Climate Change theory refers to the gradual warming of background temperatures, attributed to the release of carbon dioxide by humans. The theory of climate change has been around for over 100 years, and relies on the relationship between temperature and so called ‘greenhouse gases’, including carbon dioxide.

In order to understand climate change, we need to know how the Earth’s energy budget normally works. Here, we need to talk about the ‘greenhouse effect’.

The natural greenhouse effect

The Earth naturally regulates its temperature, keeping the Earth at a balmy 15ºC, on average. Without the natural greenhouse effect, the Earth would only be -18ºC, on average, too cold for liquid water and hence, life as we know it.

But what is the greenhouse effect?

We use the term ‘greenhouse effect’ because the Earth’s atmosphere works much like a garden greenhouse. Radiation from the Sun enters the Earth’s atmosphere and is absorbed by the Earth’s surface. Once this radiation is absorbed, it is re-emitted by the Earth as long wave radiation, infrared radiation, or heat. There are a number of naturally occurring greenhouse gases (GHGs) present in the Earth’s atmosphere, namely carbon dioxide. These act to trap some of the outgoing infrared radiation, warming the atmosphere.

Climate Change – a.k.a the ‘enhanced greenhouse effect’

Atmospheric CO2 emissions as measured at Mauna Loa, Hawaii

Prior to the Industrial Revolution, the concentration of carbon dioxide (CO2) in the atmosphere was about 280 ppm (parts per million). Since this time, the burning of fossils fuels has increased the concentration to 390 ppm in 2012.

The increased concentrations of CO2 in the atmosphere trap more and more of the Earth’s outgoing infrared radiation in the Earth’s atmosphere, warming the Earth.

It is this background warming trend in the Earth’s climate that we refer to as climate change.