The carbon cycle describes the movement of carbon between the atmosphere, organisms, sediments like fossil fuels and the ocean. Carbon is exchanged through photosynthesis, respiration, decomposition, combustion and other processes and moves repeatedly between living and nonliving matter on Earth. The carbon cycle is important because carbon dioxide regulates the climate and carbon is necessary for life through photosynthesis and respiration. Human activities like burning fossil fuels have disrupted the natural carbon cycle and increased atmospheric carbon dioxide levels, contributing to global warming.

2. WHAT IS A CYCLE?
• CYCLE: CONTINUOUS MOVEMENT OR TRANSFER OF SOMETHING.
• CYCLING IN ECOSYSTEMS:
• ALL MATTER (NUTRIENTS) CONTINUOUSLY MOVE BETWEEN ORGANISMS AND REGIONS.
• ENERGY CONTINUOUSLY MOVES BETWEEN ORGANISMS…

3. Carbon is a key element for life, composing almost half of the dry
mass of the earth’s plants (that is, the mass when all water is
removed) which is the basis of life of earth
Carbon is present in the atmosphere as the gas carbon dioxide
(CO2), which makes up approximately 0.04% of the atmosphere.
It is also present in the ocean and fresh water as dissolved carbon
dioxide. Carbons are also present in rocks such as limestone
(CaCO3).
CARBON

4. THE CARBON CYCLE.
• THE CARBON CYCLE IS THE BIOGEOCHEMICAL CYCLE BY WHICH CARBON IS EXCHANGED AMONG THE
BIOSPHERE, PEDOSPHERE, GEOSPHERE, HYDROSPHERE, AND ATMOSPHERE OF THE EARTH.
• THE GLOBAL MOVEMENT OF CARBON BETWEEN THE ABIOTIC ENVIRONMENT, INCLUDING THE
ATMOSPHERE AND OCEAN, AND ORGANISMS IS KNOWN AS THE CARBON CYCLE.
• THE SAME CARBON ATOMS ARE USED REPEATEDLY ON EARTH. THEY CYCLE BETWEEN THE EARTH AND THE
ATMOSPHERE

5. THE GLOBAL CARBON CYCLE IS USUALLY THOUGHT
TO HAVE FOUR MAJOR CARBON SINKS
INTERCONNECTED BY PATHWAYS OF EXCHANGE.
THESE SINKS ARE;
• THE ATMOSPHERE,
• THE TERRESTRIAL BIOSPHERE (WHICH USUALLY INCLUDES
FRESHWATER SYSTEMS AND NON-LIVING ORGANIC MATERIAL,
SUCH AS SOIL CARBON),
• THE OCEANS (WHICH INCLUDES DISSOLVED INORGANIC CARBON
AND LIVING AND NON-LIVING MARINE BIOTA),
• AND THE SEDIMENTS (WHICH INCLUDES FOSSIL FUELS ).

6. Carbon in Atmosphere
Plants use
carbon to make
food
Animals eat
plants and
take in carbon
Plants and
animals die
Decomposers
break down dead
things, releasing
carbon to
atmosphere and
soil
Bodies not
decomposed —
after many
years, become
part of oil or coal
deposits
Fossil fuels are
burned; carbon
is returned to
atmosphere
Carbon slowly
released from
these substances
returns to
atmosphere

7. PLANTS USE CARBON DIOXIDE
• PLANTS PULL CARBON DIOXIDE (CO2) FROM THE ATMOSPHERE. USING SUNLIGHT
WITH THE CO2 THEY MAKE GLUCOSE. THIS PROCESS IS PHOTOSYNTHESIS.
• DURING PHOTOSYNTHESIS, PLANTS, ALGAE, AND CYANOBACTERIA REMOVE
CARBON DIOXIDE FROM THE AIR AND FIX, OR INCORPORATE IT INTO COMPLEX
ORGANIC COMPOUNDS SUCH AS GLUCOSE.
• THE CARBON CAN BE USED BY THE PLANT (FOOD) AND USED TO BUILD THE
PLANT (CELLULOSE).
• THE PROCESS OF A CELLULAR RESPIRATION RETURNS CO2 TO THE ATMOSPHERE.

8. ANIMALS EAT PLANTS
• WHEN ANIMALS EAT PLANTS, THEY TAKE IN THE CARBON AND SOME OF IT
BECOMES PART OF THEIR OWN TISSUES.
• THEY GENERATE CO2 FROM CELLULAR RESPIRATION(BREAK DOWN OF GLUCOSE)
AND EXHALE THIS CO2 INTO THE ATMOSPHERE.

9. ANIMALS EAT ANIMALS
• CARNIVORES EAT THESE ANIMALS AND THEN USE THE CARBON FOR THEIR OWN
NEEDS.
• THESE ANIMALS RETURN CARBON DIOXIDE INTO THE AIR WHEN THEY BREATHE,
AND WHEN THEY DIE , THE CARBON IS RETURNED TO THE SOIL DURING
DECOMPOSITION.

10. PLANTS AND ANIMAL DIE
• WHEN PLANTS AND ANIMALS DIE, MOST OF THEIR BODIES ARE DECOMPOSED
AND CARBON ATOMS ARE RETURNED TO THE ATMOSPHERE.(CO2)
• SOME ARE NOT DECOMPOSED FULLY AND END UP AS DEPOSITS UNDERGROUND
(OIL, COAL, ETC.= FOSSIL FUELS=CARBON)
• MILLIONS OF YEARS AGO VAST COAL BEDS FORMED FROM THE BODIES OF
ANCIENT TREES THAT WERE BURIED AND SUBJECTED TO ANAEROBIC
CONDITIONS BEFORE THEY HAD FULLY DECAYED.

11. CARBON IN OCEANS
• ADDITIONAL CARBON IS STORED IN THE OCEAN.
• CO2 PASSES INTO THE WATER FROM THE
ATMOSPHERE.
• PLANTS & PHYTOPLANKTON USE FOR
PHOTOSYNTHESIS. MANY ANIMALS PULL CARBON
FROM WATER TO USE IN .
• ANIMALS DIE AND CARBON SUBSTANCES ARE
DEPOSITED AT THE BOTTOM OF THE OCEAN.
• OCEANS CONTAIN EARTH’S LARGEST STORE OF
CARBON.

12. BURNING WOOD AND FOSSIL FUELS
• RELEASES CARBON COMPOUNDS IN AIR, WATER, AND SOIL
• THE PROCESS OF BURNING OR COMBUSTION, MAY RETURN THE CARBON IN OIL, COAL, NATURAL GAS, AND
WOOD TO THE ATMOSPHERE.

13. CARBON SLOWLY RETURNS TO ATMOSPHERE
• CARBON IN ROCKS AND UNDERGROUND
DEPOSITS IS RELEASED VERY SLOWLY
INTO THE ATMOSPHERE.
• THIS PROCESS TAKES MANY YEARS.

15. WHY CARBON CYCLE IS IMPORTANT?
• MANY ELEMENTS HAVE CYCLE, BUT THE CYCLING OF CARBON ATOMS IS PARTICULARLY IMPORTANT
BECAUSE:
• THROUGH PHOTOSYNTHESIS AND RESPIRATION, IT IS THE WAY THE EARTH PRODUCES FOOD AND OTHER
RESOURCES.
• CO2 PLAYS A KEY ROLE IN TRAPPING HEAT IN THE ATMOSPHERE - ONE OF THE BASIC MECHANISMS
BEHIND THE GREENHOUSE EFFECT.
• CARBON PLAYS A CENTRAL ROLE IN COMBUSTION.

16. WHY CARBON CYCLE IS IMPORTANT?
• THROUGH DECOMPOSITION, IT SERVES AS THE EARTH'S WASTE DISPOSAL SYSTEM.
• IN ADDITION, THE CARBON CYCLE IS IMPORTANT BECAUSE CARBON-CONTAINING GASES IN THE
ATMOSPHERE AFFECT THE EARTH'S CLIMATE.
• INCREASED CARBONDIOXIDE IN THE ATMOSPHERE HAS BEEN RESPONSIBLE FOR MORE THAN HALF OF THE
CLIMATE WARMING OBSERVED IN RECENT DECADES.

17. UNBALANCED CYCLE - HUMAN IMPACT
•UNDER BALANCED CONDITIONS, FOSSIL FUELS RELEASE CARBON STORES
VERY SLOWLY INTO ATMOSPHERE.
•WHEN HUMANS BURN FOSSIL FUELS, IT RELEASES A TREMENDOUS AMOUNT
OF CARBON INTO THE ATMOSPHERE OVER A VERY SHORT TIME SPAN.
•INCREASED CARBON DIOXIDE IN ATMOSPHERE INCREASES GLOBAL
WARMING
• FEWER PLANTS MEAN LESS CO2 REMOVED FROM ATMOSPHERE

18. WHAT IS YOUR CARBON FOOTPRINT?
• A CARBON FOOTPRINT IS THE AMOUNT OF CARBON EMITTED INTO THE ATMOSPHERE BY YOUR
PERSONAL, DAY-TO-DAY ACTIVITIES.
• EXAMPLES: TYPE OF CAR YOU DRIVE, HOW FAR YOU DRIVE YOUR CAR, HOW MUCH ELECTRICITY YOU USE
(ELECTRICITY PRIMARILY COMES FROM BURNING COAL), AND AIRPLANE FLIGHTS.

19. THINGS YOU CAN DO TO REDUCE YOUR
CARBON FOOTPRINT
• PROMOTE PLANT LIFE, ESPECIALLY TREES
• BUY A FUEL EFFICIENT VEHICLE
• PURCHASE LOCALLY GROWN FOOD
• REDUCE ELECTRICITY USE
• REDUCE HOW FAR/MUCH YOU DRIVE
• TAKE LESS AIRPLANE TRIPS
• REDUCE, REUSE, RECYCLE!