Hazards - Geography

The whole unit of Hazards (WORLD AT RISK) 

Global Hazards, Disaster Risk Equation, Global Warming, Hydro-meteorological and Geo-physical hazards, hazards distribution, disaster hotspot case studies, Climate change - evidence, causes, impacts, case studies, coping with climate change, global hazards - the future


Global Hazards

Different Types of Hazards:

What is a hazard? - A hazard is something that is a potential threat to human life or property

Natural hazards can be split up into two types

Hydro-meterological hazards - Caused by CLIMATIC processes, e.g. DROUGHTS, FLOODS, TROPICAL CYCLONES & STORMS.

Geophysical hazards - Caused by LAND processes, e.g. EARTHQHUAKES, VOLCANIC ERUPTIONS & LANDSLIDES.

Disaster - When a hazard actually SERIOUSLY AFFECTS humans. 

Risk - The LIKELIHOOD that humans will be SERIOUSLY AFFECTED by a hazard

Vulnerability - How SUSCEPTIBLE a POPULATION is to the DAMAGE caused by a HAZARD. 

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Global Hazards - Disaster Risk Equation

The RISK of a HAZARD can be shown using the DISASTER RISK EQUATION: 

The RISK of a disaster INCREASES as: 

1. The FREQUENCY or SEVERITY of HAZARDS INCREASE, e.g. more and worse flooding.

2. People's VULNERABILITY INCREASES, e.g. higher populationd densities in areas VULNERABLE to flooding, like FLOOD PLAINS. 


Capacity to cope - the ABILITY to deal with the CONSEQUENCES of a hazard, e.g. people in REMOTE AREAS are further from help than people in CENTRAL AREAS, so have a lower CAPACITY to cope.

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Global Hazards - Disaster Risk Equation (CASE STUD

Kashmir, Pakistan and Izmir, Turkey

Similar sized earthquakes happened in KASHMIR, PAKISTAN (2005) and IZMIT, TURKEY (1999). 

Althought the hazard was SIMILAR the disasters caused were DIFFERENT. 

KASHMIR - suffered more DEATHS, with over 75,000 deaths COMPARED to around 18,000 in IZMIT.

Disaster Risk Equation:

1. The people of KASHMIR - LOWER capacity to cope: REMOTE, MOUNTANIOUS location which makes access DIFFICULT. 

2. The population of KASHMIR is VULNERABLE: the people are POOR & buildings are often BADLY CONSTRUCTED.

- Buildings COLLAPSED after the earthquake and people were buried underneath. 

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Global Hazards - Hydro-meteorological Hazards

HYDRO-METEROLOGICAL HAZARDS have been INCREASING in recent years, due to GLOBAL WARMING.      The reasons why hydro-meterological hazards have been increasing are due to some factors:


- Rapid Population Growth and Urbanisation - this increases the NUMBER OF PEOPLE who are VULNERABLE to hazards, especially in POOR COUNTRIES. 

- INCREASING world poverty - poor people are more VULNERABLE to hazards.



- GLOBAL WARMING - increasing NUMBER of hazards, which then INCREASES disasters.

- EL Nino events - Make the global weather more UNPREDICTABLE. 

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Global Hazards - Deaths Decreasing...

The number of deaths caused by disasters has been DECREASING because of improvements in RISK MANAGEMENT STRATEGIES: 

1. PREDICTION - IMPROVED technology: this menas some hazards can be predicted to some extent. ADVANCED warning means people can be EVACUATED and properly SECURED. 

2. PREVENTION - Natural hazards can't be STOPPED, but they can be PREVENTED from becoming DISASTERS, e.g. using SANDBAGS against effects of flooding. 

3. PREPARDNESS - EDUCATING PEOPLE on what to do in case of a disaster helps to REDUCE the number of deaths, e.g. JAPAN - have a disaster prepardeness day each year. 

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Global Hazards - Economic losses INCREASING...

The trend of decreasing deaths is due to an INCREASING number of VULNERABLE PEOPLE in POORER COUNTRIES means more people are being AFFECTED by disasters. 


- ACTUAL FINANCIAL COST: is the amount of moeny LOST - this is GREATEST in RICHER COUNTRIES. 

- RELATIVE FINANCIAL COST: is the amount of money LOST relative to how much the people have to START WITH - this is GREATEST in POORER COUNTRIES. 

LESS actual money is LOST, but the EFFECTS of the loss are GREATER. 

Disaster can lead to further INDIRECT economic losses, e.g. if a country gets a lot of MONEY from TOURISM, this could be aggected by a disaster, which could affect the ECONOMY. 

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Hazard Distribution

GEOPHYSICAL hazards usually occur near PLATE BOUNDARIES

1. The Earth's crust is made up of plates called TECTONIC PLATES that sit ON TOP of the mantle. 

2. Plates are made up of TWO types of crust:

- the THICKER (but LESS dense) crust is called the CONTINENTAL CRUST - which is ABOVE sea level. 

- the THINNER (but MORE dense) crust is called the OCEANIC CRUST - which is BELOW sea leavel. 

3. the plates MOVE because of CONVECTION CURRENTS in the MANTLE - the currents are caused by TEMPERATURE DIFFERENCES within the MANTLE. 

4. VOLCANOES and EARTHQUAKES occur at the BOUNDARIES where the plates MEET. 


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Hazard Distribution - Volcanoes and Earthquakes

Volcanoes and Earthquakes - CONSTRUCTIVE BOUNDARIES

- Constructive Boundary - is where TWO plates are moving APART.

- The mantle is under PRESSURE from the plates, so when they move APART, the PRESSURE is released at the BOUNDARY. 

- The RELEASE of PRESSURE causes the mantle to MELT, producing MAGMA. 

- The MAGMA is LESS DENSE than the plate ABOVE, so it RISES and can ERUPT to form a VOLCANO.

- e.g. the EURASIAN PLATE and NORTH AMERICAN PLATE are moving APART aat the MID-ATLANTIC RIDGE. ICELAND has been formed where magma has RISEN through the gap to form VOLCANOES. 

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Hazard Distribution - Volcanoes and Earthquakes


- the plates don't move APART in a uniformed way, e.g. some parts move FASTER than others. 

- this causes PRESSURE to build up, when the PRESSURE becomes TOO MUCH the plate CRACKS, making a FAULT LINE and causing an EARTHQUAKE.

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Hazard Distribution - Volcanoes and Earthquakes -

Volcanoes - Destructive Boundaries

- a DESTRUCTIVE BOUNDARY occurs where TWO plates are moving TOWARDS each other.- where CONTINENTAL CRUST and OCEANIC CRUST are moving TOWARDS each other, the MORE DENSE oceanic crust is FORCED UNDER the LESS DENSE continental crust (subducted) 

- the OCEANIC CRUST is HEATED by FRICTION and CONTACT with the UPPER MANTLE, which MELTS it into magma.- the MAGMA is LESS DENSE than the CONTINENTAL CRUST & so it RISE back to the surface to form VOLCANOES

- e.g. PACIFIC PLATE (oceanic crust) is SUBDUCTING beneath the EURASIAN PLATE (continental crust) at the JAPAN TRENCH. The JAPANESE ISLAND ARC has been formed where MAGMA has RISEN through the crust to form VOLCANOES.

The same process occurs where TWO plates of OCEANIC CRUST are moving TOWARDS each other, the DENSER of the two will be SUBDUCTED, e.g. this has formed the VOLCANIC ISLANDS 

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Hazard Distribution - Earthquakes : Destructive Bo

Earthquakes - Destructive Boundaries

- As one plate moves under the other they can GET STUCK,, this causes PRESSURE to build up and when the PRESSURE becomes TOO MUCH the plates JERK past each other, causing an EARTHQUAKE. 

- where TWO plates of CONTINENTAL CRUST are moving TOWARDS each toher, NEITHER is SUBDUCTED so there aren't any VOLCANOES - but the PRESSURE that builds up between them can cause EARTHQUAKES, e.g. the KASHMIR EARTHQUAKE (2005)

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Hazards Distribution - Earthquakes - Constructive

Earthquakes - Constructive Boundaries

- the TWO plates get LOCKED TOGETHER in places and PRESSURE builds up, as with DESTRUCTIVE BOUNDARIES, this causes the plates to JERK past each other, which release energy as an EARTHQUAKE. 

- e.g. the PACIFIC PLATE is moving past the NORTH AMERICAN PLATE, many EARTHQUAKES occur along this BOUNDARY and at it's fault lines, e.g. the SAN ANDREAS FAULT runs through CALIFORNIA. 

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Hazard Distribution - Tropical Cyclones

Tropical Cyclones are huge storms with STRONG WINDS and TORRENTIAL RAIN.    

       - Tropical cyclones develop ABOVE SEA WATER, that's 26.5°c or HIGHER. Ad WARM, MOIST air RISES and Condenses, it RELEASES energy which INCREASES wind speed. 

- Tropical cyclones LOSE STRENGTH when they move OVER LAND because the ENERGY SUPPLY from the WARM WATER is CUT OFF. 

- Most cyclones occur between 5° and 30° NORTH and SOUTH of the EQUATOR - more than 30° away from the EQUATOR the water isn't WARM enough for cyclones to occur. 

- Cyclones spin because of the COROLIS EFFECT (the force that DEFLECTS the path of winds due to the EARTH'S ROTATION). 

- They move WESTWARDS due to the EAST-WEST WINDS in the TROPICS, e.g. TRADE WINDS move tropical cyclones WESTWARDS across the ATLANTIC OCEAN towards the CARIBBEAN SEA. 

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Disaster Hotspot Case Study - California



- EARTHQUAKES occur when PRESSURE between the plates build up and then is suddenly RELEASED as they JERK past each other.

- CALIFORNIA has TWO or THREE EARTHQUAKES each year that are powerful enough to DAMAGE STRUCTURES. (5.5+ on the RICHTER SCALE) 

- PAST DISASTERS include the SAN FRANSISCO EARTHQUAKE of 1906 (thought to have measured 7.8), which along with subsequent fires, DESTROYED much of the city. 

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Disaster Hotspot Case Study - California


- Drought in California can be caused by ANTICYCLONES (long-lasting periods of HIGH AIR PRESSURE with DRY, SINKING AIR) - DRY, SINKING AIR means NO AIR. 

- Drought can also be caused by LA NINA events (periods when the SURFACE WATER in the EASTERN PACIFIC OCEAN is COOLER). This means LESS evaporation, so there's LESS precipitation. 

- Drought can be caused by INCREASED wind blowing WESTWARD from the DESERT AREAS that are EAST of CALIFORNIA, e.g. from ARIZONA. The DRY AIR has NO moisture, to cause PRECIPITATION. 

- The most DEVASTING effect of drought in CALIFORNIA is WILDFIRES - dry vegetation is extremely FLAMMABLE, so fires SPREAD QUICKLY over WIDE AREAS. 

- The WILDFIRES in southern california in October killed 22 people and destroyed 1300 homes. 

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Disaster Hotspots Case Study - California


- A TSUNAMI is a series of LARGE waves that can FLOOD COASTAL AREAS. 

- They can be caused by EARTHQUAKES on the SEA BED, or LANDSLIDES into the sea. 

- Earthquakes under the PACIFIC OCEAN could cause a TSUNAMI along the California coastline. 

- An earthquake off the coast of ALASKA in 1964 caused a TSUNAMI to strike the coast of NOTHERN CALIFORNIA, killing 12 people in CRESCENT CITY.

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Disaster Hotspots Case Study - California


- Landslides occur on UNSTABLE STEEP LAND. Land can be made UNSTABLE by COASTAL EROSION or EXTREME WEATHER (rainstorms). Landslides can also be TRIGGERED by EARTHQUAKES. 

- The risk of landslide disasters in California is HIGH because of building on and around STEEP SLOPES, as well as building on COASTAL LAND overlooking the ocean, e.g. LA CONCHITA. 


- There hasn't been a VOLCANIC ERUPTION in CALIFORNIA since 1915 (LASSEN PEAK) 

- But there are volcanoes being MONITORED for potential ERUPTIONS, e.g. LASSEN PEAK, MOUNT SHASTA and the volcanoes around MAMMOTH LAKES. 

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Disaster Hotspots Case Study - California

California - 

- More than 70% of California's population live within 50KM of a FAULT LINE. 

- There's a lot of building on UNSTABLE LAND - this can lead to SOIL LIQUEFICATION during earthquakes (where the ground can become more like LIQUID), which DAMAGES buildings and INCREASES the risk of LANDSLIDES. This was a MAJOR PROBLEM during the LOMA PRIETA earthquake in 1989. 

- There are many buildings along the COAST that are vulnerable to TSUNAMIS. 

- California is a WEALTHY STATE, but there are very POOR AREAS within it - around 20% of the residents in LOS ANGELES live BELOW the official poverty line. These people have the LOWEST capacity to cope, when affected by a hazard. 

- California has a HUGE economy, so there are likely to be HUGE economic LOSSES hwen a disaster occurs. 

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Disaster Hotspot Case Study - The Philippines

The Philippines

- The Philippines is a group of island in SOUTH-EAST ASIA with a VULNERABLE POPULATION at RISK from a VARIETY of HAZARDS. 


- The Philippines is near to a DESTRUCTIVE BOUNDARY, where the Philippine plate ios being SUBDUCTED beneath the EURASIAN PLATE. 

- The islands were formed by a combination of FOLDING at the boundary and VOLCANOES formed from MAGMA that has risen to the surface from the mantle below. 

- MOUNT PINATUBO - is a volcano that erupted in 1991. Many people were EVACUATED, BUILDINGS COLLAPSED, CROPS were destroyed and AGRICULTURAL LAND was ruined by FALLING ASH. 

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Disaster Hotspots Case Study - The Philippines


- The Philippine plate and the Eurasian plate can become LOCKED TOGETHER as one moves under the other. This causes PRESSURE to build up. When the PRESSURE is TOO MUCH the plates JERK past each other, causing an EARTHQUAKE. 

- Earthquakes also occur at FAULT LINES in the area, where the plate has CRACKED under PRESSURE. 

- Earthquakes occur daily, but most can't be FELT (they're low on the RICHTER SCALE) 

- An earthquake of MAGNITUDE 7.8 occured on LUZON ISLAND in 990, killing over 1500 people. 

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Disaster Hotspots Case Study - The Philippines


- The Philippines get a lot of RAIN, if a lot of RAIN falls in a SHORT psace of time in areas with STEEP SLOPES, landlsides can occur. 

- Lansdlides can also be TRIGGERED by EARTHQUAKES. 

- A landslide occured on LEYTE ISLAND in 2006 after it had been raining heavily for 10 days. A WHOLE village was buried (including a school) killing HUNDREDS. 


-The Philippines have around 10 TYPHOONS (tropical cyclones) every year. 

- They DEVELOP in the PACIFIC OCEAN and move WESTWARDS over the islands. 

- TYPHOON XANGSANE swept across Manila and the surrounding DENSLY POPULATED area in the NORTH in 2006. HIGH WINDS and TORRENTIAL RAIN destoryed homes and caused FLOODING, LANDSLIDES and the LOSS of POWER and WATER. 

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Disaster Hotspots Case Study - The Philippines


- EARTHQUAKES in any of the oceans surrounding the Philippines could cause a TSUNAMI. 

- In 1976, an earthquake of MAGNITUDE 7.9 caused a tsunami that hit the COASTLINE around the MORO GULF on the SOUTHERN ISLAND of MINDANAO. THOUSANDS were killed and several cities were DEVASTED. 


- During the WET SEASON, FLOODS can be caused by TYPHOONS and HEAVY RAIN. 

- FLOODING affects many areas, even some that are also affected by DROUGHT. 

- MAJOR FLOODS occured in the LOWLAND AREAS around Manila in the 1970s and in recent years. CROPS were devasted in the MAJOR RICE growing region. 

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Disaster Hotspots Case Study - The Philippines


- Some parts of the Philippines have a distinct WET and DRY season, e.g. Manila (and the surrounding densly populated area) is DRY between NOVEMEBER and APRIL, and WET between MAY and OCTOBER. 

- DROUGHT can occur when the WET season hasn't brought ENOUGH rain to last the DRY season, or the DRY season is particular HARSH. 

- There was a DROUGHT on LUZON ISLAND in 2005. The reduction in raindall DECREASED water flows in rivers, which AFFECTED production from HYDROELECTRIC POWER plants. This AFFECTED the POWER SUPPLY to the ENTIRE REGION. Without power for an EXTENDED PERIOD, ECONOMIC and SOCIAL activity were severly REDUCED. 

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Disaster Hotspots Case Study - The Philippines (VU

VULNERABLE - The Philippines

1. When a HAZARD strikes a DENSLY POPULATED AREA, there's GREATER RISK it will become a DISASTER, e.g. the ISLAND OF LUZON and the area around Manila are MORE at risk because they have a HIGH POPULATION DENSITY. 


3. The Philippines has a FAST growing economy, but there are still many people BELOW the poverty line who will be most severly affected by a disaster. 

4. Some FAST growing settlements have been built near to HAZARDOUS AREAS, e.g. ANGELES was built near to MOUNT PINATUBO. It wasn't thought of as a threat because it hadn't ERUPTED for a LONG TIME, (since 1380)

5. Many people live in UNSTABLE LOCATIONS, e.g. AETA TRIBE were living on the slopes of MOUNT PINATUBO when it erupted in 1991. 

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Evidence for Climate Change (GRAPH)

Long-term climate change

- Taking TEMPERATURE as an indicator of climate, there have been HUGE CHANGES over Earth's history - temperatures have been much HIGHER at some points in the PAST than they are TODAY. 

- Looking at more detailed date for the last 400,000 years, you can see a more detailed fluctuation. 

- Climate shifted between COLD GLACIAL PERIODS that lasted around 100,000 years and WARMER INTERGLACIAL PERIODS that lasted around 100,000 years. - We're in an INTERGLACIAL PERIOD NOW. 

Glacial - Below 0*c 

Interglacial - Above 0*c

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Evidence for Climate Change (GRAPH)

Medium-term Climate change

- The last glacial period ENDED around 18,000 years ago. 

- The WARMING of the climate after this was FAST at times, but it wasn't CONSTANT - about 13,000 years ago the CLIMATE SWITCHED BACK to cooler conditions for about 1000 years. 

- Around 5000 years ago, TEMPERATURES were 1-2*c HIGHER than today. 

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Evidence for Climate Change (GRAPH)

Short-term climate change

- GLOBAL WARMING is the term used for the RAPIDLY INCREASING glkobal temperature over the LAST CENTURY - there's been a SHARP RISE in temperature when you look at the last 1000 years. 

- The OVERALL PATTERN over the last centruy shows a general INCREASE in TEMPERATURE, but the pattern hasn't been constant. 

- Global temperatures ROSE STEADILY from the early 20th century until the 1940s (although they fluctuated annually), then DROPPED back down. SCIENTISTS thought there would be another GLACIAL PERIOD, but temperatures have RISEN RAQPIDLY again SINCE the 1970s (this is GLOBAL WARMING) 

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Evidence for climate change - LONG, SHORT & MEDIUM

Long-term Change

1. Ice Cores - 

Scientists drill into ICE SHEETS to extract CORES OF ICE. Ice sheets are made up of LAYERS od ice - one layer is formed EVERY YEAR. So the ice at the bottom of the core is REALLY OLD. 

They can ANALYSE the GASES trapped when the ice formed to tell what the TEMPERATURE was each year. Then they can gigure out how TEMPERATURE has CHANGED OVER TIME. 

2. Pollen Analysis - 

POLLEN from plants is often PRESERVED in SEDIMENT. 

The PRESERVED POLLEN can be IDENTIFIED and DATED to show when it was RELEASED. 

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Evidence for Climate Change

cont - long-term

3. Sea Level Change - 

SEA LEVEL is AFFECTED by things like the VOLUME OF WATER stored as ICE, 

Past sea levels are shown by RAISED BECAHES (formed when sea levels were HIGHER). Raised beaches can be DATED. They can INDICATE that LESS WATER was stored as ICE, (i.e. it was warmer) 

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Evidence for climate change

Medium-term climate change

1. Historical records - these can INDIRECTLY indicate DIFFERENT CONDITIONS in the past, (e.g agricultural reports, such as harvest times) show CHNAGING CONDITIONS throughout human history. 

2. Tree rings - A new tree ring is formed each year as a tree grows. If condition that year were GOOD, the tree ring produced will be THICK. 

Scientist take cores and count the rings to find the AGE of the tree. They hen look at the THICKNESS of each ring, to see what the climate was like EACH YEAR. 

Tree rings can reliably SHOW and DATE climate conditoons up to 10,000 years ago. 

3. Retreating glaciers - Scientist can tell HOW BIG a glacier was and how far is EXTENDED by looking at the position of ROCKS DEPOSITED by it. These rocks can be DATED to show when they were DEPOSITED. 

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Evidence for climate change

cont - medium-term climate change

The DISTANCE of the rocks from the current glacier INDICATE climate change, e.g. if the FRONT of the glacier is now miles away from the rocks it INDICATES that temperatures have INCREASED over that period of time. 

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Causes of Climate Change

Some changes in climate are caused by CHANGES in how the SUN'S ENERGY is RECIEVED, TRAPPED and DISTRIBUTED around the Earth, e.g. when MORE ENERGY is recieved, the Earth will get HOTTER. When LESS energy is RECEIEVED, the Earth will get cooler. 

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Causes of climate change

Earth's climate changes - WITHOUT human influence



The path of the Earth's orbit around the Sun CHANGES from an almost perfect CIRCLE, to an ELLIPSE and back again about every 96,000 years. 

This CHANGES the DISATNCE from the Sun to the Earth, and so the AMOUNT OF ENERGY the Earth recieves from the SUN (at different times of the year). 

Earth's orbit is ELLIPTICAL right now - it's CLOSEST to the SUN in JANUARY and furthest away in JULY. 

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Causes of Climate Change - Variations in the Earth


The Earth is TILTED at an angle as it orbits the Sun, called it's AXIS (currently 23.5*) 

This CHANGES between about 21.8* and 24.4* over a cycle of about 41,000 yeaqrs. 


When the tilt is GREATER (24.4*) areas that recieve LOTS OF ENERGY, such as the TROPICS, will be LARGER. Other climate regions, such as the TEMPERATE ZONES beyond the Tropics, will be SMALLER. 

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Causes of climate change - variations in the Earth


The AXIS of the Earth WOBBLES like a spinning top on a cycle of about 22,000 years. Because EARTH is closest to Sun in JANUARY, winter in the NORTHERN HEMISPHERE is MILD and summer is COOL. 

The WOBBLE of the AXIS means this GRADUALLY CHANGES - the SEASONS will eventually swap over. 

When this happens, the Earth will still be closest to the Sun in JANUARY, but this will now be SUMMER in the NORTHERN HEMISPHERE. The Earth will still be furthest away from the Sun in JULY, but this will now be WINTER in the NORTHERN HEMISPHERE. 

So in the NORTHERN HEMISPHERE, WINTER would then be COLDER because it would be at the time when the Earth is FURTHER from the SUN, and SUMMER would be HOTTER, because it's at the time when the Earth is CLOSER to the Sun. 

- REMEMBER - all THREE orbital changes are going on at the same time, affecting each other. 

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Causes of climate change


1. The Sun's output of ENERGY isn't CONSTANT. 

2. SUNSPOTS are DARKER AREAS on the Sun that INCREASE solar energy output.

3. They're thought to INCREASE and DECREASE in number in an 11 year cycle - though there's variation within this cycle

e.g. - A period of COOLING in the late 17th century called the LITTLE ICE AGE, is thought to have coincided with a period when SUNSPOT ACTIOVITY was VERY LOW. 

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Causes of Climate Change


1. The impact of a METEOR (up to 10m across) or an asteroid (LARGER than 10m across) forms a LARGE CRATER and can throw up HUGE AMOUNTS of MATERIAL into the ATMOSPHERE. 

2. This can RESULT in a lot of SUNLIGHT (energy) being BLOCKED out for MONTHS or even YEARS, changing the climate

3. e.g. the mass extinction of DINASOURS is widely thought to have been caused by the CLIMATE CHANGE brought about by a massive ASTEROID IMPACT. 

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Causes of Climate Change - cont..

Volcanic Eruptions


2. This can also BLOCK out SUNLIGHT (energy), which changes the climate. 

3. e.g. the eruption of MOUNT TAMBORA in INDONESIA IN 1815 is thought to have LOWERED GLOBAL TEMPERATURES by about 0.5*c. 

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Causes of climate change - HUMAN ACTIVITY

Climate is affected MOST by TWO HUMAN ACTIVITIES: 

1. Enhanced greenhouse gas emissions

- Greenhouse gases include CO2, METHANE, OZONE and WATER VAPOUR. -The GREENHOUSE EFFECT is where greenhouse gases absorb OUTGOING ENERGY so less is LOST to space. It's ESSENTIAL for keeping the planet WARM. 

- But TOO MUCH greenhouse gas in the ATMOSPHERE means TOO MUCH energy is trapped and the planet WARMS UP.  - CO2 is RELEASED into the ATMOSPHERE when FOSSIL FUELS like COAL, OIL, NATURAL GAS and PETROL are BURNT, e.g. in caqrs or power stations. 

- Since the INDUSTRIAL REVOLUTION in the mid-19th century levels of ATMOSPHERIC CO2 have INCREASED from 280ppm (parts permillion) to 380 ppm. The level had been broadly STABLE for the previous 10,000 years. 

- The INCREASE in CO2, has caused the INCREASE in TEMPERATURE (global warming) over the same period because of the ENHANCE GREENHOUSE EFFECT. 

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Causes of climate change

2. Destruction of natural CO2 sinks:

- CO2 SINK STORES CO2, keeping it out of the ATMOSPHERE - so it's NOT contirbuting to the greenhouse effect. 

- The BIGGEST sinks are the oceans - CO2 dissolves in sea water and gets MOVED to the deep ocean by natural currents. 

- Another big sink is PLANTS - plants take in CO2, and CONVERT it into ORGANIC MATTER using photosyntehsis. It is also stored in the soil as DEAD ORGANIC MATTER.

- CO2 is RELEASED into the ATMOSPHERE when trees are BURNT by FOREST FIRES or to make way for AGRICULTURE. 

- It was thought that a lot of GREENHOUSE GAS EMISSIONS from humans could be STORED in CO2 SINKS . It's now thought they WON'T be able to KEEP PACE with INCREASING emissions, so more CO2 will go directly into the ATMOSPHERE. 

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Impacts of climate change

Global Warming: 

- The melting of ICE ON LAND, e.g. the GREENLAND and ANTARTIC ICE SHEETS means that water STORED as ice returns to the oceans. 

- This INCREASES the VOLUME OF WATER in the oceans and causes the SEA LEVEL to RISE. This kind of sea level change (caused by an increase in water volume) is called EUSTATIC sea level change. 

- If all the REMAINING ice sheets melted it would cause GLOBAL SEA LEVEL to rise by between 60 and 80 metres. This THERMAL EXPANSION also INCREASES the VOLUME of the water, causing sea level to RISE FURTHER. 

- This could RAISE sea levels by between 8 and 80 cm for each INCREASE in global temperature of 1*c. 

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Impacts of Climate Change

Predictions of how much sea level will RISE in the FUTURE are UNCERTAIN and DIFFER A LOT.

An international group of scientists, called the INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC), look at RISKS of climate change -

they think that SEA LEVELS could RISE betwttn 18 and 59 cm by the end of the CENTURY. 

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Impacts of climate change

Case Studies:


1. 80% of the land area in Bangladesh is LOW-LYING. ANY rise in sea level will SUBMERGE large areas. 

2. This would affect lots of people as Bangladesh has a very HIGH POPULATION DENSITY (around 1000 people per km2)

3. Bangladesh is a POOR COUNTRY, which means the situation would be made WORSE - the population are VULNERABLE, with a LOW capactiy to cope. 


1. The Maldives are a low-lying set of islands in the INDIAN OCEAN. A RISE in sea level of 0.5m would SUBMERGE most of the country.

2. Although the population isn't POOR, the economy is DEPENDENT on TOURISM, which would be THREATENED by a RISE in SEA LEVEL.

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Impacts of climate change


1. Permafrost is GROUND that has been PERMANENTLY FROZEN fot two years or more. It covers around 20% of the Earth's land surface. 

2. Areas of permafrost are NATURAL SINKS of CO2. It's stored as ORGANIC MATERIAL in the soil. Thawing of permafrost RELEASES some of this, contributing further to GLOBAL WARMING. 

- Thawing of permafrost causes the COLLAPSE of BUILDINGS and PIPELINES built on it. It may also bring ECONOMIC BENEFITS to humans though, e.g. it's EASIER to look for and EXTRACT natural resources (like fossil fuels) in areas of UNFORZEN GROUND. 

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Impacts of climate change

Global warming - affects global weather patterns

- An INCREASE in the FREQUENCY of EXTREME WEATHER EVENTS, e.g. increasing ocean temperatures may mean an INCREASED risk of TROPICAL CYCLONES over a wider area. 

- A CHANGE in the DISTRIBUTION OF CLIMATIC REGIONS, e.g. COLDER POLAR regions may SHRINK and WARMER tropical regions may ADVANCE to higher latitiudes. 

- This affect ECOLOGY (the distrbitution and abundance of organisms). Species will have to MIGRATE to remain in a suitable climate and, if they can't MIGRATE, they may become extinct. 

- It also affects AGRICULTURE, e.g. some areas become UNSUITABLE for CULTIVATION as CLIMATIC FACTORS such as temperature and the TIMING of the seasons alter. 

- Regional climate changes may bring BENEFITS to some HUMAN ACTIVITIES, e.g. ECONOMIC BENEFITS of TOURISM where the climate has become warmer. 

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Impacts of climate change

Emissions Scenarios - used to PREDICT impacts of global warming. 

The IPCC has produced a number of EMISSION SCENARIOS, which are predictions of how human CO2 emissions will CHANGE up until 2100. 

Scenarios include: 

- Emissions NOT INCREASING much more (scenario 5, minum emissions)

- Emissions continuing to GROW as they are now 

- Emissions increasing by a lot (scenario 1, maximum emissions)  

- Emissions being controlled by SUSTAINABLE MANAGEMENT startegies. 

They can put all these different scenarios into GLOBAL CLIMATE MODELS, to see how the climate could CHANGE with each scenario. 

- Then these can be used to show how the DIFFERENT CLIMATE CHANGES can cause DIFFERENT IMPACTS. 

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Impacts of climate change cont...emissions scenari

It's DIFFICULT to predict the impacts of changes bin the climate because there's so much UNCERTAINITY. 

- We don't actually know how much emissions will CHANGE.

- We don't know how much of the emissions will be ABSORBED by things like NATURSAL CO2 SINKS. 

- We don't know what exact CLIMATE CHANGES each emission scenarios will cause. 

- The extent of climate change due to NATURAL CAUSES (withiut human influence) ISN'T KNOWN. 

- We don't know what attempts there will be to MANAGE THE IMPACTS of climate change, or how SUCCESSFUL they'll be. 

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Impacts of climate change

Tipping Point

- Climate change could reach a TIPPING POINT - where a slight RISE in temperature would cause CATASTROPHIC and IRREVERSIBLE changes to the enviuronment, creating a much more HAZARDOUS world. 

- This may happen because of positive feedback loops - where a CHANGE in the climate is SPEEDED UP by the impacts it's ALREADY CAUSED, e.g.

Global warming causes MELTING of ARCTIC ICE. As sea ice MELTS, it leaves DARKER sea water in it's place. Sea water has a LOWER ALBEDO (the amount a surface reflects the sun's radiation) than ice, so MORE radiation is ABSORBED by the water. 

This WARMS the water, which causes MORE ice to MELT..

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Climate Change - Case Studies

The ArcticThe Arctic is the area around the NORTH POLE. It includes the northern parts of ASIA, North America and Europe. GLOBAL WARMING is affecting the Arctic directly: 

1. The AREA of ARCTIC SEA ICE (frozen sea water) has been SHRINKING at an INCREASING rate - some scientists think there won't be any sea ice in the summer by 2030. 

2. The GREENLAND ICE SHEET is MELTING - most sicentists think the rate of melting has INCREASED IN RECENT YEARS. 

3. The PERMAFROST boundary is moving NORTH and the area covered by permafrost is SHRINKING. 

4. The TREELINE (the point beyond which trees can't grow) is moving NORTH and the area where trees can't grow is SHRINKING. 

5. These effects are having INDIRECT IMPACTS on the ENVIRONMENT and ECOLOGY (the DISTRIBUTION and ABUDNACE of organisms) of the Arctic

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Climate Change - Case Studies

Global warming: The Arctic

Environmental Impacts

1. Melting of ice sheets like the GREENLAND ICE SHEET will mean an injection of FRESH WATER into the sea. This will cause changes in the DENSITY of the water and could DISRUPT OCEAN CURRENTS like the NORTH ATLANTIC DRIFT. 

2. Thawing of permafrost RELEASES more CO2 and METHANE - permafrosts a NATURAL SINK. 

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Climate Change - Case Studies

Ecological Impacts

- Changing CLIMATIC REGIONS means the HABITATS (where species live) of some species are being REDUCED or LOST, e.g. POLAR BEARS use areas of SEA ICE to hunt for food. As this is LOST polar bears may become ENDANGERED in the wild. 

- Some parts of the Arctic have very SENSITIVE ECOSYSTEMS - there are FEW species, so the loss of one may have DEVASTATING impacts on other species that rely on them.

- In other parts of Arctic, like the ocean, the NUMBER and DIVERSITY of species, e.g. fish may INCREASE as SEA ICE COVERAGE is REDUCED and temperatures INCREASED. 

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Climate Change - Case Studies

Socio-economic Impacts

- Shrinking sea ice could open up NEW SHIPPING ROUTES in the summer. 

- NEW NATURAL RESOURCES mau ne exploited, e.g LESS sea ice increases the area available for FISHING. 

- It's also thought there are UNDISCOVERED OIL and GAS reserves in the Arctic - unforzen ground would make them easier to FIND and EXTRACT. 

- Access to new resources may lead to CONFLICT over which countries OWN THEM though. 

- WARMER soils and climate may INCREASE the opportunity for AGRICULTURE or FORESTRY. 

- THAWING of permafrost can result in COLLAPSED buildings and BROKEN PIPELINES where ground has become LESS STABLE. 

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Climate Change - Case Studies cont...

Arctic warming has consequences for the rest of the world...


2. OCEAN CURRENTS in the Arctic are affected by SALINITY CHANGES (freshwater from melting ice sheets changes the DENSITY of sea water), which affects GLOBAL OCEAN CURRENTS because they operate as an INTERLINKED SYSTEM. 

3. Changing TEMPERATURES, SEA ICE and LANDSCAPES affect AIR CURRENTS in the Arctic. This affects GLOBAL WEATHER PATTERNS because the atmosphere also operates as an INTERLINKED SYSTEM. 

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Climate change - Case studies


Africa has a range of DIFFERENT CLIMATES from dry deserts to tropical rainforests.

GLOBAL WARMING is having DIFFERENT impacts in DIFFERENT areas:

1. Areas that are already DRY (arid and semi-arid environments) are getting DRIER. 

2. WETTER areas (tropical and sub-tropical environments) are getting WETTER.

3. The whole continent is getting WARMER - around 0.5*c warmer in the last century. 

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Climate Change - Case Studies: Africa cont..

Africa's population is VULNERABLE (poor countries and people) the ECONOMIC impacts of global warming in Africa are COMPLEX and the RELATIVE FINANCIAL COSTS are huge: 

1. Poor people have a REDUCED capacity to cope, e.g. susbsitence farmers, who only grow enough to meet the needs of their family and have NO INCOME, will be at RISK of starvation if CLIMATE CHANGE affects their crops. 

2. Poorer countries are LESS able to PREPARE for and RESPOND to the impacts of climate change.

3. POLLITICAL TURMOIL can mean the appropriate responses AREN'T made, making the impacts of climate change WORSE. 

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Climate Change - Case Studies: Africa cont.....

Examples of Impacts in Africa: 

- Global warming is causing DESERTIFICATION, this is the process by which FERTILE land becomes UNSTABLE for agriculture. It's a MAJOR problem in the SAHEL REGION (the belt between the Sahara Desert and the fertile area to the SOUTH. This causes a DECREASE in the agricultural production, which leads to more POVERTY, UNEMPLOYMENT, MALNOURISHMENT and STARVATION. 

- Global warming may have improved CONDITIONS in some areas of Africa for MOSQUITOES, that spread Malaria - a disease which KILLs over a million people each year. The COSTS of helath care and REDUCED interest in TOURISM and INVESTMENT) mean the economies are put UNDER STRAIN and prevented from GROWING. 

- Global warming has caused a REDUCED GROWING PERIOD ovr much of the continent. This DECREASES agricultural production. In the Sahel region agriculture forms around 70% of the EMPLOYMENT, so any RECUTION leads to INCREASED unemployment, poverty and starvation. 

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Climate Change - Case Studies: Africa cont....

cont - 

- Global warming means TROPICAL AREAS are experiencing LONGER GROWING PERIODS, and may financially neefit from better agricultural conditions. 

- Global warming is causing a MORE erratic climate, e.g. MOZAMBIQUE suffered DROUGHT and widespread CROP FAILURE in 1995, then flooding in 2000, which displaced lot's of people. HOMES and INFRASTRUCTURE are DESTROYED in araes where people are unable to REBUILD or RECOVER. 

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Coping with climate change

Mitigation Strategies - Taking action to REDUCE how much climate change OCCURS, e.g. REDUCING EMISSIONS may help to SLOW the temperature to INCREASE, so LESS ICE may melt and the sea level would rise LESS. Adaptation Strategies - Taking action to REDUCE the IMPACTS that the changes are having, e.g. sea levels are rising so DEFENCES could be built to protect VULNERABLE SETTLEMENTS.                                

Mitigation Strategiese.g. Carbon Tax - taxing companies or people who produce CO2, increasing costs discourages overonsumption energy. 

Changing the energy mix - changing the mix of sources of energy, (i.e lowering the proportion  of energy made from fossil fuels and increading energy form sources that producess less greenhouse gas emissions, e.g. nuclear power. 

Modified agricultural practices - cut methane generation fro farm animals, e.g. by developing new types of formations, e.g. coal semas. 

Energy Conservation - Using less energy, e.g. switching off home appliances when they're not used. 

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Coping with climate change


Tree planting - planting new trees creates a new carbon sinks so more CO2 will be stored as organic matter. 

Waste strategies - increasing the amount of waste that recycled, which should directly cut methane emissions from landfill sites

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Coping with Climate Change

Adaptation Strategies:

- Lifestyle adaptations - people adapt the way they live to suit the new conditions, e.g. planting new crop that will flourish in the new climatic conditions. 

- Improved risk assessment - looking at the likelihood that people or property will be damaged by climate changed more impacts, and evaluating the need for insurannce policies. 

Flood adaptations - building physical defences such as flood barriers to reduce the impacts pf flooding, and having flood warning systems. 

- Water resouce management - using freshwater resources, more efficiently to cope with droughts conditions, e.g installing the water meters in homes to dicourage people from using a lot of water. 

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Coping with Climate change

Key Players: 

- Governments - devlop strategies on an INTERNATIONALM NATIONAL and LOCAL scale. 

- Businesses - can be responsible for CONTIRBUTING to climate change or can help to SLOW IT DOWN. This may LOBBY government to REDUCE RESTRICTIONS and allow them to continue producing greenhouse gases, or they may help by investing in NEW TECHNOLOGIES to COMBAT climate change. 

- Non-governmental Organisations (NGOs) - can have many roles and views depending on what they're trying to set up and do and who their members are, e.g. Greenpeace is an environmental pressure group that tries to persuade govenments to recognise and take action against climate change. 

Communities and Individuals - startegies devloped on a larger scale are carried out at a local level, e.g. government may decide to encourage recycling, but the recycling is actually done by individuals. 

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Coping with climate change

The Kyoto Protocol

- The Kyoto Protocol is an international agreement between more than 180 COUNTIRES to MONITOR and CUT greenhouse gas emissions by 2012. 

- The agreement divides the countires into two groups - developed and developing.- Devloped countires have agreed to CUT EMISSIONS (overall  by 5%).  Developing countires don't have to cut emissions, but need to MONITOR and REPORT their emissions.

- The agreement has set up a MARKET to trade in Carbon 'credits' - all countrie & businesses have beem given a limit on the emissions they can produce. If they produce less, they can SELL the extra CARBON CREDITS - if they produce money, they need to buy more credits. They also gain credits by helping to REDUCE emissions in developing countires, so developed invest in developing countries to help them develop in a sustainable. 

- Four countires witht the highest emissions, (e.g. the USA, CANADA, INDIA) didn't sign up for the orginal agreement in 1947. The USA and AUSTRALIA felt signing would affect their econimes and that the developing countries should have taregts as well. China and India thought it would slow their rate of growth. 

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