crops and increase food shortage & severe heat risks
Displacements: Millions of vulnerable climate refugees
Financial: Massive global costs

Climate Change: Impacts On Environment

Habitats melt - In the Arctic & Antarctica
Oceans - CO2 absorption causes ocean acidifiation killing marine food chains
Rainfall - Shifting rain belts cause extreme desertification
Rapid extinction - shifting ecosystems outpace how fast species can adapt