By Kabir Sharma:
Today, the world is conscious about carbon footprints. And everything has one – from a war, to watching a movie, to eating a fruit, to your shirt.
Carbon based gases like carbon dioxide and methane (also known as greenhouse gases, or GHGs) trap heat (much like a greenhouse) and play a very important role in maintaining the earth’s temperature.
However, the excessive GHG emissions post industrialization is the most probable cause of the global warming we have witnessed since the 1950s. Most of these gases get released due to the burning of fossil fuels.
Carbon footprint is a measure of the total global warming (or climate change) potential attributable to any activity.
The important thing is that the carbon footprint incorporates direct as well as indirect emissions. So, to find out the footprint of you eating a fruit: think of all the processes involved: the water pump used to water the tree your fruit came from, the factory which made the fertilizer, the storage units which kept it from getting spoilt, the refrigeration at the store, and all the transportation that went into making the meeting possible between you and your fruit. All of these burn fossil fuel directly (petrol/diesel/CNG), or indirectly through electricity (Coal/Natural Gas). A good estimate of the footprint can then be calculated by estimating how much GHG emission took place when all that fossil fuel was burnt.
What Is tCO2e?
Carbon Footprint is measured in tonnes of carbon dioxide equivalent, or tCO2e. Though carbon dioxide is the major contributor to the greenhouse effect, many other gases are important too – the climate change potential of methane and nitrous oxide are 7 and 300 times that of CO2. However, their overall impacts are far less, as they are released in smaller quantities.
We measure all other GHGs in terms how much CO2 would cause an equivalent impact on the climate, thus the ‘e’ after CO2. So, from above, one tonne of methane = 7 tCO2e.
The world wide average per capita footprint is 4 tCO2e. It varies greatly with lifestyle, and in India, urban residents have 16 times the carbon footprint of rural residents. In the US, the value is a shocking 20 tCO2e per person.
If you were to fill about 12 standard 30 litre buckets with petrol and set fire to them, you would release a tonne of CO2e into the atmosphere.
What’s In A Fossil Fuel?
Over the last hundreds of millions of years, plants and organisms like algae and plankton have been picking up carbon from the air and using it to store energy from sunlight. After death and over time, some of the body matter of these organisms gets buried deeper and deeper. The high pressure and temperature at those depths causes reactions forming fossil fuels.
When we discovered the enormous energy potential of this ancient buried carbon, we began extracting and exploiting it, without realising that it meant releasing all that carbon back into the atmosphere.
In nature, carbon absorption and release is a routine affair, as part of the carbon cycle. Feeding, excretion, death and decay govern the level of carbon in the atmosphere. And consequently, the temperature.
But in the history of our planet, carbon concentration has never increased at the rate we are causing it to now, having gone crazy after our discovery of fossil fuel. It is far beyond nature’s absorption capacity, which deforestation is further reducing.
Well, What About The Fruits?
To save us from a huge climate catastrophe, we need a drastic reduction in our total carbon footprint.
Personal choices ought to be changed keeping in mind what would make a real impact to our footprint. For example, there is little point in getting a more efficient printer when you spend your life on planes. But getting rid of two used 100W incandescent light bulbs will save about 1 tCO2e (or 800 kg if replaced with low energy bulbs).
A fruit like a banana on the other hand, is a low carbon food item, as it grows in natural sunlight, requires little packaging, and generally travels on ships and not flights if it is imported. The footprint is only 80g. So eat away!
Energy efficiency, use of public transport, green buildings and greener electricity are the choices which would all have sizeable impacts.
In a positive move, India recently registered 3 billion square feet of green building footprint, the second highest in the world. Buildings, the source of one third of all green house gas emissions, are also the most adaptable in terms of reducing carbon footprint.
Temperature changes could increase by 1.5 to 6.4 degrees by 2100, depending on the path humans take. That’s a lot and will change everything. The world’s average temperature is only 5 degrees warmer today than what it was in the ice age.