The Changing Natural Environment Part 2

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Created by roberto_spacey over 3 years ago


Flashcards on The Changing Natural Environment Part 2, created by roberto_spacey on 04/06/2016.

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Question Answer
List the four external forces that may affect the climate system Natural Causes: Changes in plate tectonics Changes in Earth's orbit Changes in sun's strengths Anthropogenic Causes: Combustion of fossil fuels Land use changes
Draw a rough diagram illustrating the internal interactions in our Climate system 627d7bff-e945-4857-8d77-4d37ed659afd.jpg (image/jpg)
List the internal repsonses that may occur due to external forces Changes in atmosphere Changes in ice Changes in vegetation Changes in ocean Changes in land surface
What is meant by the sun's corona The corona is the sun's "atmosphere" It is much hotter than the sun's surface but due to its low density it radiates much less energy into space
What is meant by a magnetic storm? a magnetic storm is another word for a solar flare These emit large quantities of UV radiation and energised charged particles
List facts about the sun ~150 million km away from Earth 15 million °C at the core 6000K at the surface (photsphere/chromosphere)
List three facts about sunspots Sunspots are cooler regions The average area of a sunspot is five times the size of Earth The 11-year sunspot cycle has a measurable but small impact on solar energy output
Define radiation radiation is energy that travels
What untis do we use to quanitfy energy Joules Joule per second = Watt Watt per square unit of area = Energy flux density
What is meant by a black body in the physical sciences? A "black body" is a term for an idealised object that absorbs and transmits EM radiation over all wavelengths At room temperature such a body looks black Both the sun and the Earth are approximately like black bodies
What is Planck's law? Planck's Law describes the amount of energy emitted at a given wavelength at a given temperature In theory it describes the spectral distribution of emitted EM radiation of a black body at a given temperature
What is meant by radiant exitance? Radiant energy that is emitted, transmitted, received or reflected (radiant flux) by a surface per unit of area
What does the Stefan-Boltzmann Law describe? This law describes the power radiated from a black body in terms of its temperature Specifically, the radiant exitance of a black body is directly proportional to the fourth power to the black body's absolute temperature
What does the Wien's displacement law describe? It states that the black body radiation cruve for different temperatures peaks at a wavelength inversely proportional to the temperature (i.e. the hotter the temperature, the shorter the wavelength)
Explain differences we'd see if there were no atmosphere No air to breathe No lakes or oceans Extreme temperature rnages without atmosphere (like on the moon) No sound without air No protection from meteorites No protection from UV radiation
Describe Earth's second atmosphere formed 4.0-3.3 billion years ago Earth cooled and developed a solid crust convective magma activity contributed to the formation of magnetic field capable of deflecting solar wind and cosmic rays high volcanic activity atmosphere contained (co2, h2o and n2) very high atmospheric temperatures (>100°C) due to volcanic & tectonic activity, frictional heating from meteorites and strong greenhouse gas effect
How did the oceans form? Once temperatures cooled down below 100°C condensation of water vapour and precipitation became possible (3.8-3.9 billion years ago) expanding oceans served as a CO2 sink anaerobic bacteria began to develop near volcanic hydrothermal vents
Describe what is meant by the 'Oxygen Catastrophe' 3.8-3.5 billion years ago prokaryote cyanobacteria appeared as first O2 producing organisms Stromatolites must have lived deep enough (>5m) to be protected from harmful radiation but still within the rnage of sunlight 1.3 billion years ago eukaryotic cells were more efficient at producing oxygen 1 billion years ago the oceans were saturated with oxygen and O2 could subsequently build up in the atmoosphere forming an ozone layer dissolved oxygen was toxic to anerobic organisms
Describe the formation of Earth's "Third Atmosphere" with development of more sophisticated forms of plant life oxygen levels iun the atmosphere continued to increase the present day atmosphere (oxygen-nitrogen) formed approximately 400 million years ago formation of ozone layer and the protection from harmful solar radiation were key to the formation of plant life on land
What are the four layers of the atmosphere From Earth to space: Troposphere Stratosphere Mesophere Thermosphere
Describe the atomspheric vertical profile in relation to pressure the global average atmospheric pressure decreases near-exponentially in vertical direction 99.9% of the atmospheric mass is below 50km 90% is below 10km
What does the atmospheric vertical profile look like in relation to temperature Troposhere: decreasing with height Stratosphere: increasing with height Mesosphere: decreasing with height Thermosphere: increasing with height
Why does temperature decrease with height in the troposphere? An air parcel cools and expands when rising vertically Conversely, an air parcel warms and is compressed when descending
Name the three main gases that make up the airs composition Nitrogen : 78.08% Oxygen: 20.95% Argon: 0.93%
What are three effects aerosols may have on us? Reduction in visibility through a haze effect They can scatter incoming light They can absorb outgoing thermal radiation (like GHGs)
Outline the processes involved in the hydrological cycle Evaporation: solar energy transforms liquid water into water vapour Transpiration: Moisture given up by plants (in form of water vapour) Condensation: Water vapour reverts back to liquid phase (formation of droplets) Precipitation: liquid or solid forms of water falling from clouds
Where is most of the water held? 97% Oceanic system 2.999% in the land system 0.0001% in atmospheric system
Describe the evaporation process Stage 1: -evaporation can occur at any temperature -at the surface, water molecules with sufficient kinetic energy will break away from the surface and evaporate into the air -with time the amount of water vapour in the air increases -condensation also will occur, however the condensaiton rate is slower than the evaporation rate
What is meant by the dynamic equlibrium in the evaporation process Stage 2: - the rate of condensation depends on the amount of water vapour in the air -once the air above the water is saturated, for every molecule that evaporates, one condenses -the amount of water vapour therefore stays the same -wind enhances evaporations as water vapour molecules are carriued away by it thus never reaching saturation
Why is cold are dryer and warm air more humid? At higher tempreatures the water molecules will have more kinetic energy and therfroe the rate of evaporation will be higher The dynamic equilibrium will therefore be reached at higher concentrations of water vapour
Deifne relative humidity Relative humidity is the ratio of the amount of water vaoupr in the air to the maximum amount of water vapour required for saturation at that particular point
What is meant by the dew point temperature The Dew point temperature represents the temperature to which air would have to be cooled foor saturation to occur Warm dew points indicated high relative humidity and cold low
Explain trends of relative humidity variation Diurnal: -water vapour amounts can remain unchanged with changing RH -RH changes mainly due to diurnal temperature variations which affect the water vapour capacity Meridional: -high RH values at tropics and cold 60° and above -low RH values at the tropics of cancer and capricorn
Define cloud A cloud is a visible aggregate of tiny water droplets or ice crystals supsended in the air
What are the different types of clouds? High clouds: Cirrus (Ci), Cirrostratus (Cs), Cirrocumulus (Cc) Middle clouds: Altostratus (As), Altocumulus (Ac) Low clouds: Stratus (St), Stratocumulus (Sc), Nimbostratus (Ns) Clouds with vertical development: Cumulus (Cu), Cumulonimbus (Cb)
How does latitude variation in solar irradiance affect the flow of air (winds)? -winds are involved with the transfer of heat, as there is a surplus of heat at the equator which has to be distributed around the globe -these vary in intensity with the Earth's tilt and its seasons
How does the pressure gradient force (PGF) affect the flow of air (winds)? the pressure gradient force is directed from higher toward lower pressure at right angles to the isobars closely spaces isobars on a map indicate steep pressure gradients and a alrge PGF
How does the coriolis force affect the flow of air (winds)? the coriolis force describes an apparent force due to the rotation of the Earth in the northern hemisphere wind deflects to the rihgt of its intended path and to the left on the southern hemisphere the higher the wind speed the stronger the deflection the force increases with latitude with zero at the equator
What is meant by geostrophic wind? Geostrophic wind is where PGF and CF are in balance As a consequence the wind will flow parallel to the isobars and will not further accelerate
What is meant by the centripetal force? The combination of PGF and CF results in a Centripetal force component which forces the wind in a circular motion Consequently wind motion is anticlockwise around a low-pressure system (cyclone) and clockwise around a high-pressure system (anticyclone) in the Northern hemisphere --> the opposite for the Southern hemisphere
How does firction in the planetary boundary layer affet the flow of air (winds)? the planetary boundary layer refers to a layer of the troposphere in which winds are affected by friction with the ground This friction reduces the wind speed which in turn reduces the CF leading to winds being able to blow across isobars At stable stratification and smooth terrain the layer is quite thin whereas when the air is unstable and the terrain rough the effect extends far further upwards due to vertical mixing
What is the intertropical convergence zone? The zone at which the trade winds meet The problem with this is that heat is desperately trying to be redistributed therefore most of the heat at the equators is distributed via ocean surface currents
What are the westerlies? The westerlies are the winds which go towards the poles at 30° north and south
What is meant by thermal cicrulations? Local circulations brought on by changes in air temperature
What factors result in the heat island effect? The interaction of the follwoing factors: -release and reflection of heat from buildings -absoprtion of heat by concret, brick and tarmac by day and the release of it at night -enhanced cloud formation as pollution traps heat -relative absence of water means that less energy is used for avapotranspiration and more for heating of the lower atmosphere -absence of strong winds to disperse heat and bring in cool rural air
How does the mountain and valley breeze form? -During the day sloped valley walls will receive more insolation and so the air above the valley warms -this air rises and cuases a gentle valley breeze -at night the cooler denser air descends the slope which is known as the mountain breeze
What is a possible impact of a subsidence inversion? Increased pollution: -during a strong anti-cyclone (high pressure) warm air is compressed and warmed, pushing toward the land -below, the colder denser air collects and creates a thick layer which traps the pollution
What is the adiabatic process? Wehn an air parcel cools and warms or expands and compreesses without exchange of matter and energy of the surrounding air
What is the environmental lapse rate (ELR)? The rate at which the temperature of an air parcel decreases with altitude the rate depends on the temperature of the surface air and whether the atmosphere is stable or not because unstable atmospheres allow vertical development It is crucial is determining the extent of vertical motion in the atmosphere
What is the dry adiabatic lapse rate (DALR)? 10°C for 1km of change in elevation This only counts for unsaturated air (RH below 100%)
What is the moist adiabatic lapse rate (MALR)? 6°C for 1km This only counts for saturated air As moist air rises temperature cools more slowly for the water vapour condenses giving off latent heat countering the temperature loss caused by the expanding air parcel
What are the two processes respoinsible for carbon uptake on land? Photosynthesis Weathering
What are the two broad processes carried out by the oceans in the carbon balance? Biological pump (through phytoplankton into food chain) Physical pump (deep water formation and ventilation/upwelling) (the warmer the oceans the less able they are to dissolve CO2)
What is a consequence of increased CO2 uptake in oceans? Uptake of increased CO2 reduces surface ocean pH value --> increasing the ocean's acidity this affects: -coral reefs (decling calcification/weaker) -cold water corals -ecosystems where aragonite is essential (aragonite) -temperature increase (coral bleaching)
What is meant by Insolation? Incoming Solar Radiation mostly at an oblique angle and not vertical average insolation equals to a quarter of the solar constant 342 W m^-2
What is the solar constant? the rate at which energy from the Sun reaches the Earth 1370 W m^-2
What are the four different atmospheric solar radiation pathways? Absorption 19%: radiative energy turned into other forms by gases or particles in the atmosphere Reflection 30%: radiative energy is reflected back into space when hitting a surface Scattering: Radiative energy is (at least partly) redirected by air molecules and particles Transmission: radiative energy passes through the atmosphere
What is the distinguishing factor between geometric scattering, Mie scatering and Rayleigh scattering? The size of the object on which he sunlight falls on
Which type of particle induces which type of scattering? Air particles --> Rayleigh scattering --> blue sky, red sunsets Aerosols (pollutants) --> Mie scattering --> Brownish smog Cloud droplets --> geometric scattering -> white clouds Darker clouds have larger water droplets which absorb some of the incoming light
Explain the effects by Rayleigh scattering Air molecules (N2) scatter shorter (blue) wavelengths more efficiently than longer ones (red) The longer the path length of light through the air, the more blue light is scatter, which results in remaining red light turning the sky red Equally the sky appears blue because of this too
What is Albedo? the ratio of reflected radiation to incoming radiation The albedo of Earth and its atmosphere is roughly 30%
What are the three types of thermal energy transfer? Conduction: through contact Convection: gases & fluids Radiation: also works in a vacuum
What are greenhouses gases? Greenhouse gases are atmospheric gases which absorb thermal radiation emitted by the Earth's surface this blanketing effect leads to increased temperatures H2O is responsible for most of the greenhouse warming, but its atmospheric proportion is not changing directly as a consequence of humans
Which are the important GHGs which are influenced by humans? Carbon dioxide, methane, nitrous oxide, chloro-fluorocarbons and ozone Carbon dioxide is the most important because after water it has the largest greenhouse effect
Outline the global pressure distribution The average surface wind and pressure distribution is largely determined by semi-permanent highs and lows E.g. the pressure difference between the icelandic low and the bermuda high determines the severity of European winters (the bermuda high drives the golf stream) interseasonal variability in the inter-tropical convergence zone which affects monsoon seasons
What are monsoons? Monsoons seasons are experienced by those countries that lie where the inter-tropical convergence zone (ITCZ) shifts India, for example, receives warm moist air from the indian ocean in july and colder dry wind from the north during winter
What factors determine climate? Latitude: determines how much solar radiation a location receives Land and water: determines continentality Ocean currents: can provide additional heat prevailing winds: moisture and thus precipitation Pressure cells: cloud coverage mountain barriers: rain shadow altitude
Outline the NAO (North Atlantic Oscillation) determined by the pressure difference between the bermuda high and the icelandic low Positive phase: strong pressure difference resulting in warm wet winters for Europe and mild and wet winters in the US Negative phase: weak pressure difference resulting in more cold air invasions phase changes take decades
What factors influence the natural variability in the Earth's global average surface temperatures? Changes in insolation Continental drift Changes in Earth's albedo Changes in outgoing terrestrial radiation (GHG effect)
Outline the Milankovitch cycles Changes in the Earth orbit's eccentricity vary with a period of about 100,000 years Variations in the obliquity (angle of tilt) of the Earth's axis have a period of about 41,000 years Changes in precession (direction of tilt) and point of perihelion (proximity to the sun) change with a period of about 23,000 years
What are the four natural influences on the energy imbalance? Plate tectonics: millions of years; regional scale Volcanic Activity: years, but longer for 'mega-eruptions'; regional/global Changes in solar irradiance: 11 years, but also much longer; global Long-term outgassing from oceans volcanoes: millenia; global
What are the four anthropogenic influences on the energy imbalance? Land-use change: instantaneous; regional/continental Aerosol emissions: instantaneous/constant; regional Ozone depletion: decades; mostly at poles but small effect globally Fossil fuel emissions: decades/centuries; global
What is radiative forcing? -one of the most commonly used climate metrics "Radiative forcing is a measure of how the energy balance of the Earth-atmosphere system is influenced when factors that affect climate are altered" it allows for the comparison of different climate mechanisms
What are two ways to describe the absolute quantity of a gas? Density - microgram per cubic metre Concentration - molecules per cubic centimetre (cm-3)
Name 2 sources and sink of methane Natural: -Wetlands -Termites Anthropogenic: -mining (petroleum) -enteric fermentation (rumenants) Sinks: -Atmoshpheric removal -removal by soils
Where can the ozone layer be found? at an altitude of 20km to 30km it contains about 90% of atmospheric ozone, which is produced via photolysis of molecular oxygen
What is tropospheric ozone? it's an air pollutant produced from oxidisation of hydrocarbons in presence of nitrogen oxide (photolysis of nitrogen dioxide)
Outline how tropospheric ozone forms ozone is formed in the presence of sunlight (never at night) Carbon monoxide (CO) or volatile organic compounds, water vapour, nitrogen oxides (NOx) and sunlight is needed pollutants must be available in the right concentration, especially NOx urban environment usually contains pollutants in the right concentration ozone production requires a reaction chain
Outline how stratospheric ozone forms ozone forms at 20km to 50km of altitude through the photodissociation of oxygen molecules it requires shortwave solar radiation (<240nm); shortwave UV-radiation (<280nm) is completely filtered out during the process
What are two instruments used to measure ozone? Total Ozone Mapping Spectrometer (TOMS) Ozone Monitoring Instrument (OMI) total ozone in the atmosphere is measured in Dobson units (DU)
What are the conditions for efficient ozone depletion at the poles? Low temperatures (formation of PSCs (polar stratospheric clouds)) Isolated conditions (for chemical processes) PSCs (reaction on surface of cloud crystals increases destruction efficiency by 100x)
When and where is ozone depletion strongest? Ozone Depletion is storngest in polar regions during the onset of spring when sunlight reaches the polar regions again (halogen gases are made reactive) Ozone depletion occurs globally but most efficient in polar regions as meteorological conditions there enhance the depletion process
What are some of the environmental impacts of ozone depletion? decrease in stratospheric ozone layer has small cooling effect (minimal compared to proportion lost due to GHGs inefficiency) Significant increase in UV radiation leading to increase skin cancer and plant damage especially in Southern Hemisphere
What are the indirect effects from aerosols? impact on cloud droplet size which affects both the cloud's albedo and the amount of precipitation other effects include impacts on heterogeneous chemistry, cloud condensation processes, etc.
What are atmospheric brown clouds (ABCs)? Indoor and outdoor pollution consisting of paerticles and gases (Nox, CO, SO2, NH3 and many other VOCs and acids)
Where are the regional hotspots for ABCs? East Asia Indo-Gangetic Plain in South Asia Southeast Asia Southern Africa the Amazon Basin Also in the Hindu Kush-Himalayan-Tibetan glacier region can also occur in East USA and Europe but dissipate quickly due to washout processes such as precipitation
What are the impacts of ABCs? -dimming of solar irradiance at the surface (sulphate aerosols) -increase in atmoshperic solar heating (black carbon, soot) -Dimming effect about 6% in China and India -black carbon is responsible for a 15% increase in average annual mean of solar absoprtion in troposphere -change in rainfall patterns -increased receding and thinning of glaciers -rainfall in northern half opf india has decreased, shift in patterns in china albedo changes and temperature increase affects glaciers and snowpacks in the Hindu Kush - Himalayan - Tibetan region
What are the consequences of ABCs? -changes in monsoon rainfall and glacier extent will affect water levels required for irrigation of crops -ground level ozone increases will affect crop yields -1985-1998 rice production decreased by 6.2 million tonnes in 9 South and East Asian countries -health effects from indoor and outdoor pollution (affecting pulmonary and cardiovascular systems leading to chronic respiratory problems)
Distinguish between Climate Change and Global Warming GW refers to an increase in globally and annually averaged air temperature near the surface (also observed in oceans and soils) GW is a good proxy for CC but it does not describe the complexity of the individual changes nor the regional differences CC refers to a significant and persistent change to the mean state of the climate or its variability.
What is the hydrological cycle? the continuous movement of all phases of water driven by solar radiation and gravity generates landscapes connects biosphere, lithosphere and oceans
Name the stores and fluxes of the hydrological cycle Stores: -atmosphere -canopy -surface water and snow -soil -ground Fluxes: Precipitation Evapotranspiration Runoff Throughflow
How does the atmosphere act as storage in the hydrological cycle? total of 11mm of rainfall across the globe highly spatio-temporally variable involved in the latitudinal and meridional transfer of energy (as latent heat) reflects solar radiation back into space
Outline the relationship between cloud cover and forests there is a strong relationship between cloud cover and forest cover clouds are important because they reduce the solar loads and bring rainfall.
Outline the canopy water interception process and its properties as a storage -captures rainfall -redistributes in space -> concentration -redistributes in time -> reduced intensity -interception loss= 10-20% rainfall -remaining 880-90% is efficient rainfall -leads to efficient ET and thus rainfall recycling (20% in Amazon)
Outline facts about dams vary in size and geographical distribution much more common in the developed world capacity growing rapidly in the less developed world
Outline the properties of snow and ice as a water storage 68% of global freshwater in snow and ice huge seasonal changes important input during the dry season (India form Himalaya) susceptible to long term change (CC and GW)
What are the important characteristics of precipitation? Seasonality -> within the year Variability - in inter-annual totals Reliability -> consistency in timing and duration Amount -> total volume (depth) of rainfall Duration -> how long it lasts frequency Intensity -> amount per unit time
Outline properties of evapotranspiration upward flux from land to atmosphere potential ET controlled by solar radiation, temperature, humidity and wind speed Actual ET controlled by availability of water varies with climate and land surface properties -used by plants and animals for colling -
Outline properties of Runoff -the lateral flux of water balance (precipitation minus actual ET) -depends on rate of rainfall vs. rate of infiltration -overland flow on land -streamflow/runoff in rivers -responsible for global river network -connects landscapers upstream and downstream
Outline properties of throughflow -slow through matrix -fast through macropores -important for redistribution in time and space -ensures rivers are perennial
Describe the problems faced in the 'world water crisis' humans have less than 0.08% of water available use is estimated to increase by 40% in the next decade one in five people lacks access to safe drinking water
Name the World's water supplies Groundwater Rivers Lakes (aquaculture) Wetlands (filtration) Dammed reservoirs (downstream problems, earthquakes, local climate)
Distinguish between physical and economic water scarcity Physical - climatically not enough water Economic - water quality and/or water infrastructure is poor
Outline the water problem in NW India intensive agriculture (wheat belt) semi-arid climate heavenly dependent on (fossil) groundwater water tables falling population and agriculture further increasing
Outline the water problem in Peru large mines are important tot he economy (Yanacocha - gold) release effluent into rivers containing cyanide used in processing many people downstream are unhappy (civil unrest)
Outline some of the anthropogenic impacts on water human water footprint is dominated by the human agricultural footprint on a global scale National scale - influence of roads and protected areas become more obvious Local scale - supply to urban areas is influenced by water diversions, aqueducts, etc.
Why is there a change in demand for water? -getting through the demographic transition - increasingly urbanised populations increasing per capita withdrawals
How does climatre variability and CC affect water warmer world = more ET more ET= more cloud cover= more rainfall spatial distribution will change temporal distribution will change some stores (snow and ice) will be lost change to intensity
Outline facts about the 1950 population boom occurred mostly in developing countries since 1920s projected to last until the 2050s we are committed to a population of 9.5 billion
Distinguish the classic and the anthrome paradigm Classic paradigm: biosphere shaped primarily by biophysical systems Anthrome: Most of the biosphere reshaped by human systems
What are some of the factors causing malnourishment on a global scale? 1 billion people remain chronically malnourished stemming from continued poverty and increasing food prices food production is industrialised and energy-dependent
What factors could impact food prices? market speculation bioenergy expansion climatic disturbance
What are some of the factors affecting recent growth in crop production increase in yield multiple cropping techniques fewer crop failures less fallow improvement in: irrigation, fertilisers, new varieties and pesticides Land expansion and intensification have contributed less as we have moved to less productive land GROWTH HAS BEEN PRODUCTIVE BUT ENV UNSUSTAINABLE
List the environmental impacts of growth in food production Impacts of land expansion: loss of grasslands, savanna, temperate forest and tropical rainforest 80% of new croplands are replacing tropical rainforests But it has done little to improve food security Impacts of intensification: irrigated cropland has doubled in past 50 years 80-90% of global consumptive water use is irrigation global fertiliser use increased by 500% increased energy use widespread pollution of water and disruption of nutrient cycles impacts on aquatic and marine fisheries
List a usually overseen impact of crop intensification Land degradation: declines in land productivity associated soil erosion and nutrient exhaustion production becomes unsustainable
How does urbanisation affect the sustainability of food production Urbanisation is increasing particularly in developing world majority of population not self-sufficient for food/water and thus dependent on infrastructure and technololgy greater supply chain complexity ->(consumer ignorance) farm prices/profits driven down more transportation of food virtual water imports/exports
Outline facts on food waste -there are significant losses at all stages -greatest for fresh food + veg -30-50% of food produced is never consumed -higher post-harvest losses for developing countries (pests, storage) -highest losses at retailer/consumer level for developed countries
What are the dangers in exploiting water for food? limited amount of rainfall available globally at a time Natural cleansing and renewing functions become disrupted 'Renewal' of water takes time through the hydrological cycle rate of consumption exceeds rate of renewal
Distinguish between withdrawal, consumption and degradation Withdrawal - total amount of water taken from a source Consumption- fraction of water withdrawn made unavailable for other purposes Degradation- change in water quality due to contamination making it unsuitable for desired use
What are the 8 drivers for chronic food insecurity? 1. increasing population 2. changing and converging consumption patterns 3. increasing per capita income linked to resource consumption 4. growing demand for livestock products 5. growing demand for biofuels 6. increasing water and land scarcity 7. Adverse impacts of CC 8. Slowing of increases in agricultural productivity
What is meant by the 'land grab' pertinaing to food security? Industrial countries buying up large leases of land in developing countries Used for crop/biofuels/meat production serious ethical concerns
What are some of the solutions to food security? -increase area of croplands -increase yields -eco-efficient agriculture -price regulation of commodities -removal of perverse subsidies -reduce use of cereals and fish in animal feed
What are some of the solutions to water security? =increase price of water -increase supply of water (waste-water as resource, better management, desalination) -increase efficiency of water use -reform water governance
List the ways in which water governance can be reformed Evidence based policy Institutional Reform Water rights and sharing Better valuation and pricing of water Improved management systems
List the five steps to double food production and reduce environmental change by 2050 1. more maize - because yield can be readily improved 2. less meat - because meat calories are inefficient and environmentally expensive 3. close the diet gap - crops for food only and less waste 4. Stop burning rainforests - it is not contributing much 5. Use fertiliser more effectively because it is highly damaging
What are the downsides of biofuels? e.g. maize, palm oil, sugar cane, soy bean NOT carbon neutral rapid growth often on agriculturally fertile land sometimes very high water consumption sometimes leading to deforestation
What are the solutions to the problems facing hydropower? many small scale instead of many large scale storages rainwater harvesting instead of irrigation from groundwater fish ladder maintain flow/connectivity international cooperation across borders
What are the solutions to the problems facing biofuels? NEVER on new cropland NEVER with food crops (eg. maize) consider full carbon costs regulation of markets to reverse perverse subsidies
Outline the different types of drought Meteorological drought - reduced rainfall for the norm at the same time and place Hydrological drought - occur after meteorological droughts, effcts seen on water table Agricultural drought - not enough water available for a particular crop at a particular time, not only rainfall but water use Socio-economic drought - when the demand for an economic good exceeds the supply as a result of a weather-related shortfall in water supply
What are the natural causes of droughts? Changes in circulation patterns due to normal seasonality, interannual/decadal variability, sunspots sea-surface temp change, periodic events (eg ENSO, more heat less rain) Significant change in land surface (albedo, ET and cloud generation) CC brings less rain and/or temepratures either seasonally or annually
What are the human causes of drought? Overpopulation (too much demand) Overcultivation (unsustainable) Overextraction Inefficient use (pollution/wastage) Degradation of soil and ladnscape reducing the capacity for the ecosystem to provide water for urban systems or agriculture
What are the consequences of drought? Ecological/Environmental - impacts on terrestrial and aquatic habitats Agricultural - crop declines/failures Water supply - reduced storage for dry seaosns Humanitarian - loss of livelihood, migration, malnutrition Off-site (fire, dust, etc.)
Outline the 2006 drought in Ethiopia -Sahel region drought conditions since 1985 -drought of 1984/85 1 million deaths -Causes = low precipitation, desertification, overpopulation, over-cultivation -GDP 110$ and life expectancy of 43yrs -2006 event affected 2.7 million people -UNICEF donated $50million to water aid projects -consequences = famine, chronic poverty, migration, disease, 46% of cattle died, debt
Outline the 2006 drought in Australia -extremely low rainfall season in South - River Murray dried up in places (most important basin with agriculture and vast irrigation) -triggered by 'El Nino' -Human causes= poor use of water resources -consequences= 6 million sheep died in 2 years, temporary migration, improvements to water resource use -floods in 2010/11
What is FEWS? Famine Early Warning System It works using: -Early Warning Variables -Vulnerability Analysis -Networking -Capacity Building -Response Planning
What measures can be taken to adapt agriculture to drought? Water efficiency Choice of crops Drought-tolerant varieties Rainwater harvesting, water transfer and local storage
How can be water use be adapted? Reducing use - low flush, low flow, reuse grey water, rainwater harvesting Desalinisation - (costly in terms of energy, water only useful for some purposes) Indsutrial and agricultural wastewater filtration/recycling for grey water uses
Define desert and desertification Desert - vegetation cover is spare or absent, land surface is exposed to atmosphere, rainfall is small and infrequent/irregular in occurrence Desertification - conversion from non-desert top desert, where desert is characterised by low or null biological production
What are the consequences of desertification? diminution or destruction of a land's biological potential effectively irreversible changes in the nature of the landscape (irreversible due to restoration costs) Harsh agricultural, health, socio-economic and aesthetic consequences
List the physical and human drivers of desertification human reaction to a drought (more crops and let livestock live) -> overcultivation/overgrazing frequent climatic variability and change in semi-arid areas response of vegetation to climate
Name the exclusively human causes of desertification Deforestattion for fuel/firewood Agirculture: -destruction of soil crumb structure -humus removal (dung for fuel) -soil erosion -difficulty in vegetation re-establishment -over-grazing Over-exploitation of water resources Pollution
What are problems of global desertification assessments? 1. lack of data 2. simplicity of causal factors 3. complexity of feedbacks unaccounted for 4. vested interest - hype and alarmist 5. not particularly useful in mitigation 6. no account for cultural and economic context 7. very little info of causes and change over time
What are the processes involved in desrtification? 1. aridification (positive feedback) 2. soil erosion ad degradation (+) 3. Changes in infiltration and runoff 4. Salinisation of soil and groundwater 5. loss of soil fertility 6. declining productivity and veg. cover
Name some of the hydrospheric components of the Mediterranean high water deficit low water storage capacity low surface water infiltration rates high deep percolation rates salt affect soils and groundwaters
What are the four main categories of Ecosystem Services (ES)? Supporting (nutrient cycling, primary roduction, etc.) Provisioning (food, water, wood. etc.) Regulating (climate, flood, disease, etc.) Cultural (aesthetic, spiritual, educational, etc.)
What is the value of ES? 17 ES values for 16 biomes US$16-54 trillion dollars a year
What are the three key hydrological ES? Water quantity (although more can be provided by agriculture through ET) Water regulation - protected ecosystems do not protect against the most destructive floods -encourage more seasonally regular flow regimes during normal periods Water quality -protected ecosystems encourage infiltration leading to lower erosion and sedimentation -unprotected tends to have more peesticides, etc.
What are the local impacts of Land Use and Cover Change (LUCC)? regional climate change hydrology, water resources soil erosion and sedimentation, landsliding biodiversity loss
What is the water balance equation for a given catchment? P= ET+Q+D+#S precipitation= ET+streamflow+groundwater recharge+change in soil water storage
How can ET and Q be obtained? ET= I+T+E ET=interception loss+transpiration+soil evaporation Q=OF+BF Streamflow= Overland flow + Baseflow
What factors do infiltration and runoff depend on? Essentially on the rate of rainfall relative to the rate of hydraulic conductivity
How is the runoff ratio determined? Discharge or runoff (Q) per unit rainfall (P) runoff ratio=Q/P observed short-term changes are the filling and draining of stores long-term changes reflect losses (canopy interception, deep percolation)
What are the 5 types of floods and their causes? Coastal flooding - high river flows combined with high tides, low pressure systems, sea surges River flooding - water tops its banks as a result of prolonged and extensive rain, snow melt, blockage with debris Flash flooding - very rapid flooding as a result of high intensity rainfall, failure of dam or flood defence or insufficient drainage Groundwater flooding - water table rises as a result of prolonged rainfall or change in abstraction Sewer flooding - when sewers fail or cannot cope with rainfall
Which factors increase flood risk? -urbanisation -deteriorating urban wastewater systems/blocked drains -agriculture-/practices -CC (wetter winters, increased high rainfall events) -loss of wetlands and floodplains -sea level rise
Which factors increase flood exposure and/or flood vulnerability? Exposure: -more infrastructure, housing, people -increased building in high risk areas -greater population densities especially at the coast Vulnerability: -poverty - urbanisation & higher dependence on infrastructure
What are the consequences of flooding? 1. Fertilisation of soils 2. Destruction of infrastructure 3. Loss of life 4. Disruption of economic activity 5. Depends on exposure
What are some mitigation techniques for flooding? -Embankments, sluices, pumps, barriers (green vs. grey) -SUDS (sustainable urban drainage) -Natural defences (ES, green infrastructure) cheaper than engineered ones (grey infrastructure)
What are some methods to aid flood adaptation? Forecasting Planned Regulations Preparedness Emergency Response Cleanup Insurance
Outline three problems the ocean faces Acidification: increased uptake of CO2 forms weak carbonic acid which is corrosive to crustaceans and coral reefs Fisheries: nearly 70% full overfished; trawling harms the sea bed Plastics: five large gyres around the world, micro and macro plastics affecting toxicity, affecting whole food chain
What are the four major pieces of evidence on which CC science and policy is based upon? 1. Emissions of CO2 and other GHGs are increasing 2. Atmospheric concentration of CO2 and GHGs are increasing 3. Global temperature is increasing 4. Atmospheric theory and General Circulation Models (GCMs) indicate if CO2 continues to increase so will average global temperatures. This will affect other climatic variables in complex ways
What are the components which are theorised to have slowed atmospheric warming? 1. oceans taking up heat 2. volcanic activity (offset) 3. tropospheric aerosols from the same pollution
What factors does the IPCC consider to generate scenarios relevant to CC modelling? 1. Understand changes in the economy 2. Understand impacts of GHG concentrations 3. Model climate 4. Look into impacts
What are the four major trends that act as proof for the 'Great Acceleration'? 1. Loss of biodiversity 2. Land degradation 3. Atmospheric change 4. Hydrological change
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