Decarbonisation - What does it mean and why is it necessary?

There has been a lot of talk in the media about decarbonisation and carbon offsetting and we have previously touched on carbon emissions in our posts about Composting. So we thought it might be worthwhile starting a series of posts on decarbonisation. 

Firstly, decarbonisation is the reduction or elimination of carbon dioxide (CO2) emissions from a process such as manufacturing or the production of energy.

Most of the CO2 in our atmosphere comes from burning fossil fuels such as coal and oil for energy. Plants and the ocean help pull the carbon component out of the atmosphere but each year we are returning much more CO2 than they can remove.  From 2011 to 2020 the land and ocean absorbed only about half of the CO2 emitted. Yet the amount of CO2 in the atmosphere is continuing to increase.  At the start of the industrial revolution, in 1750, atmospheric CO2 was about 280 parts per million (ppm). In 2021 it was around 416 ppm. The ideal amount of CO2 in the atmosphere is thought to be around 300 ppm.

So what does this actually mean for us?  Why does carbon dioxide matter?

CO2 is the earth's most important greenhouse gas. A greenhouse gas is a gas that absorbs and radiates heat and re-releases it in all directions, including back towards the earth's surface. Without CO2 the earth's natural greenhouse effect would not be strong enough to keep the surface temperature above freezing.  By adding more CO2 to the atmosphere we are increasing the natural greenhouse effect which is causing global temperatures to rise, including our ocean temperatures.

Ocean temperatures are important as they influence sea level and currents.  Currents are driven by wind and differences in the water's density.  The density is controlled by temperature and salinity.  Currents regulate our climate, distributing warm and cold water from north to south and south to north. Without currents we would have more climate extremes, it would be too hot at the equator and too cold at the poles. Much less of the earth’s land would be habitable.  Increased water temperatures will, over time, alter our currents and our climate.

CO2 also dissolves into our oceans by reacting with water molecules to produce carbonic acid, hence lowering the ocean's pH.  A lower pH means increased acidity. The known effect of increased acidity is mostly on coral and shell based sea life where the acidity reduces their ability to grow. The reduction of these in our oceans will alter the food chain and the ocean ecosystem. 

It is rate of increase that is perhaps the most alarming. The compounding effects are yet to be realised.