The Physical Environment (AS); The Atmosphere (Complete) Flashcards
1
Q
What is the atmosphere and why is it essential to life on Earth?
A
Thin layer of gases surrounding the Earth, held in place by gravity
Provides vital life support systems, e.g. solar radiation, gas resources and aiding transport of energy + water around globe
2
Q
What is the atmosphere composed of? (Include %)
A
Nitrogen-78%
Oxygen 21%
Carbon dioxide- 0.04%
Rare gases (combined)- 1%
Ozone- 0.000007
3
Q
How is a dynamic equilibrium maintained within the atmosphere?
A
Natural processes are in a state of balance- maintains average composition of atmosphere, so only changes over very long timescales; a “Dynamic Equilibrium”.
Photosynthesis and aerobic respiration are two of the important natural processes. They roughly balance each other but rates at which they occur vary over different timescales so concentration of each gas fluctuates over a mean scale.
4
Q
What is the significance of interconnected systems within the atmosphere?
A
Many processes affecting the atmosphere are interconnected, so if one changes it can cause changes to others. This is significant as it shows human actions can trigger a sequence of events. There’s still a lot to be discovered & understood about how atmospheric processes work so it’s not yet possible predict impact of human activity on them.
5
Q
In what ways does the atmosphere support life? (List)
A
-Provides gases for natural processes
-Absorbs electromagnetic radiation from the sun, which is biologically damaging
-Delays escape of infrared energy
-Distributes heat
-Provides wind which creates ocean currents
-Transport water vapour
6
Q
How does the atmosphere providing gases support life?
A
Contains C, O, H, and N. These are needed to make biological molecules used by living organisms. They’re extracted from atmosphere as N2, O2, CO2 and H2O. Carbs, lipids + proteins contain carbon, oxygen, hydrogen. Proteins contain nitrogen.
7
Q
How does the atmosphere absorbing electromagnetic radiation from the sun support life?
A
Much of ‘biologically damaging’ radiation in the ‘solar wind’ is prevented from reaching Earth by upper atmosphere. Most of UV light passing through upper atmosphere is prevented from reaching Earth’s surface by various forms of oxygen in atmosphere- one, two or three atoms (monatomic, diatomic and triatomic oxygen). These form the ozone layer/ ozonosphere. These gases absorb UV light, creating a dynamic equilibrium of chemical reactions forming and destroying ozone.
8
Q
How does the atmosphere delaying the escape of infrared energy support life?
A
Much of visible light incoming is absorbed, converted to heat and re-emitted as infrared energy. Natural atmospheric gases absorb this energy, convert it to heat and increase atmosphere’s temperature Raises Earth’s temperature in 2 ways:
-Warm atmosphere emits infrared energy, absorbed by Earth’s surface;
-Warm atmosphere reduces heat loss by conduction from land & oceans
9
Q
How does the atmosphere distributing heat support life?
A
Most energy from the sun (absorbed at Earth’s surface) is absorbed in tropical regions. Warm surface heats atmosphere above and the heat is distributed to higher latitudes by warm winds, e.g. south-westerly winds which bring heat energy to Uk from Caribbean Sea.
10
Q
How does the atmosphere creating ocean currents support life?
A
Winds blowing over ocean create currents that distribute heat by carrying warm water from tropical areas to higher latitudes, e.g. North Atlantic Conveyor. The currents can also distribute dissolved nutrients.
11
Q
How does the atmosphere transporting water vapour support life?
A
Winds transport water vapour to areas that would otherwise get little to no precipitation.
12
Q
What does atmospheric pressure do?
A
Controls the ease with which water molecules can evaporate and escape from the water surface. If it was much lower there would be no liquid water on Earth.
13
Q
How are atmospheric gases used for human exploitation?
A
Humans extract a variety of industrially important gases from the atmosphere like N, O, CO2 and inert gases like argon, neon, krypton and xenon.
14
Q
What is the structure of the atmosphere and how is it formed?
A
Altitude affects the composition and physical features of the atmosphere. This results in a series of layers, of which the stratosphere and troposphere are most significant, and those affected by human activities.
Troposphere—>Stratosphere—>Mesosphere—>Thermosphere
10km altitude———————————————-> 95km altitude
15
Q
What are the energy processes present within the atmosphere and their significance?
A
Solar energy arriving at Earth+ energy radiated to space= generally in dynamic equilibrium state
Wavelengths of electromagnetic radiation arriving= mainly UV, visible light, near infrared
Wavelengths of radiation leaving Earth= long wavelength far infrared radiation
This energy + processes it drives controls factors like climate, ocean currents, hydrological cycle and distribution of species. Any human activities affecting energy movement could affect any of these factors, thus the survival of living organisms.
16
Q
What is the natural atmospheric greenhouse effect (process) and what would happen without it?
A
Atmospheric processes that warm the troposphere.
Visible light passes through the atmosphere easily, is absorbed by earth’s surface, which warms up and emits infrared radiation which cannot easily pass through atmosphere as easily since it’s absorbed by gases in the atmosphere- “greenhouse gases” (any gases better at absorbing infrared than average in atmosphere), most important being CO2 & water vapour.
Without this effect, the mean temperature of the Earth’s surface would be 33c colder than in reality.
17
Q
What does global climate change involve?
A
Changes to the composition of the atmosphere, altering energy processes, climate, and physical + biological they control
18
Q
What are anthropogenic changes?
A
Changes resulting from human activity
19
Q
What is the enhanced greenhouse effect?
A
Human activities increasing the concentration of the greenhouse gases absorbing infrared radiation and warming the atmosphere. Some are gases naturally occurring in the atmosphere, others only released by human activities.
20
Q
Which human activities increase the atmospheric concentration of Carbon dioxide?
A
Combustion of fossil fuels & wood, ploughing of soils, drainage of marshes & bogs
Relative effects (per molecule); 1
21
Q
Which human activities increase the atmospheric concentration of methane?
A
-Anaerobic respiration by microbes in padi fields, landfill sites, intestines of livestock
-Produced during formation of fossil fuels
-Released by ventilation of coalmines, leaks from natural gas fields & pipelines
Relative effects (per molecule); 25
22
Q
Which human activities increase the atmospheric concentration of oxides of nitrogen?
A
Oxygen and nitrogen from air react at high temps in places like vehicle engines & power stations. Then they’re released into atmosphere in exhaust gases. Fertiliser use can increase NOx emissions, including nitrous oxide.
Relative effect (per molecule); 160 (nitrous oxide)
23
Q
Which human activities increase the atmospheric concentration of chlorofluorocarbons (CFCs)?
A
Were used as aerosol propellants, fire extinguishers, refrigerants, solvents, and expanded foam plastics.
Relative effects (per molecule); 25,000 (typical value)
24
Q
Which human activities increase the atmospheric concentration of tropospheric ozone?
A
Made by photochemical breakdown of NO2 + subsequent reactions with oxygen.
Relative effects (per molecule); 2000
25
What are the consequences of global climate change?
Relatively small temperature increases involved in climate change may have range of direct & indirect impacts on biotic (living) and abiotic (non-living) conditions on Earth
26
What ecological changes may take place due to global climate change?
-Species may be affected directly due to changes to other species or natural processes they rely on
-Temperature rise may cause faster plant growth—> more food for herbivores, e.g caterpillars. Many plants make toxins which build up in leaves & prevent them from being eaten- if plant growth starts sooner it could kill the caterpillars
-Precipitation changes—> wetland habitats shrink/enlarge
-Oak trees= deep roots, can survive droughts beech trees= shallower roots, less likely to survive
-Dormouse hibernation potentially disturbed by warmer winters, use up stored fat-> could starve before spring, when they feed again
-Timing of ecological events, e.g flowering may change; surviving of independent species may reduce
-Distribution of species may change as conditions change, colonise new areas
27
Which species are most likely to be affected?
Those that are closest to the edge of their range of tolerance
Some may be unaffected by changes in physical environment but other species they rely on may be. E.g. supply, disease
28
How are bats in the UK affected?
Positive and negative ways;
-Warmer, shorter winters could increase survival due to hibernation. Warmer weathers could increase populations of food species, especially flying insects.
-Wetter, stormier weather could reduce times for which bats can feed, may reduce survival.
29
When is colonisation possible?
Population of one species may decline in one area—> local extinction, survival could improve in other areas, so possible colonisation of new areas + increase in range
Only possible if suitable new areas exist , there’s a biological corridor linking areas. Birds, flying insects can often colonise new areas while less mobile animals cannot
30
What happens to populations as a result of conditions for survival changing?
As conditions for survival change, small populations may become isolated from the rest of the population, e.g sea levels rise + create islands
May be little to no population movements between these isolated populations, can cause several issues threatening future survival:
- gene pool would be divided -> smaller gene pools, inbreeding more likely;
- may not be possible for surplus individuals from other areas to repopulate to area where local population died out
- although overall population may be big enough to be viable, individual smaller ones may not
31
How are abiotic factors affected as the concentration of greenhouse gases increase?
Predicted to have significant impacts on them, therefore also the survival of species
Simplest effect; absorption of more infrared energy emitted by Earth’s surface, converted to heat so atmosphere becomes warmer. Actual temperature rise may be very small but this could affect many other processes which could have big impacts on Earth
Mean global temp rise over the past 100 years has only been 1^C, but further 2^C is predicted to have very serious consequences.
32
What are jet streams and what do they control?
Jet streams= strong winds blowing from west —> east along meandering path in upper troposphere. Caused by difference in temperature + density between two air masses, e.g cold air in polar regions and warm air in mid latitudes. Winds blow to equalise pressure diff but do not blow in straight line from high to low pressure areas as the rotation of the Earth makes a coriolis force= winds blow in spiral fashion
These control the movements of air bodies creating rain, e.g cyclonic storms, Atlantic—> UK
33
How is global climate change affecting jet streams, and changing wind patterns?
Polar regions warming faster than areas near equator—> temperature differences creating jet streams getting smaller. The ones in the northern hemisphere are moving nearer to pole, more slowly + following more meandering path. Waves created by this path= rossby waves, can carry unusually cold air southwards/warm air northwards
Slower movement can= weather systems remain over one area, making longer, more intense weather, e.g prolonged droughts/increased rainfall—> floods
34
How does global climate change cause changes in rainfall?
Higher temp. = more evaporation, eventually more precipitation (same area/elsewhere)
Higher temp. = air may have to move further to cold area before water vapour cools enough to condense and fall as rain/snow.
Changes in wind direction & velocity may affect precipitation by carrying humid air—> new areas= increased rainfall in one area, reduced in another
35
What is the cryosphere?
Earth’s ice in all forms
36
How does global climate change cause changes in the cryosphere?
Warmer temperatures may have direct effect—> ice on Earth likely to melt more rapidly
Increased evaporation could= increased precipitation + snowfall. Extremely cold areas may have less snowfall as precipitation falls before getting there. Higher temps may allow more precipitation reaching such areas
37
How do the amounts and durations of snow cover change due to global climate change?
↑temp= ↓amount of ice + snow + length it remains on ground before melting. Less cover ↓albedo of Earth’s surface= less sunlight reflected away, more absorbed—> further heating.
38
How do glaciers form and how are they affected by global climate change?
Snow falling on land may collect, become compacted -> ice, flows gradually downhill as mass builds up enough, forms glacier. Moving ice → lower altitudes, it warms up & melts. May reach sea before melting + make icebergs as glacier breaks up/ may melt before reaching sea, + to river flow
Warmer temp may = front end of glacier melts faster than it’s moving forward, ice fronts retreats up valley
Meltwater from glacier surface may flow -> through cracks in ice to bottom of glacier, can lubricate ice as slides over rock-> moves quicker. If ↑speed due to lubricated movement > faster melting= glacier front could move further down valley. Even though it’s extending further, total volume of ice in glacier may ↓ if no ↑ in snowfall where glacier forms
39
What are the different ice formations and their descriptions?
Ice sheet- Ice covering area 50,000 km² +. Only 2 exist; Greenland & Antarctica
Ice cap- Ice covering area <50,000 km², thick enough for own topography (study of area’s physical features)
Ice field- Ice covering area <50,000 km², topography of ice follows underlying land
Glacier- Large body of dense ice, moving over land under its own weight
Ice shelf- Floating ice mass, attached to ice on land. Formed when glacial ice flows off land, onto sea
Iceberg- Large piece of ice floating in sea, broke off a glacier/ice shelf
Sea ice- Relatively thin ice, forms on sea as water freezes, from sea water but it crystallises as fresh water
40
What happens to ice shelves due to Global Climate Change?
As sea levels rise, land ice doesn’t need to move far before it floats off into sea.
Some grounded ice sheets on seabed may float, break up earlier as sea levels rise & ice breaks off earlier
Ice shelves breaking up don’t directly cause sea levels to rise as they’re floating and have already displaced sea water. Ice sheets grounded on seabed block forward movement of ice on land. Once ice shelf breaks up, glaciers/ice sheet behind may flow more rapidly—> sea
West Antarctica ice sheet largely held back by ice shelves= more vulnerable to rises in temp & sea level than East Antarctic ice sheet (more completely on land w/ few ice sheets)
41
What changes to ice thickness and area occur due to global climate change?
During Arctic + Antarctic winters, area of ice forming on sea surface ↑as temp. ↓
As temp. ↑, area of ice forming declines (relatively thin ice forming as ice crystallises in sea)
Area of sea ice forming around Antarctica each winter has ↑in recent years, maybe due to ↑freshwater flowing off of land, floating on denser sea water and freezing.
42
What impact does the area of ice have on temperatures?
Ice= high albedo, reflects most sunlight. If it melts, more sunlight is absorbed= further temperature increase, even more ice melting
43
How are ice lakes made and how do they impact people due to Global Climate Change?
Water made by melting ice can collect on surface of glaciers, making ice lakes
If front wall of ice lake melts, water may be released, rushing ↓valley below= sudden flooding
As glaciers melt more rapidly, this may become more common
^ Serious threat to Himalayas → large human population in valleys downstream of glacial lakes
44
How does Global Climate Change impact ice & snow-fed rivers?
Warmer conditions —> may↓ snowfall, ↑ rainfall. Can affect river flow patterns, rainwater flows → rivers soon after falling. Some areas —> snow builds up in cold weather + melt gradually in warm weather.
Rivers fed by meltwater may = more even flow than if fed directly by rainwater
Other areas= precipitation falling as snow may ↓ river flow as snow accumulates, may = big ↑in river flow if climate suddenly warms, e.g spring thaw.
45
What are two reasons rising temperatures cause an increase in sea level?
- Thermal expansion of seawater
-Melting land ice
46
How does thermal expansion of seawater cause a rise in sea levels?
Warmer atmosphere heats seawater, which expands; sea levels rise. This change will take a very long time as there's an enormous # of water in oceans & it has a high specific heat capacity- only surface water is directly heated by contact with the atmosphere; cold deep water can only warm when slow ocean currents bring it to the surface.
47
Haw does melting land ice cause a rise in sea levels?
Earth warms up → ice melts.
Ice floating on sea surface doesn't cause sea levels↑ as it melts, since it contracts during melting & occupies same volume as volume of ice which was below water level.
But, land on ice will cause sea levels to ↑ as water having → sea ↑ its volume.
48
What is the importance of ocean currents?
Important in distributing heat around the planet. Can have a big influence on the climate on land; water warms/cools the coastal land areas & atmosphere.
49
Which atmospheric processes are ocean currents driven by?
- Winds cause surface water to move;
- evaporation due to warming → water flows in to replace evaporated water;
- heating/cooling changes density of surface water → affects ease with which surface water sinks;
- changes in salinity due to evaporation/ inflow of freshwater from melted land ice affect water density.
50
What is The North Atlantic conveyer (the 'gulf stream') and what 2 processes drive it?
Movement of layers of surface & deep water in North Atlantic Ocean, distributing heat energy and controlling the climate. Warm water from tropical Atlantic Ocean → north-eastwards → NW Europe.
2 processes drive this:
- friction with prevailing winds blowing over ocean surface from SW → NE causes surface water to flow in same direction;
- water in NE Atlantic sinks as cools → denser, draws water in to replace it.
51
How does the North Atlantic conveyer warm the UK?
Brings water from tropical regions. This prevents cold weather found in regions of the same latitude, e.g. Moscow or Churchill, Canada (polar bears found here).
52
How does global climate change cause changes in the North Atlantic conveyer?
Higher atmosphere temperatures = land ice on Greenland melts, flows into sea → dilutes seawater = salt concentration ↓ the less saline water = less dense than normal seawater, less likely to sink. Flow rate of water current ↓, could cause NE Europe to be came colder.
53
What is El Niño and what occurs in normal conditions?
Sequence of events which occur naturally, typically every 2-7 years but seem to be happening more frequently. Changes in wind patterns may be partly due to global climate change. Name = Christ child in Spanish (events start around Christmas often).
Normal conditions; trade winds blow westwards across Pacific Ocean near equator → moves surface ocean current in same direction. = deep cold water drawn ↑ near coast of S America. The water from deep ocean = rich in nutrients → large algal bloom near sea surface. This feeds rich food weblike fisheries giving food for human population. Current continues → W becoming warning as travels. Eventually → S along E coast of Australia as warm current.
54
How do El Niño currents affect rainfall patterns?
Water temp. = major determinant of where rain will fall. If current → cold at coast then any water-bearing winds → over sea towards land will be cooled. May = water vapour cools, condenses & falls as rain before hitting land.
If there's a warm coastal current = winds blowing → land - likely to retain water vapour & may allow it to reach land where it can fall as rain.
In some years the winds creating surface currents → change directions = ocean currents slow/reverse. Nutrient upwelling of S America stops, rich food web collapses
Temp↓ in W Pacific & temp ↑ in E Pacific = changes in # & distribution of precipitation. Rainfall in E Australia↓and coastal parts of S America which are normally deserts may have heavy rains & floods.
55
What are the global impacts of El Niño events?
As the world's wind systems are interconnected, el Nino events are associated with unusual weather like:
- droughts in NE Africa, S Africa & China
- fewer hurricanes in N Atlantic
- fewer tropical cyclones in Japan
Exact causes of El Niño events aren't fully understood, but may be ↑ due to human impacts on atmosphere.
56
What are some historical disasters that may have been made worse by El Niño events?
- 4000 years ago: collapse of Ur civilization in Middle East due to droughts in El Niño years
- mid 7th century: collapse of Moche civilization in Peru, S America due to floods
-1588 : storms sinking many Spanish Armada ships
- 1789 - 93: storms & crop losses;↑ discontent leading to French Revolution
-1812: cold winter weather stopping Napoleon's advance on Moscow.
- 1942: cold winter weather stopping Hitler’s advance on Moscow.
- 1912: southward iceberg movement from Greenland leading to titanic sinking.
57
What are La Niña events?
Occurs when winds blow more strongly in normal direction, so water currents speed up& temperature differences between W & e Pacific ↑.
Limited scientific agreement on link between human activities & changes in ENSO, but if they’re involved, future global weather patterns may become less predictable
58
What are the impacts of climate change on health?
- Temperatures in same areas are at the upper end of range of tolerance for humans. If climate change ↑ temperatures, heat wave = more likely to cause health problems.
- urban areas often have ↑ temperatures due to 'heat island' effect of heat emissions & light absorption by dark surfaces. Impact of heatwaves ↑.
- those with existing health issues like heart disease may be more vulnerable to extreme temperatures.
- disease vectors could change distribution as temps ↑ eg mosquitos.
- food poisoning may became more common as pathogens grow quicker on unrefrigerated food.
59
What are the impacts of climate change on water supply?
Changes in evaporation, precipitation & river flow may = water supply issues like droughts and floods.
60
What is the impact of climate change on food supplies?
Changes in temp & water availability may change crop species that can be grown. ↓ water availability may
= crop irrigation more important. Warmer winters may allow ↑ survival of pest insects → more pest damage in following growing season.
61
Whet are the impacts of climate change on infrastructure?
- Road heat stress; ↑ temperatures = melting of tar holding stone chipping together in road surfaces → roads deform. Some roads will need to be re-laid with tarmac with higher melting point
- Track buckling; ↑ temperatures can = rail tracks expand & buckle. Before being laid, track is stretched/ heated to reach length it would expand to at particular temperature. Temps ↓ this couldn't = buckling, but temp much ↑ could. ↑ temps may require track to be re-laid with pre-stretching for higher temperature.
- drainage; ↑ rainfall/ periods of sudden heavy rain will ↑ flooding risks.
- landslides; heavy rain can waterlog ground, lubricate soil & rock particles → landslides more likely, esp on deforested hillsides
- bridge damage; ↑ river flow after heavy rain can put pressure on bridge supports, esp if objects like tree trunks hit bridge, most common with old bridges with thick structures narrow arches arches.
62
Why are there difficulties in monitoring and predicting climate change?
Climate Change = complex issue, many interconnected natural systems. General trends can be predicted but individual changes are more difficult, accurate details + where & when they'll occur.
Changes may occur over different scales of time & space. Climates & natural processes often fluctuate sorts difficult to know that individual events are part of a long-term trend. E.g.:
One area ↓ rainfall, another ↑
63
What is the significance of the interconnected systems in the environment?
We don't fully understand the natural processes controlling the atmosphere,biosphere & hydrosphere or interconnections existing between them. Interactions happen over diff timescales - difficult to accurately monitor changes, predict effects. Eg in UK over diff times:
- Jet stream changes ↑ temps
- Slowing of North Atlantic Conveyor may ↓ temps
- Underlying trend of ↑ greenhouse gases may ↑ temps
64
Why is it difficult to determine whether an event is due to human actions or not?
The global climate has never been constant. Climatic factors fluctuate as they're influenced by variability of solar output, Earth's orbit & changes in Earth's surface due to previous climate variability. These natural changes can hide/ exaggerate anthropogenic changes.
Potential changes could occur naturally; hard to determine human role. One storm, or even several, do not show a pattern. The change may be the frequency with which these events occur which can usually only be assessed years later when a trend becomes clear.
65
Why is there a time delay between cause and effect?
E.g- atmosphere may warm quickly, but could be very long time before world's oceans reach same temperature as volume of oceans is so great + water has very high heat capacity.
66
Why is historic data often unreliable?
Data in past on atmospheric composition, temperature & weather patterns may be unreliable due to lack of sophisticated equipment/ data collection on global scale. e.g -
Temp records collected in towns may show warming caused by ↑ in heat-island effect as town grows rather than result of global temp ↑.
67
What is proxy data + examples?
Involves making an estimate about one factor which can't be measured by using related factor which can be measured / estimated, e.g:
- dendrochronology; width of tree ring shows growth ratemay indicate temp at time it was laid down. Age of tree ring can be easily estimated.
- some coral species make large coral heads w/ annual growth rings, can be used to estimate past sea temps.
- pollen grains; can be preserved in lake sediments. Presence of pollen of particular species shows climate
present when produced. Date when pollen was produced can be determined w/ radio-carbon dating of organic material in sediments.
68
How has ice core data provided information?
40+ ice cores have been drilled for info about historical atmosphere, mainly in Greenland & Antarctica.
Annual accumulations of snow build up into ice layers,so deeper ice layers = older. Data on ice up to 800,000 years old has been collected from 3200m care from Dane Concordia, Antarctica.
Air bubbles trapped in ice give info on atmosphere when bubble became trapped like CO2 conc. & ratio of oxygen isotopes - gives info on temp when gas was trapped.
Layers = clearest in shallower ice. Compaction due to pressure can make deeper layers ↓ distinct but radio-isotope analysis may be used to compare ice cores, identify layers of similar age.
69
How has satellite data provided information?
-Sensors carried by satellites used to collect data on things like wind velocity, ocean currents, temp, wave height,ice cover/thickness.
-Low Earth Orbit (LEO) satellites in polar orbit at altitudes of approx 800km collect info of earths wholes surface. Each orbit= 1 1/2 hrs, successive orbits in diff areas so whole surface surveyed over 15 days
-Satellites in geostationary orbit= less detailed info from constant position 36k km above equator. Many used to measure weather & climatic conditions
70
How can ocean currents be measured?
Surface currents= satellites/buoys and floats at water surface
Deeper currents= Argo floats sink to particular depth for specific durations like 10 days. Then surface, transmit data and submerge for 10 more days. Data collected on temp & salinity, etc. Sequence of position plots show direction & speed of current
71
How are computer models used/useful?
Help understanding of climate systems, allow interconnections & consequences to be estimated more accurately.
Comp model can be tested by feeding in data for particular year, like 1900 to see whether model can predict outcome for later year like 2000. If prediction = similar to real event, can be trusted w/ caution. Model can be modified w/ more data collected & by analysing diff between predicted + real outcome.
72
What are feedback mechanisms + two types?
Change in 1 environmental factor may cause other ones to change. may have impact on OG change, either increasing or reducing it.
Negative- reduce size of OG change
Positive- increase size of OG change
73
What are some examples of negative feedback mechanisms?
Increased low-level cloud: higher temp= higher evaporation—> more condensation & clouds. Clouds have higher albedo than most of Earths surface—> more sunlight reflected away, warming reduced.
Increased photosynthesis: higher temp= higher photosynthesis rate—> more CO2 removed. If stored in woody tissue, CO2 levels in atmosphere rise less, warming reduced.
74
What are some examples of positive feedback mechanisms?
Soil decomposition: rate of decomposition of dead organic matter in soil largely controlled by temp, in cooler areas can build up over time. If temp rises, rate of decay may increase + aerobic decomposition by microorganisms will release more CO2, maybe for very long # until organic matter drops to new equilibrium
Melting permafrost: land areas in Arctic/Antarctic regions may have soil waterlogged but permanently frozen, includes dead organic matter decomposed slowly under anaerobic conditions + released methane trapped by permafrost. Warming releases this greenhouse gas—> further warming.
Ocean acidification: nearly 1/2 of CO2 released into atmosphere since industrial revolution has dissolved in ocean, making carbonic acid= oceans more acidic. Reduces coral survival—> less carbon sequestration & less stored as calcium carbonate in coral
Ice + snow melting: Have high albedo so sunlight incoming reflected, not absorbed. If warming reduces area of these, more sunlight is absorbed so more warming
Methane hydrate: dead organic matter in deep sea sediments decomposes, makes methane gas. In high pressure, low temp= solid methane hydrate made. May melt in higher temp—> methane in atmosphere
Increased forest & peat fires: peat pogs have waterlogged soils where dead organic matter builds up to make peat. As areas warm up + dry out, peat fires= more frequent, CO2 release, less carbon in peat. Drier conditions= longer fires, more CO2 in atmosphere
Increased water vapour: Warmer temps from CO2 7 other gases increase evaporation. Increase in precipitation but warmer air can hold more water vapour- powerful greenhouse gas.
75
What are tipping points + examples?
Concept that human actions causing climate change may cause changes in natural processes themselves causing climate change to extent where human action no longer needed for climate change increase.
Examples of processes:
-faster soil decomposition
-release of CO2 by more forest & peat fires
-Snow on land melting due to higher temps increasing albedo of Earth so more sunlight absorbed- further temp rise, more snow melts
76
What are the control methods for carbon dioxide?
-Reduction in fossil fuel use, like through energy conservation
-Using energy resources with low carbon emissions
-Carbon sequestration; planting more trees/storing CO2 in underground geological structures
77
What are the control methods for methane?
-Reduction in landfill waste, e.g increased recycling, reduced packaging & food waste
-Reduced livestock production
-Improved recovery of gas from coal mines & gas & oil facilities
78
What are the control methods for oxides of nitrogen?
-Reduced internal combustion engines, like more public transport use
-Catalytic converters in vehicle exhaust so harmful gases are removed + converted —> N & O2. CO & hydrocarbons broken down, converted —> H2O
-Adding urea to power station effluents/diesel engine exhausts to reduce NOx concentration & convert exhaust gas into N & steam
79
What are the control methods for chlorofluorocarbons?
-Using alternative materials in manufacture & appliance operation, e.g butane/propane aerosol cans, HCFs & HCFCs in refrigerators
-Use of alternative operational processes, stick and roll on deodorants instead of aerosol
80
What are the control methods for tropospheric ozone?
Same as oxides of nitrogen
81
What are the methods of carbon storage + explain?
Carbon sequestration: planting more trees would sequester carbon in wood via photosynthesis
Carbon capture & storage (CCS): developmental technology, may remove CO2 from industrial processes like fossil fuel power stations, stages=
-Capture of CO2/removal of carbon from fuel
-Transport by road tanker/ship/pipeline
-CO2 storage in depleted oilfields/gas fields/aquifers
82
What is geoengineering + examples?
Largely untried technologies, might control natural processes to reduce anthropogenic greenhouse effect, E.g- painting roofs white to increase albedo, reflect more sunlight
-Adding more nutrients to sea, stimulating plankton growth- shells of dead animals would take carbon to sea bed
-Putting solar shades in orbit, reducing sunlight reaching Earth
These could have unpredictable consequences that could cause environmental damage
83
What are some methods of adapting to climate change + explain?
Flood control- Flooding due to rising sea levels can be reduced by building higher river banks/coastal defences. If water levels in river rise above level of surrounding land —> pump rainwater from land into river/sea
Coastal erosion control- Sea walls, wave screens protect coasts
Managed retreat- Some areas; cost of flood prevention may be too high than worth it or ineffective
Urban drainage control- permeable urban surfaces; replacing impermeable concrete and tarmac w/ permeable gravel/soil to reduce flooding. slowing runoff to reduce river flow extremes.
River flow management; Tributaries= retaining water in them/slowing flow of water from
Land may reduce flooding around main river
84
How can we protect against flooding?
-Constructing low soil dams/increasing afforestation
-Larger dams regulate river flow, storing water in times of heavy flow + releasing it to maintain river flow in dry weather.
-Maintaining flood plains & woodland, delaying runoff into rivers reduces flooding
-Raised buildings on stilts; protect against flooding up to stilt height
-Floating houses on platforms
85
How is ozone created and destroyed?
Formation:
-UV light splits molecule of diatomic oxygen
-2 monatomic oxygen atoms released
-Monatomic oxygen atom reacts with a diatomic oxygen molecules to form triatomic oxygen; ozone
Destruction:
-UV light splits an ozone molecule into stable diatomic oxygen and monatomic oxygen
-Monatomic oxygen may react with another one or with a diatomic oxygen
86
In what form is oxygen present in the atmosphere?
3 forms- O, O², O^3, in dynamic equilibrium of chemical reactions caused by UV light absorption
87
Why is stratospheric ozone important?
Concentrations- as high as 13 parts per million. Approx 12-24km above Earth surface. Prevents most of high-energy UV solar radiation from reaching Earth’s surface.
88
What are the different UV lights + characteristics?
UV A: 320-400nm. Not absorbed by ozone/diatomic oxygen
UV B: 280-320nm. Almost fully absorbed by ozone
UV C: <289nm. Completely absorbed by ozone & diatomic oxygen
89
What is the effects of UVB light on living organisms?
If not absorbed in atmosphere, will reach Earth’s surface & may be absorbed by living cells. Energy of it is absorbed, some converted to chemical energy as breaks up bio molecules—> skin & DNA damage, skin cancer, cataracts, leaf tissue damage, reduced photosynthesis, and damage to marine organisms (algae, corals, plankton)
90
What are chlorofluorocarbons (CFCs) + why are their properties ideal?
Developed in 1920s for-> air conditioning units, fridges, aerosol & solvents for electrical equipment cleaning
Properties made them ideal for use:
-Not flammable
-Most non-toxic
-Boiling points; close enough to ambient temps so gases can be liquified w/ easily achieved pressures. So aerosols don’t have to be strong, etc.
91
What are chlorofluorocarbons (CFCs) + why are their properties ideal?
Developed in 1920s for-> air conditioning units, fridges, aerosol & solvents for electrical equipment cleaning
Properties made them ideal for use:
-Not flammable
-Most non-toxic
-Boiling points; close enough to ambient temps so gases can be liquified w/ easily achieved pressures. So aerosols don’t have to be strong, etc.
92
What is the Rowland-Molina hypothesis?
1974- 2 scientists suggest chemical properties of CFCs could lead to ozone depletion in stratosphere. Was based on chemical behaviour of CFCs;
-Persistence: chemically stable so remain in atmosphere long enough to travel to stratosphere
-Dissociation by UV & chlorine release: although are stable in troposphere, in stratosphere are exposed to higher UV levels, absorb UV—> breaks down carbon to chlorine bonds, release chlorine free radicals
-Reaction of chlorine & oxygen: Chlorine reacts w/ O, preventing its reaction with O² to make O^3. Further reactions prevent formation of more ozone molecules
Other halogens: bromine & iodine cause similar reactions
93
Why is measuring ozone not used as a measure of ozone depletion?
-Atmosphere at altitude of ozone in stratosphere not normally sampled, concentrations vary at diff altitudes
-Ozone measured in Dobson Units (DU, estimates total thickness of all ozone in atmosphere as if it existed as pure ozone in sea level). 100 DU= 1mm thick ozone layer. Normal ozone levels= 300 DU.
-Ozone depletion can be mild/severe. ‘Ozone hole’= below 220 DU, level not occurring before pollution by CFCs & other ozone-depleting substances.
94
How do satellite surveys show evidence of ozone depletion?
Satellites orbit Earth at higher altitudes than stratosphere- UV passing downwards through stratosphere can’t be measured but readings of UV light reflected by Earth were higher than expected—> suggests ozone depletion
95
How does ground-based collection show evidence of ozone depletion?
Detection of higher levels of UV at ground level= evidence of ozone loss in stratosphere. First evidence of ozone depletion, carried out by British Antarctic Survey at Halley Station, Antarctica.
96
How do air samples from the stratosphere show evidence for ozone depletion?
Collected by helium balloons & high-flying research aircraft confirm chemicals caused by depletion- especially chlorine & chlorine monoxide
97
In what ways do ozone levels vary?
-Varies between different areas, times, and altitudes.
-Most severe at alt of 12-24km; where UV light splits ozone molecules, releasing monatomic oxygen (can react w/ chlorine), preventing reformation of ozone
-Worst occurs over Antarctica- levels sometimes drop to 100DU. Arctic= less severe. Globally= ozone level drop of 4%
-In Antarctica, ozone hole most severe from September to December; when levels start to recover
98
Why is ozone depletion in Antarctica significant?
Atmospheric conditions= unique, make ozone depletion more severe. Stratospheric temps over Antarctic= lower than anywhere else on Earth—> ice crystals, stratospheric clouds form= provides surfaces for chem reactions, making chlorine molecules (CI²) form chlorine of CFCs.
Winds here rotate to make ‘polar vortex’ w/ little mixing between air over it and rest off atmosphere- maintains low temps & makes higher concentrations of chlorine making ice crystals. Antarctica is dark in winter, when spring comes—> sunlight splits chlorine molecules, make chlorine free radicals causing ozone depletion
99
What was the Vienna Convention for the Protection of the Ozone Layer (1985)?
Produced agreement between every country in UN, protecting ozone layer but no legally binding goals.
100
What were the main aspects of the Montreal Protocol?
Main aspects:
-Manufacture & use of CFCs + other ozone-depleting substances (ODS) phased out then banned
-use of HCFCs phased out by 2030
-essential use of some ODS still permitted (e.g halon fire extinguishers in aircraft)
-fund available to help countries implement Montreal Protocol
101
What alternative processes & materials were suggested?
Processes: pump action sprays used for cleaning products, stick/roll-on deodorants
Materials:
-HCFCs replace CFCs for fridges/air conditioners. Less chemically stable so would break down in troposphere, not reach stratosphere were could cause ozone depletion
-HFCs replace HCFCs for many uses. Have no chlorine but more expensive + don’t work as well + are greenhouse gases
-CFCs as aerosol propellants replaced by hydrocarbons like propane, but are flammable
-CFCs in foam plastic replaced by HCFCs, then HFCs, then CO² and N.
-CFCs in asthma inhalers replaced by hydrofluroalkanes (HFAs)
-CFC solvents replaced by alcohols, CO² , HCFCs, pellet blasting,etc.
102
How are waste CFCs disposed of safely?
Waste CFCs from fridges & air conditioning drained and incinerated.
CFCs broken down into CO² & acidic gases (HCl, HF) —> can be neutralised w/ crushed lime
103
What are the successes and limitations of the Montreal Protocol + effectiveness of ozone restoration methods?
Emissions of many ODSs have been contained but story of ozone depletion isn’t over.
It’ll be many years before pollutants by human activities stop causing depletion but severity is reducing
Successes of Montreal Protocol:
-international recognition of serious consequences of ozone depletion
-agreement between almost every country that actions must be taken
-development of alt. Processes & materials so most ODS no longer needed
Limitations:
Some ODSs not banned, like dichloromethane, research continue into their impact. Use may delay ozone layer restoration
