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Understanding Carbon Emissions and Carbon Footprint



What is the greenhouse effect?

The greenhouse effect is the way in which heat is trapped close to Earth's surface by gases known as “greenhouse gases.” It is these gases that help keep the earth warm and habitable.

Which gases are considered 'greenhouse gases'?

What are fossil fuels?

I often talk about carbon emissions and carbon footprints in my environmental blogs. In this blog, I'm sharing some simplistic explanations of what those terms actually mean.

What are carbon emissions?

Carbon emissions are basically carbon dioxide emissions that stem from burning fossil fuels.

We have seen in the fast facts that methane, nitrous oxides, fluorinated gases, and water vapor also act as greenhouse gases in addition to carbon dioxide. However, carbon dioxide is the primary greenhouse gas that is emitted through most anthropogenic activities followed closely by methane, and hence carbon emissions are considered to be the major culprit driving global warming and climate change.

Human activities are altering the carbon cycle–both by adding more CO2 to the atmosphere and by influencing the ability of natural sinks, like forests and soils, to remove and store CO2 from the atmosphere. While CO2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution. - EPA

The Carbon Dioxide emission graph

Data source: Reconstruction from ice cores. Credit: NOAA

According to NASA,

Since the beginning of the industrial era (1750), human activities have raised atmospheric concentrations of CO2 by about 50%. This is more than what had happened naturally over a 20,000 year period (from the Last Glacial Maximum to 1750, from 185 ppm to 278 ppm).

Sources of Carbon Emissions

Sources of Carbon Dioxide

Sources of Methane

Transportation - fuel (gasoline, diesel) combustion

Agriculture - Livestock (digestion process, animal manure)

Electricity generation - coal, natural gas or oil burning

Energy and other industries - natural gas processing, storage, transmission etc.

Industries - burning of fossil fuels, other processes

Household and business wastes - Landfills (anaerobic decomposition of wastes)


Here it is important to note that though methane has a shorter life span than carbon dioxide in the atmosphere, it is more efficient in trapping heat than carbon dioxide. The impact of methane is 25 times greater than carbon dioxide when compared on a similar weight scale over a 100 year period.

What is a Carbon Footprint (CF)?

Whatever we do in our day-to-day lives leaves an impact on the environment. Carbon footprint is a measure of that impact.

A carbon footprint (CF) is the amount of total greenhouse gas emissions caused by an individual, event, organization, service, place, or product, expressed as carbon dioxide equivalent. The larger our carbon footprint, the larger the strain on the environment.

Our individual carbon footprint can come from a variety of sources viz., commuting, buying clothes and other materials, smoking, electricity usage, the food we eat, the wastes we throw, burning of wood, gas, or other materials for food preparation, etc. Again the amount of CF generated from a household also depends on various factors, namely, household income, lifestyle, religious practices, geographical location, etc.

Everything we own has a certain carbon footprint.

The CF includes emissions from both direct and indirect sources - direct emissions are attributed directly to individual emissions; indirect emissions are carbon emissions created by a country or a production process, attributed to a person living in that country and using that product or service.

For e.g., for an individual - emissions from personal vehicles or burning of gas stoves are direct emissions; while emissions generated in the manufacturing, shipping, and transportation of the personal vehicle owned by the individual are indirect emissions. Also, the carbon emissions from the extraction, refining processes, and transportation of the fuel used to drive the car are the indirect emissions associated with owning a private vehicle.

The CF is thus the sum total of direct and indirect carbon emissions. Consumption, including clothing, footwear, books, and other household and personal goods all account for a significant amount of an individual's CF because all these items have associated emissions starting from sourcing of materials, to production and then transport.

I hope this clarifies the terms you come across in the environmental context. Should you have any queries, please feel free to ask. You can also suggest topics you'd like to read in this blog.


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