Climate Change vs Global Warming

Climate Change:
- Any significant changes in measures of climate
- Extended periods of time
Global Warming:
- Increase in Earth’s average surface temperature
- Increasing levels of greenhouse gases

Causes of Climate Change

Natural Variability

Earth formed since 4.6 billion years ago
Earth’s climate in the past is not the same as the climate today
In the past 650,000 years, temperatures and carbon dioxide levels in atmosphere have increased and decreased
In cyclical pattern
Climate zones expand and contract over time
Temperature is used to determine boundaries of climate zones and if they have changed

Causes of Natural Variability

Long-term:
- Changes in Earth’s orbit and angle of tilt
Short term:
- Sunspots
- Volcanic eruptions

Variations in Earth’s Orbit and Tilt

Occur over tens of thousands of years
Milankovich Cycle

Variations in Solar Output

Cycles in sunspots
Periods of max sunspot activity -> high annual surface temps
Rises and falls in a cycle of every 11 years
Higher sunspot activity -> higher amounts of solar radiation
- Short term increases in average temps

Large-Scale Volcanic Eruptions

Can decrease global temperatures temporarily
Huge amount of ash released
Less solar radiation reaches earth
More solar radiation reflected

Anthropogenic Factors

(Factors caused by people yes you people)

Greenhouse Effect

Greenhouse gasses trap longwave radiation (heat that is re-emitted from Earth’s surface to the atmosphere) emitted from the Earth’s surface
Gases:
- Carbon Dioxide
- Methane
- Water Vapour
- Nitrous Oxide

Enhanced Greenhouse Effect

Occurs due to increased concentration of greenhouse gases
Most greenhouse gasses are non-condensable

Sources:

Carbon Dioxide	Methane	Nitrous Oxide
Respiration	Anaerobic digestion/decomposition	Byproduct of combustion of fuels
Combustion	Bovine Flatulence	Denitrification of chemical fertilisers in soil

Burning of fossil fuels and changing land use have contributed greatly to the enhanced greenhouse effect
Fuelled by a growth in population and modern industrialisation

Deforestation

Large-sclae removal of trees in forests
Cutting down or burning
Impacts:
- Reduces numbers of trees to absorb carbon dioxide
- Carbon that is stored is released back when decayed or burned
- Exposes soil beneath to sunlight, resulting in carbon oxidation.

Agriculture

Forests cleared to make space for agriculture
Burning of fossil fules to operate farm machinery and vehicles
Fertilise crops using chemical fertilisers
BOVINE FLATULENCE!!
Nitrogen in chemical fertilisers convert to Nitrous Oxide