final exam EESC 105 Flashcards
(130 cards)
1
Q
how do we study Earth’s history?
A
- sedimentary rocks
- ice cores
2
Q
how do greenhouse gases warm the Earth?
A
they trap outgoing IR and re-emit in all directions causing an energy imbalance so temp must rise to rebalance
3
Q
climate sensitivity
A
- the amount the temperature will increase for every doubling in CO2
- expected 2-5ºC but difference mainly depends on timescale
4
Q
what is the largest carbon reservoir?
A
geological reservoirs (rocks)
5
Q
geological exchange with atmosphere
A
- very slow
- source: volcanic outgassing (releases CO2 from rocks)
- sink: chemical weathering (pulls CO2 out of atmosphere and into rocks)
6
Q
sedimentary rocks
A
- they are formed at Earth’s surface influenced by environment
- deep ocean sediment, foraminifera (carbonate shells), coccolithophores (algae), fossils
7
Q
deep ocean sediment
A
- forms gradually and laid down over time
- can go back 200 million years, mainly go back 100 million years
- integrated ocean drilling project collected hundreds of cores in past 20 years
8
Q
foraminifera
A
- forams are carbonate shells that incorporate chemicals from seawater
- grown in different conditions and from there the ancient climate they lived in is concluded
9
Q
coccolithophores
A
- phytoplankton
- grown in different conditions and from there the temperature they lived in is concluded
10
Q
fossils in sedimentary rock
A
coral fossils indicate tropical conditions as modern corals only grow in warm tropical water
11
Q
ice cores
A
- thickness of the ice can tell the length of time of ice accumulation
- ice traps ancient air
- can only go back about 1 million years
12
Q
what did ice ages look like?
A
- northern hemisphere permanent ice sheet extended into US and Northern Europe
- southern hemisphere ice sheet looks pretty similar to today
13
Q
what drove the ice ages?
A
orbital forcing (Milankovitch Cycles): obliquity, eccentricity, precession
14
Q
obliquity
A
- Earth’s tilt
- the larger the tilt, the stronger the seasonal cycles of temperatures will be
- changes on a 41,000 year timescale
15
Q
eccentricity
A
- degree to which Earth’s orbit deviates from a perfect circle (how elliptical the orbit is)
- changes of a timescale of 100,000 years
- affects how the incoming sunlight is spread through the year
- causes perihelion and aphelion
16
Q
precession
A
- Earth’s wobble (changes the direction of the Earth’s tilt not the degree of tilt; Earth’s axis changes direction)
- changes on a 23,000 year timescale
17
Q
is Earth’s orbit constant?
A
- Earth’s orbit is not constant
- orbital parameters change because if gravitational interactions between Earth and the other bodies in the solar system
- the changing parameters affect the distribution of solar energy around the globe
18
Q
perihelion
A
- closest distance to sun during orbit
- currently at Northern hemisphere winter
19
Q
aphelion
A
- furthest distance from sun during orbit
- currently at Northern hemisphere summer
20
Q
if aphelion occurs at Northern hemisphere summer, why aren’t summers hotter in Antarctica than in the Arctic?
A
Antarctica is colder due to elevation and it has a higher overall albedo
21
Q
how do precession and eccentricity relate?
A
- they go hand in hand
- no difference in configurations when Earth’s orbit is exactly circular even w/ the changing direction of the axis because all points in the orbit would receive the same amount of insolation
22
Q
how can the climate change by orbital forcing?
A
- the total incoming solar energy doesn’t change but the spread through the year and across the planet changes
- main impact: producing better/worse conditions for ice sheet growth
23
Q
optimum conditions for an ice age
A
- need to focus on Northern hemisphere summers as ice sheets can grow there (N. hem winters are cold enough so really only depends on making summer as cool as possible)
- lowest axis tilt means smaller seasonal variations (won’t get too hot in the summer)
- for precession, want N. hem summers at aphelion so furthest from sun
- high eccentricity so precession can make a big difference
24
Q
last deglaciation
A
- northern summer insolation increased (due to orbital variations)
- this triggered ice sheets to melt
- warming worsened due to ice-albedo feedback
- CO2 buildup in atmosphere due to warmer oceans outgassing CO2 due to the lower solubility of CO2 w/ higher temps
- led to rapid warming and further CO2 release
- the warmer climate also is wetter and less windy which reduces the iron supply to phytoplankton thus slowing down their growth and weakening the biological pump
- this data is collected from ice cores
25
what levels did CO2 vary between during glacial and interglacial periods?
- interglacial ~280ppm
- glacial ~180 ppm, 5ºC cooler
26
how does the biological pump work?
- marine ecosystems pump CO2 to deep ocean where it is locked and can't exchange w/ atmosphere which leaves surface undersaturated
- more CO2 is then absorbed by ocean to return to saturation (equilibrium)
27
de glacial iron limitation
- dust supply is enhanced in cold, windy, dry climates like an ice age
- dust supply declines during deglaciation
- southern ocean productivity declined and CO2 was released from ocean
- positive feedback loop is created
28
ocean iron supply
- Southern ocean has lowest dust deposition anywhere in the world
- dust carries iron
- plankton need iron to grow so iron is a limiting factor to plankton growth and carbon uptake in the southern ocean
29
cretaceous climate
- high volcanic activity
- sea level higher by 120-140m
- CO2 levels between 1200ppm
- 10ºC warmer on average
- poles and continental interiors never freeze
- tropical forests and fauna spread to poles
- extinction of polar species
30
what affects sea level?
- thermal expansion which means seawater expands when heated
- ice sheet melt
- volume of ocean basis which means when ocean ridges are spreading, they are broader and take up more space
31
sea levels in Cretaceous
- sea level higher by 120-140m (know this from chalk deposits)
- thermal expansion, rapid spreading of ocean ridges from tectonic movement, ice sheet melt
32
holocene period
- most recent interglacial period
- includes end holocene climate and anthropocene
33
end holocene climate
-climate reconstructed from tree ring records and historical/instrumental records
- includes medieval warm period and little ice age
- these events are often used as examples in the argument that climate changes naturally so we can show we that we understand the natural processes, and they are not responsible for recent warming
34
medieval warm period
- global average slightly warmer than pre-industrial by 0.2ºC
- period of stronger solar activity
- as mid-atlantic warmed, vikings were able to voyage further
- more regional impacts than global
35
little ice age
- global average was about 0.5ºC cooler than pre-industrial
- period of much weaker solar activity
- Europe and North America were much cooler
- artwork helped show what climate was like
- caused issues globally like dynasties falling, military death from storms, food riots from failed harvests
36
anthropocene
-eras when Earth has been dramatically perturbed by humans
37
what happened to the vikings during the little ice age and why is this important?
- vikings could not adapt to cooling climate and died out
- Native Americans already living there survived just fine because their culture was steeped in traditions and technologies from long before the Medievel warm period
- shows that climate is important part of how a civilizations grew and going outside of climate range experienced we've experienced across history is dangerous
38
what drove the climate changes during the end holocene period?
- changes in sunspots which affects the amount of solar activity
39
what are sunspots?
- dark patches that grow on sun's surface
- regions of intense activity where solar flairs are common
40
what has the paleoclimate taught us?
- largest climate shifts in Earth's history have been driven by CO2
- smaller shifts driven by factors like sunspots
- changing atmospheric CO2 naturally takes millions of years from geological reservoirs or thousands of years from the ocean
- relatively small climate shifts have large impacts on human civilizations (little ice age)
- CO2 changes similar to those we expect to see in next 100-300 years will have huge impacts on sea level
41
general overview of fuels and energy
- atmospheric CO2 has risen since 1750 when industrial revolution began
- rate of increase has increased
- coil, oil, and gas supply > 80% of energy worldwide
42
what are fossil fuels?
carbon-containing compounds that can be burned for energy
43
what are the different types of fossil fuels?
- coal
- oil
-natural gas
44
coal
- from terrestrial plants
- made mainly in swamps
- anoxic conditions prevented decomposition + time, pressure, and heat to turn into hydrocarbons
- impurities w/in coal grades come from sulfur, nitrogen, and mercury
45
energy in creation of fossil fuels
- energy from pressure and heat is put into the plants to go from oxidized to reduced
- that same energy is the energy released when it is burned
46
oil and natural gas
- forms in coastal regions (sea shelves w/ high biological activity)
- derived from algae (dead plankton)
- matter is preserved in anoxic sediment
- oil forms on top with heat, time, and pressure
- gas forms below with more heat
- coal is a mixture of hydrocarbons and alcohols
- gas is mostly methane
47
why is oil and gas hard to obtain?
- they're spread out too thinly in sedimentary rocks
- has to naturally concentrate so an oil/gas well can be tapped
48
energy yield
the amount of energy a system produces in its actual operating environment
49
what is the reason for energy yield?
- want as many Hydrogens per unit C
- the hydrogens will oxidize to H2O so less bonds with carbon therefore less CO2 is released
50
energy yield of coal
- least amount of hydrogen bonds
- thus dirtiest because releases most amount of CO2
51
energy yield of oil
between coal and gas
52
energy yield of gas
- most amount of hydrogen bonds so most amount of hydrogens can be oxidized
- least Carbon per unit energy
53
oxidation states and fossil fuels
- gain energy by oxidizing
- oxidation state refers to electron gain/loss by carbon atom
- going from reduced to oxidized loses electrons by breaking bonds
- the breaking of bonds will result in a release of energy
54
what is the time length fossil fuels will last?
~50 years for oil
~50 years for gas
~ 114 years for coal which is most accurate
55
why are the estimated fuel stocks of these fossil fuels inaccurate?
- technology and discovery of new reserves make these estimates inaccurate
56
how are fuel stocks calculated?
reserves/ production
57
where are most oil reserves and why is this problematic?
- most located in Middle East
- politically unstable which can be problematic
58
where was coal first used?
- England during industrial revolution
59
how long back do tree ring records date back?
about 1000 years
60
what are the different fossil fuels used for?
- coal: electricity
- oil: transport
- gas: heating
61
what are additional oil sources?
- oil/tar sands
- oil shales
62
oil/tar sands
- common technique is injecting hot steam to heat rock and decrease viscosity so hydrocarbons can flow
- more CO2 released because more energy is required to extract
63
fracking
- low concentrations of oil can be extracted
- inject very high pressured water in the well to break the rock, release the oil, and allow it to flow to the central channel to be sucked out
64
how are future CO2 emissions predicted?
- Hubbert's peak theory
- Kaya Identity model
65
what is hubbert's peak theory?
- when there is a finite but valuable resource, exploration/production continues ramping up
- normal distribution curve
66
what is the Kaya Identity model?
- CO2 emissions are related to:
- population
- GDP/capita
- energy intensity
- carbon intensity
67
in Kaya terms, what is the increase in emissions due to?
rising economic productivity worldwide
68
what countries are the biggest emitters?
- China
- US
- India
- EU
69
who are taking over as largest CO2 emitters?
- rapidly developing countries like India and China
70
US emissions
- highest emissions per person
- over time US has released a lot more CO2 which has helped them become wealthiest because economy can flourish by releasing CO2
71
what are total current worldwide emissions?
~11 Gton C/year
- about 1 Gton C/year of that is due to deforestation
72
how much of CO2 emissions actually stay in the atmosphere?
about half (~5/6 Gton C/year)
73
where does the CO2 that doesn't stay in the atmosphere go?
- land carbon sink (more uptake from expansion of forests into warming polar regions and densification of forests from CO2 fertilization)
- ocean carbon sink (reach a steady-state partitioning of CO2 between land and ocean)
74
ocean in perturbed carbon cycle
- CO2 dissolves in ocean
- after some chemical processes, H+ is released and the ocean pH decreases (acidifies)
75
why is H+ harmful in the ocean
- dissolves calcium carbonate shells (corals)
- many organisms will not tolerate more acidic pH levels
76
how do we estimate global-mean temperature?
- spatial averages across land and ocean
- gather data from international weather devices
- then perform some quality control
- bin data
77
what are some biases when estimating global mean temp?
- inaccurate data due to land use and human structure changes (cities are little heat hotspots)
- inaccurate older measurement methods
78
recent changes in Earth's surface temp
- warmed by 1.1ºC
- continental interiors (due to thermal inertia) and north polar regions (due to ice-albedo) have warmed more rapidly
- cooling in North Atlantic likely due to weakened North Atlantic meridional overturning circulation
79
recent changes in hydrological cycle
- increase in atmospheric moisture content
- increases and decreases in precipitation
80
recent changes in sea ice extent
- summertime extent very sensitive (declined by >30%)
- little wintertime change because always cold enough
- Antarctica sea ice extent has changed very little
- in southern ocean, upwelling of deep water keeps surface ocean cold
81
recent changes to ice melt and sea level
- melting land ice raises sea level once it runs into ocean
- mountain glaciers has lost between 200-400 Gton/year of ice
~ 10% global glacier mass has been lost by warming
- biggest contributors are greenland and antarctica ice sheets
- sea levels have risen ~24 cm (ankle deep)
82
does sea ice melt impact sea level
no because most of mass of ice is already underwater and is displacing the water equal to the volume of the melt water that would be added
83
what are the causes of recent sea level rise?
- thermal expansion of water
- mountain glaciers melting
- ice sheets melting
84
what is radiative forcing?
the difference between the amount of energy that enters and leaves a planet's atmosphere (think energy balance)
85
what factors impose radiative forcing?
- geological carbon cycle (weathering vs volcanoes)
- orbital forcing
- sunspots
- volcanoes (aerosol effect)
- human ghg emissions
86
how much heat (radiative imbalance) has built up in the system?
2.5 W/m^2
87
why is orbital forcing not the cause of recent warming?
- happens on very predictable timescales
- would be pushing us towards next ice age which is not occuring
88
why are sunspots not the cause of recent warming?
- too small radiative forcing (~0.2 W/m^2) to explain the +2.5 W/m^2 per year
- no major recent increase in sunspots
89
why are volcanoes not the cause of recent warming?
- CO2 emissions from short, spatially isolated eruptions are vanishingly small (would need huge eruptions for thousands of years like the Cretaceous)
- no long term in volcanism since 1900
- smaller eruption's ash clouds scatter incoming solar radiation which would actually cause cooling
90
why are ghgs the only reasonable candidate for recent warming?
- current radiative forcing from all ghgs is ~3.5 W/m^2 which is even more than the current energy imbalance
- about -1 W/m^2 of this offset by human aerosol emissions (fog, mist, dust, geyser steam, smoke)
-
91
list some current ghgs and what they come from
- CO2 from burning fuels and deforestation
- CH4 from agriculture (farting cows and rotting waste) and fossil fuel industry (leakage from pipes)
- N20 from agriculture (fertilizers)
- CFCs (refrigerants)
- ozone (chemical reactions involving other emitted compounds)
92
how can future climate be predicted?
- climate models
- SSPs
93
climate model
represents our best quantitative understanding of all of Earth's processes that govern global climate (absorption/reflection, radiative transfer, atmospheric circulation, Earth's surface processes, ocean processes)
94
what does SSP stand for?
Shared Socioeconomic Pathways
95
what do the SSPs represent?
- different assumptions of how much CO2 we'll emit in the future
- they all are adapted from Kaya Identity model
96
what does SSP5 represent?
- business as usual scenario
- >5ºC of warming
- does account for technological advances
97
what does SSP1 represent?
- best case scenario
- 1.5 or 2ºC of warming depending on which SSP1
98
what does the -# represent in SSPs?
radiative forcing (amount of energy imbalance in W/m^2)
99
what is the difference between SSP5 and SSP3?
- the difference is how costly it is to adapt to future climate change
- SSP3 has much lower CO2 emissions even though the cost to adapt is much higher (mostly due to lower GDP growth which will slow down CO2 emissions)
100
what is the difference between mitigation and adaption?
- mitigation is prevention by reducing emissions
- adaption is accepting the consequences and adjusting lifestyle to it by continuing to burn fossil fuels
101
spatial patterns of temp change
- high latitude amplification due to ice-albedo feedback
- continental amplification due to thermal inertia
102
future precipitation
- a lot of uncertainty
- business as usual likely result in +10% global precipitation
- warmer atmosphere makes precipitation more likely (especially in tropics w/ strong convection)
- subtropics are an outlier and get drier due to Hadley Cell circulation
103
future extreme weather- heatwaves
- in SSP5, 60% of summer days that exceed the 1960 "hot temperature"
- standard for hot temp is set and then see how many days exceed that number
- heatwaves have major negative human health impacts
104
future extreme weather- heavy rain
- % change by 2100 in amount of rain on rainiest day of year
- much of East Coast in 20-30% range
- tropics experience largest changes due to strong convection
- warm ocean surface drives the low surface pressure, convection, and strong winds associated w/ a hurricane
- warmer oceans predicted to strengthen hurricanes
105
future sea level rise
- up to 10m higher by 2300
- SSP5 ~1m higher than pre-industrial (waist deep)
- 100 year timescale limiting due to lag in climate systems
106
what is future sea level caused by?
- thermal expansion
- mountain glacier melting
- large ice sheet melt
107
future arctic sea ice decline
- all other SSPs besides SSP1 would lead to a practically sea ice free ocean by 2100
108
future coral reef loss
- coral bleaching due to variations in water temp
- acidification of ocean
- none by 2100 in SSP5
109
biological impacts
- habitat migration
- species differ in temp optimum and range (when > CTmax , must migrate)
- a species that cannot migrate as fast as its habitat will find themselves unable to remain in their preferred habitat
- 15.7% species extinction in SSP5
- 5.2% species extinction in SPP1
110
AMOC collapse disaster
Atlantic Meridional Overturning Circulation is a heat pipeline from tropics to North Atlantic
- scientists worried surface ocean warming and ice melt could collapse AMOC
111
ethics and cost of adaption-only solution
- human relocation due to loss of homes
- infrastructure and property repair after extreme weather events
- infrastructure adaptation (sea walls and storm drains)
- health care costs
- ecological costs
- total cost difficult to quantify
- suggested ~$38 of damage costs for each tonne of CO2 emitted
(cumulative to date- $22 trillion)
- larger the costs, the uglier the future (international conflict and turmoil)
- difficult to convince emitters to act due to consequences being in future
112
mitigation and stopgap strategy
- depends on how soon/aggressively we act
- mitigation may not be enough so add carbon dioxide removal and solar radiation management
- focused on improving carbon efficiency (reduce carbon intensity)
113
solar radiation management
- SO2 aerosols released into stratosphere to increase Earth's albedo so less energy is absorbed
- maybe cost effective
- could cause acid rain, reduced sunlight
114
CO2 removal
-planting trees (only net draws down while growing; limited by free space)
- grow plants, burn for energy, capture carbon (could cost a lot to deploy at scale)
- ocean iron fertilization (mimic natural processes by which dust deposition drives phytoplankton growth and draws down CO2; iron fertilization likely drove ice age and could be dangerous for marine ecosystems)
115
what are some carbon-neutral energies?
- carbon capture and storage
- biomass fuel
- nuclear energy
- solar energy
- wind energy
116
what is carbon capture and storage?
- CO2 separated from other gases during energy production and then compressed
- compressed CO2 injected into ground
- uses 20-40% of energy generated so makes it more expensive
- no successful large scale application yet
117
what is biomass fuel?
- grow plants and burn them to produce energy (closed loop for CO2, no net emissions)
- requires huge amount of land
- deforestation and fertilization
- considered using food waste which creates no additional emissions
118
what is nuclear energy?
- splits atoms to release energy/heat which spins a turbine
- ample supply of uranium
- technology well-established and energy generation relatively cheap
-toxic nuclear waste
- public resistance to nuclear plant construction
- nuclear enrichment (paves way for nuclear weapon development)
- nuclear plants are hugely expensive so need government to pay
119
what is solar energy?
- photovoltaic: harness energy to induce an electrical current
- deployed at large/small scales
- mining for rare earth elements can cause environmental degradation
- solar thermal (mirrors focus sunlight to heat water to generate steam to turn turbine)
- easier to store but slightly less effective
- less materials-intensive
- drawbacks for both: intermittency, need to be a part of diverse energy profile
120
what is wind energy?
- wind turns turbine to generate electricity
- on shore: each turbine requires 50 acre of land and need a few hundred to match output of coal-fired plant
- land beneath can be used for agriculture or other purposes
- off shore: winds are stronger but expensive to built and hard to fix problems due to being in ocean
- drawback for both: intermittency
121
cost of renewable energies
- solarvoltaic and on shore are very competitive with fossil fuels
- solar thermal and off shore are very close to being same price range as fossil fuels
122
if renewables have competitive pricing, why aren't they being utilized more?
- high installation costs (need government subsidies)
- political pressures from fossil fuel industry to reject subsidies
- misinformation about technical and environmental concerns
123
misinfo about technical and environmental concerns about wind energy
- no proven whale deaths associated w/ offshore wind turbines
- onshore turbines kill a lot fewer birds than cats do by a lot
124
what is a tragedy of the commons?
- problem in which individuals' actions produce an "external" cost that is share among all users of the resource
- require regulatory solution where harmful actions are prohibited or external cost is "internalizzed"
125
w/ increasingly viable renewable energy options, why has there not been a widespread transition away from fossil fuels?
- individual emitters don't bear the costs of climate change induced by their emissions
- they would bear the cost of transitioning away from fossil fuels
126
what is conventional regulation?
- require all emitters to meet specific across-the-board standards
- though to be too heavy handed
- no incentive to keep cutting emissions below target
127
what is a carbon tax?
- goal: internalize cost of CO2 emissions
- set tax per tonne of emitted CO2 determined. by government and emitters can find most cost effective emissions' reductions to make
- recovered funds could be invested in cleaner technologies, environmental damage, or redistributed to consumers
- hard to choose "correct" tax rate
- government sets the cost of emissions and free market sets total emissions
128
what is a cap and trade scheme?
- goal: take market-based approach to reducing emissions
- governing body issues permits for emissions and each permit allows for set amount of CO2 emissions
- all emitters must have enough permits to cover their emissions
- those who emit less than expected can sell their permits
- how to distribute permits is controversial either auction (harder on biggest emitters) or giveaway based on current emissions (unfair because rewards poor performance)
- government sets total emissions and free market sets carbon price
129
what are the international agreements/
- Conference of Parties (COP) began in 1995
- goal: come to international agreement to reduce emissions to hit warming target
- countries differ in their economic status and their past/ future contributions to climate change
- developing countries will never agree to emissions reductions unless developed world reduces more and must include financial support
130
what is the new warming target?
1.5ºC
