Final Flashcards
Climate system
Multidimensional system of mainly interacting parts Including: Atmosphere Hydrosphere Geospnere Biosphere Cryosphere (ice and snow(
How is climate change tracked
- Historical records only go back a couple of centuries (good for 1000 years)
- Recorded in glacial ice
- Tree rings archives of environmental history
Historical records for climate change
Reconstruction;of past climate change i the field of paleoclimatology
-scientists use proxy data (indirect evidence of climate change
Proxy records - climate change recorded in glacial ice
Some ice cores represent over 200,000 years of climate history
- oxygen isotope analysis
- carbon dioxide and methane (air bubbles trapped in ice)
Tree rings- archives of environmental history
Growth rings added each year
-thickness and density of rings reflect environmental conditions
Tree things not tied to local trees called floating chronologies
Dendrichronology
Study of tree rings
O2 isotopes and ice volume
Isotopes are atoms of an element that have varying number of neutrons
Proxy records - deep sea sediments
-variety of proxies in sediments
—foraminifera (singe felled organisms)
—pollen
—organic and inorganic compounds
Deep sea sediments foraminifera
Disturbance of, changing abundance, and extinction of species describe environment
Guemnerlitria
Increases during environmental stress
Deep se sediments also lake sediments pollen records
Distribution changes in abundance etc tell us about changing environments
Climate forcing mechanisms
Any process capable of altering the global balance, capable of affecting climate
Can be: internal process-occur within the climate system such as oceanic current circulation
External processes-occur from without and ca be natural or anthropogenic
—time scales can vary wildly from years to millions of years
Important easternal forcing mechanisms
1. Plate tetctonics Milankovitch cycles (orbital variations) Atmospheric chemistry Volcanism Solar activity
Plate tectonics as an external facing mechanism
The earths surface consists of a variety of large and smaller tectonics plates
-super continents have existed several times and have broken apart
Plate tectonics impacts:
Changing oceanic currents (poleward heat advection)
Land surface area near the equator, near the pols (latitudinal radiation balances)
Mountain ranges (atmospheric circulation, silicate weaterhing) and more
Closing of the Central American isthmus
-more moisture carried to high latitudes=more freshwater for sea ice and more snow for glaciers to build
Milankovich cycles (orbital variations)
Driving force behind gladiator cycles
Orbital variations
-eccentricity-changes in orbital shale (100,000 year cycle)
Tilt-(or obliquity) tilt varies between 22.1 and 24.5 degrees (41,000 cycle)
—today 23.5 degrees
-precession-(26000 year cycle) also called wobble
—axis points to different spots in the sky during a cycle of about 26,000 years
Atmospheric chemistry as an external mechanism
Greenhouse gas concentrations
—more greenhouse gasses=trapping more long ave radiation=higher temps
—from volcanoes too
Volcanism as an external forcing mechanism
Volcanic eruptions release aresols (high albedo, reflects more shortwave radiation) which can cool earth
Mount St. Helens, 1980-cooling less than .1C
El chichón, 1982- cooling around .3 to .5 celvius
Mount pinatubo, 1991 cooling around .5 c
Solar activity as a;external forcing mechanism
Suns output is not constant
-varies according to sunspot numbers
—sunspots are darkened spots on the sun with temps 400 to 1800 c lower than areas around the spot
-increased solar output is due to faculae which are very bright spots near the sunspot
—11 year cycle
Medieval war:period and little ice age
Due to less sunspots means colder which accounted for the little ice age
Human climate impacts
Humans have been modifying the environment for thousands of years
-ground cover has been altered by fire and overgrazing
—results in modifications of reflexivity, evaporation rates, and surface winds
-rising CO2 levels: carbon dioxide in greenhouse gas
—let’s show wavelength solar radiation
Ass through the earth but traps long wavelength earth radiation from passing back into space
Rising co2 levels
Humans add carbon dioxide to the atmosphere through burning fossil fuels and deforestation
—CO2 Levels are the highest in the past 600,000 years
Response to more co2
Global temperatures have increased in response to increases atmospheric carbon dioxide
-global temperatures have increases .8 C in the past century
—the warmest 16 years (since 1850) have occurred since 1995
But we do need them!! Without greenhouse gasses the earth would be about 33 C cooler on average and we couldn’t live if it was this cold
Expectations for future of with co2
Temperatures are expected to continue to increase in the future
-amount of increase depends on amount of emitted greenhouse gases
IPCC
Intergovernmental panel on climate change formed in 1988 under control of the UN
IPCC findings
REPORTS IN 1990, 1995, 2001, 2007, and 2013
-the 2013 report stated if CO2 ppm is doubles there will be a likely increase of 2-4.5 C
—an increase of <1.5 c is very unlikely
—the IPCC defines likely as 66-90% probability and VERY unlikely is 1-10% probability
2018 report focuses on limiting warming to 1.5 C
—were already seeing the affects of 1 C through more extreme rather, rising sea levels, and diminishing arctic sea ice, among other changes
Role of trace gasses
Methane (CH4) nitrous oxide (N2O) chlorofluorocarbons (CFCS) and ozone (O3) all absorb wavelengths of outgoing radiation from earth
Methane as a trace gas
Produced by anaerobic (don’t like air) bacteria in swamps, wetlands, and animal waste
- 20 s’more effective at absorbing infrared radiation
- .4% per year growth
Nitrous oxide (N2O)
Laughing gas mostly from agricultural activity but also from fossil fuels combusting
-.2% per year growth
CFCS-chlorofluorocarbons
Manufactured chemicals -man made
- industrial propellants and coolants
- very stable and long lived
- 5% per year growth
Ozone O3
Tropospheric zone
- lightening, automobiles ignitions, and other photochemical reactions
- .5% per year growth
Aresols
Tiny, liquid and solid particles that are suspended in the air
-natural sources include wildfires, dust storms, breaking waves, and volcanoes
-human generated aerosols come fro the combustion of fossil fuels and burning vegetation
—black carbon is spot generated by combustion process
Absorbs incoming radiation
Possible effects of these changes in trace gasses and ozone on temperature
Because the climate system is so complex’ predicting specific regional changes related to increased levels of CO2 is speculative
- magnitude of temperature increase is not globally uniform
- precipitation changes will also vary across the globe
Possible affects on sea level rise
Sea level has risen 25 centuries since 1970
-will affect low-lying countries and regions with a gently sloping shoreline
—Atlantic coast of the us
What is sea level rise driven by
Melting glaciers
Thermal expansion
-if all the glaciers and ice sheets melted sea level would rise 23 feet
The changing artic as a possible affect of global warming
Amount of sea ice in artic has declined by 13% since 1979
-Greenland and Antarctica ice sheets have dropped an average of 475 gigatons/year
(1 gigaton=1 billion metric tons)
Permafrost (frozen ground)
Thawing permafrost is a positive feedback mechanism
-organic material stores in the permafrost will start to decay and release carbon dioxide and methane
Possible effects of global warming on increasing ocean acidity
When atmospheric carbon dioxide dissolves in seawater, the oceans become acidic
-makes it harder for calcite-secreting marine organisms to grow hard parts
The potential for surprises with global warming
Due to complexity of earths climate system, we might experience relatively sudden, unexpected changes or see some aspects of climate shift in an unexpected manner
—a constant state of change is very likely
Climate feedbacks
Feedback - in indirect or secondary change either positive or negative that occurs within the climate syste in response to a forcing mechanism
Positive: self feeding/sustaining feedback that further enhances the impacts of the climate forcing
Negative: a feedback that pushes the climate system back towards the initial state
Important climate feedbacks
- Oceanic warming-positive
- warm water can hold less carbon dioxide than cold water so more carbon dioxide released - Ice cover/albedo feedback-positive
- increase temperatures leads to decreased ice cover, which drops the albedo and causes temperatures to increase further - Cloud atmospheric vapor feedbacks
- higher temp leads to higher evaporation and higher atmospheric vapor content
- high thin clouds have very low albedo, but trap outgoing radiation(greenhouse gas)-positive
- low think clouds (cumulus) have very high albedo reflecting radiation back to space - positive - Methane clathrate and frozen soils-positive feedback
- increases surface temperatures are leading to the thawing of frozen soils (permafrost)
- this allows organic matter to become oxidized in soils and to the release of methane
Coast
Oceans moderate climate and whee society meets the ocean
Major oceans
Pacific Atlantic Indian Arctic Southern
What is the significance of the coasts
Ocean covers 70.8%
Regulates climate
60% of humans live near the coast
Under sea landscape
The current configuration of tectonic plates
- most continental crust is in northern hemisphere
- most oceanic crusts in the Southern Hemisphere
Bathymetry
Describes to topography (elevation) of ocean Bain’s
- continental shelf: shallow gentle slope (.3d)
- continental slope: descends from 500 m to 4 km at 2 d
- continental rise: transition zone from 4 to 4.5 km
- abyssal plain: flat, low relief bottom below 4.5 km
Oceans and coast as a result of tectonics
Oceans exist because of tectonic differences
-continental crust is higher, oceanic crust is lower
Continental and oceanic crust boundaries: coast
-passive margins are located far from a plate boundary
-active margins are located close to a plate boundary
Passive margins
East coast of the us is passive nd also submerging clastline, resulting from either sea level rise or subsidence
Characteristics:
-wide sloping beaches
-estuaries (downed river valleys)
-depositional features (barrier islands, spits)
Active margins
West cost of the us is active and also emergent coastline, resulting from either Sealevel fall or uplift Cararcteristics: -thin rocky beaches -wave cut platforms and wave cut cliffs -sea stacks and sea arches
How are margins affected by tides
Sea level rises and falls twice daily
- high tide: maximum tidal flooding
- low tide: maximum tidal withdrawal
How are tides formed
-Tides are caused by a tide generating force: gravitational pull of the moon and sun
-the orbiting moon creates the strongest tidal effects
—the sublunar bulge follows the moons orbit
—the smaller bulge occurs on the opposite side of earth
—the bulge makes high tide; between bulges are low tides
How do lunar and solar tidal effects interact
Positive alignment yields enhanced “spring” tides
-once a month during new or full moon
Negative alignment results Iower “neap” tides
-twice during first and third quarter moons
How does the tidal bulge shift
The moon revolves around the earth every 29.5 days and hence the tidal bulge shifts about 50 minutes later each day
Three types of tidal patterns
- Diurnal
- Semidiurnal
- Mixed
Ebb tides vs flood tides
Ebb tide: falling tide
-creates ebb flow delta
Flood tides: rising tides
-creates flow tide deltas
What are surface waves the result of
Surface waves are the exults of wind, which is the exult of the unequal heating of the earth by the sun.
Weak winds-produce small waves
Strong winds-produce big waves
Parts of a wave
Crest-top of a wave
Trough- low between crests
Wavelength-distance between;wave crests
Depth of influence (wave base- 1/2 the wave length
Frequency-the time it takes for successive wave crests to pass a certain point of tome
Wave size depends on
Wind speed
Duration wind blows
Fetch-distance that the wind has travelled
As the wave approaches shore….
Wave base hits bottom
- friction slows wave motion near the sea floor
- near the surface, waves continues moving fast
- the wave crashes: breakers
Shoreline
Interface between the land and the ocean
What is the one constant about the coast
Change
Summer beach profile vs winter beach profile
Summer: Berm or sea cliff/rock and no sand bars
Winter (storm): little or no berm and sand bars present
How do beach sediments compositions reflects geology
Quartz common
- carbonate (shell) beaches in tropics
- basalt black sand beaches
Long shore current
Produced from wind aiding beach erosion and deposition
Beach drift: the movement of sand along the beach
-swash: movement of water up the beach at angle
-backwash: water flows back down in a zig zag pattern
—direction of beach drift to make a split
Wave refraction
As waves approach-usually at an angle-one side of the wave hits the bottom before the other and so refracts
- waves erode beaches just by their impact but also are eroded by abrasion: impact of sand and water
- notice that refracted waves concentrate on headlands
Rip currents
Develop when wave attack is straight on
-water piles up on beach and must return seaward
—A rip current develops perpendicular to the beach
—rip currents often strong people drown fighting them
Barrier Islands
Elongated loner sandbars parallel to the coast
-create a protected backwater area called a lagoon
—change constantly
Coastal problems 1. Beach distraction (erosion)
-from storms (hurricanes)
-human construction along coasts affected
-mitigating beach loss (man made structures)
-factors to consider
—cost, habitat, sediment, Composting/size
Coastal problems
- Beach destruction (erosion)
- Rising sea level (global warming)
- Pollution- garbage,sewage, agriculture runoff, oil spills
- Storms (hurricanes)
Coastal problems 4. Storms (hurricanes)
Low pressure cyclones with winds exceeding 119 km/hour (74mph)
- driven by warm water (27 C)
- form between 5-10 d latitude
- called hurricanes,cyclones,and typhoons depending on where in the world u are
- starts with a tropical depression followed by named tropical storm at 63 kph 39 mph
Hurricane process
Form summer-late fall off west coast of Africa Low pressure zone pulls air in Warm air rises Warm air condenses Warm air releases heat Warm air rises more
Damage from hurricanes
Storm surge (worst)
Wind
Inland floooding
Classifying a hurricane
Safari Simpson scale Category 1: 119-153 kph 2: 154-177 kph 3. 178-209 kph 4. 210-250 kph 5. Over 250 kph -based off wind speeds but we know there are many other types of damage that can occur due to storm surge,inland flooding, etc
Societies need resources
Must balance cost against need against environment
- reserves and resources represent world supply
- must be balanced against world demand
Five fundamental sources of energy
- Nuclear fusion of sun
- Energy stores in chemical bonds
- The pull of gravity
- Nuclear fission reactions
- Energy in the interior of the earth
Fusion vs fission
Fusion is a nuclear reaction in which atomic nuclei of low Arouca number fuse to form a heavier nucleus with the release of energy
Fission is a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle with the release of energy
Solar energy stores in fossil fuels
Coal, oil, and natural gas derive from living organisms
-energy is preserved in this H-C bonds
—created by photosynthesis, solar energy from the past
Coal
- black, brittle, carbonaceous or metamorphic rock
- remains of organic matter from vegetation
- only found in rocks younger than 420 mya
Coal forming periods
Carboniferous (354-286 ma)
Cretaceous (144 to 65 ma)
Coal formation
Vegetation accumulated in an oxygen free setting
-absence of oxygen prevents organ matter from decaying
—marine deltas, tropical coastal we lands
-sea level rise and fall buries wetland deposits
Coal rank of carbonic content and sulfur content
Peat *(50%) Lignite (70%) Bituminous (85%) Anthracite (95%) Sulfur content Low (0-1%) Medium (1.1-3%) High (>3%) —most us coal is low sulfur —coal with high sulfur: —-lower, treat or capture it by scrubbing
Coal mining
Mining type depends on the depth of the coal seam
- within 100 m coal is strip mined
- for deeper coal seams, underground mining is required
Strip mining
Landscape removed to reach coal
-exposed coal is removed
-Spoil is stockpiled nearby for later use during reclamation
—reclamation: returning land to prior conditions
—excavation is backfilled with spoil and soil, then planted
Coal underground mining
Coal removed by tunneling
-for coal deeper than 100 m shafts are advanced to seam
—-coal mining is specialized,expensive, and dangerous
Possible mining hazards
Tunnels can collapse Methane gas -asphyxiation -explosions Black lung disease
—-sago mine disaster, 2006 13 miners trapped for 2 days only one survived
Oil and gas
Are hydrocarbons
-complex organic molecules
-made of hydrogen and carbon
-from once living creatures
Oil and gas genesis:
Come from plankton and marine algae
-heating breaks the organic down into waxy kerogen
-karogen: rich source rocks are called oil shales
Oil and gas form in specific temperature ranges
5C-15C-80C-120C
Hydrocarbon systems
-a known supply of oil is called an oil reserve
-most oil is in super giant fields in the Persian golf
-oil and gas migrate from source rocks to reservoir rocks
—reservoirs are porous and permeable
—rock fractures and ground water facilitate migration
—traps help concentrate and enrich carbons
Types of hydrocarbon traps
Anticlinal trap
Salt dome trap
Fault trap
Stratigraphic trap
Birth of oil industry
Oil from seeps has been used for millennia
The first oil well was drilled in Titusville pa in 1859
-initiated an oil boom
Within years, 1000s of oil wells has been drilled
Oil production
Primary recovery
-uses reservoir pressure and pumping to extract oil
-inefficient only able to recover about 30% of the oil
Secondary recovery
-fluids (steam, co2) ar injected to heat and push oil
-hydrofracturing: artificially increases permeability
Alternative to oil
Natural gas
Tar sands
Oil shale
Gas hydrate
Natural gas
Volatile short chain hydrocarbons
- methane ethane propane and butane and others
- gas floats on top of oil in a reservoir
- more abundant than oil and cleaner fuel
Tar sands
Deposits of residual petroleum in sand
-heavy oil, or bitumen, is residue of a former oil field
-tar sands must be minded and processed
-extensive deposits in Alberta Canada and Venezuela
Tar sands are being piped from Canada to the gulf coast
-recent spills jabs occurred in Michigan and Arkansas
-most expensive on land oil cleanup
Oil shale
Shale containing abundant kerogen
-burning transforms the kerogen into liquid hydrocarbons
-large supplies occur in
—Estonia, Scotland, China, Russia, western us
—fracking increases permeability
Gas hydrate
Methane (CH4) in a structure of water ice
- CH4 is from bacterial decomposition of organic matter
- methane hydrate forms in water depths exceeding 300 m
- stores more carbon (C) than all other reservoirs combined
- recovery is not currently feasible
Nuclear fission
Energy from breaking apart atomic nuclei
-neutrons stoke the fuel and start fission
-fission splits a large nucleus into smaller fragments
Reactors are loaded with uranium oxide field rods
Nuclear power
A high speed neutron initiates fission creating:
-nuclear fragments
-a large yield of energy
-more high speed neurons
Released neutrons strike other 235U atoms: chain reactions
Control rods anyone a neutrons, slowing fission
—fission produces an enormous amount of energy
Nuclear fission process
Fission occurs within a
-concrete reinforced containment structure
Chain reaction fission happens within reactor core
Rods with uranium fuel pellets capture neutrons
-inserting slows fission, withdrawing increases
Water coolant pumped into reactor
-water slows fission and is heated
Heated water enters steam generator
-h2o in 2nd loop turned to steam
Steam turns a turbine
-turbine generates electricity, electricity produced
Coolant in reactor kept separate
Water is radioactive byproduct
Why is nuclear power so great
- major source of electricity
- emirs zero greenhouse gasses
Geology of uranium
-uranium 235 is the most common nuclear film
-uranium has two major isotopes
—u238 99.3% not fissionable
—u235 .7% fissionable
-u 235 must be enriched 2-3 times (to 3%) to be fissionable
Uranium occurs naturally in all rocks
-dissolved uranium transported by water
-radiation detectors can locate uranium
Nuclear concerns
Nuclear power is explosive
Loss of actor control may start core meltdown
-molten reactor materials could bore through containment
-a steam explosion could then spread radioactively
Generates highly radioactive wastes
-extremely toxic, wastes are poisonous for 1000s of years
-high level waste storage is. Major societal issue
Wastes also generated by ore processing
Geothermal energy
Energy from earths internal heat
-geothermal gradient 15C/km-50C/km
-high geothermal gradients: hotter at shallower depths
No water, no greenhouse gases or air pollution
Two ways geothermal energy is utilized
- Not water is pumped and used to heat buildings (direct)
- Steam is used to drive electric turbines (in direct)
Geothermal is a dominant energy source in some areas
-island, New Zealand
Hydroelectric power
Flowing water turns potential energy into kinetic energy
- hydroelectric power dams arrest the flow of water
- water is directed past turbines to create electricity
Positive aspects of hydroelectric power
- reduces flooding risk
- reserves were for drinking, irrigation. And recreation
- provides renewable energy
- little waste
Negative aspects of hydroelectric power
Dams destroy landscapes and alter ecosystems
Reservoirs accumulate sediment
-reservoirs require expensive dredging
-erosion is accelerated downstream of dams
Wind power
Wind drives a large turbine to produce electricity
-wind derived electricity is renewable and carbon free
-high tech wind farms are sprouting world wide
Drawbacks
-wind farms have negative aesthetic impacts
-turbine blades are noisy and kill birds
Solar energy
Most abundant source of energy
-solar energy dwarfs hydrocarbon resources
Concerns:
Diffuse
Highly variable on a seasonal and daily basis
Difficult to convert into more usable forms of energy
Two ways to use solar energy directly
- Solar collects concentrate sunlight for heating
2. Photovoltaic cells convert suns energy into electricity
Biomass
Energy from plant and animal matter -early humans used biomass (wood, charcoal, dung) -ethanol: alcohol derived from corn —burned as a motor fuel —unproven as a gasoline replacement
Hydrogen fuel cells
-produce energy electricity via chemical reactions
-hydrogen reacts with oxygen in an electrolyte bath
—generates electricity, heat, and h2o
—the reaction is environmentally benign
-Fuels cells are useful as engines for motor vehicles
Energy problems
Global energy use continues to increase dramatically
-rapid industrialization
-oil, the dominant energy source, is dwindling
-many countries import oil to meet demands
In the future, humans will have a different energy mix
—oil extinction is likely to occur between 2050 and 2150
—-we are now close to the peak of global oil production
——perhaps we have passed it
——the “oil age” may just last 200-300 years
