Earth

What re the 4 global spheres 

1. Biosphere

2. Lithosphere

3. Atmosphere

4. Hydrosphere

What is the Lithosphere?

• Consists of solid rock

• The cold brittle and elastic outermost shell of our planet

• It doesn’t include the molten rock found in the mantle

What is the biosphere?

• The living parts of the Earth

• All organisms make up the biosphere

What is the hydrosphere?

• The mass of water lying over or under the surface of the Earth

  • Oceans

  • Seas

  • Rivers

  • Lakes

• 97.5% of water on Earth is saline

• 2.5% of water of Earth is fresh - 68.7% of that is ice

• The cryosphere is the part of the hydrosphere where water is frozen

What is the atmosphere?

• Consists of gases

  • Nitrogen 78.09%

  • Oxygen 20.95%

  • Carbon Dioxide 0.039%

  • Water vapor 1%

• Further broken down based off altitude

How are all the global spheres connected?

• The hydrosphere enters the lithosphere

• The lithosphere enters the hydrosphere

• The hydrosphere used the biosphere for climate change

• The biosphere uses the hydrosphere for aquatic life

• The lithosphere uses the atmosphere as volcanic erosion

• the atmosphere uses the lithosphere for wind erosion

• The biosphere uses the atmosphere to breath

• The atmosphere uses the biosphere 

• The hydrosphere uses the atmosphere for the water cycle

• The atmosphere use the hydrosphere as the water evaporates

• The biosphere uses the lithosphere

What is the carbon cycle?

The carbon cycle is the process by which carbon atoms move between the Earth’s atmosphere, oceans, land and living organisms

Where does carbon come from?

• It comes from natural sources like the formation of the stars and from Earth-based processes including

  • Volcanic eruptions

  • Plant and animal respiration

  • Decay of organic matter

How does the carbon cycle work/what occurs?

• Photosynthesis

  • Plants use CO₂ during photosynthesis so they can grow

  • Absorbs CO2 from the atmosphere

• Cellular Respiration

  • Release CO2 into the atmosphere

  • Comes from land and water animals as well as humans

• Diffusion

  • CO2 diffuses into the ocean

  • Too much causes ocean acidification

• Combustion

  • Burning of fossil fuels

  • This is a carbon source 

What is a carbon sink?

Any natural or artificial reservoir that absorbs more CO2 from the atmosphere then it releases, storing it over time

• e.g. 

  • Forests

  • Soils

  • Oceans

What is a carbon source?

Anything which releases more CO2 into the atmosphere then it absorbs

• e.g.

  • Burning of fossil fuels

  • Volcanic eruptions 

  • Deforestation

Greenhouse gas explanation

Greenhouse gases exist in our atmosphere and absorbs heat. For example, carbon dioxide, methane and water vapor. Sources of carbon dioxide include, car exhaust, burning of fossil fuels and forests. Sources of methane include, cows - digestive gases

Greenhouse effect explanation

The greenhouse effect is the natural warming of the earth that results when gases in the atmosphere trap heat from the sun that would otherwise escape into space.

Enhanced greenhouse effect explanation

The enhanced greenhouse effect is increased trapping of heating of the earth, due to increased amounts of greenhouse gases in the atmosphere due to human activities

Global energy use…

• Increased by 70% since 1970

• Will increase 2% annually over the next 15 years

• Combustion engine emissions increasing as economies develop and become more affluent 

Global warming explanation

• Global warming describes the gradual increase in the average global temperature of the earth due to increase levels of ‘greenhouse gasses’

• The current trend has been compounded by human activity - the release of certain greenhouse gases such as CO₂ and methane into the atmosphere

Changes in atmospheric CO₂

• Due to the expansion of agriculture additional CO2 has been pumped into the atmosphere

• The build up of atmospheric carbon dioxide will continue to warm the earth

Climate change

• Climate change is the altering of weather patterns over a long period of time.

• Enhanced Greenhouse Effect ---> Global Warming ---> Climate Change

  Contributing human actions:

  • Burning of fossil fuels

  • Deforestation (reduced removal of carbon dioxide from photosynthesis)

Enhanced greenhouse effect on Earth

• Changing climates

  • The winters become colder

  • The summers become hotter

  • There is not much in between 

• Melting ice

  • The rising temperatures lead to the ice melting 

• Severe weather events - more frequent

  • Storms

  • Droughts

• Sea levels rising 

  • The melting ice and more rain in the winter leads to the sea levels rising

Ocean Acidification Definition

The process of oceans becoming more acidic

Causes of ocean acidification

• Increasing CO2 levels in the atmosphere drive ocean acidification

• Oceans absorb CO2 from the atmosphere

• The pH of surface ocean waters has fallen by 0.1pH units - ~30%

CO₂ and Seawater

• When CO2 is absorbed a series of chemical reactions occur resulting in the increased concentration of H ions

• Water and CO2 combine to form carbonic acid a weak acid which dissociates into H and bicarbonate ions

• The oceans average pH is 8.1 which is basic

• As more CO2 gets absorbed the pH decreases and oceans become more acidic

Impact on shell builders

• As ocean acidification increases available carbonate ions bond with excess hydrogen resulting in fewer carbonate ions available for calcifying organisms to build and maintain their shells, skeletons and other calcium carbonate structures 

• If the pH gets too low shells and skeletons can even begin to dissolve

Impact on fish and seaweed

• The ability of some fish like clownfish to detect predators is decreased in more acidic waters

• Decreased pH levels also affect the ability of some fish to find suitable habitats and shelter

• When these organisms are at risk the entire food web may also be at risk

• Algae and seagrass benefit from higher CO2 levels in the ocean as they require it for photosynthesis

Coral bleaching

• Warmer water temperatures can result in coral bleaching

• When water is too warm corals will expel the algae which causes coral to have a  colour

• This results in the coral becoming white

• When a coral bleaches it is not dead

• Corals can survive a bleaching event but they are under more stress and are subject to mortality 

Climate change and oceans

• Over one quarter of all marine life relies on coral reefs at some point in their life cycle

• Corals are the building blocks of reef ecosystems and vital to life on earth

• Climate change is one of the biggest threats to coral reefs and is making heatwaves hotter, longer and more frequent

  • Marine heatwaves cause coral bleaching

  • Global warming/Global heating

  • Increase in intensity of 

    • Cyclones

    • Ocean acidification

    • Extreme weather events