THE CARBON CYCLE

Carbon is an element It is part of oceans, air, rocks, soil and all living things. Carbon doesn’t stay in one place.

Carbon moves from the atmosphere to plants. Atmosphere-carbon is attached to oxygen in the form of carbon dioxide (CO2). CO2 with the help of the sun, using a processes called photosynthesis, is pulled from the air to make plant food. (C6H12O6)

Photosynthesis 6CO2 + 6H2O Light Energy C6H1206 + 602

Carbon moves from plants to animals Carbon that is in plants move to animals that eat the plants. Animals that eat other animals get the carbon from the plants the other animals have eaten

Carbon moves from living things to the atmosphere Exhaling releases CO2 into the atmosphere. Animals and plants get rid of CO2 gas through a process called respiration.

Carbon moves from plants and animals to the ground When plants and animals die, their bodies, wood and leaves decay bringing carbon into the ground. Some becomes buried miles underground and will become fossil fuels in millions and millions of years.

Carbon moves from fossil fuels to the atmosphere when fuels are burned. When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as CO2 Yearly five and a half BILLION tons of carbon is release by burning fossil fuels (or the weight of 100 MILLION adult elephants) 3.3 billion tons enter the atmosphere and the rest becomes dissolved in seawater

Carbon moves from the atmosphere to the oceans Oceans and other bodies of water, soak up some carbon from the atmosphere. Animals that live in the ocean use carbon to build their skeletons and shells White Cliffs, Dover, England Coccolith

Carbon dioxide is a greenhouse gas CO2 traps heat in the atmosphere Without CO2 and other greenhouse gases, Earth would be a frozen world Humans have burned so much fuel that there is about 30% more CO2 in the air today than there was about 150 years ago. More greenhouse gasses such as CO2 in our atmosphere are causing our planet to become warmer.

Carbon moves through our planet over longer time scales Over millions of years weathering of rocks on land may add carbon to surface water which eventually runs off to the ocean. Shells and bones are made of limestone, which contains carbon. When the shells and bones are stored on the sea floor they are removed from the carbon cycle Carbon can be released back to the atmosphere if the limestone melts or is metamorphosed in a subduction zone.

Carbon Cycle Feedback The carbon cycle is naturally a negative feedback loop. The burning of fossil fuels and deforestation interferes with this feedback loop. Deforestation increases atmospheric CO2. Burning of fossil fuels also increase atmospheric CO2.

Feedback Systems Negative Feedback The case where the output of a system counteracts the input of the system. Body temp Sweating

Feedback Systems Positive Feedback The case where the output of a system increases the input of the system Bank account balance Interest earned

Carbon Cycle Negative double feedback