Carbon saved by not using a plastic bag
Given the fact that plastic bags are a ubiquitous feature of modern-day living, it is hard to imagine a time when they never existed. In reality bags only really materialised in the 1970s, and their use only became widespread in the 1980s when handles were added on.
Since then they have multiplied alarmingly, and being so light and durable make their way into streets and gutters, catch on trees and bushes, and litter beaches, rivers and seas across the planet. UK consumption is a colossal 17.5 billion bags a year,
and worldwide figures are between 500 billion and a trillion a year.
Manufacturing this many bags will have released around 60 billion kg CO2.
Plastic bags can take anything up to 1000 years to degrade, and when they do they photodegrade, rather than biodegrade, breaking down due to light into all its tiny component toxic fragments that end up contaminating the soil and our water.
Even more alarmingly, thousands end up being swept into rivers and seas, and are ingested by hundreds of thousands of dolphins, turtles, seals and whales, who mistake the bags for food. In 1998 an endangered leatherback turtle was found dead with 57 kg of plastic bags blocking up its internal system, and in 2002 a dead Minke whale was washed up and found to have 800kg of plastic bags in its stomach.
In addition floating plastic debris in the sea is thought to harm around a million birds a year.
And because it takes so long to degrade the animals who ingest them decompose much quicker than the plastic, releasing them once again into the ecosystem.
Every piece of plastic that has ever been manufactured is still on the planet somewhere, and will be so for the next millennium, not to mention being added to year after year.
Many countries have taken steps to rid their cities of their plastic bag epidemic. In 2001 Ireland imposed a bag tax of 9p per bag. By 2002 consumption had fallen by 90%, and it has became socially unacceptable to use them.
In 2002, Bangladesh banned plastic bags in its capital Dhaka after the devastating 1998 floods which submerged much of the country. A significant factor was found to be the vast quantity of plastic bags blocking the city's drainage systems.
Italy, Belgium and Switzerland have all introduced charges for plastic bags, and they have been banned completely or in part in Taiwan, Kenya, San Francisco, and Tanzania to name just a few.
Switching to a reusable cloth bag is in itself just a simple action, but its benefits are much further-reaching than we might ever anticipate. And just a few individuals changing their habits will encourage others to do the same, and send a signal to governments and industry that people care about such issues.
Most supermarkets sell inexpensive 'bags for life', or see below for a list of other places you can find them.
So, as we've seen by far the biggest problem with plastic bags is its toll on the environment. But there will still also be an appreciable accumulated carbon saving by switching to reusable bags as the raw material used in its manufacture is oil.
Calculating carbon saved by not using plastic bags, and replacing with a reusable bag instead:
According to environmental consultancy Best Foot Forward, the carbon intensity of plastic is 6.25 kg CO2 per kg.
In comparison the carbon intensity of cotton is 4.10 kg CO2 per kg.
17.5 billion bags are used in the UK each year, which is about 380 per shopper. Assuming that the weight of a single plastic bag is about 10g:
Amount of CO2 emitted by manufacturing plastic bags: 6.25 kg CO2 x 0.01 kg = 0.0625 kg per bag or
0.0625 kg x 380 = 23.75 kg per year.
Assuming that a cotton bag is around 150g
Amount of CO2 emitted by cotton bag: 4.10 kg CO2 x 0.15 kg = 0.615 kg per bag
= 0.615 kg per year
So carbon saved by not using plastic bags and using a reusable cotton bag instead:
= 23.75 kg - 0.615 kg = 23.14 kg CO2 per year.
Where to find reusable bags
Origins - Organic Cotton bags
http://www.origins.co.uk/templates/products/sp_nonshaded.tmpl?ngextredir=1&CATEGORY_ID=CAT3629&PRODUCT_ID=PROD78843
Trolley Dolley, a compact solution for shopping trips
http://www.zpm.com/products/living/trolley-dolly/default.aspx
Reusable bags
http://www.reusablebags.com
Turtle bags - ethically sourced bags
http://www.turtlebags.co.uk/index.html
Footnotes
