The Challenge of Natural Hazards: Atmospheric Hazards Flashcards
Global atmospheric circulation
The movement of air around the Earth to try to balance the temperature.
Weather
Day to day conditions (e.g. rain).
Climate
Average conditions gathered over a period of time (e.g. cold winters).
Stages of global atmospheric circulation:
1) At equator sun warms earth, causing it to heat air above it making it rise. Low pressure forms clouds (rain).
2) As warm air rises it cools and sinks. This process moves air 30 degrees north and south of equator (@ tropics), creating the Hadley cell.
3) At 30 degrees north and south of equator, cool air sinking creates high pressure which causes cloudless skies and low rainfall.
4) Cool air reaches surface of Earth and move as surface winds from high pressure to low pressure - either back to equator (trade winds) or to poles (westerlies).
5) At 60 degrees north and south of equator, warmer surface winds meet colder air from poles. Warm air is less dense so it rises causing low pressure (rain). Ferrel cell.
6) At poles cool air sinks, creating high pressure (no rain). High pressure air is drawn back towards equator as surface winds. Polar cell.
Surface air
Transfers heat and moisture from one place to another.
Coriolis effect
Winds are deflected (to the right in the northern hemisphere and to the left in the southern hemisphere) due to the spinning of the Earth.
Global distribution of tropical storms
Found on either side of equator, in between the Tropic of Cancer and the Tropic of Capricorn.
Mostly found in Indian Ocean in east and travel west.
Formation of a tropical storm (hurricane):
1) Tropical ocean of at least 27 degrees heats up air above it causes the warm, moist air to rise. Low pressure.
2) As air rises it draws in more air and water vapour to cause torrential rain.
3) Trade winds and Coriolis effect causes air to start rotating.
4) Colder air above storm is denser and sinks in the calm eye. Heat is given off as it cools, powering storm.
4) Warm air condenses to form clouds, which cause precipitation.
5) Winds outside of hurricane keep it spinning and cause it to travel west, to land.
6) On meeting land it loses its source of heat and moisture, so loses power.
How has climate change affected tropical storms?
Frequency of tropical storms has not changed.
Sea heats up due to climate change, and more moist and warm air to fuel hurricanes makes them more intense.
Reasons for MORE people to be affected by a tropical storm:
Light weight building materials Coastal location Low lying land Storm path not predicted High population density High wind speed Lack of communications and warnings High storm surge
Reasons for FEWER people to be affected by a tropical storm:
Sturdy building materials Cliffs on coastline A means to move inland Cold air there, to reduce hurricane’s energy Storm path predicted Low wind speed Higher land Low population density Good communication and warnings
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Primary effects
- At least 6340 killed, most drowned by storm surge
- 5m storm surge
- 130,000 houses destroyed
- 90% of Tacloban city destroyed
- Habitats and crops destroyed
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Secondary effects
- $14 billion of damage
- Water supply polluted
- 4.2 million homeless
- Looting and violence in Tacloban
- Airports unusable for supplies
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Immediate responses
- Nearly 1,600 evacuation centres set up
- Field hospitals set up to help injured
- UK aid charities provided shelter, food and medical supplies
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Long-term responses
- UN appeal raised $300 million
- Typhoon warning systems have been improved
- People are now better educated on how to respond
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Prediction/monitoring
Philippines is an LIC, so minimal investment went into prediction, planning and protection schemes.
Actual path of tropical storm was further south then predicted, so people who were evacuated to the south were in more danger.
Lack of scientific equipment and good building materials.
Prediction for an atmospheric hazard
Use of satellites to monitor wind patterns allows for paths of tropical storms to be predicted.
This can help with evacuations.
Planning for an atmospheric hazard
Avoid building in high risk areas.
Emergency drills.
Evacuation routes.
Protection for an atmospheric hazard
Reinforced buildings and stilts to make safer.
Flood defences such as levees and sea walls.
Replanting Mangroves.
Severe weather
Weather that damages property and land, and puts humans, animals and plants at risk.
Examples of severe weather events in the UK
2003 - heatwave in UK and Europe, over 2000 people may have died due to hottest European summer since 1540.
2006 - tornado in London, 6 people injured and £10 million in damage.
Case study of an extreme weather event in the UK: Beast from the East 2018
Social impacts
- 10 people died
- NHS cancelled non-urgent operations
- Hundreds of people stranded across UK as roads became impassable
Case study of an extreme weather event in the UK: Beast from the East 2018
Economic impacts
- Local businesses lost trade
- Supermarkets across UK ran out of food as many “panic bought” supplies
- Flights and train services delayed or cancelled
Case study of an extreme weather event in the UK: Beast from the East 2018
Environmental impacts
-Snow drifts in excess of 7m in places.
Case study of an extreme weather event in the UK: Beast from the East 2018
Short-term responses
- Met Office issued a red weather warning to prevent unnecessary travel
- Churches opened their doors for the homeless
- Armed forces deployed to rescue stranded drivers and transport NHS workers
Case study of an extreme weather event in the UK: Beast from the East 2018
Long-term responses
- £1 billion per day was lost from people not being able to get to work
- Repairing roads and filling pot holes
- Government is reviewing emergency plans so we are better prepared in the future
Has weather become more severe in the UK?
-No change in UK’s total annual precipitation.
- More winter rain has fallen in heavy events since the 1980s.
- The frequency and magnitude of winter river flooding has increased since the 1980s.
-We are not sure if evaporation has increased or not.
•Temperature has risen by 1 degree.
Glacial period
A cold period of time lasting between 80,000 and 100,000 years.
Ice age
An extended period of time when it is cold.
Interglacial period
A warm period of time lasting between 10,000 and 15,000 years.
Quaternary
The last 2.6 million years of geological time.
Evidence for climate change:
Written records
Farmers would keep a log of when they take the harvest in.
Writers such as Dickens and Shakespeare would include detailed descriptions of the weather in their work.
People made weather diaries.
Evidence for climate change:
Seasonal changes
The width of gaps between tree rings have gotten wider, showing that trees have been growing more due to a hotter climate.
A study of birds nesting discovered that 65 species nested an average of 9 days earlier than in the 1970s.
Evidence for climate change:
Ice cores
Scientists can drill deep for ice cores and measure the amount of carbon dioxide and ice in each layer to reconstruct temperature patterns.
Evidence for climate change:
Increased carbon dioxide levels
Graphs show that as carbon dioxide levels rise, the interglacial periods between glacial periods have also risen in temperature.
Evidence for climate change:
Rising sea levels
Between 1901 and 2010, average global sea level rose by 0.19 m. This is due to ice melting (from glaciers and ice caps) and thermal expansion, both of which is caused by an increase in temperature.
Evidence for climate change:
Glacial retreat
When the Earth’s climate is stable the size of glaciers stay the same. However, glaciers throughout the world have been melting, causing them to retreat. This is due to an increase in global temperatures.
Evidence for climate change:
Paintings and photographs
There are Tudor paintings that show the River Thames frozen over during winter. This doesn’t happen anymore, suggesting that it was previously much colder.
Natural causes of climate change: Volcanic activity
Big volcanic eruptions produce volcanic ash and sulfur dioxide, which can rise into the atmosphere and block out sunlight, causing the climate to become COOLER.
Natural causes of climate change: Asteroid collisions
When an asteroid strikes the Earth, the impact throws up millions of tonnes of ash and dust into the atmosphere. This blocks out sunlight, causing the climate to become COOLER.
Natural causes of climate change: Solar output
The amount of sunspots on the surface of the sun is linked to how much solar energy the sun emits.
When sunspot activity is at a maximum every 11 years, the solar output energy increases, making the Earth’s climate WARMER.
Natural causes of climate change: Orbital changes
Earth’s orbit is sometimes circular, sometimes elliptical.
The tilt of the Earth’s axis can shift 1 degree either way.
The axis can wobble.
These changes effect the sun’s energy on the Earth’s surface, therefore changing the climate.
Greenhouse effect
Earth absorbs most of the radiation from sun and warms up.
Earth radiates energy as infrared radiation (heat) and some of the infrared radiation goes into space.
However some of the infrared radiation is absorbed by greenhouse gases in the atmosphere then re-emitted in all directions, heating up the climate.
Human enhanced greenhouse effect
Human activities produce a range of pollutants such as carbon dioxide and methane.
These greenhouse gases trap more heat in the atmosphere then normal, heating up the Earth’s climate.
(Power generation, deforestation, expansion of rice farms, agriculture, CFCs, industry)
Mitigation
Action taken to reduce or eliminate the long-term risk to human life and property from natural hazards.
Adaptation
Actions taken to adjust to natural events such as climate change.
Managing the impacts of climate change through mitigation
Alternate energy sources
- Burning fossil fuels contributes to 87% of all human-produced CO2 emissions.
- Using alternate energy sources will reduce the use of fossil fuels and therefore reduce CO2 emissions.
- UK aims to produce 15% energy from renewable sources by 2020.
Managing the impacts of climate change through mitigation
Carbon capture
- CCS captures CO2 from emission sources and stores it underground.
- It’s possible to capture up to 90% of CO2 that would otherwise enter the atmosphere.
- This means countries can use fossil fuels in a less damaging way.
Managing the impacts of climate change through mitigation
Planting trees
- Afforestation means more trees to: absorb CO2 from the atmosphere and also release moisture into atmosphere, which will produce more cloud and reduce solar radiation which will make the climate cooler.
- Plantation forests can absorb CO2 faster than natural forests for up to 50 years.
Managing the impacts of climate change through mitigation
International agreements
•Paris Agreement 2015 - 195 countries signed the legally binding agreement:
- keep global temp increase below 2 degrees
- strengthen global response to threats caused by climate change
•The pledges do not come into effect until 2020.
Managing the impacts of climate change through adaptation
Agricultural adaptations
•Farmers will have to adapt as some crops may not be able to grow in a warmer climate. However, other crops (eg. oranges and grapes) will be able to be planted.
Managing the impacts of climate change through adaptation
Managing water supply
- Unreliable rainfall and periods of water shortage require careful management.
- The artificial glacier project will supply water to villages in Ladakh, India:
- water collects and freezes in winter
- when this ‘glacier’ melts in spring it will provide water for locals
Managing the impacts of climate change through adaptation
Reducing risk from rising sea levels
- Areas at risk from sea level rise may need sea defences to protect the land from being eroded away.
- Construction of artificial islands in Maldives
- Building houses raised of ground on stilts
- Sea walls and sand bags
- Restoration of coastal mangrove forests (roots trap sediment)
