Climate Change Topic

The carbon cycle:

  • carbon and other nutrients cycle through nature

  • The Earth has 4 spheres: biosphere, lithosphere, atmosphere, and hydrosphere.

  • The carbon cycle is the movement of carbon through the different spheres.

The carbon cycle goes through various processes (either increasing or decreasing the carbon dioxide in the atmosphere):

  1. Photosynthesis

  2. Transfer of carbon via the food chain

  3. Respiration

  4. Decomposition or excretion

  5. Formation of fossil fuels

  6. Combustion

  7. Formation of limestones

Photosynthesis (carbon input)

During photosynthesis, plants absorb carbon dioxide. The carbon dioxide interacts with the water (absorbed by the roots), making glucose (C6H12O6).

carbon dioxide + water → glucose + oxygen

6CO2 + 6H2O → C6H12O6 + 6O2

Transfer of Carbon via the Food Chain

All living organisms are made up of carbon. Carbon is the primary component of macromolecules, including proteins, lipids, nucleic acids, and carbohydrates.

Animals obtain carbon by consuming other plants and animals; their carbon content is transferred through the food chain.

Respiration

Plants and animals breathe in oxygen to break down glucose, forming carbon dioxide and water.

glucose + oxygen →carbon dioxide + water

C6H12O6 + 6O2 → 6CO2 + 6H2O

Decompostion & Excretion

Dead organic matter is broken down by decomposers, which respire, releasing carbon dioxide back into the atmosphere.

Urine, feces, and even fallen leaves consist of carbon content.

Formation of Fossil Fuels

The carbon content of these animals and plants (organic matter) is broken down (over millions of years) into usable fuels to provide us with energy.

Fossil fuels include: coal, oil, gas, etc.

Combustion

When fossil fuels are burned in oxygen (combustion), carbon dioxide and water are formed, causing carbon dioxide to enter the atmosphere.

Formation of Limestone

Carbon dioxide from the atmosphere can dissolve into the ocean, forming carbonic acid.

Shells and bones from dead animals sink to the seabed. Over millions of years, the compaction of these shells forms limestone.

Limestone is a sedimentary rock.

Earth is a greenhouse. It keeps its heat in.

Infrared radiation (50% goes into the Earth’s atmosphere):

  • When it is emitted from the sun, it is a shorter wavelength (high energy), but when it is re-emitted from the earth, it has a longer wavelength (lower energy).

  • long wavelength, but small frequency

  • Radiation loss is heat loss