Earth Science Exam #1 (10/14/24) Flashcards
earth system
atmosphere - air
hydrosphere - water
geosphere - land
biosphere - life (outlier - limiting the human influence on the Earth system so that Earth can last)
definitions: system
- an entity composed of diverse but inter-related parts that function as a complex whole
- coordinated or related sets of processes and components through which material or energy flows, characterized by continual change
- dynamic, constantly changing
- different states of Earth through time
definitions: earth model
includes all the biodiversity, atmosphere etc
definitions: components
- individual parts of the system (the ocean, the atmosphere)
- component within components (friction is part of the atmosphere)
definitions: state
- attributes that characterize the system at a particular time
Earth photo: Blue Marble (1972)
- represents Earth as a small dot in a sea of black
- marks a point in earth science in which people started to reexamine the earth system of interconnected parts
- people started to run models that included all the different components of the earth system so they could make projections of the future and scenarios of the past
systems approach in human physiology
- homeostasis: when everything is in balance
- when everything is wrong in one system, it’s not always clear what the problem is
Global average temp 1850-1990
- temp has gone up 0.8 degrees
- in 1988 the IPCC Was started to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts
IPCC report style
- policy relevant, not policy prescriptive: climate scientists aren’t deciding policies but are giving the facts so that policies can be made keeping them in mind
IPCC 1st report questions (1990)
- is global warming occuring?
- are human activities responsible?
- can we quantify the factors responsible?
Fingerprinting Challenge (1st report)
- attribution science
- identifying changes in the earth system and figuring out what is causing them
- requires knowledge of the Earth System and its history
- thought that the increase in temp was related to the sun
- observed change in solar luminosity over time but it only gets brighter 1% every 100 million years
Jean-Baptiste Joseph Fourier (1820s)
- hypothesized the idea that the atmosphere acts as an insulator for the earth: greenhouse effect
John Tyndall: 1862
- certain gases opaqaue to IR: greenhouse gases
Svante Arrhenius: 1890s
- CO2 as Geologic temp control
- thought about what would happen if we doubled the amount of CO2 in the atmosphere
- theory that volcanic eruptions had been increasing
- found more evidence of CO2 going into the atmosphere due to volcanic eruptions but there hasn’t been an increase in very big global eruptions
(more likely that as population increases, more abilities to observe things)
Keeling curve
- made lots of observations about CO2 concentration in Hawaii because the atmosphere there is very well mixed due to Pacific winds
- In Russia they drilled to 800,000 years ago and found lots of variability in amount of CO2 but nowhere near as much as we have now
4th IPCC report (2007)
- earth is warming
- unequivocal that it is human-caused
6th IPCC report (2022)
- what’s the rate of change?
- what are the tipping points?
- how can we mitigate?
- how can we adapt?
definitions: couplings
- components do not exist in isolation, they are linked
- describes the relationship between components
- can be positive, negative or nonexistent
Ex:
CO2 → temperature + (positive, CO2 goes up, temp goes up)
Temperature ―⚬ sea ice - (negative, temp goes up, sea ice goes down)
definitions: feedback loop
- self-perpetuating mechanism of change and response to that change
- a linkage of 2 or more system components that form a round trip flow
- can be positive (self-reinforcing) or negative (self-diminishing)
Ex:
Temperature ⟺ water vapor + (as temp increases, WV increases, as WV increases, temp increases)
Temperature ⟺ low-level marine clouds (temp increases, clouds increase which deflect sunlight causing temp to go down)
definitions: stability
- characterizes how a system of components will react to small perturbations in any or all of the system’s components
- achieved if negative feedback in a system is stronger than positive feedback
- a system is unstable if positive feedbacks are stronger than the negative feedbacks
definitions: perturbation
- temporary disturbance of a system
- for example, volcanic injection of SO2 into the stratosphere
definitions: forcing
- persistent disturbance of a system
- for example, increasing solar luminosity through time
planetary energy balance
Energy absorbed by planet → planet → energy emitted by planet
- some of the energy from the sun is absorbed by the earth and some of it is emitted back into the atmosphere/space
Formula for energy absorbed
= energy intercepted - energy reflected
= Πr2 x S - Πr2 x SA
S = a constant
A = albedo, set amount of radiation that automatically reflects and never enters the earth system
= Πr2S (1-A)
formula for energy emitted
= 4Πr2 x σT4
σT4 = S/4 (1-A)
Gaia hypothesis
- living organisms increased with their inorganic surrounding to form self-regulating complex system that helps perpetuate habitable conditions on Earth
Criticism: Biota would need the capacity for foresight to prevent large fluctuations in the surface environment
Daisyworld properties
- tells us things about planetary systems with varying levels of complexity
- white daisies and grey soil
- no atmosphere
- no clouds
- solar luminosity rapidly increasing
Daisyworld pertinent properties
- Albedo: measure of the reflectivity of the surfaces
- Daisies are sensitive to temp
relationship between daisy coverage and SFC temp
- as daisy coverage increases, average surface temp decreases
- negative coupling has a negative slope
- Daisy coverage ―⚬ average surface temp
- as average surface temp increases, daily coverage increases until the optimum point is reached and it’s too hot for daisies, then begins decreasing (upside down parabola)
- optimum point identifies where the relationship in the coupling
- Average surf temp → daisy coverage | average surf temp ―⚬ daisy coverage
Daisyworld small perturbation feedbacks
- At P1 we are in a stable equilibrium state because the temp allows for daisies to thrive and reflect which decreases the average temp = Negative feedback loop
- At P2 there is an unstable equilibrium state because we are above optimum temp, so daisies are killed and therefore there will be nothing reflective =positive feedback loop
Daisyworld climate history
- threshold behavior identified - lifeless case
- if we add daisies the temp evolution of the planet will dip