In an article entitled ‘Energy for the Common Good’ Sachs informs us that earlier this month, the Ecumenical Patriarch Bartholomew and Pope Francis each convened business, scientific and academic leaders, in Rome and Athens, respectively, to hasten the transition from fossil fuels to safe renewable energy. He states:

According to Francis and Bartholomew, we need politics, economics, and technology to serve a far greater purpose than power, wealth, or economic growth. We need them to promote human wellbeing today and for future generations.[1]

Efforts to persuade the leaders of governments and industry are laudable but we are all aware that extremely powerful vested interests will continue to block their efforts.  Another important factor is the time it will take to implement any changes that are eventually agreed and to be frank, we do not have that luxury.

My main point is that both the recent declaration and Sachs’s article continue to focus on the production of fossil fuels whilst ignoring the impact of the animal based diet on climate change.  Whilst these powerful Christian leaders are right to continue their efforts, it is argued that they would be far more effective in producing real and lasting changes to our climate if they encouraged their faithful to immediately adopt a fully vegetarian diet or significantly reduce the amount of animal based food in their diets. In 2013, Knight[2] provided us with the following important information.

  • In 2006, the United Nations Food and Agriculture Organisation (Steinfeld et al,) calculated that when measured as carbon dioxide (CO2), 18 percent of worldwide greenhouse gases (GHGs) – totaling 7.5 billion tons annually, result from the production of cattle, buffalo, sheep, goats, camels, horses, pigs and poultry. These emissions result from land-clearing for feed crop production and grazing, from the animals themselves, and from the transportation and processing of animal products.  In contrast, all forms of transportation combined were estimated to produce around 13.5 percent of global GHGs.
  • The GHGs produced by animal production are composed of CO2, methane, nitrous oxide, and ammonia. Steinfeld and colleagues calculated that the livestock sector is responsible for 9 percent of anthropogenic CO2 emissions-that is, those attributable to human activity-which mostly arise from deforestation caused by the encroachment of feed crops and pastures.  Animal production occupies some 30 percent of the Earth’s land surface and is increasingly driving deforestation, particularly in Latin America.  Seventy percent of previously forested Amazonian land has now been converted to pastures, with feed crops covering a large part of the remainder.
  • Animals kept for production emit 37 percent of anthropogenic methane- which has been calculated as exerting seventy-two times the global warming potential (GWP) of CO2, over a twenty-year time frame, mostly from gastrointestinal fermentation by ruminants (particularly, cows and sheep). They also emit 65 percent of anthropogenic nitrous oxide-with 296 times the GWP of CO2, the great majority of which is released from manure. They also emit 64 percent of anthropogenic ammonia, which contributes significantly to acid rain and ecosystem acidification.
  • However, in 2009 Goodland and Anhang calculated that at least 22 billion tons of CO2 emissions attributable to animal production were not counted and at least 3 billion tons were misallocated by Steinfeld and colleagues. Uncounted sources included livestock respiration, deforestation and methane underestimates.  They concluded that animal production actually accounts for at least 51 percent of worldwide GHGs and probably significantly more.  Although the precise figures remain under study, it is nevertheless clear that the GHGs resulting from animal production are one of the largest contributors to modern climate change.

Despite these facts, the impact of the animal food based diet on global warming continues to be underestimated and unreported.

Dr. Christina Nellist,


[1] Available at

[2] Knight, A, “Animal Agriculture and Climate Change.” In The Global Guide to Animal Protection, ed. A. Linzey, 254-256. Urbana, Chicago and Springfield: University of Illinois Press, 2013.