The document summarizes the carbon cycle in 3 parts: 1) The natural pathway which involves photosynthesis, respiration, decomposition, and weathering of rocks cycling carbon between the atmosphere, living things, and soil. 2) The national reservoir of carbon stored in sedimentary rocks in the Earth's crust, oceans, and atmosphere. 3) How the carbon cycle is affected by human activities like burning fossil fuels, deforestation, and different levels of industrialization in less developed and more developed countries.

1. The Carbon Cycle
By John Roberts and Adrian Rios

2. The Natural Pathway
 Photosynthesis: Carbon exists in the atmosphere as carbon dioxide. It enters
the food web when photosynthetic organisms, such as plants and certain
algae, absorb carbon dioxide through their leaves. The plants capture the
carbon dioxide and are able to convert it into simple sugars like glucose
through the biochemical process known as photosynthesis. They are makers of
their own food, and remove carbon dioxide from the atmosphere. When
plants are eaten by animals, their carbon is passed on to those animals.
 Respiration is the next step in the cycle occurs in plants, animals, and even
decomposers. Respiration is the process in which oxygen is used to break
down organic compounds into carbon dioxide and water. For an animal
respiration is both taking in oxygen, and releasing carbon dioxide, and
oxidizing its food in order to release the energy the food contains. In both
cases, carbon is returned to the atmosphere as carbon dioxide.

3. The Natural Pathway (cont.)
 Decomposition is the largest source through which carbon is returned to the
atmosphere as carbon dioxide. Decomposers are microorganisms that live
mostly in the soil but also in water, and which feed on the rotting remains of
plants and animals. It is their job to consume both waste products and dead
matter, during which they also return carbon dioxide to the atmosphere by
respiration.
 Weathering of rocks: Often carbon becomes trapped in limerock, a type of
stone formed on the ocean floor by the shells of marine plankton. Sometimes
after millions of years, the waters recede and the limerock is eventually
exposed to the elements. When limerock is exposed to the natural process of
weathering, it slowly releases the carbon atoms it contains, and they become
an active part of the carbon cycle

4. National Reservoir
 The Earth’s Crust: The largest amount of carbon on Earth is stored in
sedimentary rocks within the planet’s crust. These are rocks produced either
by the hardening of mud into rocks over geological time, or by the collection
of calcium carbonate particles, from the shells and skeletons of marine
organisms, into limestone and other carbon containing sedimentary rocks.
 Oceans: The Earth’s oceans contain 38,000 Pentagrams of Carbon, most of
which is in the form of dissolved inorganic carbon stored at great depths
where it resides for long periods of time. A much smaller amount of carbon,
approximately 1,000 Pg, is located near the ocean surface. This carbon is
exchanged rapidly with the atmosphere
 Atmosphere: The atmosphere contains approximately 750 Pg of Carbon, most
of which is in the form of CO2, with much smaller amounts of methane and
various other compounds. Although this is considerably less carbon than that
contained in the oceans or crust, carbon in the atmosphere is of vital
importance because of its influence on the greenhouse effect and climate. The
relatively small size of the atmospheric Carbon pool also makes it more
sensitive to disruptions caused by an change of C from the Earth’s other
reservoirs.

6. Why is it so important?
 The Carbon in the air is very important, its what keeps the Earth warm and
from freezing.
 The atmosphere is made up of .04% carbon and that percent is going up
because of fossil fuels polluting the air.
 Because there is more carbon in our atmosphere, the earths temperature is
rising, causing global warming.

7. How the cycle is affected by LDCs
and MDC’s
 The carbon cycle is most affected by LDCs as they have factories that are releasing
fossil fuels in the air.
 LDCs like Brazil and Honduras, cut down trees for land, when the trees are cut
down a major part of the carbon cycle is being skipped because there are less trees
to take the carbon in and make carbon dioxide, this also leads to more carbon in the
air which we know causes global warming.
 MDCs such as America and Canada on the other hand don’t cut down trees as
excessively or mine for coal, but they do release fossil fuels into the atmosphere
through pollution but not as much as LDCs.

8. Pathway Affected by
Human Activity
 Since the start of the industrial age humans have harvested and
burned deposits for energy, releasing the carbon compounds that
were stored in the coal, oil, and gas deposits, much faster than they
would have been released naturally, and this rapid release is the
primary cause of global warming. Deforestation also decreases the
amount of vegetation that can decrease the amount.