Lecture Notes

  

Lecture 3

PLANET EARTH

•         third planet in distance from the Sun in the solar system

•          the only planet known to harbor life, and the “home” of human beings.

•         About 71 % of Earth’s surface is covered by water, which is essential to life.

•         rest is land, mostly in the form of continents that rise above the oceans.     

 Origin of the Earth

•         EARLY THEORIES 
 Nebular Hypothesis                                       

•         German philosopher, Kant and French mathematician, Laplace

•         Earth, planets and sun originated from Nebula.

•         Nebula was large cloud of gas and dust. It rotates slowly.

•         Gradually it cooled and contracted and its speed increased.

•         A gaseous ring was separated from nebula

•         Later the ring cooled and took form of a planet

•         On repetition of the process all other planets came into being

• •          The central region, nebula became sun.

            Planetesimal Hypothesis

• •Chamberlin and Moulton proposed the theory in 1904
• • the solar system originated from matter which was in form of tiny dust grains called      "Planetesimals".
• •The planets evolved from a cloud of planetesimals which revolved around the sun.
• •The planetesimals, the tiny cosmic fragments collided with each other and united together to form larger bodies which became planets and satellites revolving around the sun.

          Gaseous Tidal Theory

• Jeans and Jeffrey proposed the theory in 1925
• Large star came near the sun.
• Due to gravitational pull a gaseous tide was raised on the surface of the sun.
• As the star came nearer, the tide increased in size.
• Gaseous tide detached when star move away.
• The shape of the tide was like spindle.
• It broke into pieces-forming nine planets of the solar system

   Modern Theory

        scientists in later period took up the problem of origin of universe rather than     that of just the earth or the planets.

          Big Bang theory(expanding universe hypothesis)

•     According to cosmologists, the dawn of the universe started with a Big Bang

•     entire matter of the universe was condensed into a cloud of gas and dust

•     after  consecutive expansion and contraction it exploded into the Big Bang

•     The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe.

•     According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly.

•     This rapid expansion caused the Universe to cool and resulted in its present continuously expanding state.

•     According to the most recent measurements and observations, the Big Bang occurred approximately 13.75 billion years ago, which is thus considered the age of the Universe.

•     After its initial expansion from a singularity, the Universe cooled sufficiently to allow energy to be converted into various subatomic particles, including protons, neutrons, and electrons.

•     protons and neutrons combined to form the first atomic nuclei only a few minutes after the Big Bang,

•     it took thousands of years for electrons to combine with them and create electrically neutral atoms.

•     The first element produced was hydrogen, along with traces of helium and lithium.

•     Giant clouds of these primordial elements would coalesce through gravity to form stars and galaxies, and the heavier elements would be synthesized either within stars or during supernovae.


Lecture 2

                                         Earth System  (4 physical systems)

  Atmosphere 
– derived from the Greek words for air (atmo), 

      – Layer of gases that surround Earth. Allows you to breathe and protects earth.      – The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount 
      – remaining is composed of carbon dioxide and other gasses
      – Troposphere, Stratosphere, Mesosphere, Ionosphere (or Thermosphere), Exosphere and the Magnetosphere

Lithosphere

§  Surface of the planet that forms the continents and the ocean floor.

§  derived from the Greek wordsfor stone (litho)

§  This crust is inorganic and is composed of minerals.

§  It covers the entire surface of the earth from the top of Mount Everest to the bottom of the Mariana Trench.

Hydrosphere

–       derived from the Greek words for water (hydro)

–       All the water on Earth (ocean, ice, and water vapor in the atmosphere)

–       Ninety-seven percent of the earth's water is in the oceans.

–       The remaining three percent is fresh water; three-quarters of the fresh water is solid and exists in ice sheets

Biosphere

–       derived from the Greek word for life (bio).

–       Part of Earth where life exists.

–       Plants, animals, and one-celled organisms are all part of the biosphere

–       Most of the planet's life is found from three meters below the ground to thirty meters above it and in the top 200 meters of the oceans and seas.

•         All four spheres can be and often are present in a single location.

•         a piece of soil will of course have mineral material from the lithosphere.

•         Additionally, there will be elements of the hydrosphere present as moisture within the soil,

•          the biosphere as insects and plants,

•         the atmosphere as pockets of air between soil pieces.

Lecture 1

Environmental History ?

Introduction

• ž  environment is one of the most pressing concerns   in the 21st century 
•  ž  highly complex with cultural, social, economic, moral, political and scientific dimensions
•  ž  Environmental History which provides an valuable long-term perspective on environmental change is very crucial in this debate
•  ž  Historians provides fascinating insights into the relations between humans and their environments in the past
•  ž  Throughout history, humans have affected the natural environment-

 in a sustainable manner

  often in a destructive manner

Origins

ž  new discipline came into being during the 1960's & 1970's

ž  direct consequence of the growing awareness of worldwide environmental problems

¡  pollution of water and air by pesticides

¡   depletion of the ozone layer

¡   the enhanced greenhouse effect caused by human activity

ž  historians started to look for the origins of the contemporary problems, drawing upon the knowledge of a whole field of scientific disciplines and specializations which had been developed during the preceding century

ž  two important 19th century origins of environmental history:

ž  ecology and geography:-

¡  In modern environmental history, ecological concepts are used to analyse past environments

¡  and geography used to study the ever-changing face of the earth

ž  Two other roots of environmental history are

¡   archaeology and anthropology of which the latter introduced ecology into the human sciences

ž  The emergence of world history, with works by McNeill and Thomas among others, introduced interdisciplinary and continental wide, even world scale studies into history

ž  Ecology and the interdisciplinary method became later two important features of environmental history

ž  Rodrick Nash coined the term environmental history in 1972

ž  the works of Worster, Pfister, Brimblecombe, Ponting and others made  environmental history mature

ž  Now environmental history is an international and interdisciplinary undertaking

ž  What is environmental history?

ž  always about human interaction with the natural world (interaction between culture and nature)

ž  goal of environmental history is to deepen our understanding of how humans has been affected by the natural environment in the past and also how they have affected that environment and with what results    (bilateral approach of environmental history )

ž  environmental history is studying the interaction between humans and the environment in the past

ž  To study the relationships between humans and the surrounding world, we must try to understand how the interaction between the two works

ž  Donald Worster has recognised three clusters of issues to be addressed by environmental historians

¡  The first cluster deals with the human intellectual realm consisting of perceptions, ethics, laws, myth and the other mental constructions related to the natural world.

¡  Ideas about the world around us influence the way we deal with the natural environment

¡  the socio-economic realm

¡  Ideas have an impact on politics, policies and the economy through which ideas materialise in the natural world

¡  the natural realm (deals with understanding nature itself)

¡  world is not static, it reacts on our actions to influence the material world

¡  The impact of human actions on the natural world is causing a feedback that changes our ideas, policies, economy etc

ž  Envi Hi: is about

¡  includes analysis of data on tides, winds, ocean currents, the position of continents in relation to each other and geology

¡  the history of climate and weather

¡  the pattern of diseases

¡  the story of human exploitation of the natural world

¡  impact of agriculture on soil and landscape

¡  the history of forests

¡  the effects of hunting and grazing

¡  the environmental impact of mining, transportation, urbanisation and industrialisation.

¡  last, but not least, environmental history is about unmasking myths and distorted perceptions of the past

¡  Myths and false perceptions are not based on historical facts and can be highly influential

¡   It is an important task of environmental history to correct these misconceptions of the past

ž  The subject matter of environmental history can be divided into three main components.

ž  1. Nature itself and its change over time, includes the physical impact of humans on the     Earth's land, water, atmosphere and biosphere.

ž  2. How humans use nature, includes the environmental consequences of increasing population, more effective technology and changing patterns of production and consumption.

ž    The transition from nomadic hunter-gatherer communities to settled agriculture in the Neolithic revolution, the effects of colonial expansion and settlements, and the environmental and human consequences of the industrial and technological revolutions.

ž3. Environmental historians study how people think about nature - the way attitudes, beliefs and values influence interaction with nature, especially in the form of myths, religion and science.