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Dr Kate Meyer


Tel: +64 22 6566213

Understanding the ten planetary quotas

The planetary quotas explained

If you would like to learn more about how you can help us to help the planet, click join to select a membership, or support to give a donation.

Carbon Dioxide Emissions

CO2 is a greenhouse gas which means it traps heat into the atmosphere. It is released when we burn fossil fuels or organic matter and when we make concrete. Some CO2 (20 – 35% of what is emitted) remains in the atmosphere for hundreds of thousands of years. CO2 not only warms the atmosphere, it also makes our oceans more acidic which is harmful to marine life. We have already gone beyond safe limits for CO2 in the atmosphere so the quota shows how much we need to remove each year to return to safety this century.

Methane & Nitrous Oxide Emissions Quota.
Methane and Nitrous Oxide (Agricultural GHG) emissions

Methane and nitrous oxide are two other “long-lived” greenhouse gases which means that they stay in the atmosphere – warming it up – for a long time (tens to hundreds of years). Both are predominantly produced during agricultural processes. Each gas causes a different level of warming per kilogram emitted so it is common practise to measure them in terms of “CO2 equivalent” which is the amount of CO2 that would produce the same warming.


The amount of forestland on the planet is critical to the health of the planet ...<learn more> because forests absorb CO2, and because they provide important habitat for a large percentage of the world’s species. If cut down too much forest then we risk causing abrupt change to the whole planet. The sahara desert was once a lush forest. We have already removed too much forest so the quota shows how much land must be reforested each year to return to safety this century.

Emissions of Ozone Depleting Substances

Ozone depleting substances such as CFCs created a hole in the Earth’s ozone layer. This is a problem because the ozone layer protects us from the most harmful types of UV rays. The Montreal Protocol is a global agreement to stop emitting (most) ozone depleting substances. Substances included in the protocol are often referred to as “Montreal Gases” and are measured in a unit
called “ozone depleting potential” (ODP) – a measure of how harmful each gas is to the ozone per kilogram of gas emitted.

Emissions of Aerosols

Aerosols are small particles in the air. They cause smog and acid rain. They are extremely harmful to human health. A limit for aerosols can be thought of as a minimum air quality standard. A new indicator called “aerosol optical depth equivalent” (AODe) has been developed to measure the impact on air quality of aerosol emissions. This indicator allows us to quantify different
aerosols within a single indicator and can be thought of as an “air quality footprint”. Although aerosols are harmful to health, they also have a cooling effect on the climate. In this way, aerosols have slowed down global warming – without aerosols the planet would be warmer. For this reason there is both an upper and a lower limit.

Water Consumption

The water we consume directly from the tap is a very small fraction of our total water consumption. Most has been used or contaminated in the production of goods and services. For example, a cup of coffee that uses 150mls of water from the tap has a water footprint of approximately 140 litres. This water was used to grow the coffee beans, to process them, and to transport them to your home. Much of our water footprint happens at a great distance to where we live, so the local weather and water availability should not be relevant to our overall water consumption targets. The limit includes water consumed from water bodies, rainwater, and water contaminated by human activities.

Reactive Nitrogen released into the environment

Reactive nitrogen is a necessary component to grow food. It occurs naturally in animal and plant matter and can also be produced synthetically using non-reactive nitrogen gas. However, the over use of nitrogen fertilisers has led to run off into water ways which can cause excessive plant growth (algal blooms) which prevent oxygen reaching the water below and thus kills off all life in
these areas. If all these dead zones in the oceans were put together they would be the size of NZ.

Phosphorus released into the environment

Phosphorus is also necessary to grow food. It is present in animal and plant matter .. <Learn more> and in phosphate rock. Most of the phosphorus used in agriculture is mined from phosphate rock which causes local environmental damage. Phosphorus, like nitrogen, can run-off into waterways and cause algal blooms.

Biodiversity Loss

Human activity can impact biodiversity in many ways including disrupting habitat...<learn more> introducing alien species, overexploiting species, altering the climate, and polluting the climate. Many of these impacts are addressed through other quotas. However, human impacts on biodiversity loss are very severe. We are currently experiencing a level of species extinction similar to
when the dinosaurs became extinct. For this reason a specific quota has been determined to address biodiversity loss. The indicator estimates the impacts on biodiversity of occupying different land types and of changing land types from on to another. The land areas are converted into an estimated percentage of disappearing fraction of species.

Imperishable Waste

Humans have created hundreds of thousands of “novel entities” ...<learn more>... things that would not occur naturally without human intervention. These do not typically undergo rigorous testing and the impacts of such things are often only discovered much later. Now there are predictions that there will soon be more plastic than fish in the oceans.




Feel overwhelmed by global environmental issues such as climate change?

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We quantify what YOU need to do to operate within the planet's limits:
you as an individual, an employee, a CEO, or a government official.

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