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How our diet choices impact our carbon footprint?

The livestock industry is the single largest sectoral source of greenhouse gas (GHG) emissions. With a share of 18% of global GHG emissions, it accounts for more than the transportation, industrial or energy sectors.

Carbon emissions & global warming

Carbon dioxide is naturally present in the atmosphere as part of the Earth's carbon cycle (the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals). By preventing heat escaping the earth’s surface, carbon dioxide & other greenhouse gases lead to an increase in global temperatures, causing what is actually a natural ‘greenhouse effect’ that helps keep our planet warm and habitable.

However, small changes in the average temperature of the planet can translate to large and potentially dangerous shifts in climate and weather. How small are we talking?

2 degree centigrade

Leading scientists and organisations globally (including the G8 and the IPCC) have settled on 2 degree centigrade, as the limit of warming before dangerous climate changes start affecting our life on the planet. Consequences of crossing this limit include an unacceptable rise in sea levels devastating populations across coastal regions across the world, extreme weather fluctuations and natural disasters.

Co2 concentration levels

Global Co2 concentration levels have risen dramatically over the last couple of decades, and are significantly above even historical highs

Reaching 2 degree mark

Humanity is coming dangerously close to crossing this 2 degree mark within our current generation. The global average temperature increased by more than 1.4°C over the last century. In fact, according to the National Oceanic and Atmospheric Administration (NOAA), the decade from 2000 to 2010 was the warmest on record, and 2010 was tied with 2005 as the warmest year on record. And the United Nations' Intergovernmental Panel on Climate Change (IPCC) reports that 11 of the past 12 years are among the dozen warmest since 1850.

Livestock's role in carbon emissions

As per the United Nations1,the livestock industry is the single largest contributor to greenhouse gas emissions globally (18% of global carbon emissions = 7.8 bn tons of carbon dioxide per annum). To put this in perspective, the livestock sector contributes:

  • 38% more emissions than that produced by all our oil, coal, gas and other power plants (energy share: 13%)
  • 28% more emissions than all the cars, buses, planes, ships, trucks, trains in the world put together (transportation share: 14%)
  • 12.5% more emissions than every factory in the world (industrial share: 16%)

Particularly damaging, are the relatively higher shares of certain extremely dangerous greenhouse gases with a much higher global warming potential (GWP) than Co2. This includes:

  • 37% of anthroprogenic methane (23x GWP of Co2) – mostly through enteric fermentation by ruminants
  • 69% of anthroprogenic nitrous oxide (296x GWP of Co2) – primarily through manure
  • 64% of anthroprogenic ammonia emissions – which contribute significant to acid rain and the acidification of ecosystems.

In a rapidly warming world, can society afford a sector (i.e. Livestock) that contributes less than 2% of global GDP but 18% of global greenhouse gas emissions?

Carbon emissions & diet

Plant based foods (i.e. a vegan diet) result in significantly lower carbon emissions, as compared to meat & dairy products. By reducing our consumption of meat & dairy products in favour of plant based foods, we can significantly reduce the carbon footprint of our diet. The chart below depicts the potential carbon savings that can result from even small changes in our diets.

Carbon foodprints of common food items

The production of meat & dairy products result in significantly more emissions of harmful greenhouse gases, than plant based foods. A shift to a vegan diet is the single largest personal lifestyle change that can help reduce your carbon footprint. (Source: Clean Metrics)

Are carbon emissions from livestock greater than the 18% UN estimate?

It is well known that livestock production is the single largest contributor to global deforestation. The UN Livestocks Long Shadow report does take into account the greenhouse gases that are released into the environment as a result of deforestation (due to the loss of carbon stores in trees and soil).

However, while there is a direct contribution related to the loss of carbon stores in forests, there is a more indirect opportunity loss of the significant amount of greenhouse gases that forests naturally reduce as part of their photosynthesis process. This is a very real and substantial loss of potential greenhouse reduction forest cover, and this lost opportunity has not been factored into the UN calculations. World watch recently came out with a report titled Livestock & Climate Change which included this lost opportunity with staggering results – including the lost opportunity of carbon reduction by forests due to deforestation increases the contribution of the livestock sector to 50% of all human cause global carbon emissions

References: 

1) UN FAO, Livestock's Long Shadow