Photosynthesis is a key part of the carbon cycle. It involves producers converting inorganic carbon dioxide into organic compounds like glucose. Primary consumers obtain these organic compounds by eating producers, and secondary consumers obtain carbon by eating primary consumers. Cellular respiration by all organisms returns carbon dioxide to the atmosphere. Humans have disrupted this natural cycle by extracting and burning fossil fuels, releasing carbon that has been locked away for thousands of years back into the atmosphere as carbon dioxide, contributing to increased global warming.

1. Photosynthesis
The Big Picture

2. Carbon cycle
 Process by which carbon moves from organic
to inorganic compounds and back
 Producers convert inorganic carbon (CO2) into
organic carbon compounds (glucose)
 Primary Consumers obtain organic compounds
by eating producers
 Secondary consumers obtain organic carbon
by eating primary consumers
 Cellular Respiration by producers and
consumers return CO2 to atmosphere

3.  In the natural carbon cycle, there are two
main processes which occur
 Photosynthesis
 Metabolism/Cellular Respiration

8. Carbon in Ocean and
Sediments
 CO2 is slightly soluble
 Can be absorbed into water
 Some of the dissolved CO2 remains in the water, the warmer the water the
less carbon dioxide remains in the water
 Some CO2 is used by algae and phytoplankton through the process of
photosynthesis
 Coral and shelled marine organisms take up CO2 from the water and
convert it into calcium carbonate
 When these organisms die pieces of shells/coral fall to ocean floor and make
sediments
 The carbonate sediments are constantly being formed and redissolved in the
bottom of the ocean
 Over long periods of time, the sediments may be raised up as dry land or
into mountains
 This type of sedimentary rock is called limestone
 The carbonates can redissolve releasing carbon dioxide back to the air or
water

11. Humans and the Carbon
Cycle
 Combustion of any type of fossil fuel, which may
include oil, coal, or natural gas
 Fossil Fuels formed thousands of years ago from
plant or animal remains that were buried,
compressed, and transformed into oil, coal, or
natural gas
 This carbon is said to be "fixed" in place and is
essentially locked out of the natural carbon cycle
 Humans intervene during by burning the fossil fuels
 During combustion in the presence of O2, CO2 and water
molecules are released into the atmosphere

12. Photosynthesis and Global
Climate
 CO2 makes up 0.03 percent of Earth’s atmosphere
 300 parts per million
 Greenhouse Effect
 CO2 traps heat from sun in Earth’s atmosphere (otherwise it would escape into space)
 Not a bad thing
 Keeps world climate warm enough to sustain life
 Keeps Earth 10% warmer than it would be without CO2
 Currently CO2 in atmosphere is rising
 360 parts per million
 Burning fossil fuels
 Deforestation
 Natural Causes
 Photosynthesis
 Cellular respiration
 Decomposition
 Volcanic eruptions
 Ocean/limestone
 Global Warming
 Overall rise in Earth’s average temperature over a period of time