Hazards and climate change Flashcards
Hazard
Something which has potential to threaten people + property
Risk
Chances of the hazard being realised + potential severity
Disaster
When a hazard becomes an event + causes damage to people + property
Formation of a storm
1) rising air draws water vapour from ocean creating clouds
2) condensing releases heat, powering the storm
3) multiple storms join to form giant rotating storm
4) Coriolis effect spins storm at over 120 km/h
5) this creates a cloud spiral with a central, calm eye of rapidly descending air
6) prevailing wind drifts storm over ocean, gathering strength and energy
7) on reaching land the energy supply (evaporated water) is cut off and the storm will weaken
Conditions of a storm
- Summer and autumn
- oceans above 27°C
- 5 to 15° north and south of the equator
Destructive plate boundaries
- radioactive decay of inner core drives convection currents
- where these meet and descend, the oceanic subducts as it is denser
- as it sinks it melts, generating heat and the magma rises
- trench and fold mountains form e.g. Andes
- bulging causes cracks which magma rises through
- thickness of crust causes the magma to cool + solidify and eventually enough pressure builds and eruption occurs
Constructive plate boundaries
- radioactive decay of inner core drives convection currents
- as mantle plume reaches the crust it spreads, dragging tectonic plates apart
- the pressure of the rising plume causes crust to bulge and it cracks. Magma rises through cracks
- fissure eruptions which occur frequently but at low magnitude, earthquakes are also frequent and at low magnitude
Conservative plate boundaries
- radioactive decay of inner core drives convection currents
- causes 2 plates to move past each other
- friction between the plates lead to EQ
- stresses gradually build up over many years and these are released suddenly when the plates slip and shift
- no volcanoes, no magma
Reasons and economic opportunities for living on a plate boundary
ICELAND:
Energy: geothermal activity (GTE)
- provides 20% of Iceland’s electricity
- over 89% of homes are supplied by it
Agriculture
- 50000 m2 of greenhouses are heated + lit by GTE
- Seaweed is dried by it
Tourism:
- 700000 visit volcanic features
- 6% of GDP
Mining:
- basalt quarried for road building
- pumice for light concrete
Bangladesh
- bicycles used to give warnings to remote communities
- cyclone centres built made of strong concrete with shutters over windows
Examples of extreme weather the UK
Strong winds : feb 2014
Heavy snow/extreme cold : dec 2010, -18.7 degrees C
Drought/extreme heat : 2003, 20000 dead
Effects on recent warming
- artic sea ice melting (bad for habitats, good for global trade) thinned by 65% since 1975
- land ice melting (temperatures rise more as less reflection of solar radiation)
- sea-levels rise (covers land, coastal flooding) >10 cm in last 100 years
- seasons changing (birds migrating and nesting earlier than 1970s, trees flowering sooner)
Collecting evidence of climate change
- ice cores: air bubbles help us see CO2 concentrations at different periods of history
- pollen data: soil cores tell us which species lived in a place and we can work out temperatures
Natural causes of climate change
Eccentricity- 100,000 - orbit shape changes (circular -> elliptical)
Tilt - 41000 - axis moves between tilts of 21.5-24.5 degrees
Precession - 26000 - spinning of earth has a ‘wobble’
Sunspot cycle of 11 years
Volcanic ash can block sun e.g 1816 ‘year without summer’ due to Mt Tambora in Indonesia
Also Volcanic activity releases CO2 causing global temperatures to rise
Human causes for climate change
CO2:
Cars, deforestation, burning fossil fuels
Contributes to 60% to the net warming by greenhouse gas, levels increased by 30% in 50 years
Methane:
Livestock, burning biomass, 20% of enhanced greenhouse effect
Nitrous oxides:
Fertilisers, cars, burning fossil fuels, 300 times the impact on heating than CO2
Impacts of climate change
Economic:
Lower crop yields, sea-levels rise threaten major coastal cities
Social:
More heat related diseases eg malaria, increased risk from hazards
Environmental:
Stronger storms, desertification, ecosystem change: human- induced climate change occurs at faster rate than species can adapt and evolve to
Mitigating to climate change : renewable energy
Renewable energy:
87% off all CO2 emissions are from burning fossil fuels
UK wants 15% of all energy from renewable by 2020
Mitigating to climate change : carbon capture
90% of CO2 from power stations can be captured and stored as liquid gas underground
Mitigating to climate change : planting trees
Plantation forests absorb CO2 faster, trees help release moisture which has cooling effect
Mitigating to climate change : international agreements
-Paris 2015
195 countries agreed to keep global temperature increase below 2 degrees C and commit $100 billion a year to support developing countries to reduce carbon emissions
Adaption to climate change: agriculture
Farming in areas threatened by desertification can adapt using drought-resistant crops, water harvesting techniques and planting trees for shade which increases interception and reduces soil moisture loss
Adaption to climate change: land ice melting
16000 Himalayan glaciers are retreating. In Ladakh they created fake glaciers by collecting and freezing water in winter to use the meltwater in summer
Adaption to climate change: rising sea levels
Maldives
- coastal defences are built to protect the population of 380000, 3m sea wall built to protect capital, Male
Monitoring
Volcanoes:
• remote sensing : satellites detect heat increases
• seismicity : seismographs record microquakes
• ground deformation : laser beams measure changes in the shape of the ground
Earthquakes:
• microquakes before main tremor
• bulging of ground
• raised ground water levels
Events leading up to volcanic eruption
- rising magma
- sides of volcano swell
- rocks fracture causing earthquakes
- heat melts snow
- water heated by magma causes steam eruptions
- gases released from rising magma
Prediction
Volcanoes :
Monitoring allows accurate prediction and effective evacuation eg Iceland 2010
Earthquakes :
Accurate predictions are impossible due to lack of clear warning signs but historical records can help determine probability
Protection
Volcanoes:
Little can be done to protect property due to high temperatures, but embankments and explosives have been used to divert lava flows eg Italy
Earthquakes:
Reinforced windows and shock absorbers at the bottom of the buildings and earthquake drills
Planning
Volcanoes:
Hazard maps showing the likely areas to be affected, where to evacuate or restrict building
Earthquakes:
Risk assessment and hazard mapping to identify areas to protect buildings and infrastructure
Global atmospheric circulation
Involves a number of interconnected circular movements called cells
Low pressure equator- humid air rises, cools and condenses causing heavy rain
High pressure tropics- dry descending air with little rain with hot daytime temperatures and very cold nights (30° north and south)
UK- located 55° north, Close to the Boundry of cold polar air and warm subtropical air, this Boundary is unstable and the rising air cools, condenses and forms clouds and rain.
