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Our Diet: Leading to a Sustainable Future or Killing the Planet - Part 2

Transcript for the following video on changing our diet to save our planet:

Personal health is clearly very important, but I’m going to move on to the environmental aspects of our dietary choices –

And I’m going to start by showing you how much water is used in order to produce different kinds of food.

Did you know that 70% of the world’s water supply is used by the agriculture sector? It takes 1000 x more water to produce food for the human population, than the amount we actually drink.

In a world where fresh water is becoming more and more scarce, in a world where droughts are becoming more severe and where over 1 billion people do not have access to clean water for drinking, we are using from 15 000 up to 100 000 litres water to produce one kilo of beef.

When it takes less than 2000 litres of water to produce the same amount of wheat.

To put things into perspective, 15 000 litres water is equivalent to the amount of water used by a typical family for all of its combined household purposes for a period of one month.

It is estimated that the amount of water needed to produce meat from a single cow is enough to float a large ship.

This is some data from the Food and Agriculture Organization of the United Nations, who calculate that:

  • Growing 1 tomato requires using 13 litres water
  • 1 potato requires 25 litres
  • 1 slice of bread 40 litres
  • 1 orange 50 litres
  • 1 bag of potato crisps 185 litres
  • And 1 hamburger 2400 litres of water

No wonder the UN says that “the world is thirsty because it is hungry”

Most of our freshwater is being used to produce our food, mainly meat

Fertile land is not in limitless supply either, yet according to the WHO, if we use one hectare of land to produce beef, we can feed one person a year. And for sheep, we can feed 2 people in a year.

But the same area of land used to produce plant foods such as rice and potatoes can feed twenty times as many people.

That is, any given acreage can feed about twenty times as many people eating a plant-based diet as it could people eating the standard industrialised -country diet. This is an important point especially in developing countries.

You might think – so what – there’s plenty of land – but actually there isn’t – according to UN, the extent of pasture land in the world is already 3.4 billion hectares -there is no further room for expansion of pasture land except into forests.

And we are doing just that – we are expanding into our precious rainforests by cutting down millions of acres of ancient virgin tropical rainforest in order to create pasture land for grazing animals - who we can feed to one person per hectare used, per year. I’m going to tell you more about deforestation in a moment.

But first let’s look at the energy used in the production of meat.Very few of us realize how much our food choices have to do with the use of energy and the wasting of energy.

We waste a lot of energy by cycling plant food through animals rather than eating it directly ourselves because most of the calories in the food we give animals are no longer available to us – most of the food is converted into energy used for movement, or energy to form and excrete  manure, or energy to grow body parts not eaten by us.

So animals that are fattened with plant protein take more energy and protein from their feed, than they return in the form of  food for humans, that is, only a fraction of the energy is returned to us in the form of edible flesh.

In this way, we end up with far fewer calories available to feed humans, as would be available if we ate the grain directly - this is a very energy-inefficient way of feeding the human population.

Producing any kind of food takes energy. But some foods take considerably more than others.

In general, producing one calorie of  animal protein requires burning 10 times more fossil fuel than producing one calorie of plant protein— and as a result, releases 10 times as much carbon dioxide.

In other words, producing 1000 calories of beef requires burning 10,000 times more fossil fuel than producing 1000 calories of, say, soybeans, and as a result produces 10,000 times more carbon dioxide - meat production is extremely energy-intensive and polluting in nature.

It seems therefore, that in order to support a meat-eating diet, we need to use a a phenomenal amount of water, vast areas of land, we burn 10x more fossil fuels with 10 x more carbon emissions and in the whole process we lose a lot of energy.

Apart from the massive amounts of water, land, grain and energy that is necessary to support a meat-eating diet, how else does it affect us?

This is how it affects us.

Every year, we destroy 164,000 square kms of virgin tropical rainforest, an area which equals almost the entire size of the British Isles, and one of the major reasons is in order to provide more land to farm livestock.

Livestock farming is by far the single largest human-designed user of land. It accounts for 70% of all agricultural land, and 30% of the world’s surface area (Dr Pachauri’s slideshow).

The rainforests that are destroyed in order to support livestock farming,  are home to over two thirds of all the living animal and plant species on the planet.

In many parts of the world  the major cause of rainforest destruction is  cattle ranching. Every year, 2.4 million hectares of ancient tropical virgin forest, which may be thousands of years old, are destroyed and converted into grass…grass to feed cattle.

To date, 70% of the Amazon rainforest has been destroyed in order to create pasture land for grazing cattle.

And another half a million hectares every year are destroyed in order to create land for growing crops.

Currently 470 million hectares on Earth are used for the purpose of feedcrops.

But the saddest fact is that the crops are not fed to starving people - much of the crops grown on rainforest soil are fed to livestock. Over 90% of the world’s soybean production, for example, is fed to livestock

Each second, an area of tropical rainforest the size of a football field is destroyed to produce 257 hamburgers

That is why it is said that when we take a bite from a burger, we take a bite out of the world’s forests.

This is very sad, because actually rainforest soil is very infertile. The whole fertility is found in the vegetation itself, and a very thin layer of topsoil. Below that, the soil is not of any use for growing crops.

Which means that once forest is cleared, the land can only be used for a year, maximum 2 years, before the soil runs out of nutrients and becomes virtually useless for growing anything.

And without vegetation, heavy rains rapidly cause erosion of that thin layer of topsoil, making the land more and more barren and eventually changing what was once an area of lush rainforest

where once every hectare was home to over 300 species of trees –  

-       into this

Increasing desertification as a result of deforestation, is a major problem in the world today.

This is not a wise action on our part.

- because every year about 2.4 billion tons of carbon dioxide are released into the atmosphere as a result of deforestation for the purpose of livestock maintenance,  making this a significant contributor to global warming.

Our forests and grasslands, along with the oceans, are huge, natural carbon sinks, which absorb and retain much of the carbon dioxide in our atmosphere.

However there is now concern that these natural carbon absorbers can no longer keep up as CO2 levels continue to rise, and instead of continuing to absorb  carbon as they do now, these systems will switch to becoming producers of carbon, and thus contribute to an acceleration in climate change.

Dr. Mike Raupach, co-chair of the Global Carbon Project and scientist at Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), says: “Such a change would have drastic consequences for the predicted magnitude or speed of climate change occurring.”

Destroying our forests is also affecting our climate because rainforests are crucial in determining weather patterns. Deforestation causes drastic changes in global wind and rainfall patterns with increasing droughts, floods, storms, hurricanes -

-these so-called ‘natural disasters’ are already occurring all over the planet –

And deforestation can be a contributor to some of the extreme and unpredictable weather patterns that we are seeing around the world today, and this is just the beginning, because they are predicted to increase in severity and frequency

Furthermore deforestation is a major cause of species disruption – every year there are thousands of endangered species and even extinctions in the world, and most are due to destruction of the rainforests and their related habitats in the tropics .

The IUCN or International Union for Conservation of Nature and Natural Resources,
 identifies livestock as one of the threats to 3428 endangered species, which they have placed on their red list.

As a race we have been very arrogant in our notion that we can use and abuse other species on this Earth in our never-ending pursuit of economic growth. We have been very ignorant in this regard. Because as humans we are dependent on natural ecosystems such as forests, and we are dependent on other species for our own survival. If frogs were to become extinct, for example,  (and there is evidence that many amphibians are being wiped out at a rapid rate), this will affect humans.  Because as one of the chief predators of insects, losing frogs would result in an enormous surge in insect numbers, with a subsequent increase in insect-borne diseases and the destruction of many food crops.

Albert Einstein once speculated that "If the bee disappeared off the surface of the globe, then man would only have four years of life left. No more bees, no more pollination, no more plants, no more animals, no more man."

It would be wise for us to remember that Mankind cannot live alone on this planet – our survival is dependent on the wellbeing and survival of many other species of animals and plants - and right now we are killing off many other species on this planet rapidly through the process of deforestation for meat production, and this is at our own peril


Dr Aryan practices as a Consultant Physician in Respiratory Medicine in the Hutt Valley, New Zealand.  Dr Aryan is also interested in the many-fold and far-reaching effects of our diets, and particularly how our diet affects the environment. She has written and spoken widely about this topic and has presented her talk, Our Diet: Leading to a Sustainable Future or Killing Our Planet? in many venues around New Zealand. She has been interviewed about the link between diet and climate change by both local and national radio and newspapers.

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