The Carbon Cycle & Changes in Atmospheric Carbon Dioxide

IB Biology – Topic 5.2

Carbon

Crucial element to living organisms The term organic implies that carbon must be

present Life on Earth is referred to as carbon-based life

Where is carbon found? Carbohydrates, lipids, proteins, vitamins In the atmosphere (CO2) Lithosphere (rocks)

Carbonates, fossil fuel Petroleum

Gasoline, kerosene, plastics

Carbon is constantly recycled

Photosynthesis Plants take CO2 in These producers are eaten by consumers,

which use the carbon In their bodies Cellular respiration

All trophic levels & decomposers produce CO2 which is released back into the atmosphere

Even plants

Other sources of carbon dioxide Humans!

Burning wood or non-renewable resources Petroleum products

Volcanic activity Marine organisms can take carbon out of the

water to make their shells Shells accumulate as sediments at the bottom of

the ocean Trap carbon for millions of years in limestone Limestone is one of the main ingredients for

cement Making cement carbon is released as CO2

The Carbon Cycle

Changes …

Ever since the industrial revolution (1800s), humans have produced increasing quantities of carbon dioxide Machines Factories Transportation Deforestation Burning wood (cooking, heating)

It all comes down to burning fossil fuels (coal and oil)

Rising CO2 levels

Over the decades, human pollution has produced enough CO2 to raise its percentage in the atmosphere

Some suggest levels have increased by about 25% compared to pre-industrial revolution levels

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NASA data on CO2 levels

Why do CO2 levels fluctuate? Plants, phytoplankton, and

photosynthetic bacteria are more active in the summer months Think about Chicago in the winter … do

you see a lot of green? Therefore, more CO2 is taken out of the

atmosphere during the summer months According to NASA data (previous slide),

there has been a 19.4 % increase in the mean annual concentration of CO2 over the past 47 years.