Global warming

Since the industrial revolution in the 1800s, average global surface temperatures have risen by 0.85C [1]. This may not seem like a significant increase to us, but it has occurred over a very short period. The suddenness of this change has meant that many species, including humans, have not had enough time to adapt.

Already, 300,000 human deaths every year are linked to climate change [2], globally. Already, climate change has been linked to the outbreak of the Syrian Civil War [3], where thousands of humans died and were displaced. Already, we are seeing increases in the frequency and severity of extreme weather events such as heatwaves [4; 5], droughts [6], flooding [7], hurricanes [8] and wildfires [9].

All of this with just a 0.85C temperature rise, and we are currently on a trajectory for a global average temperature rise of 3.2C [10]. In the future, we are likely to see significant decreases in crop yields in many areas of the world [11], with areas of Northern Africa and the Middle East potentially becoming uninhabitable [12; 13].

Animal farming and fishing is responsible for, at a minimum, 14.5% of all greenhouse gas emissions worldwide [1] (more than global transportation). This is the most conservative estimate available, as it does not include key sources of carbon emissions such as deforestation for pasture and animal feed. Despite this, it still concludes that animal agriculture is a leading contributor to climate change.

As part of this, animal agriculture contributes 37% of global methane emissions and 65% of nitrous oxide [14]. These gases are much more potent than CO2, having global warming potentials of 56 and 280 times that of CO2 [15] respectively over a 20 year period.

The combination of these facts makes animal agriculture one of the biggest (if not the biggest) contributors to climate change.

  1. IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland. –
  2. Human Impact Report: Climate Change, 2009. Global Humanitarian Forum. Geneva. –
  3. C. P. Kelley, S. Mohtadi, M. A. Cane, R. Seager, and Y. Kushnir, 2015. Climate change in the Fertile Crescent and implications of the recent Syrian drought. PNAS. –
  4. P. B. Duffy and C. Tebaldi, 2012. Increasing prevalence of extreme summer temperatures in the U.S. Climatic Change, 111, 487-495. –
  5. N. Christidis, P. A. Stott, and S. J. Brown, 2011. The role of human activity in the recent warming of extremely warm daytime temperatures. Journal of Climate, 24, 1922-1930. –
  6. J. Sheffield, E. F. Wood, and M. L. Roderick, 2012. Little change in global drought over the past 60 years. Nature, 491, 435-438. –
  7. S. Doocy, A. Daniels, S. Murray, & T. D. Kirsch, 2013. The human impact of floods: A historical review of events 1980-2009 and systematic literature review. PLOS Currents Disasters. –
  8. G. A. Vecchi & B. J. Soden, 2007. Effect of remote sea surface temperature change on tropical cyclone potential intensity. Nature, 450, 1066-1070. –
  9. A. L. Westering, H. G. Hidalgo, D. R. Cayan & T. W. Swetnam, 2006. Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity. Science, 313 (5789), 940-943. –
  10. A. E. Raftery, A. Zimmer, D. M. W. Frierson, R. Startz & P. Liu, 2017. Less than 2 °C warming by 2100 unlikely. Nature Climate Change, 7, 637–641. –
  11. C. Zhao, B. Liu, S. Piao, X. Wang, D. B. Lobell, Y. Huang, M. Huang, Y. Yao, S. Bassu, P. Ciais, J. L. Durand, J. Elliott, F. Ewert, I. A. Janssens, T. Li, E. Lin, Q. Liu, P. Martre, C. Müller, S. Peng, J. Peñuelas, A. C. Ruane, D. Wallach, T. Wang, D. Wu, Z. Liu, Y. Zhu, Z. Zhu, & S. Asseng, 2017. Temperature increase reduces global yields of major crops in four independent estimates. PNAS, 114 (35), 9326-9331. –
  12. J. Lelieveld, Y. Proestos, P. Hadjinicolaou, M. Tanarhte, E. Tyrlis & G. Zittis, 2016. Strongly increasing heat extremes in the Middle East and North Africa (MENA) in the 21st century. Climate Change, 137, 245–260. –
  13. J. S. Pal & E. A. B. Eltahir, 2016. Future temperature in southwest Asia projected to exceed a threshold for human adaptability. Nature Climate Change, 6, 197-200. –
  14. Livestock’s Long Shadow –
  15. United Nations: Climate Change. Global Warming Potentials (IPCC Second Assessment Report):