1A: The Challenge of Natural Hazards Flashcards
What is a natural hazard?
An event that has the potential to cause damage, disruption, destruction and death
What are Tectonic Hazards?
Hazards which involve the movement of tectonic plates e.g. volcanoes
What are Atmospheric Hazards?
Hazards which involve the conditions in the air around us e.g hurricanes
What are Geomorphological Hazards?
Hazards which occur on the Earth’s surface e.g. flooding
What are Biological Hazards?
Hazards which involve living organisms e.g. forest fires
Define ‘Hazard Risk’
The chance or probability of being affected by a natural hazard
How is Deforestation a human influence which increases hazard risk?
Cutting down trees increases the risk of flooding. Trees intercept and absorb water, slowing the movement of water down
How is Urbanisation a human factor which increases hazard risk?
More people are living in urban areas therefore there is a greater risk of injury and death
How is Climate Change a human factor which increases hazard risk?
In a warmer world, the atmosphere will have more energy, leading to more intense storms and hurricanes. Climate change may cause some parts of the world to become wetter and increase the risk of flooding
How is Poverty a human factor which increases hazard risk?
In poorer parts of the world, poverty may force people to live in areas of risk and poorly constructed buildings
Describe the process of convection currents in the Earth’s mantle
- The core heats up the magma in the mantle
- The hot magma is less dense than its surroundings, so it rises upwards
- When it reaches the top, it cools
- It becomes more dense, and therefore sinks back down to the bottom
- It is heated up again, and the cycle continues
- The plates, which lie on top, are pushed and pulled by the convection currents in the magma
Compare the thickness and density of continental crust to oceanic crust
Continental crust is thicker and is less dense (cannot sink) than oceanic crust
Describe what happens at a constructive plate margin
- At a constructive plate margin, the plates are moving away from each other
- When the two plates are pulled apart, magma rises in between the gap left by the two plates separating. Lava (when magma is above ground it is classed as lava) then pours out onto the surface
- Volcanoes form in the areas where lava pours out. This lava is usually runny and free-flowing, which creates flatter volcanoes. Earthquakes also occur here as the plates shake and vibrate when they move apart
- This process can happen on continental crust or oceanic crust
-When new land is formed on the ocean floor, this is known as sea floor spreading (as the floor spreads and gets wider) - When lava cools, it forms rock. Over time, this rock builds up and can form islands, for example Iceland is a volcanic island. Iceland sits on the Mid-Atlantic ridge, which is where the lava pours out from
Describe what happens at a destructive plate margin
- The denser oceanic crust is subducted below the continental crust
- The plate that is subducting leaves a deep ocean trench
- Friction between the two plates causes strong, deep earthquakes
- The oceanic crust is melted as it is pulled deeper into the mantle, creating magma
- This magma causes pressure to build up under the crust
- Eventually the magma pushes out through weaknesses in the crust, creating explosive volcanoes
(When two continental plates meet, fold mountains are formed)
Describe what happens at a conservative plate margin
- At a conservative plate margin, parallel plates move in different directions or at different speeds in relation to each other
- When these plates move side by side, friction builds between the plates
- The friction builds up over many years, and eventually the pressure becomes so large that the plates eventually move in a sudden jolt
- This releases a lot of energy which sends vibrations through the the ground (Earthquake)
- On oceanic crust, this movement can displace a lot of water, which causes tsunamis
- On continental crust, fault lines can occur where the ground is cracked by the movement
- There are no volcanoes on conservative plate margins because no magma is being generated
Primary effects of tectonic hazards
The effects that are directly caused by the natural hazard itself. For example, people being killed or injured when an earthquake causes buildings to fall down, or lava and ash damaging infrastructure
Secondary effects of tectonic hazards
The effects that are as a result of the primary effects. For example, homelessness due to homes being destroyed or a tsunami or landslide caused by the original earthquake
Immediate responses to tectonic hazards
Actions taken as soon as the hazard happens and in its immediate aftermath. Immediate responses usually aim to reduce loss of life and provide vital aid and resources. e.g. search and rescue, food and water, shelter.
Long-term responses to tectonic hazards
Actions taken after the immediate responses when the effects of the hazard have been minimised. Long-term responses aim to restore normality and reduce risk in the future. e.g. rebuilding infrastructure and homes, building defence mechanisms, setting up warning systems
When was the Nepal earthquake?
25th April 2015
What was the magnitude of the Nepal earthquake?
7.9
How many people died in the Nepal earthquake?
9,000
How many people were injured in the Nepal earthquake?
19,000
Overall, how many people were affected by the Nepal earthquake?
Over 8 million (1/3 of Nepal’s population)
How many people were left homeless by the Nepal earthquake?
4 million
How many schools were destroyed in the Nepal earthquake?
7,000
How many shops were destroyed and how did this affect the population?
50% of the shops were destroyed, which limited food supplies in Nepal and affected people’s sources of income
How many people were in urgent need of food, water and shelter after the Nepal earthquake?
1.4 million
How did the Nepal earthquake affect utilities?
Electricity, water, sanitation and communications severely affected due to damaged and destroyed infrastructure
What was the estimated cost of the Nepal earthquake?
$5 billion USD
What were the secondary effects of the Nepal earthquake?
- Landslides and avalanches triggered
- Landslides blocked rivers like the Kali Gandaki river and flooded areas
- 17 people were killed by an avalanche at Mount Everest base camp
How did Nepal source relief supplies immediately after the earthquake?
Nepal relied heavily on international aid from areas such as China, India and the UK. These countries supplied medical support and essential suppplies
How much was raised internationally after the Nepal earthquake?
Over £87 million in donations alone
What did Nepal use for search, rescue and support?
Helicopters were used to search for survivors and reach those trapped from landslides and avalanches. They were also used for resource distribution to the cut off communities
How and why were tents so heavily relied upon after the Nepal earthquake?
Half a million tents were supplied and used for shelter for the homeless, classrooms and temporary hospitals/health care centres. Hospitals were severely overwhelmed and there were fears of more severe aftershocks causing more damage to buildings
How many people immediately fled Kathmandu after the earthquake?
300,000
How was social media used immediately after the earthquake?
Social media sites such as Facebook allowed people to mark themselves as safe and to let family members know they were out of danger
How did Nepal respond to damaged and destroyed buildings in the long-term?
In 2019, 3/4 of homes were either fully rebuilt or under repair. The government introduced stricter building codes
What issues associated with landslides did Nepal have to respond to in the long-term?
Lakes formed by landslides needed to be carefully drained and cleared so rivers could return to normal. Roads also has to be repaired after landslide damage
What were the long-term responses to Mount Everest routes?
By August 2015, base camp and the routes on Mount Everest were repaired and mountaineers could return
What happened in September 2015 that severely hindered Nepal’s recovery process?
India imposed a blockade at the order which stopped fuel, medicines and earthquake relief material from being transported to Nepal
When was the Christchurch earthquake?
22nd February 2011
How long did the Christchurch earthquake last?
10 seconds
What was the magnitude of the Christchurch earthquake?
6.3
How deep was the epicentre?
4.99km south of the centre of Christchurch
How many people were killed in the Christchurch earthquake?
185
How much damage was caused in the Christchurch earthquake in USD$?
$28 billion
What collapsed in the Christchurch earthquake?
The cathedral spire collapsed
How many people were injured as a result of the Christchurch earthquake?
3100
How many years have economists suggested it will take for New Zealand’s economy to recover? (secondary effect)
50-100 years
What fraction of the population migrated from Christchurch after the earthquake?
1/5
How many Rugby World Cup matches were cancelled as a result of the Christchurch earthquake?
5
How much international aid was immediately provided? (Christchurch earthquake)
$6-7 million
How many residents were provided with chemical toilets? (Christchurch earthquake)
30,000
How many Australian police officers flew into Christchurch three days after the earthquake?
over 300
In the long-term, how many affordable homes were constructed in Christchurch?
10,000
By when were the water and sewage restored to normal after the Christchurch earthquake?
August 2011
Why do people live near volcanoes?
- Farming: fertile soils -> more yield -> more crops to sell -> more profit -> can afford medicines/education -> higher quality of life
- Jobs in Tourism: tourists visit volcanoes for the spectacular views and relaxing hot springs - millions of jobs are created e.g. tour guides, hotel workers. The money that this brings into the economy improved quality of life
- Fatalistic Viewpoint: don’t really care and believe they will receive warning and be able to evacuate and get out of the way of any dangers
- Geothermal Energy: major source of electrical power. It is renewable energy - won’t run out, reduce greenhouse gas emissions and the likely effects of climate change
- Family Connections: family + friends live there so people don’t want to move away from communities + be lonely
- Mining: jobs are created in the mining industry. There are dangerous conditions, but a salary of $6 per day means that they continue to live and work there
How can Monitoring reduce the risks from a tectonic hazard?
Earthquakes:
- difficult to monitor as they do not usually display any warning signs. Small tremors can be monitored by seismologists but as of now there is no technology that can indicate with certainty that an earthquake is coming
Volcanoes
- Ground deformation: bulges in the ground can indicate the movement of magma
- Gases: certain gases indicate rising magma, such as sulfurous gases
- Changes in heat: temperature differences also indicate processes beneath the surface
- Vibrations underground: small earthquakes can indicate changes underground
- Small eruptions of smoke and steam: indication of a larger eruption coming
How can Prediction reduce the risks from a tectonic hazard?
Earthquakes:
- if an earthquake hasn’t happened for a while, scientists can predict the next earthquake will be bigger because energy has been building up for longer
- animals are believed to act strangely when there is likely to be an earthquake
- seismometers are used to measure foreshocks which can give people time to evacuate.
Volcanoes:
- thermal heat sensors detect changes in the temperature which can show the rising magma.
- monitoring ground deformation
- gas trapping bottles measure radon and sulphur gases.
How can Protection reduce the risks from a tectonic hazard?
Earthquakes:
- cross-bracing steel cage to stabilise building
- shock absorbers between foundations and building above ground
- shutters that come down automatically to prevent broken glass injuries
Volcanoes:
- not possible to prevent damage to properties and infrastructure but all we can do is try to divert the lava flow to less densely-populated areas
How can Planning reduce the risks from a tectonic hazard?
Earthquakes:
- residents taught how to seek shelter and reduce the risk of a building falling on them
- earthquake drills
- prepare an emergency supplies kit
- evacuation plan put in place by local authorities
Volcanoes:
- prepare an emergency supplies kit
- evacuation plan put in place by local authorities
- scientists can map previous pyroclastic flows to help plan safe routes out of an area
- FEMA give out warnings
What are pressure belts?
Air circulations that create different areas of pressure
-> When air rises, it creates an area of low pressure underneath
-> When air sinks, it creates an area of high pressure
At high pressure, cold air is sinking and getting warmed up which results in it evaporating so the weather is sunny and clear skies.
At low pressure, warm air is rising and cooling which results in it condensing so clouds and rain form.
Wind (Global Atmospheric Circulation model)
Wind moves from a high to low pressure.
Winds are deflected right in the northern hemisphere and left in the southern hemisphere due to the Coriolis effect
What is the climate at the equator?
The sun shines directly on the equator, meaning it is consistently warmer than at the poles.
Hot, moist air rises here, creating an area of low pressure. When the moist air rises, it condenses to form rain clouds. This causes the climate at the equator to be humid and very rainy. Tropical rainforests are found here due to the warm and wet weather.
What is the climate at the Subtropics?
Dry air sinks at the subtropics, meaning it forms an area of high pressure. Clouds do not form here because the air isn’t rising, so it is very dry. This is where we find many of the world’s deserts. It is very hot in the day because of the intense sunlight, but very cold at night because there are no clouds to retain heat
What is the climate at the Subpolar latitudes?
At around 60º north or south of the equator, there is a low pressure between, causing the climate ti be cloudy and wet. The climate here is not warm as the sun shines less directly than at the equator
Define Tropical Storm
A tropical storm is an extremely large, powerful and destructive storm with winds over 120km/h and heavy rainfall. Tropical storms create huge waves called storm surges which can be several metres high and travel far inland
What is the global distribution of tropical storms?
Always form in the sea and can never form over the equator. Once they are formed they travel west. Most tropical storms form in the Western Pacific Ocean.
Hurricane: In the USA and Latin America, Caribbean
Cyclone: Australia (Oceania) and Madagascar
Typhoon: India, Japan and the Philippines
Cause of Tropical Storms: Temperature
Ocean temperatures must be around 26-27ºC and at least 50 metres deep. Warm water provides the storm with energy. This is why storms form during late summer, when the ocean has had time to heat up.
Cause of Tropical Storms: Wind Shear
Winds must be present for the swirling motion to form, but not too strong or the storm system will be ripped apart in the early stages.
Cause of Tropical Storms: Air Pressure
Must be in areas of unstable air pressure - usually where areas of high pressure and low pressure meet - so that warm air rises more readily and clouds can form (this air must be humid for cloud formation) Warm air rises because it is less dense than cold air
Cause of Tropical Storms: Rotation
Tropical storms only form around the equator (5-30º) but not on the equator. The Coriolis effect is the effect of the Earth’s rotation on weather events. The storm spins because the Earth is spinning but there is no coriolis effect at the equator, hence why these storms will only form a certain distance away from it
Formation of a Tropical Storm
- The sun sends incoming solar radiation to Earth which warms the ocean
- This warms the oceans to a critical 26.5ºC
- This causes warm, moist air to rise through the air in thermals
- This air cools as it rises, this causes condensation to occur and clouds form
- Some cooled air sinks back down, helping to create the eye
- Air rushes in from outside the storm creating wind
- The whole storm rotates because of the Coriolis effect.
- When the tropical storm reaches a coast, the low pressure and high winds will cause a large amount of sea water to be pushed onto the coast, which is called a storm surge
- When the storm reaches land, it no longer has a supply of energy and the eye eventually collapses and the storm dissipates. Heavy rain can persist for days
Define the Eye
The centre of a tropical storm where sinking air causes relatively calm, clear conditions
Define the Eye Wall
The towering bands of cloud bearing heavy rainfall which surround the eye. Here the winds are in excess of 120km/h
Define the Rain Bands
Bands of clouds and thunderstorms that spiral out from the eye wall. Heavy bursts of rain and wind are usually associated with rain bands. These structures form the outer most fringes of the tropical storm structure and the winds contained within the bands decrease outward from the eye wall
How can climate change affect the Distribution of tropical storms?
The locations of tropical storms may increase as warmer seas mean that the source areas may extend further north and south of the equator. Low-lying coastal communities within the tropics are the most vulnerable especially where the population density is high, and the income level is low.
How can climate change affect the Frequency of tropical storms?
Evidence suggests that although tropical storms may become more intense, they will not become more frequent.
How can climate change affect the Intensity of tropical storms?
- Warmer seas mean there is more energy to increase the intensity of tropical storms
- Rising sea levels means that the risk of coastal flooding from storm surges will be greater
- More people living in coastal communities in the future means that more people will be affected
What are primary effects of tropical storms?
The effects that are directly caused by the tropical storm itself. e.g. strong winds knocking over power lines
What are secondary effects of tropical storms?
The effects that are as a result of the primary effects. e.g. landslides caused by flooding
What are immediate responses to tropical storms?
Actions taken as soon as the hazard happened and in its immediate aftermath. Immediate responses usually aim to reduce loss of life nd provide vital aid and resources. e.g. search and rescue, food and water, shelters.
What are long-term responses to tropical storms?
Actions taken after the immediate responses when the effects of the hazard have been minimised. Long-term responses aim to restore normality and reduce risk in the future. e.g. rebuilding infrastructure and homes, building defence mechanisms, setting up warning systems.
How can Monitoring reduce the effects of tropical storms?
As tropical storms form away from land, it is possible to track cloud formations and movements using satellite technology. Scientists monitor the areas where tropical storms usually form to see if one is on the way. Also, it is possible to monitor the route a tropical storm is taking to see if there is potential for the tropical storm to make landfall.
How can Prediction reduce the effects of tropical storms?
Using monitoring and computer modelling, it is possible to predict the route a tropical storm is going to take as well as its intensity up to days in advance. The population can be informed of the estimated time that the topical storm will hit them, and can take action accordingly.
How can Protection reduce the effects of tropical storms?
- Sea walls can be built on the coast lines to block storm surges
- Storm drains can be constructed to divert water after high levels of rainfall to reduce the risk of flooding
- Power lines, doors, windows, transformers etc. can be reinforced to be resistant to high winds
- Houses can be built on higher ground or even on stilts to reduce the flooding risk
How can Planning reduce the effects of tropical storms?
- Hazard Mapping: identifying the areas that are most at risk and taking action. For example, ensuring important buildings such as hospitals and nuclear power plants are built away from high risk areas
- Evacuation Routes and Safety Protocols: creating evacuation routes and developing warning systems ensures the population is prepared for a storm and will be alerted when one is coming. e.g. hurricanes sirens signal to people that they must take shelter
- Raising Awareness: if the community is aware of the risk they face from tropical storms, they can lower their risk by planning in advance. e.g. getting important supplies, organising documents, being aware of their local shelter
In the USA there is National Hurricane Awareness Week every year which aims to educate communities on the dangers of the upcoming hurricane system
When did Typhoon Haiyan hit the Philippines?
7th November 2013
How strong was Typhoon Haiyan?
Category 5 super typhoon
What were the sustained (10 minute) wind speeds of Typhoon Haiyan at its peak intensity?
230km/h
What were the sustained (1 minute) speeds of Typhoon Haiyan at its peak intensity?
315km/h
How many people died in Typhoon Haiyan?
6,300
On average, how large were the storm surges caused by Typhoon Haiyan?
Over 5 metres
How many fishing boats were destroyed?
30,000
How many people were displaced due to Typhoon Haiyan?
Over 600,000
How many homes were damaged or destroyed in Typhoon Haiyan?
40,000
How much of the city of Tacloban was destroyed by Typhoon Haiyan?
90% of the city
As well as the storm surge, what were the other primary effects of Typhoon Haiyan?
- Heavy winds damaging infrastructure
- Heavy rain (over 400mm) causing flooding
How many people were affected by Typhoon Haiyan?
14 million people
How many people lost their source of income due to Typhoon Haiyan?
6 million
How did Typhoon Haiyan affect health?
There were major shortages of food, water and shelter. The outbreak of disease was feared due to poor sanitation conditions in shelters and overwhelming amounts of dead bodies.
How long was the power out for in some places after Typhoon Haiyan?
Up to a month after the Typhoon
What other effects did flooding have after Typhoon Haiyan?
Triggered landslides, which clocked roads and slowed relief efforts
What slowed the distribution of aid after Typhoon Haiyan?
Major disruption to flights and ferry services, making it difficult to reach remote communities
How did Typhoon Haiyan affect crime?
Looting and violence broke out in Tacloban
How did international aid organisations respond to Typhoon Haiyan?
They brought food, water, aid supplies and temporary shelters to support those affected
How did the Philippines Red Cross prepare for Typhoon Haiyan?
They pre-positioned emergency supplies ahead of the typhoon which meant they could be distributed quickly after the typhoon hit
How many people did the Red Cross supply clean water to after Typhoon Haiyan?
1.1 million
How did Canada and the USA respond to Typhoon Haiyan?
Deployed military aircraft’s to assist with search and rescue and supply distribution
How did France, Belgium and Israel immediately respond to Typhoon Haiyan?
They set up field hospitals to help the injured
How many evacuation centres were set up after Typhoon Haiyan?
1,200
How did the UNDP support locals whilst also funding the clean-up process after Typhoon Haiyan?
Set up cash-for-work schemes which paid villagers to clear debris and medical waste
How was the risk of disease outbreaks limited in the long term?
Polio and measles vaccines were given to children in a mass immunisation program
What was the ‘build back better’ strategy implemented by the Philippines government and how successful has it been?
A scheme for 205,000 homes to be rebuilt away from high risk coastal areas. In 2016, only 1% of the target had been achieved
How have fishing and agricultural sectors recovered from Typhoon Haiyan in the long term?
Fishing boats donated by organisations like Oxfam supported the fishing sector. Rice farming was quickly re-established but coconut farming is taking longer as trees take years to grow
What have environmental organisations been doing in the long-term after Typhoon Haiyan?
Protecting and replanting mangrove forests, which are important for fishing and act as a barrier against storm surges
Types of weather hazard experienced in the UK
- Rain -> flooding - damages infrastructure and can kill people
- Wind -> damage properties, disrupt transport, uprooted trees, kill people
- Hailstorms -> make driving dangerous, damage properties, destroy farmers’ crops
- Snow and ice -> injuries due to slipping, death due to cold, transport disruption
- Heatwaves -> deaths, breathing difficulties due to pollution build up, transport disruption BUT tourist industry benefits
- Thunderstorms -> lightning can cause death and fires can damage property and the environment
- Drought -> water supplies run low causing economic impacts such as crop failures. Hose pipe bans have been introduced
Beast from the East causes
- Happens when a big area of high pressure sits over Scandinavia
- Very cold air from the East
- As it moves over the North Sea it picks up moisture -> snowfall
What were the social impacts of the Beast from the East?
- 10 deaths linked to cold and snow including a 60yr old man who fell into a frozen lake whilst trying to save his dog
- Thousands of schools and workplaces were closed for more than one day
- UK issued with a gas deficit warning
- Hundreds of people stranded across the UK as roads became impassable
- NHS cancelled non-urgent operations
What were the economic impacts of the Beast from the East?
- The weather cost the UK millions. The AA estimated that there were 8,260 collisions on Britain’s roads from the snow chaos in just three days, with the insurance cost above £10 million. Two thirds of them due to snow and ice.
- British Airways cancelled hundreds of short-haul flights from Heathrow, and London City Airport also cancelled many services
- Major shopping centres and businesses closed early
What were the environmental impacts of the Beast from the East?
- Wind speeds exceeding 70mph blowing over trees
- Many coastlines were also issued with flood warnings
Explain how the management strategies in response to the Beast from the East reduced the risk/impacts
- A red weather warning was issued for parts of Scotland, Devon, Somerset and South Wales. First in 7 years. -> This helped to reduce the number of casualties because people were less likely to go outside. They were also more inclined to stock up supplies which allowed them to stay warm and healthy
- The RAF were drafted in to help transport doctors and patients in Lincolnshire -> Anyone who was ill or having emergency surgery could get to hospital and have their life saved
- High in the Pennines on the M62, the military was called in to help rescue vehicles -> Abandoned vehicles get very cold - potentially dangerous to people’s lives. If people abandon their car with no key, it is an obstruction and can cause crashes
What is evidence that the weather in the UK is becoming more extreme?
- The way atmospheric circulation affects moisture and pressure is changing due to climate change, which has led to altering precipitation patterns
- There is evidence that the weather patterns in the UK are getting stuck due to the changing climate, meaning we are experiencing prolonged weather events more frequently.
- Rainfall has become more intense in recent years. Studies have shown that this may be due to climate change affecting atmospheric circulation, and altering rain patterns. This may lead to flooding events becoming more frequent and more extreme. Strong winds and storms may also become more common due to the increasing intensity of tropical storms
- Prolonged periods of hot, dry weather are becoming more commons in recent year in the UK. It is projected in the future that warmer summers will be more frequent in the UK and heatwaves will be more severe as well as more frequent. The average summer temperature is projected to ruse by 3-4ºC in the UK.
Evidence for Climate Change - Ice and Sediment Cores
- Ice sheets are made of layers of ice; one layer is formed each year
- Scientists drill into ice sheets to get long cores of ice. By analysing gases trapped in layers of ice, they can tell what the temperature was each year
- One ice core from Antarctica shows the temperature changes over the last 400,000 years
- The remains of organisms found in cores taken from ocean sediments can also be analysed. These can extend the temperature record back at least 5 million years
Evidence for Climate Change - Tree Rings
-As a tree grows it forms a new ring each year - the tree rings are thicker in warm, wet conditions
- Scientists take cores and count the rings to find the age of the tree. The thickness of each ring shows what the climate was like
- Tree rings are a reliable source of evidence for climate change for the past 10,000 years
Evidence for Climate Change - Pollen Analysis
- Pollen from plants gets preserved in sediment e.g. at the bottom of lakes or in peat bogs
- Scientists can identify and date the preserved pollen to show which species of plant were living at the time
- Scientists know the conditions that plants live in now, so preserved pollen from similar plants shows that climate conditions were similar
Evidence for Climate Change - Sea Level Rise
The average global sea level has risen by 21-24cm since the 1800s, and a third of this rise has occurred within the last 25 years.
Sea level rise has been occurring because higher temperatures have caused glaciers and ice sheets to melt, and this freshwater then flows into the sea
Furthermore, water expands when it gets warmer so as the Earth warms, the whole sea is expanding and rising
Evidence for Climate Change - Changes in Ecological Patterns
Many ecological studies have shown that seasonal patterns of wildlife have been changing. This is evidence that the climate must be influencing the seasons
Bird migration, plant flowering patterns and breeding seasons have been shifting throughout the world.
Natural cause of climate change - Orbital Changes (Milankovitch Cycles)
- Eccentricity:
- the orbit of the Earth around the Sun changes from a near-perfect circle to an ellipse
- this affects how intense the Sun’s rays are in Earth. If the Earth is orbiting in an elliptical shape, it will be further away from the Sun at certain points than if it was orbiting in a circle
- 1 cycle takes around 100,000 years - Obliquity (tilt):
- the tilt of the Earth’s axis, which changes from 21.5º and 24.5º
- affects the contrast between summer and winter seasons
- to change between 21.5º and 24.5º takes around 41,000 years - Precession:
- describes the wobble of the Earth’s axis
- affects the length of days, especially in the poles
- a full cycle takes just over 20,000 years
Natural cause of climate change - Solar Output
Scientists have identified cycles of change in the output of solar energy from the sun. These changes are linked to the presence of sun spots. A sun spot is a dark patch that appears from time to time on the surface of the sun. The number of sunspots increases from a minimum to maximum them back to a minimum over a period of 11 years. This 11 year cycle is called the sunspot cycle.
At the sunspot cycle’s minimum, there is a reduced solar output. At the sunspot cycle’s maximum, there is an enhanced solar output.
Natural cause of climate change - Volcanic Activity
- Violent volcanic eruptions blast huge amounts of ash, gases and liquids into the atmosphere.
- Volcanic ash can block out the Sun, reducing temperatures on Earth. This tends to be a short-term impact
- The fine droplets that result from the conversion of sulphur dioxide to sulphuric acid act like tiny mirrors reflecting radiation from the Sun. This can last longer and can affect the climate for many years
- The cooling of the lower atmosphere and reduction of surface temperatures is called a volcanic winter
Human cause of climate change - Use of Fossil Fuels
- Fossil fuels are used in transportation, building, heating homes and the manufacturing industry
- When they are burnt, greenhouse gases are released. They concentrate within the atmosphere, contributing to the enhanced greenhouse effect.
- Accounts for over 50% of greenhouse gas emissions
- Fossil fuel use will increase due to the world’s population growing and wealth increasing -> people will become more demanding of more energy
Human cause of climate change - Agriculture
- Accounts for 20% of greenhouse gas emissions
- Cattle produce methane during digestion, and microbes produce it as they decay organic matter under the water of flooded rice paddy fields
- The demand for food will increase in the future as the population will increase and countries will increase their standard of life and will consume more meat
Human cause of climate change - Deforestation
- The process of cutting down trees, mainly to make space for agriculture
- Trees take in CO2 from the atmosphere and store it inside them as carbon. Deforestation removes large amounts of trees, which in turn reduces the amount of CO2 that is being taken in and stored, resulting in higher levels in the atmosphere
- Also, forested areas often burnt to make space quickly and chopped wood is also burnt for fuel. The burning of wood releases CO2 that was originally stored in the trees and puts it in the atmosphere
Social effects of climate change
- Average temperatures are likely to increase -> increased risk of skin cancer and heat strokes
- Health: heat waves lead to deaths
-Malaria would increase so health in Africa would decline
Economic effects of climate change
- Increased flooding - infrastructure damage
- Agriculture affected
- Skiing resources may close
- (+) less ice in the Arctic Ocean would result in more shipping and extraction of gas and oil reserves
Environmental effects of climate change
- Loss of habitat for polar bears and seals
- Warmer rivers affect marine wildlife
- Extinction
- Drought
Climate Change Mitigation method: Alternative Energy Production
- Renewable energy doesn’t produce CO2
- It is also becoming cheaper
- However, it is dependent on weather conditions and is more expensive than fossil fuels
Climate Change Mitigation method: Carbon Capture and Storage
- Captures CO2 from emission sources and safely stores it
- Could provide more than 20% of the UK’s electricity and save the UK more than £30bn a year
- However, we don’t know the long term prospects of it and it doesn’t promote renewable energy
Climate Change Mitigation method: Planting Trees (afforestation)
- Recovering forests - trees are carbon sinks so will reduce the amount of CO2 in the atmosphere
- Increases forest carbon storage by 28%
- Increases biodiversity
- Reduces flooding
- However, we need land to plant these trees on
Climate Change Mitigation method: International Agreements
- Countries are agreeing to reduce their emissions
- Reduce emissions by 60% by 2050
- However, some countries can afford to mitigate climate change change more than others, and some are considered more responsible for causing climate change than others
Climate Change Adaptation method: Changing Agricultural Systems
- In some regions, biotechnology is being used to create new crop varieties which are more resistant to extreme weather events
- It may be necessary to plant new crop types that are more suitable for the new climate conditions in an area
Climate Change Adaptation method: Managing Water Supply
- Water meters can be installed in people’s homes to discourage than from using a lot of water
- Rain water can be collected and waste water can be recycled to make more water available
Climate Change Adaptation method: Coping with Rising Sea Levels
- Physical defences such as flood barriers are being built and better flood warning systems are being put in place. An example of this is the Thames barrier in London which can be closed to prevent sea water flooding the city
- In areas that can’t afford expensive flood defences, such as Bangladesh, people are building their houses on top of earth embankments and building raised flood shelters to use in emergencies
