GEO 102 Terms/Concepts
How much energy is required to be absorbed/radiated change water in each phase?
80 cal from solid/liquid, 100 cal to warm water, 540 between liquid/gas
Wein's Law
A hotter object emits more of its light at shorter wavelengths
How are mountain glaciers formed?
Accumulation of snow year-on-year in high altitude regions, building up a thick column of ice that increases pressure on deep ice, causing downhill flow Ice flows from accumulation to ablation zones
How does air expend/absorb energy as it rises?
Air expands as it rises, using kinetic energy to do so, releasing it into the surrounding atmosphere
Specific heat capacity/thermal inertia
Amount of energy required to cause an object to warm up/cool down Water has a high specific heat capacity (relative to air and land in particular) of 4186.0 J/(kg*°C) dE = dT *m*HC So far the ratio of ocean to atmosphere warming is ~20.7 due to different heat capacities
Water vapor/air temperature feedback loop
Amplifying feedback loop where changes in Earth's surface temperature increases the amount of atmospheric water vapor, increasing the intensity of the greenhouse effect, thus further increasing Earth's surface temperature
Glacial ablation zone
Area below the snow line on a glacier where more ice is lost to melting than gained due to snow accumulation
Terminal moraine
As ice recedes from the edge of a glacier over time, the sediments it leaves behind carried there by ice flow forms this structure
What would cause a "nightmare" West Antarctic Ice Sheet scenario?
As ice shelves on the edges of the Antarctic ice sheet decrease, the inner glacier can melt and flow into the ocean more easily, increasing ice loss Also, w/ lower pressure on edge of ice sheet, water can make it under the ice at points where bedrock is below sea level, possibly causing ice sheet to slide/collapse. Could cause 5m+ of sea level rise
How does latent heat move between the oceans and land?
As water evaporates, it absorbs latent heat, and as it precipitates over land, it releases it, generally transporting latent heat from the ocean to the land. This process will lead to climate change warming the land more than the ocean. Evidence is proxies from early Cenozoic, where sea surface temp was 7°C warmer than present while land was 12°C warmer
What types of molecules absorb IR radiation?
Asymmetric molecules, or symmetric molecules w/ 3+ atoms that bend and can thus be asymmetric at some angles This indicates why water vapor, CO2, and methane are the most abundant greenhouse gasses. They are simple molecules that don't break down in the atmosphere and can absorb IR radiation
Where are erosion and weathering most likely to happen and why?
At high altitudes in mountains, b/c bedrock is being exposed by mountain formation to precipitation/dissolve carbon, may even break off from gravity at sharp inclines. This is why sediments from mountainous regions make up greater proportion of ocean sediment than those from lower regions w/ less weatherability
Chemical conversion of organic carbon to carbon dioxide
CH2O + O2 <--> CO2 + H2O
Milutin Milankovitch
Carried out the first detailed calculations of sunlight intensity changes based on orbital cycles. His theory for ice age cycles/sawtooth pattern was that glaciation occurs when NH summer occurs when Earth is at aphelion by preventing snow accumulated during winter from melting as much, allowing it to survive until subsequent winter, gradually accumulating into glaciers/ice sheets. Deglaciation occurs when NH summer occurs at perihelion, allowing more melt during summer than accumulation in winter Effectively argues that intensity of summer insolation is a radiative forcing on the ice/albedo feedback Milankovitch hypothesis does okay job explaining past ice ages, but not as well as atmospheric CO2 concentration, which is much more accurate
Paleo-Eocene Thermal Maximum (PETM)
Climate change period of about 5-8°C of warming between the Paleocene and Eocene. Characterized by significant species evolution spurred by massive climate change over ~200,000 years. Occurred about 55.5 million years ago
How is climate distributed globally, and how will climate change affect this?
Climate is distributed as a bell curve, with the equator at the warmest and the poles at the coldest. Climate change will both shift the entire curve upward while also flattening it. We know from previous climates on Earth that warmer world = flatter curve, caused by less sea ice/albedo at the poles, so they warm more.
Heinrich events
Cold intervals in Greenland/North Atlantic region caused by rapid ice flow into the North Atlantic, dramatically decreasing salinity and shutting off deep water formation in region. Younger Dryas cold event was a massive Heinrich event caused by global deglaciation at the end of the last ice age
How did Earth stabilize its climate during the PETM?
Combination of CO2/weathering feedback and the exceptionally high concentrations of CO2 in the atmosphere dissolving the calcium carbonate in the ocean, producing bicarbonate that was stored in the ocean. The later process happens faster, in thousands of years versus millions
How do we know CO2 increase is from fossil fuels?
Concentrated in NH where most fossil fuels burned, mostly organic carbon in atmosphere (low C13/C12 ratio), low C14 radiocarbon means it's very old bc it takes a long time to decay, and we should actually see more CO2 in atmosphere given current fossil fuel burning
Hadley's hypothesis
Convection cells move air towards the Earth's poles, while surface flow moves it back towards the warm equator. This hypothesis was partially correct, but because of the Coriolis effect, the Earth actually has closer to three cells in Earth hemisphere, cut off by the tropics and the polar regions
How does global warming affect coral?
Coral bleaching, where higher ocean temperatures expel symbiotic algae from the corals that they need to survive.
Why did CO2 decrease over the Cenozoic period?
Current hypothesis is an increase in Earth's weatherability, which was caused by an increase in temperature/precipitation/vegetation density
Convection
Cycle where a material becomes less dense, gains energy, rises, becomes more dense, and then falls, w/ changes in density occurring due to conduction (often exchanging energy w/ surrounding air)
How does pressure change with atmospheric height?
Decreases at an increasing rate
What is obliquity and how does it affect climate?
Degree of Earth's tilt. 1 cycle = 41k years High obliquity = high degree of seasonality, low obliquity means little variation between seasons
What are the effects of sulfate aerosols?
Direct: Scatter and reflect some sunlight back into space Indirect: Shift water droplets in clouds from few large ones to many small ones, making clouds more reflective surfaces
Ice sheet ice streams
Discrete intervals of faster flowing ice w/in a ice sheets, typically at the margins
Why did emissions quadruple since 1960?
Doubling of global population and affluence w/ only small reductions in energy and carbon intensity
How does energy enter the Earth's system?
EM radiation from the Sun, which is produced via nuclear fusion, w/ the Sun's hydrogen atoms being compressed by its gravitational forced, yielding helium
Climate sensitivity
Earth's sensitivity to a given radiative forcing
1st Law of Thermodynamics
Energy is neither created nor destroyed
2nd Law of Themodynamics
Energy is spontaneously transferred from hot to cold objects, not from cold to hot
Conduction
Energy transfer mechanism where molecules directly collide into each other
Power
Energy transferred per time
IPAT relation (Kaya Identity)
Equation for estimating global emission rate of CO2 per year, used by IPCC E = P * A * T = P * A * EI * CI Emissions = population * affluence (($/yr)/person) * technology (energy intensity (joule/$) * carbon intensity (Pg C/joule))
La Nina
Event of higher trade winds, producing more upwelling along the equator, cooling the atmosphere b/c more upwelling = greater heat uptake relative to heat release in deepwater formation
El Nino
Event of lower trade winds, producing less upwelling along the equator, warming the atmosphere b/c less upwelling = less heat uptake relative to heat release in deepwater formation Future El Nino years will make extreme heat events even worse, possibly pushing them into dangerous territory for human/animal species health and surival
Why have we not observed the full amount of expected warming due to fossil fuel emissions?
Feedback cycles haven't had time to fully kick in yet. Sans action, models predict about 5 degrees C warming
Why does a lower O18/O16 ratio in foraminifera fossils indicate a higher temperature and/or lower ice volume at the time of fossilization?
Foraminifera prefer O18 to O16 isotopes when producing their shells, more so at lower temperatures. Additionally, O16 is preferred in ocean water evaporation, meaning that if there is more in the ocean, there must be lower ice volumes.
How does ice flow within ice sheets?
From high to low latitudes
What are possible options for carbon sequestration and what are their pros/cons?
Geological sequestration of carbon into deep reservoirs like saline aquifers. Mimics existing extractive technology, but negatives includes leaks or unknown reactions from stored carbon Acceleration of natural sequestration by planting trees, etc. Works, but only while trees are growing, and clearing trees reverses the effects Accelerating ocean as a carbon sink by liquifying CO2 3km in the ocean or reacting grinded silicate rock w/ CO2 emitted by power plants. Might work, might not, hasn't been widely tested Direct air capture of carbon dioxide (DACS): Giant filters collecting CO2 from atmosphere or smaller filters collecting directly from power plant and storing them using existing sequestration options. Factored into RCP2.6, more optimistic IPCC scenario
What is the relationship between wavelength and energy?
Greater wavelengths have lesser energy due to their lower frequency
Latent heat
Heat absorbed/radiated during phase changes of a material. In thunderstorms, as water vapor rises/cools, it radiates latent heat, causing the air around it to rise even further, preventing it from immediately cooling and precipitating. This buildup causes instability and greater precipitation
Why does a vacuum sealed mug still gradually cool?
Heat radiates from the inner wall, through the vacuum, to the outer wall, through which it conducts to the outer air
Glacial accumulation zone
Higher altitude zone of a glacier that's above the snow line where more snow accumulates than is lost to melt
Representative Concentration Pathways (RCPs)
IPCC estimates of CO2 concentration in the atmosphere. Labelled based on the radiative forcing by 2100
What would cause a "bad dream" Greenland scenario for sea level rise?
If water reaches the bed of the ice sheet, it can cause the ice to slide off more easily into the ocean and melt
Coriolis effect
In the Northern Hemisphere, winds diverge to the right of their initial trajectory. In the Southern Hemisphere, winds diverge left of their initial trajectory
Why does atmospheric CO2 concentration vary over the year?
Increased biosphere plant growth during warm months increases photosynthesis faster than respiration, taking CO2 out of atmosphere. Mostly in Northern Hemisphere bc of greater land mass.
Carbon footprint
Individual Kaya identity, w/ population set to 1
What happens as air moves from warm to cooler areas?
It can hold less water vapor, causing it to convert latent to sensible heat, causing precipitation. This transfer of latent heat between regions evens out Earth's climate
Why is permafrost melt a doomsday scenario?
It could allow massive decomposition of organic material, releasing significant amounts of potent methane. However, there is no evidence this is occurring, though it could if warming levels increase far beyond historic levels (we just don't know, uncharted territory)
How does the water vapor capacity of air change as its temperature increases?
It increases at an increasing rate
How does climate change affect the probability of extreme weather?
It increases the likelihood of extreme warm events while decreasing the likelihood of extreme cold events
What is the impact of methane on climate change?
It's a greenhouse gas, but it's concentration change has been ~10x less than CO2, though it is 30x more potent. Unlike CO2, it's broken down the in atmosphere by other particles, making it only last ~10 years
What's wrong with the claim that the earth hasn't warmed over the past 17 years? (Why is Ted Cruz a *******?)
It's cherry-picking data, with 17 years ago being a particularly high climate anomaly. The long-term trend shows clear warming.
What has been the greatest contributor to sea level rise so far?
Land glacial ice melt
Electromagnetic radiation
Light, transfer of energy via the emission of photons
Faint young sun problem: At current greenhouse levels and lower solar intensity, Earth couldn't have had liquid water, but it did. How was this possible?
Lower solar radiation led to decreased weathering, which increased atmospheric CO2, causing a stronger greenhouse effect, increasing Earth's surface temperature to support liquid water. As solar intensity increased, this process worked in the reverse direction while still stabilizing Earth's climate
Albedo
Measure of a surface's reflectivity of light, w/ 0 being complete absorption and 1 being complete reflection
Subtropical dry region
Meeting between the Hadley and Ferrel cells where air is warming up and falling, absorbing more water vapor and making the atmosphere drier. Key exceptions in FL, East Asian monsoon region. Caused by hot land surface due to high insolation just North of the equator causing significant amount of air to rise, expand, cool, precipitating more water and causing hurricanes/monsoons
How can North Atlantic deepwater formation be decreased/shut off?
Melting of ice sheets would greatly reduce North Atlantic ocean salinity, decreasing water density, and potentially shutting off deepwater formation, as has happened before A "climate surprise" could be if Greenland ice sheet, NA ice caps, and sea ice melt, this could shut off the NADW formation, causing slower warming/cooling in Europe while increasing warming in the SH. Will also decrease ocean heat uptake overall. Current trends indicate this may be in the early stage due to cooling patch in the NA
What are major barriers to lowering CI in our energy production/
Mismatches between power supply and demand, both in when power is needed (no solar at night, etc.) and where power is needed (deserts/plains are windy but most people live in cities) States and private actors have already made high-capital investments in fossil-fuel energy infrastructure High initial capital investment required to realize the economic efficiency of low-CI energy sources
What properties of EM radiation cause it to have greater energy?
More photons Shorter (favorite) wavelengths of each photon
What role does weathering and mountain formation play in stabilizing Earth's climate?
Mountain formation causes a spike in Earth's weathering rate, decreasing atmospheric CO2/greenhouse effect intensity/temperature
Subsidence
Natural and human caused gradual sinking of land. Makes some regions more vulnerable to sea level rise than others, increasingly so Happening significantly in places like Galveston, TX
What is the feedback loop between Earth's surface temperature and outgoing IR flux?
Negative feedback, stabilizing Earth's climate. As surface temperature increases, outgoing IR flux increases, decreasing surface temperature
CO2 / rock weathering feedback loop
Negative/stabilizing feedback loop wherein, hypothetically, an increases in Earth's surface temperature would increase rainfall and silicate weathering, the latter of which would decrease atmospheric CO2, decreasing the intensity of the greenhouse effect, thus decreasing Earth's surface temperature
Dry bulb temperature
Normal ambient air temperature measured by a thermometer.
What migration have we observed as a result of climate change over the past ~40 years?
Observed organisms/species migrated an average of 17 km/decade poleward and 11 m/decade vertically
Pycnocline layer (density gradient)
Oceanic layer between surface layer and deep layer of the deep ocean
What component of Earth's system is taking up the most energy?
Oceans, by a large margin
What are the opportunities associated w/ reducing carbon intensity?
Only 11% of the US energy grid is powered by renewables, w/ only 21% and 6% coming from wind/solar respectively. Massive room to grow Over last decade, utility-scale solar and wind have become cheap that coal, gas, and nuclear, and trend appears to be continuing. Decarbonization is sound economic policy
Why is the solar power intensity average on Earth over a day S/4?
Only ~1/4 of Earth is exposed to Sunlight at any given moment, meaning every spot on Earth receives about 1/4 of the solar intensity of S over a day. This is shown by the fact that Earth would cast a circular shadow, which has 1/4 the surface area of a sphere
What types of species will benefit from climate change?
Opportunistic/generalist species, which can respectively thrive in new ecosystems (often as invasive species) and do well in a broad array of environments
Photons
Particles of light, both particle and wave
What part of Earth is the greatest determinant of its albedo and why?
Parts closer to the Equator b/c the Equator receives more sunlight on average
Aphelion
Point in a planet's orbit that is farthest from the Sun
What factor has the potential to increase sea level rise by the greatest amount over time, and why has it not yet?
Polar ice sheets. Mountain glaciers have a greater surface area to volume ratio, causing them to absorb lots of heat w/ a relatively lower melting point, while ice sheets have a significant volume not exposed to sunlight/heat, making them melt slower This is not good, because this means ice sheets are likely to continue to melt even if we stop emitting CO2
What is the relationship between the number of positive/negative connections in a feedback loop and whether that loop is positive/negative?
Positive feedback loops have zero or even numbers of negative connections Negative feedback loops have odd numbers of negative connections
Ice/albedo feedback
Positive feedback process where increased ice/snow cover increase planetary albedo, decreasing Earth's surface temperature, and increasing snow/ice cover further
Stefan-Boltzmann Law
Power intensity = sigma * T^4. The rate of light emission per area from an object is proportional to its Kelvin temperature to the 4th power
Power intesnity
Power per area
What is Ekman transport and what effect(s) does it have?
Process by wind affects the flow of the ocean. In NH, surface waters flow to the right of the winds, in SH to the left. Ekman transport causes upwelling along the equator b/c trade winds blow west coming from both directions. This upwelling pulls up NA deepwater
Weathering
Process of precipitation dissolving CO2, forming carbonic acid in the soil, which reacts w/ calcium silicate and transports the ions to ocean, where they form calcium carbonate (limestone) and silicate
What is North Atlantic deepwater formation and how does it affect Earth's climate?
Process where as surface ocean is transported to higher latitudes by subtropical gyres, it cools, becoming more dense, and sinks b/c it is now cold and salty. As this occurs, the cooling water releases its heat into the atmosphere, warming it, sinks, is transported to the equator and to the Southern ocean, where it upwells at both, and moves back North. Deepwater formation warms the NH and cools the equator and South Pole.
Polar amplification
Processes in which global warming causes greater temperature increases at polar regions, in part due to changes in latent heat transport and the melting of polar ice
Metamorphism
Reaction of calcium carbonate and silicate that produces calcium silicate and carbon dioxide. The calcium silicate returns to the Earth's calcium silicate reservoirs while the CO2 returns to the atmosphere through volcanic activity
Why has atmospheric CO2 increased by less than expected based on fossil fuel use?
Reforestation of ancient cleared land absorbing some emissions, ocean absorbs some emissions into deep water
Dansgaard-Oeschger cycles
Regional climate events where Greenland and Antarctica have asymmetric warming/cooling cycles that are opposite each other, causing various regional temperature flickering during larger global trends
What is the equation representing the balance of energy in and out of Earth's system in a simplified perfect 1-layer atmosphere model?
S/4 * (1 - albedo) = sigma * T_ground^4
Sensible heat
Temperature of the air, or average kinetic energy. What can be measured w/ a thermometer
What are the types of energy in an air parcel?
Temperature/sensible heat, water vapor content/latent heat, and height/GPE
Why would a climate change event like the PETM on a rapid time scale be disastrous for life on Earth?
The PETM led to climate stabilization and species evolution over thousands of years, while current global climate change is happening at a much more rapid rate, and would likely lead to mass extinctions if it were to the scale of the PETM at the current rate
Why do shifts of carbon from Earth's reservoirs to the atmosphere have such a significant impact on Earth's climate?
The carbon in Earth's reservoirs is orders of magnitude more than that in the atmosphere, ocean, and on land
What is precession and how does it affect climate?
The direction in which Earth's axis is aimed. 1 cycle = 22k years, a full cycle looks like Earth is spinning like a top It affects Earth's climate by changing the time of year when each hemisphere experiences summer, and in combination w/ eccentricity affects the insolation intensity at its most intense period each year in each hemisphere
Radiative forcing
The immediate difference in energy between Sunlight absorbed at the top of Earth's atmosphere and the IR radiation emitted into space by Earth due to a change in the Earth's system Over time Earth's temperature changes to balance out the radiative forcing
Wet bulb temperature
The lowest temperature that can be obtained by evaporating water into the air. Will be cooler than dry bulb b/c it includes process of evaporative cooling 35°C is the limit of human survivability. Will died in ~5 hours at this temperature. Northern Indian, North China Plain expected to have extreme heat events >35°C wet bulb temperature due to climate change
What is the Earth's dominant heat sink and over what time scale does it act?
The ocean. It acts over the long term, w/ CO2 dissolving in the surface ocean, reacting with the water and calcium carbonate to form bicarbonate ions/limestone
What is the Holocene?
The period beginning after the last global ice age covering the last 10-11k years. Distinguished by relatively stable climate w/ moderate cooling ~5k years ago. Coincided w/ development of human civilization
What is eccentricity and how does it affect climate?
The shape of Earth's orbit around the Sun. 1 cycle = 100k years High eccentricity magnifies the effect Earth's precession has on insolation
How do Earth's orbital features affect its climate?
They affect Earth's seasonality and how insolation is distributed, but not total solar insolation Earth's feedback cycles cause these shifts in distribution/seasonality to affect overall climate
Do sulfate aerosols have a short or long term effect?
They stay in the upper atmosphere for 5 years due to limited weather, but are not constantly emitted (mostly all at once during volcanic eruptions)
Post-glacial rebound
Upper Earth is rebounding from removal of weight of glacial ice at end of last ice age, causing some land uplift in a few places, leading to decrease in sea level
Why is reducing carbon intensity more important than reducing energy efficiency?
We've already reduced energy intensity significantly, and it hasn't had nearly enough impact, while carbon intensity has barely decreased so far.
Sawtooth pattern
We've seen this over the last ~1.2m years in Earth's O18/O16 ratio, indicating progressive glaciation, then rapid deglaciation within a 5-10k year time period
How does ocean acidification occur?
When CO2 is absorbed by the ocean, it reacts with water to form carbonic acid (H2CO2). This then breaks down into hydrogen ions, increasing the water's pH.
How did Earth break the ice/albedo feedback cycle during "snowball Earth" ice ages?
When Earth was sufficiently covered by ice/snow, weathering halted, leading to a buildup of CO2 in the atmosphere/increase in greenhouse effect intensity, thus increasing the Earth's surface temperature and melting much of the ice
Subduction
When older parts of the lithosphere are forced back into the Earth's mantle when ocean and continent plates meet
Perihelion
When the planet is closest to the sun.
Intertropical Convergence Zone (ITCZ)
Zone near the equator where atmosphere is highly saturated with water vapor, causing significant condensation and producing a band of clouds
What is Earth's climate sensitivity based on GCM and does it incorporate feedbacks?
~0.8 degrees C / W/m^2, and yes
What is the cumulative radiative forcing over the past century?
~2.3 W/m^2, or about 1% of solar energy
