What is the most important step – Go Solar or Go Vegan?


Edited by James O’Donovan from Wikipedia and ‘Carbon Yoga’ by Sailesh Rao


Planetary boundaries (see wikipedia) are an attempt to develop a set of indicators to monitor the health of the global planetary system and to provide governments timely information on what activities need to stop or be changed in order to keep the planet in a healthy state.  They are a concept of nine Earth system processes proposed in 2009 by a group of Earth system and environmental scientists led by Johan Rockström and Will Steffen.  The group wanted to define a “safe operating space for humanity” as a precondition for sustainable development.  The scientists assert that once human activity has passed certain thresholds or tipping points, defined as “planetary boundaries”, there is a risk of “irreversible and abrupt environmental change”.  The nine Earth system process boundaries mark a theoretical safe operating zone for the planet.

Estimates indicated that three of these boundaries—climate change, biodiversity loss, and the biogeochemical (excess nutrients from agriculture) flow boundary—appear to have been crossed.


From Holocene to Anthropocene

It’s obvious to most people that the planet Earth is a finite system, which means it has limits.  The Holocene began about 12,000 years ago.  It is the current interglacial period, and it has proven to be a relatively stable environment of the Earth during which we developed agriculture, villages, cities, and contemporary civilizations.  There have been natural environmental fluctuations during the Holocene, but the key atmospheric and biogeochemical parameters have been relatively stable.  This stability and resilience has allowed agriculture to develop and complex societies to thrive.

According to Rockström et al., we “must take the range within which Earth System processes varied in the Holocene as a scientific reference point for a desirable planetary state.”  Since the industrial revolution, the planet has entered a new epoch, the Anthropocene.  In the Anthropocene, humans have become the main agents of change to the Earth system.

There have been other well publicised scientific warnings about risks to a range of biophysical processes.  In 1992 scientists issued a warning to humanity using a number of environmental indicators.  This was updated in 2017 as shown below with all but ozone depleting chemicals continuing to deteriorate.

Y-axes do not start at zero and data range varies for each graph – Union of Concerned Scientists.


Since the advent of the Anthropocene, the rate at which species are being extinguished is 100 times higher than the background rate, and humans are now the driving force altering global river flows as well as water vapor flows from the land surface.  Continuing pressure on the Earth’s biophysical systems from human activities raises concerns that further pressure could be destabilizing, and precipitate sudden or irreversible changes to the environment.

“Our planet’s ability to provide an accommodating environment for humanity is being challenged by our own activities.  The environment—our life-support system—is changing rapidly…….to an unknown future state of significantly different conditions.” Steffen, Rockström & Costanza (2011)

The proposed framework lays the groundwork for shifting the approach to governance and management, away from the essentially sectoral analyses of limits to growth aimed at minimizing negative externalities, toward the estimation of the safe space for human development.
Transgressing one or more planetary boundaries may be highly damaging, irreversible, or even catastrophic, due to the risk of crossing thresholds that trigger non-linear, abrupt environmental change within continental – to planetary-scale systems.


The Earth Doctor’s Diagnosis – Adapted from Carbon Yoga by Sailesh Rao

Imagine that we are Earth doctors and we are being asked to diagnose the Earth’s condition and prescribe a course of action for healing and reversal.  Let’s take each of the planetary boundaries and examine the root cause for the human induced perturbations in the underlying nine Earth processes.

  1. Take the number one violated limit in the scientists’ list:  the unsustainable extinction of species on the planet.  Species are stressed by multiple factors including habitat loss, invasive species, pollution, climate change, and just plain human consumption.  But habitat loss caused by animal agriculture through deforestation and desertification (from overgrazing) and egregious fishing practices such as bottom trawling and drag-net fishing, has been estimated to be responsible for 80% of species extinctions.
  2. The second major safe limit violation, the Nitrogen and Phosphorous cycles, is also primarily due to Animal Agriculture since more than half the industrially grown fertilised mono-cultured crops of the world are fed to animals directly.  This is also added to by the billions of tons of nutrient rich animal manures.  These nutrients are causing an increase in the number of ocean dead zones globally (as shown above).
  3. With respect to the third safe limit violation, the Carbon cycle, human burning of fossil fuels is responsible for an estimated 57% of all anthropogenic greenhouse gas (GHG) emissions, using a 100-year window for calculating CO2 equivalences of methane and other short-lived GHGs.  But even here, Animal Agriculture is a substantial contributor to anthropogenic GHG emissions, with end-to-end lifecycle estimates ranging as high as 51% of the total, if we use 20 year time windows for calculating CO2 equivalents.
  4. Fossil fuel burning produces significant CO2 emissions, the prime culprit for ocean acidification.  Deforestation, biomass fires and the consumption of plant biomass are also significant sources of CO2.
  5. Concerning Land Use, the below WWF diagram shows that (not counting forests) 79% of the biologically productive land is now occupied by agriculture, and 77% of that is for animal agriculture predominantly grazing.


WWF Living Planet Report 2016 – indicates approximate global land areas.


  1. As for fresh water, 55% of human fresh water use is for Animal Agriculture in the US, while the fossil fuel industry accounts for about 25% of fresh water use (most of that is for cooling and is non-consumptive use being returned to the same catchment).
  2. With respect to ozone depletion, one of the primary mechanisms for it is during the conversion of methane to CO2 in the upper atmosphere.  In turn, Animal Agriculture is one of the primary sources of anthropogenic methane emissions.  However, among fossil fuels, natural gas systems leak methane as well, though the true magnitude of these leaks is in dispute.
  3. With respect to aerosol loading, the major source of human emissions of aerosols is during the burning of fossil fuels.
  4. Finally, with respect to chemical pollution, most of the herbicides, pesticides and insecticides are used in the agricultural production of animal feed.  Therefore, if Animal Agriculture ceases, a significant portion of the chemical pollution on the planet will cease as well.

As Earth physicians, let us imagine that we are asked to write a prescription for each and every human being to fill so that humanity’s overall relationship with the Earth changes to a more benign, safer, steady state version.  What should we tell people to do?  Should we tell them to focus on weaning themselves from fossil fuel use, i.e., go solar, or should we encourage the ongoing transition away from animal products, i.e., go vegan?

Imagine that we wave a magic wand and get everybody to go vegan instantly.  This immediately impacts 8 of the 9 planetary boundaries and instantly begins to reduce the violated safe limits as well.  If everybody went vegan, it would immediately release 35-40% of the land area of the planet back to Nature, to regenerate forests and re-wild the planet.

  1. Since habitat gets returned to wildlife, the safe limit violation on species extinction rates would be reduced immediately.
  2. The safe limit violation on the nitrogen and phosphorous cycles gets reduced immediately as we no longer need to produce vast quantities of inefficient animal feeds and we eliminate the generation of billions of tons of animal wastes.
  3. The safe limit violation on the carbon cycle gets reduced as regenerating forests sequester CO2 from the atmosphere in trees, plants, insects, animals, birds, and in the soil.  The “Lifestyle Carbon Dividend” paper showed that recovering forests can sequester 265 Giga tons of Carbon (GtC) on just the 41% of current grasslands that used to be forests in 1800.  That is more carbon than has accumulated in the atmosphere since 1750 (240 GtC)!
  4. As the CO2 in the atmosphere gets sequestered in regenerating forests, the acidification of the ocean reduces as well, as the ocean outgases CO2 to reach a new equilibrium.
  5. Around 40% of the cropland can be returned to Nature, restoring overgrazed degraded lands back to healthy ecosystems.
Restricting grazing in the Chinese Loess Plateau re-established vegetation (source: Wikipedia).
  1. Around 50% of the fresh water use is avoided as Animal Agriculture ceases.  Besides regenerating forests this creates more fresh water as well.
  2. As methane emissions are reduced, ozone depletion is also improved.
  3. A transition to an organic vegan agricultural system substantially reduces the emission of chemical pollutants (pesticides, and GMO’s, etc.).

Next, let us consider a second thought experiment.  Imagine that we can wave the same magic wand and turn our entire energy infrastructure over to solar, wind and other clean sources instantly so that fossil fuels no longer have to be burnt to run the human enterprise.  Let us assume that we leave everything else unchanged as at present so that we continue to eat animal foods and indeed, double our consumption by 2030 as envisioned by the UN FAO.  As a result of this instant change to our energy infrastructure, we stop pumping a majority of the GHGs, especially carbon dioxide (CO2), into the atmosphere and we immediately stop exacerbating human impact on 4 of the 9 planetary boundaries.  That is the good news.  But the bad news is that:

  1. The surface temperature of the planet will start increasing at a faster rate and it will increase approximately by an additional 0.5 deg C (1 deg F) within a decade as aerosols disappear from the atmosphere.  This temperature increase occurs because when we burn fossil fuels, we release aerosols like sulphur dioxide (SO2) that are partially shielding us from incoming solar energy.  While CO2 persists for hundreds of years in the atmosphere, aerosols precipitate and disappear from the atmosphere within a couple of weeks, thereby exposing us to the true effects of our GHG emissions to date.  Think of aerosols as the haze that prevents the sun from shining brightly on our Earth.  When the haze disappears, the Earth heats up.
  2. The CO2 in the atmosphere will not diminish for hundreds of years even though we no longer burn any more fossil fuels.  Furthermore, since our land use changes will continue unchecked, CO2 emissions from deforestation, desertification and animal respiration and also methane emissions will continue to add to the atmospheric GHG levels.
  3. As the CO2 concentration in the atmosphere increases due to deforestation and conversion of plant biomass to CO2 by farm animals the ocean will continue to become more acidic, but significantly less than it would with the burning of fossil fuels.

Therefore, in this second experiment, the conversion of the energy infrastructure does nothing to heal the climate and would actually make the situation worse.



As Earth doctors, our diagnosis task is a no-brainer, really.  Considering all the symptoms that the Earth is exhibiting and considering the results of our thought experiment, we can now see that it is primarily Animal Agriculture, with its deliberate, institutionalized violence on other beings on a gargantuan scale, that is the main source of the cancer underlying the Earth’s fever.

However, that doesn’t mean we should stop converting our energy infrastructure over to clean sources.  In fact, the two steps, go vegan and go solar, will be accomplished simultaneously.  Those of us in the global North who have access to food abundance will go vegan right away and then convert the energy infrastructure over to clean sources over the next 1-2 decades, as solar technologies get produced in volume.  This is the optimal order for the change to occur since the carbon sequestration due to the vegan transition will then compensate for the temperature increase due to the atmospheric aerosol reduction from the clean energy transition.




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