Lecture 1 Flashcards
(37 cards)
The earth system
A system is any assemblage or combination of interacting components (for example the human body)
The earth system has four major interacting parts, with flows of matter and energy between them.
What are the four major earth systems?
Biosphere
Atmosphere
Hydrosphere
Geosphere/lithosphere
What is anthroposphere ?
Human impacts and the built environment
Geosphere/lithosphere
Rocks and sendimemts.
The solid earth. The upper part of the solid earth, which interacts with the other components of the Earth System, is called lithosphere.
Atmosphere (a mixture of gases)
The air
Mainly nitrogen (N2) and oxygen (O2)
Carbon dioxide (CO2) essential for life.
Transfer of heat and light
Hydrosphere (totality of Earth’s water)
Salt or fresh, liquid, or vapor
Surface waters, glaciers, and ground water
Cryosphere is the perennial frozen parts
Biosphere
All the planet’s living organisms
As well as recently decreased and decaying organic matter
** Ecosphere
The term ecosphere includes the biosphere plus its interactions with the physical systems.
Anthroposphere (human realm)
Anthroposphere =technosphere
- encompassed parts modified by humans
- interaction of the anthroposphere with other subsystems of earth = environmental science.
Earth system science
In earth system science, the findings of physical and biological sciences are integrated into a global view of our planet.
This approach considers the complex interconnecting web of physical, chemical and biological processes, and the modifications of these processes and of the earth system’s components through time.
There are two sources of energy to fuel the earth system:
External energy and internal energy
External energy comes from solar radiation, which drives the hydrologic cycle and the circulation of atmosphere and oceans; these, in turn, cause erosion of the land surface.
Internal energy which drives volcanism and lithospheric deformation (plate tectonics) – from radioactive decay in the earth’s interior.
Global change
The modification of the earth system’s components and of the interactions between these components, both natural and human-induced, are referred to as global change.
** change is not a recent phenomenon, it is a characteristic aspect of the earth system.
Types of global change
Gradual– takes place over long periods of geologic time (millions to billions of years)
Catastrophic - takes place rapidly in geologic time (from seconds to centuries)
Unidirectional– evolution o solid earth, evolution of atmosphere, evolution of life .
Cyclic– supercontinent cycle, sea-level cycle, glacial-interglacial cycle
Graphs of environmental systems in space and time
Graph shows characteristic spatial scale and time scale
Example of natural change – great oxidation event (GOE)
Caused by photosynthetic events inside the oceans. (Know more details)
GOE occurred around 2.4 billions years ago.
Evidences like red stone (the Fe2+ inside the rock are oxidized –rusty- red)
Human induced change? –weakening of the stratospheric polar vortex by arctic sea-ice loss
A recent study predicts that as the world gets warmer, parts of North America, Europe and Asia paradoxically could be hit by such cold snaps more often due to blasts of arctic air.
Shrinking sea ice could allow more energy to be transferred from the warmer ocean waters beneath it into the atmosphere.
That energy weakens and distend the polar vortex, which actually is a huge cyclone of swirling high-speed winds that keep cold air trapped in the arctic.
When the vortex weakens, it allows the cold air to slip southward.
Population growth has driven our environmental impacts
Why so many humans?
- old Stone Age
- agriculture revolution
- industrial revolution
- medical-technological revolution
Human needs energy and resources!!
Human population bombed after industrial revolution-two reasons
The production of fertilizer from ammonia (but the cost of massive energy)
The improvement of health care
Humans require energy
The results of this are: Deforestation Desertification Enhanced greenhouse effect (climate change) Loss of habitats and biodiversity Air and water pollution Soil degradation and erosion Ozone hole Ocean acidification Acid rain
Our universe (introduction)
- the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them.
- created from a very small, dense conglomeration of matter and energy (called a singularity) that then exploded - the BIG BANG!
Aftermath of the Big Bang
- hot cloud containing only H (98%) and He (2%)
- gases clump into separate clouds (nebulae)
- collapse of nebulae leads to formation of protostars
- the high pressures and temperatures reached within protostars lead to nuclear fusion processes (fusion of hydrogen atoms to create helium atoms)
Stars: ‘’ element factories’’
- Fusion reactions: fusion of H to produce He until H is used up, then fusion of He to form heavier atoms until He is consumed, and so on up to the formation of Fe in large stars (10-30 times the mass of the sun)
- When a very massive star runs out of fuel, a very energetic explosion occurs, so that elements heavier than Fe are formed (supernova)
- Star death seeds the universe with heavier elements that mix with residual gas from the Big Bang.
- a subsequent generation of stars containing a larger proportion of heavier elements forms out of the more compositionally diverse nebulae.
- today 99% of the mass of the universe consists of H and He; only 1% is heavier elemental matter.
Formation of our solar system
- The Sun is a third - or fourth- generation star developed 5 b.y ago from a nebula that contained all 92 elements (99% H and He, the rest 1%)
- Planets developed from the residual ring of dust and gas surrounding the newly formed Sun.
Formation of planets
- The gas and dust from the protoplanetary nebula condensed into planetesimals that then clumped together to form protoplanets, and eventually true planets.
- Inner, rocky planets made up of heavier elements: iron, magnesium, silicon and oxygen.
- Outer, gaseous and icy planets made up of frozen gases and lighter elements: hydrogen (H), helium (He), methane (CH4) and ammonium (NH3)
