Causes of global climate change
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What is the global energy balance?
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All Flashcards in Topic 2.1
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2.1.112 cards
What is the global energy balance?
Incoming short-wave **solar** radiation balancing outgoing long-wave **terrestrial** radiation, keeping Earth's temperature steady.
Short-wave vs long-wave radiation?
The Sun sends **short-wave** energy in; the cooler Earth re-emits **long-wave** heat out.
Define albedo.
The share of incoming radiation a surface **reflects** straight back, without warming it.
Define terrestrial albedo.
The reflectivity of the **Earth's surface** - high for ice and desert, low for ocean and forest.
Name two high-albedo surfaces.
Fresh **snow/ice** and bright **desert** sand (also cloud tops) reflect most radiation.
Outline the natural greenhouse effect.
Greenhouse gases **absorb** outgoing long-wave heat and **re-radiate** some back down, warming the lower atmosphere.
Without the natural greenhouse effect, Earth would be…
About **33C colder** and largely frozen.
Name two greenhouse gases that are NOT carbon dioxide.
**Water vapour** and **methane** (also nitrous oxide and ozone).
What is the enhanced greenhouse effect?
The **extra** warming when **human activity** raises greenhouse-gas levels, trapping more heat than the natural effect.
Why is it called a 'greenhouse'?
Like greenhouse glass, the gases let **short-wave** light in but trap some **long-wave** heat leaving.
Roughly how much insolation is reflected (the albedo)?
About **30%** of incoming solar radiation is reflected straight back to space.
Outline vs Explain on these short parts?
**Outline** = give the main points briefly; you do not need a full developed mechanism unless asked to Explain.
2.1.211 cards
Define the global energy balance.
The balance between incoming solar energy and energy radiated back to space; it sets Earth's temperature.
Name two natural causes that can WARM the climate.
Higher **solar output** (sunspot cycle) and **orbital (Milankovitch) cycles**.
Name a natural cause that COOLS the climate.
A large **volcanic eruption** -> sulfate aerosols -> **global dimming**.
What is global dimming?
A fall in sunlight reaching the ground because particles in the air reflect or block it.
How do volcanoes cool the planet?
Aerosols thrown high into the atmosphere reflect sunlight back to space, so less reaches the surface (cooling for 1-3 years).
What are Milankovitch cycles?
Slow changes in Earth's orbit shape, axial tilt and wobble over tens of thousands of years that change incoming sunlight and drive ice ages.
Define a positive feedback loop.
A change that **amplifies itself** -- the change triggers more of the same change.
Explain the ice-albedo feedback.
Warming melts bright reflective ice; the darker surface absorbs more heat; that warms it further, melting more ice.
Explain the permafrost-methane feedback.
Warming thaws permafrost, releasing methane (a greenhouse gas), which traps more heat, thawing more permafrost.
What did Mount Pinatubo (1991) show?
Its aerosols cooled global temperatures by about **0.5 degrees C** for ~a year -- natural cooling / global dimming.
Why is today's warming seen as mainly human, not natural?
Natural forcings are small or cooling recently, while CO2 from fossil fuels has risen sharply since ~1850, tracking the rapid warming.
2.1.311 cards
Name the two main greenhouse gases from human activity.
**Carbon dioxide (CO2)** and **methane (CH4)**.
Define a greenhouse gas.
A gas that traps heat in the atmosphere, warming the Earth.
What is the enhanced greenhouse effect?
Extra warming caused by **human-added** greenhouse gases on top of the natural effect.
Define albedo.
How reflective a surface is — bright surfaces reflect sunlight (high albedo), dark surfaces absorb it (low albedo).
Give two human sources of CO2.
**Burning fossil fuels** (energy, transport, industry) and **deforestation**.
Give two reasons methane is rising.
More **livestock** (cattle) and more **rice farming**; also fossil-fuel leaks and landfill.
How does building a city change albedo?
Dark tarmac and roofs **lower** albedo, so more sunlight is absorbed and the surface warms.
How can expanding trade raise emissions?
More export manufacturing burns more fuel (CO2) and more long-distance shipping/flying adds emissions.
Why can economic development raise OR lower emissions?
Early growth adds industry and cars (rise); later, wealthy economies can afford clean energy and services (fall).
Data command term: what does 'State' require?
Read the value **straight off** the graph or table — no explanation needed.
How does deforestation cause warming?
It removes trees that absorbed CO2, and burning them releases stored carbon.
Topic 2.1 study notes
Full notes & explanations for Causes of global climate change
Geography exam skills
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