UNIT 4 - AOS 1 Flashcards
Climate change
Changes in patterns of weather, and related changes in oceans, land surfaces and ice-sheets, occurring over decades.
Earths energy budget
The tracking of the balance between incoming and outgoing solar radiation from the sun and earth. Important for maintaining earths temp needed to support life.
Points about the sun
- Primary source of energy
- Earth is in ‘goldilocks zone’
- Hydrogen gas (72%), Helium gas (28%)
- Solar energy created -> nuclear fusion
Nuclear fusion
Combing 2 hydrogen ions together to create solar energy.
- When the gases move = powerful magnetic field is created
Solar cycle & 2 types
The suns magnetic field activity level cycle (11 yrs)
SOLAR MIN: Decreased solar activity (decreased sunspots)
SOLAR MAX: Increased solar activity (increased sunspots)
Sunspots
Flares of energy on the sun
Natural cause of climate change (+ notes)
VOLCANIC ERUPTION:
Releases greenhouse gases (mostly CO2) into atmosphere
- Also releases, sulfur dioxide, hydrogen sulfide and hydrogen halides (toxic at diff concentrations)
Avg amount of CO2 released from volcanoes per yr and there importance.
180-440 mill tonnes per yr
- Important for life’s processes and maintaining natural greenhouse effect.
Types of un-natural causes of climate change
FOSSIL FUEL COMBUSTION ->for energy (transport, heating etc.)
AGRICULTURE -> (crop production, cattle = methane prod.)
Atmosphere definition
Gaseous envelope of air that is held close to the earths surface by gravity
Layers of the atmosphere
- TROPOSPHERE (15kms)
- Nitrogen, oxygen, argon & CO2
- Air is most dense (from gravity)
- Visible clouds & weather - STRATOSPHERE (35kms)
- Ozone layer
- Air is 1000x thinner than sea level - MESOSPHERE (30kms)
- Meteors & not alot is known - THERMOSPHERE (470kms)
- Includes ionosphere (layer of ionised air)
- Satellites, space shuttles & auroras are found
Trends between the layers of the atmosphere
As you move further away from earth’s surface:
- Temperature increases
- Air pressure decreases
- Air density decreases
How is solar energy transferred from sun to earth?
- SOLAR ENERGY is emitted from the sun until it reaches the troposphere
- Solar energy becomes VISIBLE LIGHT & INFRA-RED SOLAR RADIATION. (66% of solar radiation is reemitted from earths surface back to atmosphere)
Types of solar radiation + %
38% = VISIBLE LIGHT
53% = INFRARED LIGHT (longer wavelengths & lower frequency)
9% = ULTRAVIOLET LIGHT (shorter wavelength & higher frequency) -> what burns you
**Different greenhouse gases in atmosphere will absorb different wavelengths of light
How solar energy interacts with layer of atmosphere and earth
- Ozone in stratosphere absorb most ULTRAVIOLET LIGHT (burns you)
- INFRARED SOLAR RADITATION is absorbed in troposphere & earths surface (heat)
- VISIBLE LIGHT travels to earths surface to be reflected, absorbed and reradiated in form of INFRARED RADIATION
Albedo effect
- LIGHT SURFACES = reflect more radiation = higher albedo
- DARKER SURFACES = Absorb more radiation
- Range = 0(no reflection) to 1(100% reflection)
- Diff enviros = diff albedo values
Natural greenhouse effect
- Some of re-emitted infrared radiation is trapped by gases in atmosphere = maintains global temp & life on earth
- WATER VAPOUR is most responsible for natural GHE
Enhanced greenhouse effect
- 1760-1840 = Industrial revolution
- Development of machinery = increased burning fossil fuels
-> ^ GHG in atmosphere (CO2, Methane, nitrous oxide)
Causes of enhanced GHE
- ^ combustion of FF
- Decreased vegetation cover due to expansion of agriculture
- Manufacturing of artificial gases -> Chlorofluorocarbons (CFCs) & Hydrochlorofluorocarbons (HCFCs)
Purpose of ocean circulation
(Oceans store & distribute heat energy (majority earths stored heat))
- Ocean currents move circular patterns to distribute the heat energy across the globe & stabilise global climate patterns
- Responsible for local weather patterns, cycling of gases & distribution of nutrients
Types of ocean currents
SURFACE:
- Formed by -> wind patterns & rotation of earth
- Move vertically & horizontally
- CORIOLIS EFFECT = Currents formed by winds are deflected by earths rotation & increases circular movement
DEEP WATER:
- Create thermohaline circulation
- Driven by different ocean water densities - this is effected by temp (thermos) & saline (haline) -> e.g. cold, salty water = more dense)
- Moves dissolved CO2
- Currents regulate global climate by counteracting uneven distribution of solar radiation
Carbon cycle
CO2 is continuously cycled through organisms into the atmosphere
Carbon sink
Something that stores carbon, such as forests and oceans
TREES: Use photosynthesis to take in carbon dioxide
OCEAN: absorbs carbon
ARTIFICAL CARBON SINKS: Limited & inefficient (not developed enough) & prone to leaks
Role of carbon sinks in the carbon cycle
removes carbon from the carbon cycle for long-terms storage
Carbon sequestration
Storage of CO2 in vegetation such as grasslands or forests, as well as in soils and oceans (carbon sinks)
Notes about sequestration in forests
forests = most widely cited carbon sink
- Tropical & old growth forests = ^ carbon storage potential
- Some can store carbon for centuries
- Bushfires/deforestation = releases the stored carbon
-> not all carbon is released when forests are destroyed
When a forest is destroyed what happens to the carbon that isnt released
- Remains: As plants consumed by animals or added to soil as litter
- Soil: carbon is stored as soil organic matter (stay there for millenia)
Notes about sequestration in oceans
= major carbon sink
- If water chemistry is altered it decreases ability to sequest carbon
- absorbs and stores 40% of earths carbon emissions
- CO2 dissolves -> carbonic acid
ocean acidification
When CO2 dissolves into seawater it becomes carbonic acid
– Bleach coral and dissolve animal shells
How temperature effects sequestration of oceans
COOL = better carbon sinks
WARM = Less carbon dioxide absorbed
Shells in terms of carbon and there threats
- Carbon is shells of organisms = calcium carbonate
- As these organisms die, fall to ocean floor -> over long time period they are compacted into limestone = carbon stored for thousands of years
THREATS:
- Increases acidic ocean & decreases dissolved limestone (the calcium dissolves instead of sinking = ^ carbon dioxide released & less is stored.
Global Warming Potential
“The ability for gases to trap extra heat in the atmosphere over time & develops comparison of the global warming impact of different gases”
- Provides common unit of measurement for greenhouse gases
(calculated over 100yrs -> relative value compared to CO2)
Measurement of GWP
“Measure of how much energy can be absorbed, by the emission of 1 tonne of gas over its lifetime, relative to CO2”
Absorption of solar radiation & wavelengths effect
Gases absorb solar radiation at different frequencies = some gases absorb more heat than others
METHANE:
Absorbs lower wavelengths (closer together) = closer to infrared R = heat
CARBON:
Absorbs higher wavelength radiation = UV = less heat
(the larger the GWP, the more gas can warm earth of a 100yr period compared to CO2)
Methane
CH4
GWP = 28-26 over 100yrs (26-28x the impact of CO2)
METHANE EMITTED TODAY:
- lasts a decade (less than CO2) but has higher absorption of energy than CO2
Nitrous Oxide
N2O
GWP = 265-289x the impact of CO2 over 100 years
Stays in atmosphere for 120-150 years
How Carbon dioxide concentrations have altered
NATURAL CHANGES:
Millions of yrs ago, oceans formed = ^ carbon sequestration
CHANGES IN PHOTOSYNTHETIC RATE:
Daily - ^ during day, decrease at night
Seasonal - ^ summer & spring, decrease autumn & winter
COMBUSTION OF FOSSIL FUELS:
- Since industrial revolution, CO2 concentrations ^ 43%
- CO2 ^ by 0.5% per yr
- Evidence of CO2 ^ in Keeling curve
CEMENT PRODUCTION:
- Concrete prod. = 9% all CO2 prod.
- In cement a component is converted from limestone to lime = released CO2 as a product
- During WW2 limited material = ^ cement prod.
AGRICULTURE:
- Trees cut down for land use = CO2 in tissues (sequested) is released
- Machinery used in agriculture = combust fossil fuels
How methane concentrations have been altered
NATURAL CHANGES:
- Volcanic eruptions
- break down of organic material (occurs in enviros of low O2 where CO2 cant form)
AGRICULTURE AND LANDS CHANGES:
- Methane released from coal seams during extraction & breakdown of coal
- Humans (garbage breakdown, rotting vegetation, burning biomass
- Ruminant animals ^ (cows, sheep, goats etc) = produce methane during digestion
Nitrous oxide & concentration alteration causes
Found in low concentrations but high GWP (265-289)
NATURAL EVENTS:
- Soils under vegetation, tundra and ocean
ANTHROPOGENIC FACTORS:
- ^ manufacturing chemical, fertilizer, cultivation of soil, legume crop agriculture
Chlorofluorocarbons (CFC) & Halons
- Synthetic
- Breakdown ozone layer
- GWP = 125-152
- last 100yrs (resist chemical breakdown)
- Currently being phased out
CFC’s = from 1930s refrigeration & air conditioning
Halons = fire extinguishers
Perfluorocarbons (PFC)
- Synthetic
- GWP = 6,500
- Last 50,000 yrs (extremely stable)
- Produced during -> prod. aluminium, electronics & refrigerants
- Emissions decreased 90.4% in Aus since 1990
Ozone
- Greenhouse Gas & in stratosphere
- Becomes apart of enhanced greenhouse effect when produced in troposphere
- Ultraviolet light interacts with hydrocarbons (CFC, PFC) & nitrous oxides in troposphere = TROPOSPHERIC OZONE
- (currently = low concentrations but increases from non-renewable energy usage)
Water vapour
- Decreased dramatically 4 bill yrs ago when earths temp decreased
- Global warming increased earths temp = increased atmospheric WV
Aerosols
- Produced through fossil fuels
- Aerosols produce haze & change cloud formation = scatters and reflects short wave radiation
Mitigation
Action to reduce emissions that cause climate change
e.g.
- Development of sustainable transportation
- Clean energy technology
- Energy efficiency
Adaptation
Action to manage the risks of climate change impacts
(happens after CC)
e.g.
- Disaster management & business continuity
- Flood protection
- Infrastructure upgrades
Examples of both mitigation and adaptation
- Water conservation
- Development of new energy systems
- Growth of local food
- Education programs
- Urban forests
Risk and opportunities of climate change
INCREASE IN RANGE OF EXOTIC SPECIES:
Enviro changes = species moving to other enviros = ^ competition with native species.
CHANGES IN LENGTH OF PLANT GROWING SEASONS
Colder enviros warmer climates = longer summer = ^ growing time and absorbing more CO2
CHANGES TO ANIMAL BREEDING CYCLES
^ climate temp = some species breed earlier = less time = more competition
PHENOLOGICAL CHANGES FOR PLANT=POLLINATOR INTERACTIONS
^ in chance of plants & pollinators coming out of sync
INCREASED RISK TO COASTAL INFRASTRUCTURE
- Damage
- Degrdation of structures
REDUCTION IN AGRICULTURAL PRODUCTION FROM WARMER CLIMATES
Enviros are less favourable (e.g. drought) = farmers ^ $ if stock numbers decrease.
Ways to measure current changes in climate
- Changes in snow and ice coverage
- modeling of atmospheric and ocean temperatures
- sea level rise
Ways to measure changes in climate from the past
- Ice core sampling
- Paleobotany
- Tree Rings
- Deep sea sediments
Technologies
CCS = capture, transport, storage
ELECTRIC PLANES
METHANE SATELLLITE
Climate change projections
- International Panel on climate change - Modell to predict future
- Ratings of confidence
