100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
Summary Lectures System Earth (MAQ23306) $3.74
Add to cart

Summary

Summary Lectures System Earth (MAQ23306)

 16 views  0 purchase
  • Course
  • Institution

Extensive overview of the contents of the lectures from System Earth (MAQ23306)

Preview 4 out of 61  pages

  • May 21, 2021
  • 61
  • 2020/2021
  • Summary
avatar-seller
Summary
Chapter 1: Global change




Climate and global change impacts:
- Netherlands: Potential flooding depth and economical damage
- Bangladesh: increased risk of flooding

Largest impacts of climate change might be seen in regions:
1. That contribute relatively little to the problem
2. Where society cannot easily adapt to climate change

Effects of climate/global change:
- Sea level rise
- Salt intrusion
- Drying
- Amazon die-back
- Permafrost melting
- Ocean acidification
- Changing ocean circulations
- Changing food distribution
- Declining biodiversity
- …

Natural drivers of climate system and of climate change/variability:
1. The sun
o Sun is becoming brighter
o In the past, solar radiation was very low
2. Earth’s orbit
o Earth rotates and wobbles like a top
▪ Moon reduced wobbling; how is this relevant for Earth’s climate?
3. Atmospheric composition
o Greenhouse effect
4. Continents and tectonics
o Position of continents
o Radiation balance

, o Volcanism and weathering
▪ Weathering takes CO2 out of the atmosphere
5. Ice dynamics
6. Life
o Already around 3.8 billion of years ago
o Enhances weathering
o Photosynthesis lowers CO2
▪ CO2 + H2O → CH2O + O2
o Methane production
enhances greenhouse
effect
▪ CO2 + 4H2 → CH4 +
2 H2O
o The Anthropocene

Geological clock




Rise of oxygen about 2 billion years ago:
- Ecosystem changed radically: ecological disaster
- Strong decrease in CH4 and CO2: ice ages

Very limited information through small number of observations.
To close the story we need:
1. To conduct system analysis
2. To understand the behaviour of system Earth
3. Combining the information based on limited observations with models & development of
hypotheses
To learn from understanding the past how the future might be

Chapter 2: Daisy World

What are systems?
- An entity composed of diverse but interrelated parts that function as a complex whole
- Examples:
o Human body; respiration system
o Biosphere; photosynthesis system
o Economy; capitalistic system

The state of a system is a set of attributes, state variables, that characterizes the system at a
particular time
- State variables:
o E.g. temperature, pressure, mass

, o State variable is a parameter, develops depending on where it comes from

System Earth
- Subsystem of the solar system
- Components:
o Atmosphere
o Biosphere
o Hydrosphere
o Lithosphere
o Cryosphere
o Anthroposphere
- State variables
o Energy balance
o Pressure
o Earth’s orbital rotation state
o Composition
- Component interactions
o Exchange of energy, H2O, matter, etc. ‘

Feedback is a self-perpetuating (enable or effect) mechanism of a change and a response to that
change

Jimmy Carter with electrical blanket example

Equilibrium state: the state in which the system will remain unless the system is disturbed
- How far do we have to push as system to reach an alternative stable state
- Are we currently pushing our system Earth so far away from a stable equilibrium that we
might soon reach this peak where the system will switch to another (unknown) stable
equilibrium?
- Reaching a tipping point
- Examples:
o Ecosystems
o Glaciation

Perturbations: temporary disturbance of the system
- E.g. Vulcanic eruption
- Fertilization of oceans from mineral dust of Sahara

Forcing: a more persistent disturbance of the system
- Milankovitch cycles

Daisy world:
- Self-regulating systems
- Natural systems can be self-regulating on a global scale without the need for intelligent
intervention
- Forcing, albedo and temperature
o High albedo, low T
o Low albedo, high T
- Daisy growth depends on temperature
o Minimum, optimum, maximum
- Daisy coverage leads to lower average surface temperature
- Daisy coverage is affected by temperature
- When both graphs are put into one, the points where lines connect (p1, p2) are the
equilibrium states

, - On any other point then p1 or p2 on the parabola, the effect of T on daisy cover is correct but
not the effect of daisy cover on T
- Assuming that daisy cover does not increase with solar luminosity but only depends on
temperature
o Temperature increases, T line moves up
o Parabola: smaller temperature change, than temperature change without the
feedback
o Delta Teq = Delta T0 + delta Tfeedback (<0)
o Feedback factor f = Delta Teq / Delta T0
▪ Value of feedback factor is between 1 and 0
- Positive feedback loop: no feedback factor (or >>1) for the system in the unstable state:
o Runaway effect

Gaia hypothesis:
- Living organisms interact with their inorganic surroundings on Earth to form a synergistic and
self-regulating, complex system that helps to maintain and perpetuate the conditions for life
of the planet
- Livelock suggested that global biological feedback mechanisms could evolve by natural
selection, stating that organisms that improve their environment for their survival do better
than those that damage their environment
- Doolittle argued that nothing in the genome of individual organisms could provide the
feedback mechanisms proposed by lovelock and therefore the Gaia hypothesis is not relying
on any specific mechanism
- Dawkins stated that organism to act in concert would required foresight and planning, which
is contrary to the current scientific understanding of evolution
- Evolutionary biologist Hamilton added that it would take another Newton to explain Gaian
self-regulation takes place through Darwinian natural selection

CLAW hypothesis:
- Proposes a negative feedback loop that operates between ocean ecosystems and the Earth’s
climate
- Phytoplankton produce DMS are responsive to variations in climate forcing, and that these
responses act to stabilise the temperature of the Earth’s atmosphere

Summary
- Introduction in the key parameters of Earth system studies: systems, components, state,
couplings and feedbacks
- Use of system diagrams and advantage of following a system approach
- Feedback is a self-perpetuating mechanisms of a change and a response to that change
- Combination of- and quantification of feedbacks
- Equilibrium, stability
- Perturbations and forcing
- Self-regulating systems; Daisy world

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller Dierwetenschapper. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $3.74. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

53022 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 14 years now

Start selling
$3.74
  • (0)
Add to cart
Added