Able to be decomposed naturally by bacteria or other living organisms. The term biodegradable when applied to a product usually means that that the item will break down into harmless substances, reasonably quickly, when disposed of.


Biodiversity is the variety of life to be found in any one area – be it a garden, a river or the whole planet. It encompasses everything from microorganisms and fungi to plants and animals. All these living things connect with each other in finely tuned eco-systems that have to maintain their balance to remain stable. It has long been known that climate change reduces biodiversity, but more recently it has been generally acknowledged that maintaining high biodiversity actually counteracts climate change, so the two are interconnected.


Carbon is a chemical element. Graphite, charcoal and diamond are all made of carbon. It also forms compounds that make up living things and is in almost everything we eat.

In the context of climate change, ‘carbon’ is commonly used as a shorthand for carbon dioxide. This shorthand can sometimes cause confusion, because ‘a tonne of carbon’ will often be used to mean ‘a tonne of carbon dioxide’.

Carbon dioxide

Carbon dioxide is a colourless, odourless gas made up of one carbon atom to every two oxygen atoms.

There are natural processes that change the levels of carbon dioxide in the air, but some of them have been over-used by the human population, and other processes have been added by us. These are upsetting the natural balance.

Processes that increase the amount of CO₂ in the air include:

Burning fossil fuels
Destroying a living thing by fire – as occurs with deforestation
Combustion of petrol and diesel in cars
Cement production

Processes that decrease the amount of CO2 in the air include:

Photosynthesis by plants (The process by which a plant converts carbon dioxide and water to make their own food, glucose) – another reason to stop deforestation
Absorption in peat bogs/soil – which is why buying peat-free compost will help

Carbon Footprint 

Carbon footprint is a measure of the amount of carbon dioxide, or the carbon dioxide equivalent of all the greenhouse gases, that are released by the activities of a person, a group of people, or a company. A person’s carbon footprint is affected by many things but especially the type of fuel they use, food they consume and products they buy. It is difficult to calculate precisely but it is a useful term to describe our approximate personal impact on the environment.

Climate Change

Climate change is a term that encompasses all the long-term changes to weather patterns our planet is undergoing. The catalyst behind these changes is the rise in temperature of the Earth’s atmosphere, caused by the increase of particular gases, known as greenhouse gases.

Climate Footprint

Climate footprint is a more comprehensive measure of human impact upon the climate than a carbon footprint. However, like our carbon footprint, it is very complex to calculate. It measures the total amount of carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons (PFCs) and sulphur hexafluoride (SF6) emissions of a defined population, system or activity.​


The clearing or thinning of trees in forests in order to use the land for other purposes.


In the context of climate change and this website, the word emissions is used as a general term for the total sum of greenhouse gases that are created by an action or in the production of something.

Fossil Fuels

Carbon-rich deposits such as coal, oil and natural gas that were formed millions of years ago from the remains of plants or animals. They are a finite resource and will eventually run out. They release greenhouse gases into the atmosphere, when burned.

Global Warming

Global warming refers to the overall increase in worldwide temperatures caused by rising greenhouse emissions.​

Greenhouse Effect

The greenhouse effect is the retention of heat in the atmosphere by greenhouse gases. Without it, the Earth would be too cold to support life as we know it. However, the increasing amount of greenhouse gases in the atmosphere are increasing the heat retention, and causing a rise in average temperature of the earth’s atmosphere (global warming). 

Greenhouse Gases

These are any gases that can trap heat in our atmosphere. They absorb heat (infrared radiation) emitted from Earth’s surface and reradiate it back to Earth. The activities of humans are increasing the levels of all greenhouse gases in the atmosphere while, at the same time, reducing the planet’s capacity to absorb them. This upsets the natural balance by increasing our planet’s temperature. Carbon dioxide, methane and water vapour are probably the three most significant greenhouse gases.


Methane (CH4) is a highly flammable greenhouse gas composed of one carbon atom and four hydrogen atoms. Methane is the primary component of natural gas and is used to produce heat and electricity around the world. When burned in the presence of oxygen, it produces carbon dioxide and water vapor.

Unnatural processes that increase the amount of CH4 in the air include:

Burning fossil fuels
Extracting coal, oil and natural gas from the earth
Raising livestock (particularly cattle)
Rice paddies
Dumping waste in landfill

Non-renewable energy

Energy produced by burning coal, oil or natural gas. These resources are running out and also produce carbon dioxide when burned.

Renewable energy

Energy produced from a sustainable source (one that won’t run out), such as electricity generated from wind turbines or solar panels.


A plan, method or system designed to use resources at a level that won’t damage the environment or deplete the resource. For example, if you buy wood from a sustainable source, it means that the trees felled are replaced by planting more trees, so that the resource will never run out.

Water vapour

Water vapour is one of the biggest contributors to the greenhouse effect. As a greenhouse gas, it reflects heat back to earth but the warmer the surface of the earth, the more water evaporates, therefore having an ever-increasing cycle, speeding up the greenhouse effect. The amount of water vapour in the atmosphere cannot, in general, be directly altered by human behaviour but it is formed as a consequence of the increase in other greenhouse gases.

161 Total Lifetime Changes
357 Total Positive Changes

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