The sun is constantly sending the Earth light and heat. Light and heat are also constantly escaping from the Earth’s atmosphere.


There is a balance between the heat received from the sun and the heat that escapes from the Earth into space, which means that the Earth stays more-or-less the same temperature, year after year.

The atmosphere contains greenhouse gases. These gases trap the heat as it tries to escape the Earth. These greenhouse gases do a great job. Without them, the Earth would be about 15 degrees colder than it is now, and life on Earth would not be possible.
The problem is that humans are now radically increasing the amount of heat that is trapped in the atmosphere.

We are doing this by sending more and more greenhouse gases into the atmosphere. Lately, we’ve been sending so many greenhouse gases into the atmosphere that the Earth cannot cope. We’re heading for disaster.

The Greenhouse Gases

Carbon Dioxide


The most common Greenhouse Gas is carbon dioxide. Burning fossil fuels (petrol, diesel, coal…) releases carbon dioxide into the atmosphere.

Using a litre of fuel in your car releases a little over 3 kg of carbon dioxide into the atmosphere.

Plants remove carbon dioxide from the atmosphere as they grow. The permanent removal of forests all over the world (including converting forests into dairy land here in New Zealand) has a large impact on the Earth’s ability to remove carbon dioxide from the atmosphere.

The world is burning fossil fuels like there is no tomorrow, which is why carbon dioxide emissions are such a problem. However, carbon dioxide is actually not so bad, when you compare it with other greenhouse gases.



Methane is 34 times worse than carbon dioxide. This means that is you release a kilogram of methane into the atmosphere, it will prevent 34 times more heat from escaping the planet than a kilogram of carbon dioxide.

Very little methane is released when you burn fossil fuels, but a whole lot of methane is released in the farming of sheep and cattle.

This is because sheep and cattle release a lot of methane when eating and digesting grass. Our desire for red meat and dairy products has sent the number of sheep and cattle skyrocketing, and is contributing significantly to the warming of our planet.

Nitrous oxide


Nitrous oxide (N2O) is 298 times worse than carbon dioxide (one kilogram of nitrous oxide is 298 times more effective than carbon dioxide at preventing heat from escaping into space).

Nitrous oxide is released when you burn fossil fuels and when you use nitrate fertilisers.

It is also trapped in the soil, so when you disturb the soil (for example by converting a forest into a dairy farm) you release significant amounts of nitrous oxide.

There are other greenhouse gases as well, some of which are thousands of times more effective than carbon dioxide at trapping heat in the atmosphere, however these gases exist is very small quantities and are restricted to specific industries. Dealing with the three greenhouse gases above is enough to win us the battle.

We can talk about all greenhouse gases together by relating all greenhouse gases to carbon dioxide.

  • if 1 kg of carbon dioxide is equivalent 1 kg of carbon dioxide (makes sense!)
  • then 1 kg of methane is equivalent to 34 kg of carbon dioxide
  • and 1 kg of nitrous oxide is equivalent to 298 kg of carbon dioxide.

If I release 1 kg of carbon dioxide, 1 kg of methane and 1 kg of nitrous oxide into the atmosphere,
then I’ve released 1+34+298=332 carbon dioxide equivalents (CO2e) into the atmosphere.
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