spaceship earth: week 1

Earth system science

The interdisciplinary study of Earth as an integrated system of interacting
components (atmosphere, oceans, land, ice, and life)

The spaceship earth analogy

Viewing Earth as a closed system with finite resources, drawing
parallels with spacecraft like Apollo missions

Closed systems

Systems where matter is contained within the boundaries and there is no exchange
of matter with the external environment, although energy can enter and leave

Finite resources

The limited availability of materials within a closed system

Recycling

The process of converting waste materials back into usable resources, crucial for
sustainability in closed systems.

System stability and balance

The state where inputs and outputs of a system are in equilibrium, maintaining stable conditions

The role of energy

The fundamental requirement for all system functions, without energy systems cease to operate

The earths unique characteristics

The presence of liquid water, an oxygen-rich and carbon dioxide-poor
atmosphere, and the existence of life, distinguishing it from other planets in our solar system

Human impact on earths systems

The significant and unprecedented ways in which human activities
are altering the Earth's atmosphere, oceans, lands, and life forms.

Global climate change

The existential threat resulting from rising carbon dioxide levels and
associated increases in global temperatures.

The earths climate control system

The processes that maintain relatively stable surface temperatures
over long periods, including the presence of water in its three phases

The importance of data modelling and action

The necessity of monitoring Earth system function
through big data, using simulations to understand processes and project changes, and translating
understanding into informed action.

Earth system science approach

• Earth System Science (ESS) provides an integrative and holistic framework for understanding our
planet, viewing Earth as a single, complex, and adaptive system comprised of interacting subsystems.
• It contrasts with reductionist approaches by emphasizing the connectivity of, and interactions
among, the different parts of the Earth system to determine how they regulate planetary function.
• ESS is a scientific pursuit that employs the scientific method, including observation, measurement,
and hypothesis testing

System

A collection of component parts that are arranged and interconnected to work together to fulfil a particular function

Isolated system

Theoretically have no exchange of either matter or energy

Do no truly exist in the natural world

Closed systems

allow energy passage but contain an essentially finite amount of matter that is cycled
internally; the Earth approximates a closed system

Open system

characteristic of most natural systems, exchange both matter and energy across their
boundaries and readily interact with their environment

Hierarchy of systems

Exists where the earth contains interconnected open subsystems that can be further broken down. The level of detail depends on the research question.

Black box concept simplifies internal processes for broader modelling

Feedback

occurs when outputs are folded back into inputs, modulating system response to
environmental changes.

Negative feedback loops

act in opposition to initial changes, promoting stability and homeostasis (a
state of "similar standing still") within a narrow range

Positive feedback loops

amplify and accelerate an initial perturbation, leading to directional change

Dynamic equilibrium in a system

Many natural systems tend towards a dynamic equilibrium or "steady state disequilibrium," where
stability is maintained by constant exchange and a balance of forces and fluxes requiring a continuous
supply of external energy, rather than being static

Six shared qualities of natural systems

• They are in motion.
• They are sustained by a flow of energy from an external source.
• Matter cycles through and is recycled within them.
• Feedbacks operate to maintain them in a narrow range of states, typically a dynamic equilibrium.
• They are nested hierarchically, containing subsystems and contributing to larger systems of systems.
• Their function can alter over time in response to external change and internal system behaviour

What 4 spheres is the earth system represented by

Geosphere, hydrosphere, atmosphere, biosphere

Geosphere

Solid earth including rock sediments and soils

Hydrosphere

All water on the planet, ex. Oceans, lakes, snow, ice and ground water

Atmosphere

The mixture of gases surrounding the earth, primarily nitrogen and oxygen

Biosphere

All living organisms and undecomposed organic matter

Biosphere makes earth unique among all known planets

Reservoirs

Stores of material within the earth system

Fluxes

describe the continuous flow of material from one reservoir to another within a cycle, such as
the hydrological cycle's exchange of water among the atmosphere, ocean, and land via processes like
evaporation and precipitation.

Residence time

is the average duration a substance remains within a particular reservoir, calculated
by dividing the reservoir size by the incoming or outgoing flux (for a steady-state system). For
example, water's residence time is approximately 3740 years in the ocean but only about 11 days in
the atmosphere.

Bretherton diagram

introduced in a 1986 NASA report, provides a framework for understanding
Earth system function at decadal to century scales, importantly acknowledging human activities as a
significant driver of global change

Anthrosphere

Part of the environment which is made of modified by humans for their activities

Reductionism

is a scientific method that simplifies complex problems by breaking them into smaller,
analysable parts. This approach has been powerful in establishing fundamental laws, such as E=MC²

Determinism

the belief that a system's future
state can be predicted given sufficient knowledge of its current state. While effective in certain
contexts, these classical assumptions often break down when applied to complex natural systems.

Systems thinking

contrasts with reductionism by emphasising that understanding a system requires
knowledge of the relationships among its components, not just the components themselves. It posits
that “the whole is greater than the sum of its parts”

Complicated system

like a jet engine, has many parts that function predictably due to an
organisation imposed by designers and control by a single agent

Complex system

such as a flock of birds, lacks central control or imposed organisation.
Its organisation arises spontaneously from local interactions among its components, leading to
emergent behaviour

Self organisation and emergent behaviour as hallmarks of complex systems

where coordinated
patterns arise from individual components following simple, local rules without central direction. This
is exemplified by bird flocking

Agent based models

simulate these systems by endowing individual components with "agency" – the
ability to make autonomous decisions based on simple rules.

Challenges of prediction complex system

• Complex systems exhibit sensitivity to initial conditions, meaning even minor differences in a
system's starting state can lead to vastly different future outcomes.
• This unpredictability is captured by chaos theory, which states that "the present determines the
future, but the approximate present does not approximately determine the future".
• The "butterfly effect" illustrates this concept, where a small perturbation can lead to significant,
distant consequences. This inherent uncertainty in initial conditions fundamentally limits the long-
term predictability of complex systems, such as weather

Earth as a complex system

• Spaceship Earth is recognised as a complex system. Earth system science integrates systems thinking
and complexity theory to complement classical reductionism in its study.
• Predicting Earth's future behaviour is challenging due to numerous interconnected variables with
non-linear interactions, emergent behaviour, sensitivity to initial conditions, incomplete information,
and the adaptive nature of the system itself.