Gcse geo paper 1

Natural Hazard

A natural event that has the potential to cause harm or damage.

Factors Affecting Hazard Risk

• Urbanisation (more people in risky areas)

• Poverty (can’t afford protection)

• Farming (e.g. deforestation → landslides)

• Climate change (more extreme weather)

Tectonic Hazards

Natural hazards that result from the movement of tectonic plates.

Destructive Plate Boundaries

Plates move together, the denser oceanic plate subducts, earthquakes and volcanoes occur.

Constructive Plate Boundaries

Plates move apart, magma rises, new crust forms, and volcanoes/earthquakes happen.

Conservative Plate Boundaries

Plates slide past each other, causing earthquakes but not volcanoes.

Tectonic Hazard Case Study: Chile 2010

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Tectonic Hazard Case Study: Nepal 2015

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Reasons for Living in Hazard-Prone Areas

• Fertile volcanic soils

• Tourism and mining

• Family and cultural ties

3Ps for Tectonic Hazards

Prediction: monitoring signs like seismic activity and gas release.
Planning: evacuation routes, drills, education, emergency kits.
Protection: earthquake-resistant buildings, strengthened structures, land-use zoning. AQA groups these with monitoring as ways to reduce risk

Global Atmospheric Circulation

• Warm air rises at the Equator, moves poleward high in the atmosphere, sinks around 30°, rises again around 60°, and sinks at the poles.

• This creates the Hadley, Ferrell and Polar cells

• And pressure belts and surface winds that shape global weather.

How are tropical storms formed?

• Warm ocean water evaporates; rising air condenses into clouds, releasing energy that fuels powerful storms.

• Rising air creates low pressure, drawing in strong surface winds.

• Low wind shear keeps clouds intact, maintaining storm structure.

• Easterly winds near the equator push storms west; they spin due to the Coriolis effect from Earth’s rotation.

• Over warm water, storms gain energy and wind speeds increase.

• Moving over land or cooler water cuts energy supply, so storms weaken.

What tropical Storms need

They need:

• sea temperatures above about 27°C

• lots of warm, moist air

• low wind shear

• low pressure

Characteristics of Tropical Storms

• Wind: Very strong, can exceed 120 km/h. Causes structural damage.

• Rainfall: Extremely heavy, can lead to flooding and landslides.

• Size: Can be hundreds of km across.

• Duration: Lasts days to weeks, moves with prevailing winds.

Distribution of tropical storms

• Found between 5°–30° north and south of the Equator

Coriolis effect

The deflection of moving air and water due to Earth's rotation

Tropical Storm Case Study: Typhoon Haiyan 2013

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What is the effect of climate change on Tropical Storms gcse

• Increase in temperature

• More of Earth's seas will be warmer than 26.5^oC

• So there will be more storms and those that happen will have more energy.

Causes of Extreme Weather in the UK

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UK Extreme Weather Case Study: Somerset Levels Floods 2014

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Evidence for Climate Change

• Ice cores

• Temperature record

• Tree rings

Ice core

• Ice sheets are made of layers of ice - one layer is formed each year

• Analysing the gas trapped in the layers - they can tell what the temperature was each year

Temperature records

• Global temperatures have been measured accurately since the 1950s using thermometers

• This gives a record of temperature change over the last few decades

Natural Causes of Climate Change

• Orbital changes

• Volcanic activity

• Sunspots

Orbital Changes

• Earth’s orbit changes from more circular to more elliptical over ~100,000 years → affects distance from the sun.

• Earth wobbles on its axis over ~26,000 years → changes the timing of seasons

Over thousands of years, this can trigger ice ages or warmer periods, because less or more energy reaching the Earth affects global temperatures.

Volcanic activity

• Major eruptions release ash and sulfur dioxide into the atmosphere.

• Ash can block sunlight → temporary cooling.

• Volcanoes also release CO₂, contributing to greenhouse gas concentrations increasing

Sunspots

• Sun’s energy output fluctuates naturally in cycles

• Periods with more sunspots = slightly warmer Earth, fewer sunspots = slightly cooler Earth.

• Contributes to short-term climate variability

Human Causes of Climate Change

• Burning fossil fuels

• Agriculture and deforestation

• Cattle ranching

Managing Climate Change

• Planting trees

• Carbon capture - Capturing carbon and storing it in safe places like underground

• Replacing fossil fuels with renewable enrgy, reduces greenhouse gas emissions

Ecosystem

An ecosystem is a system where living things and non-living things interact.

Biome

A large ecosystem with a similar climate, vegetation and animal life.

Biotic factors

Living things such as plants, animals and decomposers

Abiotic factors

Non-living things like temperature, rainfall, soil and light.

Nutrient Cycle

• When dead material decomposes nutrients are released into the soil

• The nutrients are then taken up from the soil by plants. Plant may be eaten by consumers

• When the plant or consumer dies, the nutrients are returned to the soil

Characteristics of tropical rainforests

• They are hot and wet all year, with dense layered vegetation, very high biodiversity, and rapid nutrient cycling.

• Soils are often thin and nutrient-poor because nutrients are quickly taken up by plants or washed out.

Plant and animal adaptations

• Drip tips - leaves shed water quickly preventing bacteria growing

• Buttress roots - Support tall trees trunks in the shallow soil

Animal adaptations

• Poison dart frogs use bright warning colours and secretes toxins which deters predators.

• Sloths move slowly and live in trees to avoid predators and save energy

Rainforests four layers

• Emergent layer

• Canopy Layer

• Understory Layer
  Forest Floor

Emergent Layer

• Tallest trees (up to 50m) that rise above the canopy.

• Exposed to strong sunlight and wind; home to birds and some insects.

Canopy Layer

• Dense layer of trees forming a roof over the forest.

• Most animals live here; blocks sunlight from reaching lower layers.

Understory Layer

• Shaded, humid layer under the canopy.

• Home to snakes, jaguars, insects, and small plants adapted to low light.

Forest Floor

• Very dark and humid, receives less than 2% of sunlight.

• Rich in decomposing material; home to large mammals and decomposers.

case study of a tropical rainforest

Management of tropical rainforests

• Selective Logging: Instead of clear-cutting, only mature, commercially viable trees are felled, allowing the canopy to recover and younger trees to grow. Techniques like horse logging or helicopter logging can further reduce environmental damage.

  Afforestation/Replanting: Planting new trees to replace those cut down ensures the forest can regenerate, a practice supported by local nurseries.

• Ecotourism: Promoting low-impact tourism educates visitors and provides local income that is dependent on conserving the forest, rather than destroying it.

Hot Desert characteristics

• Very dry and little rainfall - less than 250mm

• High daytime temperatures

• Cold nights

• Sparse vegetation

Plant adaptations

• Cacti store water and have spines instead of leaves, which deter herbivores

• Extremely long plant roots to reach deep water

Animal adaptation

• Camels store fat, have long eyelashes and can survive long periods without water.

• Fennec foxes have large ears to lose heat.

Hot desert case study

Desertification

• Land becoming drier & less fertile, often turning into desert

Causes of desertification

• Climate change - Reduces rainfall, so less water for plant growth

• Overgrazing - too many cattle, consume plant fast than they re-grow

• Overcultivation - If crops are continually planted in the same areas, all the nutrients in the soul are used up, so plants cant be grown here

Solution of desertification

• Tree planting - Trees reduce wind erosion and prevent desert from encroaching on farm land

• Soil Management - Leaving areas of land to rest in between planting lets them recover nutrients

• Growing crops that need little water, reduces water usage

Case study of desertification sahel