The 4 Conditions for Life The 4 Conditions for Life on Earthon Earth

1. A Constant and Relatively Mild 1. A Constant and Relatively Mild TemperatureTemperature

-50 to about +50 degrees Celsius-50 to about +50 degrees Celsius Average temp. has been between 10-Average temp. has been between 10-

20 degrees C for 3.5 billion years20 degrees C for 3.5 billion years The Greenhouse effect allows for The Greenhouse effect allows for

heat in the atmosphere (carbon and heat in the atmosphere (carbon and water vapor)water vapor)

Without proper water and carbon, Without proper water and carbon, the earth would be -73 degrees C.the earth would be -73 degrees C.

The Greenhouse EffectThe Greenhouse Effect Plants play a significant role in creating a stablePlants play a significant role in creating a stable temperaturetemperature through releasingthrough releasing water vapor and oxygenwater vapor and oxygen by the processes ofby the processes of photosynthesis andphotosynthesis and transpirationtranspiration They also absorbThey also absorb heat from the sun’sheat from the sun’s rays and limit the rays and limit the albedo effectalbedo effect

The Real Greenhouse EffectThe Real Greenhouse Effect

2.The Importance of Water2.The Importance of Water First water likely came from volcanic First water likely came from volcanic

activity and the vapors releasedactivity and the vapors released Biologists believe earth first began in the Biologists believe earth first began in the

oceans – blue-green algaeoceans – blue-green algae Oceans trap heat and distribute it around Oceans trap heat and distribute it around

the world (2/3 of the earth)the world (2/3 of the earth) No living thing consists of less than 50% No living thing consists of less than 50%

waterwater Water is the metabolizing agent that Water is the metabolizing agent that

allows plants and animals to dissolve allows plants and animals to dissolve minerals and nutrients to create energyminerals and nutrients to create energy

PhotosynthesisPhotosynthesis

3. The Importance of Gases3. The Importance of Gases 78% nitrogen, 21% oxygen, carbon dioxide 78% nitrogen, 21% oxygen, carbon dioxide

0.03%0.03% The plants have removed most of the The plants have removed most of the

carbon dioxide that originally existed and carbon dioxide that originally existed and produced lots of oxygenproduced lots of oxygen

Without life on earth, carbon dioxide would Without life on earth, carbon dioxide would increaseincrease

The production of carbohydrates, fats, and The production of carbohydrates, fats, and proteins require oxygen, carbon, and proteins require oxygen, carbon, and nitrogen atoms from the atmosphere, and nitrogen atoms from the atmosphere, and hydrogen from waterhydrogen from water

4. The Role of the Atmosphere4. The Role of the Atmosphere Layer of gases about 80-100kms thickLayer of gases about 80-100kms thick Helps maintain a consistent temp.Helps maintain a consistent temp. Shields earth from collisions with cosmic Shields earth from collisions with cosmic

particles (meteors)particles (meteors) Oxygen levels at 21% allow for life, if they Oxygen levels at 21% allow for life, if they

drop, animal life would not be possible, if it drop, animal life would not be possible, if it exceeds 25% most plants would be exceeds 25% most plants would be consumed by fireconsumed by fire

Oxygen is produced by plants and Oxygen is produced by plants and consumed by animals and the burning of consumed by animals and the burning of plants and fossil fuelsplants and fossil fuels

The 4 SpheresThe 4 Spheres

Lithosphere – earth’s crust (soil, Lithosphere – earth’s crust (soil, rocks, and minerals)rocks, and minerals)

Hydrosphere – earth’s waterHydrosphere – earth’s water Atmosphere – the gases in the airAtmosphere – the gases in the air Biosphere – all living things (plants, Biosphere – all living things (plants,

bacteria, animals)bacteria, animals)