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The Living Environment 2.0 UNFINISHED (PG 109)
Terms in this set (120)
Adaptation to the environment (evolution)
Species become adapted via random mutations followed by natural selection, giving an increased chance of survival to better adapted individuals. A population with a large gene pool is likely to survive environmental changes as some individuals will have adapted.
Survival and distribution of species is controlled by abiotic factors. Factors that affect distribution include light, pH, water, mineral nutrients.
Survival of a species may depend on the presence or absence of another. Biotic factors that affect species distribution include food supply, pollination, seed dispersal, disease.
Pioneer species must adapt to extreme abiotic conditions. Populations increase over time and make conditions more suitable for further advanced colonisers which may outcompete pioneer species. Continues until climax community is reached.
A sere is the sequence of stages in ecological succession where an uncolonized habitat develops into the climax community.
- Freshwater is quickly colonised by single celled algae from soil
- birds and flying insects can bring spores and seeds of algae and plant
- lake edges start to be colonised by rooting plants, e.g. reeds
- as more plants colonise there are more habitats for animals, so more arrive
- as plants grow and die the lake fills with dead organic matter and soil and it becomes shallower so plants emerge from water
- larger species, e.g. trees can colonise in shallower water and transpire, which removes water, and dominate the area.
- Development on bare rock by cliff fall, retreated glacier, or volcano
- initially temperatures are extreme, water availability is limited, and there is no soil
- dead organic matter and rock fragments gradually accumulate, mosses colonise, and a thin layer of soil forms
- grasses and ferns form as abiotic conditions become less harsh
- pollinating insects colonise and bring flowering plants
- as soil gets deeper, trees can colonise and become the dominant species.
- Succession that starts on sand where plant nutrients aren't available, drainage is rapid so water supply is low, and moving sand stops roots from holding
- as plants succeed in colonising the sand becomes more stable, nutrient supplies increase, and more water is available
- eventually climax community is reached.
Approaches used to manage plagioclimaxes
- hay meadow = mowing
- upland moorland = grazing or burning
- garden lawn = mowing
- coppiced woodland = felling at intervals of 8 to 20 years.
Human activities can disturb climax communities, e.g. tree felling, ploughing, and burning. This recreates conditions that were suitable for earlier species in succession. If the area is left alone succession will continue and the climax community will be reached again. Process is much quicker than primary succession.
Estimating total number of species
Past rate of discovery can be used as a basis for estimating the number. 20,000 species are being discovered per year. An estimated 5 to 100 million species exist; 2 million have been named so far.
Population will increase if reproduction rate is high and death rate is low and will decline if vice versa. Successful conservation will maximise population increasing factors. Environmental factors affecting death rates can be controlled by good environmental management.
Max rate is determined by the natural ability of the species to reproduce. Evolution has produced birth rates appropriate for the death rate. Species with lower survival rate have higher birth rates.
Controlled by environmental factors, e.g. disease, drought, predation, and food shortage.
Species that respond rapidly to low survival rates, reach sexual maturity quickly, produce many young, and disperse widely. E.g., mice, locusts, greenfly.
Recover slowly from population decline, reach sexual maturity at older age, produce few young, live for a long time. Increase in death rate caused by change in habitat or human exploitation and could cause a population crash. E.g. whales, elephants, rhinos.
Homeostatic population regulation
Population dynamics are critical in monitoring the survival of a species, breeding success, and assessing MSY, which is a estimate of the greatest possible exploitation without causing long term population decline.
Forecasting population change
following variables are required;
- current population
- numbers of births and deaths
- number of immigrating and emigrating individuals
population = (starting population + births + immigrants) - (deaths - emigrants).
Factors affecting mortality rates;
density independent factors
Factors where population density has no effect on chances of survival of an individual, e.g. drought, flood, volcanic eruption.
Factors affecting mortality rates;
density dependent factors
Factors where the chances of survival depend on the species population density. Survival chances are higher when population density is low and lower when population density is higher, e.g. food supply, diseases.
Greatest population that an area can support indefinitely without damaging or over-exploiting the environment. Mortality rate of a population will change if size is above or below carrying capacity so that population size changes back.
Predator-prey population relationships
When prey population rises there is a lot of food for predators, so their population rises. High predator population causes food shortage for predators so their population declines. Low predator population allows prey population to rise.
Artificial population control
Culling may be required to enable species or habitats to survive where natural control mechanisms no longer regulate the population, e.g. if breeding rate of endangered species is low a captive breeding programme may be needed, or if a non-indigenous species is introduced it may reduce indigenous populations.
Grouping organisms according to the similarities in their features.
Group of closely related organisms that resemble each other more than members of other groups. They form a reproductively isolated group that naturally breed with each other to produce fertile offspring.
Process that changes a gene pool of a species, in some cases separating gene pools that eventually become more than one species, driven by increased chance of survival and better adaptation to conditions.
An area or location where a species or community of species lives, e.g. moles live in soil of a grassland.
Role that a species plays in its habitat, e.g. how it uses environmental resources and its relationship to other species, such as pollination or seed dispersal. Two species cannot occupy the same niche as one will be better adapted and outcompete the other.
Includes all the individuals of a single species that live in a particular area.
Community of species
All the members of all the species that live in an area.
A combination of the biotic and abiotic features of an area. Includes the community and their inter-relation with each other and the physical environment. Usually relatively self-contained with few movements in or out of the ecosystem. E.g. tropical rainforest, coral reef.
A large geographical region with specific climatic conditions within which a characteristic community of a species lives. Includes all the areas where the community is, e.g. tropical rainforest, tundra.
A thin layer of gases surrounding the Earth held in place by gravity. Provides vital life support systems such as protection from solar radiation, gas resource, and aiding transport of energy and water around the globe.
Importance of the atmosphere to life on Earth
- source of gases for natural processes
- absorbs electromagnetic radiation from the sun
- delays escape of infrared energy
- creates moving air which distributes heat and water vapour
- provides winds over the ocean which create ocean water currents
- creates pressure which allows liquid water to exist
- source of gas for human exploitation.
Composition of the atmosphere
Nitrogen = 78%
Oxygen = 21%
Carbon dioxide = 0.04%
Rare gases (combined) = 1%
Ozone = 0.000007%
Process that affect the atmosphere are interconnected, so a change in one will change others. So, human actions can trigger a sequence of change.
Gases for natural processes
N2, O2, CO2, and H2O are needed to make the biological molecules used by living organisms. Carbohydrates, lipids, and proteins all contain carbon, oxygen, and hydrogen and proteins also contain nitrogen.
Absorption of electromagnetic radiation from the sun
Radiation in 'Solar Wind' is prevented from reaching Earth by the upper atmosphere. Most UV light is blocked by forms of oxygen in the atmosphere (ozone layer).
Delaying the escape of Infrared energy
Most incoming visible light is absorbed, converted to heat, and re-emitted as infrared energy, which is absorbed by gases in the atmosphere to convert it to heat and heat the atmosphere. This increases Earth's heat as the surface absorbs infrared energy, and blocks heat loss from land and oceans.
Most energy from the sun is absorbed by Earth's surface in tropical regions. The warm surface heats the atmosphere above and this heat is distributed to higher latitudes by winds, e.g. south-westerly winds bringing heat to UK from Caribbean sea.
Winds blowing over the oceans create currents that distribute heat by carrying warm water from tropical areas to higher latitudes, e.g. North Atlantic Conveyor.
Transport of water vapour
Winds transport water vapour to areas that would otherwise get little or no evaporation.
Controls how water molecules can evaporate and escape from the water surface. If atmospheric water was much lower there would be no liquid water on Earth.
Gases for human exploitation
Humans get many industrially important gases from the atmosphere, e.g. nitrogen, oxygen, carbon dioxide, and inert gases (argon, krypton, xenon).
The structure of the atmosphere
Altitude affects the composition and physical features of the atmosphere resulting in a series of layers; troposphere, stratosphere. These layers are affected by human activity.
Energy processes in the atmosphere
Solar energy arriving at Earth and the radiated energy from Earth are in dynamic equilibrium. Wavelengths of radiation leaving are mainly UV, visible, and near infrared. This energy controls climate, ocean currents, hydrological cycle, and distribution of species.
The natural atmospheric greenhouse effect
Visible light passes through the atmosphere easily and warms the Earth's surface by absorption. Earth's surface emits infrared radiation which cannot pass through the atmosphere as easily as visible light because it is absorbed by gases in the atmosphere, e.g. CO2 and water vapour (greenhouse gases).
The Enhanced Greenhouse Effect and global climate change
Human activities are increasing the concentration of the greenhouse gases that absorb infrared radiation and warm the atmosphere. Some are gases that naturally occur in the atmosphere, while others are only released by human activities.
Human activities that increase atmospheric concentrations of greenhouse gases
- Carbon dioxide = combustion of fossil fuels and wood, ploughing soils, draining marshes.
- Methane = anaerobic respiration by bacteria in padi fields, landfill sites, livestock intestines, during formation of fossil fuels.
- CFCs = used as aerosol propellants, fire extinguishers, fridges, solvents.`
Ecological changes due to climate change
- species may be affected by temperature, or by the affect it has on other species near them
- temperature change affecting the environment by increasing or decreasing growth of plants
- precipitation changes causes wetlands to grow or shrink
- hibernation affected by warmer winters
- change in distribution of species
Effect of climate change on bats in the UK
- warmer, shorter winters may increase survival during hibernation
- warmer weather may increase populations of food species (night-flying insects)
- wetter, stormier weather may reduce the time when bats can feed, which may reduce survival.
Species distribution as a result of global climate change
Population may decline in one area and become locally extinct by my colonise an uninhabited area, increasing the range of the species. Birds and flying insects can colonise new areas easily but many plants and animals cannot. Small populations may become isolated so gene pools are divided and inbreeding is likely.
Changes in climatic processes
The retention of more heat energy in the atmosphere produces changes in atmospheric pressure and the evaporation of water that produce new weather patterns.
Wind pattern changes
Jet streams are strong winds that blow from west to east along a meandering path in the upper troposphere. They are caused by the difference in temperature and density between two air masses, e.g. warm air in midlatitudes and cold air in polar. Winds blow to equalise pressure differences but don't blow straight from high to low pressure due to rotation of the Earth (Coriolis effect).
Changes in rainfall
Increased temperatures cause evaporation, which eventually causes more precipitation in the same area, or elsewhere. Higher temperatures may cause air to move towards cold areas before water vapour condenses as rain or snow. Changes in wind direction may also carry humid air to elsewhere, increasing rainfall in some areas and decreasing it in others
Changes in the cryosphere
Warmer temperatures can effect ice as it will melt quickly, but increased evaporation may increase precipitation (more snow). Extremely cold areas may have low snowfall because precipitation falls before it gets there; higher temperatures may allow precipitation to reach there.
Reductions in the amount and duration of snow cover
Higher temps reduce the amount of snow and ice, and how long it lasts. This reduces the albedo of Earth's surface so less sunlight is reflected away and more is absorbed, causing further heating.
Changes in the extent and speed of movement of land ice
Snow that lands may compact into ice which flows downhill when built up, forming a glacier. As it reaches lower latitudes and melts, icebergs are produced, or it could add to river flow. Warmer temps can cause the front to melt faster than it is moving forward, so it retreats.
Relatively thin ice that forms on the sea as water freezes. It forms from sea water, but the ice crystalises as fresh water.
Loss of ice shelves
Floating ice shelves that break up don't directly cause a rise in sea level. Ice sheets that are grounded on the seabed often block forward movement of ice on land, e.g. ice sheet of West Antarctica is largely held back by ice shelves, so is more vulnerable to rises in temp and sea level.
Changes in ice and thickness
Arctic and Antarctic sea ice area fluctuates with the seasons and has a big impact on future temperatures due to the albedo effect.
Sea level rise; thermal expansion of seawater
warmer atmosphere heats seawater, which expands and causes sea level rise. Change takes a long time due to high specific heat capacity. Only surface waters are heated directly by the atmosphere, and the rest is warmed slowly by ocean currents.
Sea level rise; melting land ice
Ice will melt as the Earth warms. Floating ice doesn't cause rise as it occupies that same volume. Ice that is on land causes sea level rise as it is flowing into the sea and increasing the volume.
Changes in ocean currents
Ocean currents distribute heat around the planet;
- winds cause surface water to move
- evaporation causes water to flow in to replace removed water
- heating or cooling changes the density of surface water, affecting how it sinks
- salinity changes cause by evaporation or melting land ice effects water density.
The North Atlantic Conveyor (the 'Gulf Stream')
The North Atlantic Conveyor involves the movement of layers of surface and deep water in the North Atlantic Ocean which distribute heat energy and control the climate.
The natural North Atlantic Conveyor
Warm water from tropical Atlantic Ocean travels NE towards NW Europe;
- friction with prevailing winds blow water from SW to NE
- water in the NE Atlantic Ocean sinks as it cools and draws water in to replace it.
The UK is warmed this way as water is brought from tropical regions (warmer than countries like Russia or Canada that are in the same latitude).
Changes in the North Atlantic Conveyor caused by global climate change
Higher temps cause land ice on Greenland to melt and flow into the sea, diluting the seawater so it is less dense and doesn't sink as much. This reduces the flow rate of the water current and could cause NW Europe to become colder.
El Niño (normal year)
Naturally occurring sequence every 2-7 years, although have been happening more frequently;
- trade winds blow westwards, creating strong ocean current across the Pacific along the equator.
- cold nutrient-rich water is drawn up to the S. American coast, creating thriving food chains (commercial fishing) and dry conditions.
- water warms as it moves from S. America to Oceania/S. Asia.
- warm water brings rain to east Australian coast as it can evaporate easily.
El Niño (El Niño year)
- Direction of trade winds is reversed, so current slows or reverses.
- nutrient upwelling in S. America stops and rich food web collapses.
- weather conditions in S. America and Australia swap as warmer water isn't moving in the same direction.
- Australia experiences drought, S. America may have heavy rain and floods.
Global impacts of El Niño events
- Droughts in NE Africa, S Africa, and China
- fewer hurricanes in the N Atlantic
- fewer tropical cyclones in Japan.
Occurs when winds blow more strongly in the normal direction, so currents speed up and temperature differences are increased.
Impacts of climate change on human society; health
People with existing health problems, e.g. heart or respiratory disease, may be more vulnerable to extreme temps.
Disease vectors may change distribution as temps rise, e.g. malaria mosquitoes.
Food poisoning may be more common as pathogens grow more rapidly on unrefrigerated food.
Impacts of climate change on human society; water supplies
Changes in evaporation, precipitation, and river flow may create water supply problems, e.g. droughts, floods.
Impacts of climate change on human society; food supplies
Changes in temp and water availability may change the crop species that can be grown. Reduced water availability will make irrigation more important. Warmer winters may allow more pests to survive, so they can cause more damage.
Impacts of climate change on infrastructure; road heat stress
High temps cause melting of the tar that holds stone chippings together on road surfaces, causing roads to deform. Some roads will need to be re-laid using tarmac with a higher melting point.
Impacts of climate change on infrastructure; track buckling
High temps can cause rail track to expand and buckle. Before being laid, track is stretched or heated to reach the length it would expand to at a particular temperature (27 degrees C in UK). Rising temperatures may require the track to be re-laid with pre-stretching for a higher temperature.
Impacts of climate change on infrastructure; drainage
Higher rainfall or periods of sudden heavy rain will increase flooding risk.
Impacts of climate change on infrastructure; landslides
Heavy rain can waterlog the ground and lubricate soil and rock particles, making landslides more likely especially on deforested hills.
Impacts of climate change on infrastructure; bridge damage
High river flow after heavy ran can put pressure on bridge supports, especially if objects such as tree trunks hit the bridge or block the arches. This is most common with old bridges with thick structures and narrow arches.
Difficulties in monitoring and predicting climate change; time scales
- Short term, e.g. a sudden storm or wetter winter.
- Long term, e.g. a trend of winters with increasing rainfall.
Difficulties in monitoring and predicting climate change; spatial scales
- Local, e.g. a sudden slow-moving storm causing local flooding.
- Regional, e.g. an area with increased rainfall due to increased evaporation or changed wind direction.
- Global, e.g. increased global temperatures due to increased infrared absorption.
Difficulties in monitoring and predicting climate change; interconnected systems
Interactions between the atmosphere, biosphere, hydrosphere make monitoring difficult.
- Changes in the jet stream may raise temperatures.
- A slowing of the North Atlantic Conveyor may lower temperatures.
- The underlying trend of increasing greenhouse gases may raise temperatures.
Difficulties in monitoring climate change; natural fluctuations
All climatic factors fluctuate because they are influenced by variability in solar output, the Earth's orbit, and changes in the Earth's surface caused by previous climate variability. Potential changes can occur naturally so it is difficult to determine if an event is caused by humans.
Difficulties in monitoring and predicting climate change; time delay between cause and effect
E.g. the atmosphere may warm up quite quickly, but it could be a very long time before the world's oceans reach the same temperatures because the volume of the oceans is so great and water has a high heat capcity.
Data collection; historic data
Historic data on atmospheric composition, temperature, and weather patterns may be unreliable due to lack of sophisticated equipment and lack of collection on a global scale.
Data collection; proxy data
Making an estimate about one factor that can't be measured by using a related factor that can, e.g.;
- dendrochronology; tree rings show growth rate and can indicate temperature when it was laid.
- some coral species produce large coral heads with annual growth rings that can be used to estimate past temperatures.
Data collection; ice core data
Air bubble trapped in ice preserve carbon dioxide concentration, and the ratio of oxygen isotopes, which gives information on the temperature at the time.
Data collection; satellite data
Sensors carried by satellites can collect information on wind velocity, ocean currents, temperature, wave height, ice cover, ice thickness, and vegetation cover.
Data collection; monitoring ocean currents
Surface currents can be monitored using satellites or buoys and floats at the water surface. Argo floats can be sunk to certain levels to monitor deeper currents.
Data collection; computer models
Computer modelling allows interconnections and their consequences to be estimated more accurately. If a computer model can be trusted, it can predict real outcomes in the future.
A change in one environmental factor may cause other factors to change. These may have an impact on the original change, either increasing or reducing it.
- Negative feedback mechanisms reduce the size of the original change.
- Positive feedback mechanisms increase the size of the original change.
Negative feedback mechanisms - increased low-level cloud
Higher temperatures increase evaporation, which leads to increased condensation and produces more clouds. Clouds have a higher albedo than most of Earth's surface, so more sunlight is reflected away and the amount of warming is reduced.
Negative feedback mechanisms - increased photosynthesis
Higher temperatures increase the rate of photosynthesis which removes more carbon dioxide from the atmosphere. If this carbon dioxide is stored in woody tissue then carbon dioxide levels in the atmosphere will rise less and warming will be reduced.
Positive feedback mechanisms - soil decomposition
In cooler areas organic matter can build up over time. If the temperature rises, the rate of decay may increase and aerobic decomposition by microorganisms will release more carbon dioxide for periods of time until the organic matter level has dropped to a new equilibrium level.
Positive feedback mechanisms - ice and snow melting
Ice and snow have a high albedo so most of the incoming sunlight is reflected and not absorbed. If warming reduces the area of snow or ice then more sunlight may be absorbed, causing further warming.
Positive feedback mechanisms - ocean acidification
Carbon dioxide in the atmosphere dissolves in the ocean, producing carbonic acid and making the oceans more acidic. Ocean acidification reduces coral survival and reduces carbon sequestration as less carbon dioxide is stored as calcium carbonate in the coral.
Human actions that cause climate change may cause changes in natural processes that themselves cause climate change to the extent that the original human actions are not longer needed for climate change to continue increasing. Human activity would not stop climate change at this point. Climate change needs to be controlled before tipping points are reached.
Examples of natural processes that may become unstoppable if temperatures rise too much
- Faster soil decomposition.
- Release of CO2 by increased forest and peat fires.
- Snow on land melting, caused by increasing temperatures reduces the Earth's albedo so more sunlight is absorbed, raising temperatures further and causing more snow to melt.
Control of carbon dioxide emissions
- reduction in fossil fuel use
- use of energy resources with low carbon emissions
- carbon sequestration, e.g. planting more trees, in geological structures.
Control of methane emissions
- reduction in landfill waste, e.g. recycling, less packaging, less food waste
- reduced livestock production.
Control of nitrogen oxide emissions
- more use of public transport
- catalytic converters in exhausts so CO and hydrocarbons are converted to CO2 and H2O
- addition of urea to power station effluents to reduce NOx concentration.
Control of chlorofluorocarbons emissions
- alternative materials, e.g. propane in aerosols, alcohols as solvents for cleaning electronic equipment
- alternative processes, e.g. roll on instead of aerosols.
Control of tropospheric ozone emissions
- controls and processes which reduce NOx emissions also reduce the formation of ozone in the troposphere.
Planting more trees would sequester carbon in wood through photosynthesis.
Carbon capture and storage (CCS)
1. Capture of the CO2 or removal of carbon from the fuel.
2. Transport by road tanker, ship, or pipeline.
3. CO2 storage in depleted oil fields, gas fields, or its use in secondary oil recovery.
Geoengineering (untried technologies - could be damaging)
- painting roofs white to increase their albedo and reflect more sunlight
- adding nutrients to the sea to stimulate plankton growth. The shells of the dead animals would take carbon to the seabed
- putting solar shades in orbit to reduce sunlight reaching the Earth.
Reduced by building higher river banks, or coastal defences. If water levels in the river rise above the level of the surrounding land, it would be necessary to pump rainwater from land up into the river or sea.
Coastal erosion control
As sea level rises, coastal erosion rates rise as waves strike the upper shore for longer in each tidal cycle. Sea walls and wave screens can be used as protection.
Important areas need to be protected, even if it is expensive. Some areas cost more to protect than they are actually worth and may be abandoned.
Urban drainage control - permeable urban surfaces
Replacing impermeable concrete and tarmac with permeable surfaces, such as gravel or soil, reduces flooding in urban areas. Slowing runoff also reduces extremes in river flow and helps prevent flooding downstream.
Urban drainage control - river flow management
Tributaries flowing into a river will increase the river water level. Retaining the water in the tributary or slowing the flow of the water from the land may reduce flooding around the main river. Low soil, afforestation, or larger dams regulate rural land runoff, flow, and will prevent flooding.
Urban drainage control - raised buildings
Raising buildings on stilts protects against flooding up to the height of the stilts.
Urban drainage control - floating houses
In low lying areas where flooding is common, constructing houses on tethered floating platforms would protect the from flooding, e.g. Netherlands, India.
Importance of stratospheric ozone
- ozone concentration is as high as 13 parts per million
- 12 to 24 km above Earth's surface.
- prevents most of the high-energy ultraviolet solar radiation from reaching the Earth's surface.
Types of UV light
- UV A; 320-400 nm; not absorbed by O3 or O2
- UV B; 280-320 nm; almost fully absorbed by O3
- UV C; <280 nm; completely absorbed by O3 and O2.
Effects of UV B on living organisms
If UV B reaches Earth's surface;
- skin damage
- reduced photosynthesis
- damage to marine organisms.
- low boiling points (aerosols, fridges, ACs didn't need to be powerful)
- dissolve grease and oils but not damage electricals
- not flammable
- not toxic
The Rowland-Molina hypothesis
1974; American research scientists suggested CFCs could deplete stratospheric ozone.
Persistence of CFCs
Chemically stable so remain in the atmosphere long enough to be carried up to the stratosphere.
Dissociation by UV and the release of chlorine
In the stratosphere, CFCs are exposed to higher levels of UV. They absorb UV which breaks carbon to chlorine bonds and releases chlorine free radicals.
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