Carbon is released into the atmosphere in many natural and human-driven ways, but human activities like burning fossil fuels and cutting down forests now add carbon much faster than natural systems can absorb it. These extra emissions are a major driver of climate change today.

Big-picture: Natural vs Human

  • Natural processes constantly move carbon between land, ocean, and air in the carbon cycle (for example, respiration and decay).
  • Human activities add extra carbon on top of this natural cycle, mainly by burning coal, oil, and gas, and by changing how land is used.

Natural ways carbon is released

  • Respiration
    • Animals, plants, fungi, and microbes breathe out carbon dioxide as they break down sugars for energy.
  • Decomposition (decay)
    • When dead plants and animals rot, decomposers break them down and release carbon dioxide or methane into the air.
  • Ocean release
    • The ocean both absorbs and releases carbon dioxide; when surface waters warm or circulate, some dissolved CO₂ escapes back to the atmosphere.
  • Natural fires and volcanoes
    • Wildfires that occur naturally and volcanic activity release stored carbon from vegetation and rocks as gases and particles.

Human ways carbon is released

  • Burning fossil fuels (biggest source)
    • Burning coal, oil, and natural gas for electricity, heating, industry, and transport releases huge amounts of carbon dioxide.
* Globally, about 90% of energy-related carbon emissions come from fossil fuels, especially coal, oil, and gas.
  • Transport (cars, trucks, planes, ships)
    • Engines burn petrol, diesel, aviation fuel, or marine fuel, turning the carbon in those fuels into carbon dioxide that goes straight into the air.
  • Industry and factories
    • Factories burn fuels for heat and power and also release carbon dioxide from certain chemical reactions, such as making steel, chemicals, and cement.
* Cement production is a notable example, because heating limestone releases carbon dioxide directly from the rock as well as from the fuel.
  • Deforestation and land-use change
    • When forests are cut down or burned for farming, ranching, or development, the carbon stored in trees and soils is released as carbon dioxide.
* Land-use change, especially tropical deforestation, contributes a significant share of human-caused greenhouse gas emissions.
  • Agriculture
    • Farm machinery and fertilizer production rely on fossil fuels, releasing carbon dioxide.
* Soils can also lose stored carbon when grasslands and forests are converted to croplands or when soils are heavily disturbed.

Simple classroom-style summary

If you need to remember “what are ways in which carbon is released into the atmosphere” , you can group them like this:

  1. Natural
    • Respiration (breathing out)
    • Decomposition of plants and animals
    • Oceans releasing dissolved CO₂
    • Natural fires and volcanoes
  2. Human
    • Burning fossil fuels for electricity and heat
    • Cars, planes, and other transport
    • Factories and cement production
    • Deforestation and land-use change
    • Agriculture and soil disturbance

All of these release carbon, but the extra carbon from human activities—especially fossil fuels and deforestation—is what is rapidly increasing carbon dioxide in the atmosphere and driving modern climate change.

Information gathered from public forums or data available on the internet and portrayed here.