How Excess Carbon Dioxide Affects the Greenhouse Effect

Despite only forming around 0.04% of our atmosphere, carbon dioxide (CO2) has certainly developed quite a reputation for itself, though perhaps for more urgent reasons in comparison to other key figures of the 21st century, such as Kim Kardashian. In fact, I think you’d be hard pressed to find someone in the Western world who has neither heard of this gas nor – as a courtesy of heavy industry – inhaled a mouthful of it. On the other hand, knowledge related to this substance is quite varied and leads to some heated (couldn’t resist the pun) debate on its role in the greenhouse effect and climate change, particularly as a result of human activity since the Industrial Revolution.

Greenhouse gases re-radiate heat in the atmosphere

Basically, the greenhouse effect is an Earth warming phenomenon in which infrared radiation from the Sun is absorbed by the landmasses and oceans on Earth. This heat is re-radiated back into space, but a portion is trapped in the lower atmosphere by infrared active species of gas (such as CO2, methane and water vapour). These gases continue to re-radiate this energy in the atmosphere, thereby producing a warming effect. Without this process, the Earth would not be able to support life as we know it. The name of the effect takes its inspiration from the common construction, the greenhouse, which utilises heat to grow vegetables in cold climates (though the effects are not the same).

A common greenhouse used to grow vegetables, from which the effect takes its name. Source: Pexels.

So, what’s the problem with having more CO2 in the atmosphere?

Just like chocolate, alcohol and white men in positions of power, having too much of something can be a bad thing and this doesn’t change when talking about gases. As you would expect more insulation to retain more heat in your standard house, the same can be said for higher levels of atmospheric CO2, which has been shown to be sharply on the rise in recent history since the Industrial Revolution. There are a multitude of natural sources of CO2 such as plant and animal respiration, decomposition, ocean and atmosphere exchange, as well as volcanic eruptions. On the flip side we have photosynthesis which, in conjunction with ocean and atmospheric exchange, are the only natural sources of CO2 removal on the planet.

So, in other words: the Earth has a natural way of regulating the CO2 levels in the atmosphere, though the total atmospheric concentration is dynamic and has varied throughout history. In terms of recent history (since the Industrial Revolution), think of it like a sink with the tap on without a plug. There is both water – here analogous to CO2 – going in and coming out and at relatively similar rates, meaning the water in the sink stays at a rather constant level. Now, have someone put their finger over the drain so that less water goes through (deforestation), while they pour water into the sink themselves (burning fossil fuels). Eventually a point is reached and the water will flow over the edge due to the disruption of this equilibrium, resulting in a wet bathroom floor. This is the effect that humans are having, except the wet bathroom floor is analogous to rising sea levels, extreme weather, climate refugees, a lack of resources, habitat destruction and species extinction among other problems; it doesn’t just mean soggy socks and a dark spot on your kitchen ceiling.

Global temperature won’t increase a lot due to human activity

There are two things that we know for sure: CO2 warms the atmosphere and CO2 is produced when fossil fuels are burned. These are not opinions, but observable facts. Logic then dictates that burning fossil fuels contributes to warming the atmosphere. Nonetheless,h you can argue on the extent to which the atmosphere is warmed by this.

The global temperature is expected to only increase by a few degrees because of human activity, as we aren’t the main source of heating for the planet. In fact, for some climates such as that of my home in the UK, a temperature increase is often seen as desirable. However, a recent study has shown that a global temperature increase in comparison to pre-industrial levels of even 1.5oC to 2oC – the former being the ideal situation in the Paris Agreement – would be devastating for several parts of the world, with problems including coral reef destruction, even lower crop yields and even longer droughts. Plus, it wouldn’t even make the UK that much more bearable.

Humans are influencing the composition of gases in the atmosphere

Even still, the topic is deeper and more complicated than what I’ve covered here, these are just some important parts of the CO2 debate that needed to be highlighted and brought together in order to present the only logical conclusion: humans are influencing the climate and something needs to change. While on this point, I do find the comparison of a glass construction and our atmosphere quite interesting, both being relatively fragile and necessary to their inhabitants for survival. If you smash the greenhouse, the plants will die, if you mess up the chemical composition of the atmosphere, animals will also die. Though I guess in the grand scheme of things, this “Chinese conspiracy” isn’t quite as important as what the Kardashians are up to.

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Jack McGovan is a recent graduate in chemistry with a specialisation in ‘Energy and Sustainable Chemistry’ from the University of Groningen, the Netherlands. Following a job as a student journalist covering the energy transition, he has moved to Berlin where he is following his passion for working towards creating a fairer and more sustainable world. Seeing a gap in the way in which the world of science was communicated, he founded Delta-S. By writing source based content, he hopes to communicate his findings to a wider audience.