Natural Environment Notes

The Natural Environment

  • Definition: What constitutes the natural environment.
  • Framing: Scales of space and time are crucial for understanding the natural environment.
  • Cronos: Reference to time.
  • Space: Consideration of spatial scales.
  • Spheres: Conceptualization of Earth's components as spheres.
  • Systems: Understanding the natural environment as interconnected systems with equilibria and feedbacks.

Built vs. Natural Environments

  • Distinction: Examining the differences between "built" (e.g., log cabin, beehive) and "natural" environments.
  • Question: Where does the defining difference lie?

Space/Time Scales

  • Scales: Ranging from nano/micro to macro scales.
  • Timeline of the Universe:
    • Big Bang: 20 \, billion years ago.
    • Inflation.
    • Universe Cooling.
    • First Galaxies and Stars Form: A few billion years ago.
    • Expansion of the Universe Begins to Accelerate.
    • Life on Earth Begins.
    • Present Day.

Scale Examples:

  • Atom: 10^{-9} m
  • Small Molecules
  • Lipids
  • Proteins
  • Virus
  • Bacteria
  • Eukaryotic Cells

Geological Time Periods

  • Precambrian Time: First life forms (bacteria) appear and produce oxygen (before 540 mya).
  • Cambrian Period: No life on land, shellfish flourish in oceans (540-500 mya).
  • Ordovician Period: Early fish-like vertebrates appear, Sahara glaciated (500-425 mya).
  • Silurian Period: First land plants, fish with jaws, freshwater fish (425-408 mya).
  • Devonian Period: First insects and amphibians, large ferns and mosses (408-362 mya).
  • Carboniferous Period: Vast warm fern swamps form coal, first reptiles (362-290 mya).
  • Permian Period: Conifers replace ferns, widespread deserts (290-245 mya).
  • Triassic Period: First mammals, seed-bearing plants spread, Europe in the tropics (245-208 mya).
  • Jurassic Period: Dinosaurs widespread, Archaeopteryx (earliest bird) (208-145 mya).
  • Cretaceous Period: First flowering plants, dinosaurs die out (145-65 mya).
  • Tertiary Period: First large mammals, birds flourish, widespread grasslands (65-1.64 mya).
  • Quaternary Period: Many mammals die out in Ice Ages, humans evolve (1.64 mya-present).

Temperature and CO2 Concentration

  • Data Source: Vostok ice core in Antarctica.
  • Time Span: Past 400,000 years.
  • Correlation: Demonstrates the relationship between temperature and CO2 levels in the atmosphere.

Recent Heat Records

  • India (May 2016): Extreme heat records were broken.

The "Little Ice Age"

  • Timing: 1645-1715 (2nd phase).
  • Time Scale: Macro - Meso - Micro.

Human History

  • Timeline:
    • 6 Million Years Ago: Sahelanthropus tchadensie.
  • Key Hominids:
    • Australopithecus (e.g. Lucy).
    • Homo (e.g. Homo sapiens, Homo neanderthalensis, Homo erectus).

Zoology

  • Kingdom Animalia:
    *Phylum Porifera
    *Phylum Platyhelminthes
    *Phylum Nematoda
    *Phylum Cnidaria
    *Phylum Mollusca
    *Phylum Annelida
    *Phylum Echinodermata
    *Phylum Arthropoda
    *Phylum Chordata

Human History: The Written Record?

  • Early Map: Possible Stone Age map from Ukraine (12,000-11,000 B.C.) showing dwellings beside a river.

Biodiversity

  • Estimated Described Species: 1.8 million non-bacterial plant & animal species.
  • Breakdown:
    • Insects: 56.4%
    • Plants: 20.1%
    • Invertebrates: 20.2%
    • Brown algae, fungi, lichens: 1.8%
    • Fish: 1.77%
    • Birds: 0.56%
    • Reptiles: 0.5%
    • Amphibians: 0.36%
    • Mammals: 0.31%

Spheres of the Natural Environment

  • Atmosphere: Air.
  • Lithosphere: Land.
  • Hydrosphere: Water.
  • Biosphere: Life.

Atmosphere

  • Description: Gaseous body enveloping the Earth, safeguarding life.
  • Density: Decreases with elevation above sea-level.

Atmosphere: Paleo-record

  • Source: Gas bubbles trapped in ice.
  • Information: Provides samples of ancient atmosphere, thousands of years old.

Lithosphere

  • Examples:
    • Colorado River and Grand Canyon.
    • Mid-Atlantic Ridge, Iceland (converging continental plates).
    • Soil and underlying rock.
    • Volcanoes.

Hydrosphere

  • Characteristics:
    • Phases: Solid, gas, liquid.
    • Volumes: Droplets to oceans.
    • Locations: Above, at, and below sea level.

Biosphere

  • Extremophiles:
    • Cryptoendoliths: Algae, lichens, and bacteria living under the surface of rocks.
    • Importance: Relate to life maintenance and origin.

Systems

  • Flow: Of matter and/or energy between components.
  • Type: Can be open flow or closed flow depending on what crosses system boundary.

Open-flow

  • Definition: Matter and/or energy enters & leaves the system (e.g., the atmosphere, river system).

Closed-flow

  • Definition: No matter leaves(e.g., the atmosphere, river system).

Equilibrium

  • Static:
    • Properties of system remain unchanged over time.
  • Stable:
    • Properties of system return to equilibrium after disturbance.
    • Example: Mountain-lake system.
  • Dynamic equilibrium:
    • Properties of system establish a new equilibrium after disturbance.

Positive Feedback

  • Definition: Self-perpetuating changes that reinforce or increase the effect of original changes.
    Example: Snowball effect* .

Negative Feedback

  • Definition: Process that diminishes the initial change.
    Example: Air rises (thermal), cools, moisture condenses, clouds form and precipitation follows, cools surface/atmosphere, decreases precipitation*.