With 20th century industrialization it was realized in the late 1970’s - early 1980’s that human induced climate change could be a problem over the next century and by the 1990’s climate change had be come a mainstream science.

Climate change is usually a natural phenomenon, which continually occurs on our planet. It can be a gradual or a sudden process and can be catastrophic. What is discussed in the newspapers is the climate change associated with humanities use of fossil fuels. When burned, these fuels emit the gas carbon dioxide and in turn the carbon dioxide acts to trap the heat in Earths atmosphere in much the same way that heat is trapped in a greenhouse, hence the name the “greenhouse effect”. There are many greenhouse gasses but CO₂ is the largest problem and methane CH₄ is also very significant. The picture below shows the main greenhouse gasses as they have built up in the atmosphere over time and the relative greenhouse effect they have (the radiative force).

Activities on our planet continually emit greenhouse gases, natural and human induced, and these gases are continually reabsorbed by various processes on the planet. It is the balance of the rate these gases are emitted vs. how fast they are reabsorbed that matters to climate change and the temperature of the planet. Whilst other greenhouse gasses continue to grow in concentration it is the concentration in CO₂ that continues to grow significantly year on year, which means it cannot be reabsorbed fast enough by the planet and so will increase the temperature.

It may surprise you to know that the volumes of greenhouse gasses that are emitted through natural processes massively outweigh the volumes that humanity throws into the atmosphere. However the volumes that the planet can reabsorb naturally is also massive, but not limitless. Prior to industrialization the natural emission from the oceans and living systems was in balance with the planets ability to reabsorb it. Simply put we have now overtaken the planets ability to soak up natural greenhouse gasses together with those produced by industrialization.

Power generation and industrial processes emit about 36Gt (2015) of carbon dioxide each year, and currently this is increasing each year, because we are burning more fossil fuels in spite of renewable energies. Climatologists often present the total weight of carbon that we can add to the atmosphere that limits the global temperature increase to an “acceptable” level of 2^oC. This number is 335Gt, at current rates we will be there by 2024. The picture below illustrates this, if you click on the image there is much more information.