EVS 1101 Chapter 1

Introduction to Environmental Sciences

The Big Bang

matter condensed into single dense point 13.8 Ga

extreme heat made unstable, lead to rapid expansion

Vastness of space

big bang led to this

unknown how many stars/galaxies in the Universe - believe its infinite

The milky way

• our galaxy

• formed 13.6 Ga

• grew from 1 or several overdensities (increased areas of mass, form nuclei of galaxies) shortly after the Big Bang

• 200-400 billion observable stars

• contains our solar system

star

celestial body of gas that shines by radiation derived from nuclear fusion reaction

nuclear fusion reactions

crushing of elements to allow new elements to form

ex. sun - hydrogen fuses to form helium

what is one of the most important characteristics of a star

mass - this size determines a stars lifespan, behaviour during its evolution, and the end of its life

• must have minimum mass for the conditions of temperature and pressure within the central region (core) to allow for initiation and maintenance of nuclear reactions

• the bigger mass, bigger the star, as more nuclear reactions can occur

solar system

created 4.6 Ga

began when a gigantic cloud of gas and dust covered with ice began to collapse under its own gravity

"second-generation" meaning it formed from material recycled from earlier stars.

precursors leading to Earth

collapse of cloud of dust → formation of protostar + protoplanetary disk (with protoplanets) → sun formation at centre via nuclear fusion

thus, the progressive agglomeration/accretion of dust gave rise to planetesimals, which gave rise to 8 planets and satellites

oxford languages definition of life

The condition that distinguishes animals and plants from inorganic matter, including the capacity for growth, reproduction, functional activity, and continual change preceding death

E. Javaux, Ulièges definition of life

Life is a series of chemical processes confined in a compartment (cell), exchanging energy and matter with its environment and transforming it (metabolism), reproducing itself through the transfer of information (genetic code) by natural selection

NASA definition of life

Life is a self-sustaining chemical system capable of Darwinian evolution

habitability

set of conditions necessary for life (even if it does not itself exist)

ex. a house - people can live in a house

3 criteria for planetary habitability

1. source of energy

2. chemical elements essential for life

3. liquid water (at optimal temp. and pressure)

habitabile zone

the defined area around a star, where temp. conditions allow for liquid water to exist on planet surface

• earth is is the habitable zone of the sun

geosphere

solid (physical) part of the earth, includes rocks and minerals

3 parts: core, mantle, crust

core

rich in Fe and Ni

• heavy metals that sink down

mantle

variable composition (Fe, Mg, Al, Si, and O)

• less heavy elements, still some

crust

rocky outer “skin” composed of O, Si, Al, Fe, Ca, Mg, Na, etc

continental crust

thick, primarily granite

Oceanic crust

thinner, primarily composed of basalt

tectonic plates

• created by the internal heat of Earth drives convection currents in mantle, that causes movement of overlying crust

• 15 main tectonic plates

• when they move, they collide, driving surface geographic processes (ex. formation of new crust, earthquakes, volcanism, mountain building)

hydrosphere

combined mass of water found on, under, above surface of earth

• oceans, glaciers, ice, underground, atmosphere, rivers and lakes, living organisms, ground

cryosphere

all masses of ice, snow, frozen ground (permafrost) present on earth

atmosphere, what are gases composing it

gaseous envelope surrounding certain celestial bodies (ex. earth, venus, mars)

• N₂ : 78.08%

• O₂ : 20.95%

• Ar : 0.93%

• CO₂ : 0.041% - but increasing

• water vapor + few noble gases Ne, He, Kr, Xe, H₂

biosphere

areas where life develop - all living organisms on Earth and habitats they occupy (ie. planets ecosystems)

anthroposphere

human presence throughout the Earth system

• not just our physical being - culture, technology, built environment, associated activities

• appeared 1Ma

• rapidly changed all other spheres

how do different spheres interact?

environment

everything that surrounds and affects an organism (biotic and abiotic)

ecology

study of living beings and their interactions

environmental issues and history

environmental issues have persisted throughout human history (not new problem)

• Prof. Jared M. Diamond: collapse of pre-industrial civilizations were self-inflicted ecological disasters. factors like environmental damage, climate change, globalization, population growth, and poor political choices have historically led to societal collapses.

Sumerians - example of how anthropogenic activity created problems which were accelerated by natural processes

• Ancient civilization 4100-1750 BCE

• first to build cities - collectivization of human race

• depended on irrigated agriculture, diverted water from Euphrates (river) → causing evaporation rate and salt concentration to increase (salinization) in fields over centuries → contributed to climate change - drought → reduced agricultural production → collapse of civilization (emigration, depopulation, wars)

what is meant by “earth is a closed system”

nothing enters or leaves planet in large quantities

• resources are finite limited

• waste does not disappear

planetary boundaries

set of 9 environmental limits within which humanity can safely operate to maintain Earth's stability and resilience

• proposed framework to describe limits to the impacts of human activities on the Earth system

• beyond these limits, no longer able to self-regulate, earth system would leave period of stability

climate change - planetary boundary

Refers to the concentration of greenhouse gases in the atmosphere. Staying within safe limits is crucial to maintaining a stable climate

• stakeholder: atmosphere

• main driver: global greenhouse

Biosphere Integrity - planetary boundary

Includes genetic diversity (biodiversity loss) and functional diversity. Loss of species and ecosystems undermines Earth's resilience.

• stakeholder: biosphere (land and sea)

• main driver: over exploitation and pollution

Stratospheric Ozone Depletion - planetary boundary

The reduction of the ozone layer increases harmful UV radiation, posing risks to life.

• stakeholder: atmosphere

• main driver: ozone depleting substances

ocean acidification - planetary boundary

change in pH of ocean (make too acidic), it reduces marine biodiversity and damages coral reefs.

• stakeholder: biosphere (sea)

• main driver: CO₂ emissions

biochemical flows - planetary boundary

Refers to the global cycles of nitrogen and phosphorus. Overloading these nutrients in ecosystems changes how life is supported and causes pollution and dead zones.

• stakeholder: biosphere (sea)

• main driver: fertilizer in agriculture and waste water

land system change - planetary boundary

Involves the conversion of forests, grasslands, and wetlands into agricultural or urban areas, affecting ecosystems and carbon storage.

• stakeholder: biosphere (land)

• main driver: over exploitation and pollution

freshwater use - planetary boundary

Relates to the consumption of freshwater resources. Excessive use can disrupt ecosystems and water availability.

• stakeholder: lithosphere

• main driver: freshwater resources within the Earth's crust (outermost layer) - both surface water and groundwater

Atmospheric Aerosol Loading - planetary boundary

microscopic particles in atmosphere from pollution, which affects air quality, climate systems, and living organism.

stakeholder: atmosphere

main driver: from burning of fuels

novel entities - planetary boundary

Refers to organic pollutants, radioactive materials, nano-materials, and microplastics. Things made more and more since industrial revolution occurred, and we are releasing into environment disrupting ecosystems.

• stakeholder: atmosphere, biosphere, lithosphere (crust and upper mantel)f

• main driver: human made products

earth overshoot day

day when humanity's demand for ecological resources and services exceeds what Earth can regenerate in that year.

• over time, we are using more and more resources relative to what earth can supply - Earth Overshoot Day has been moving earlier over the decades. In the 1970s, it fell later in the year, but now it often occurs in late July or early August, signalling increased unsustainable consumption.

doughnut economics

provides perspective on realistically balancing the needs of people “social foundation” with the limitations of our planet “ecological ceiling”

• meeting of anthroposphere and natural world → foundations for environmental science

• anything that falls outside doughnut results in irreversible poverty or irreparable environmental damage

• emphasizes need to maintain a balance between our needs and sustainability

sustainability

• the goal

• meeting our own needs without compromising the ability of future generations to meet theirs

• requires a complex balancing of social, environmental, and economic aspects