What’s the deal with carbon dioxide?

The lowdown on CO2

Carbon dioxide (CO2) in its most basic form, is a gas that consists of one part carbon and two parts oxygen. One of the most important gases on the earth, plants use CO2 to produce carbohydrates in a process called photosynthesis in conjunction with the Sun, that in turn provide living things with oxygen, which we breathe. It sounds like a wonderful balance, doesn’t it?

Well, it is. Until you get overproduction of CO2. It is not just an important part of the life-sustaining cycle that gives us the basic function of breathing, but it also is part of a group of greenhouse gasses that work to trap heat close to Earth. In small amounts, CO2 helps Earth hold the Sun’s energy, so it doesn’t all escape back into space. If it weren’t for CO2, Earth’s oceans would be frozen and life on our planet would be either very different or nigh impossible. The trapping of heat inside Earth’s atmosphere is called the Greenhouse Effect, which is much like a greenhouse itself, which traps heat in order to promote plant growth. Our challenge is that the very thing that can be life-giving can also be damaging beyond repair.

All living things on Earth contain carbon. Even us. So, when living things die and are buried under water and dirt for centuries, heat and pressure turn the dead entities into what we call fossil fuels: oil, coal, and natural gas. This is the stuff we use to power our world. We burn these carbon-rich materials in vehicles and power plants, and many other places that require energy to function. And this is when we get an overproduction of CO2 – a byproduct of burning carbon-based fuels.

Some might argue that CO2 is not the only cause of the Greenhouse Effect and is therefore not responsible for global warming. Water vapour is the dominant greenhouse gas in our atmosphere but it has “windows” that allow some of the infrared energy to escape without being absorbed. Even though it occurs in smaller amounts than water vapour, CO2 is by far the most damaging due to its impenetrable nature.

From greenhouse gas to climate crisis

What do carbon levels have to do with climate change, you ask? I’m glad you did!

Earth’s inhabitants depend on energy coming from the Sun and just about half the light reaching Earth's atmosphere passes through the air and clouds to the surface, where it is absorbed and then radiated upward in the form of infrared heat. About 90% of this heat is then absorbed by the greenhouse gases and radiated back toward the surface – the greenhouse effect mentioned earlier. This, in the correct amounts, is life-sustaining and, well, good.

Like other greenhouse gases, CO2 absorbs radiation and prevents heat from escaping from our atmosphere. The high amounts of atmospheric CO2 collect and store heat, disrupting weather patterns, causing global temperatures to increase and other climate changes. There are many gases that trap heat – such as methane and water vapour – but CO2 puts us at the greatest risk of irreversible damage if it continues to accumulate unabated in the atmosphere.

However, human activity is changing the natural greenhouse balance. Over the past century, the burning of fossil fuels has increased the concentration of atmospheric CO2 because the burning process and the clearing of land for agriculture, industry, and other activities has increased concentrations of greenhouse gases. Humans have increased atmospheric CO2 concentration by 47% since the Industrial Revolution began. This is effectively warming up our atmosphere at an alarming and uncontrollable rate, in which our atmosphere is bouncing back energy and heat to the Earth’s surface more than we need (or want), thus heating up the world more and more to temperatures we cannot handle.

The effect of the heat? Our delicately balanced climate is thrown off balance.

It's getting hot in here

Life on our planet depends greatly on this fine stability and predictability of the weather. As mundane and tired as it may sound, let’s take the world’s largest predator, the Arctic, as an example. The cycle of life in the Arctic is reliant on its ice being there at a certain time of year so that polar bears have a chance to hunt seals. If the seals are forced out to sea, they have nowhere to give birth. They, in turn, become easy prey for orcas, which then overrun the Arctic Ocean. Orcas then become overabundant, leading to legal reasoning for whale hunting, and the balance is thrown off completely.

And that’s just one area of concern. Our recent record high temperatures, wildfires, and meteorological anomalies are just some of the signs we are destroying this balance on which we so desperately depend.

That’s the science in a nutshell. So why has this reached critical mass now?

The "too much CO2" problem

A global CO2 forecast for 2021 devised by the UK Met Office from the Mauna Loa Observatory in Hawaii sees a continued rise of emissions ahead. While CO2 is natural in certain amounts, we are burning fossil fuels and releasing way too much of it into the atmosphere at an uncontrollable rate. This, coupled with deforestation, means there are too few trees – or should we say a declining number of trees – to cope with processing this excess CO2 into oxygen.

Because CO2 stays in the atmosphere for a long time, emissions consistently add to those from previous years and cause the amount of CO2 in the atmosphere to keep increasing. Although the COVID-19 pandemic meant 7% less CO2 was emitted worldwide in 2020 than previously, it still added to the ongoing build-up in the atmosphere. The pandemic saw emissions cut by an estimated 2.4 billion metric tonnes, overwhelming previous annual declines, such as 0.9 billion metric tonnes at the end of World War II or 0.5 billion metric tonnes in 2009 when the global financial crisis hit. However, with world economies being opened up again in varying degrees, emissions have now returned almost to pre-pandemic levels.

TL:DR

CO2 plays a key role in plant life and helps keep the earth warm. Increasing levels of CO2 in the atmosphere, though, are intrinsically linked to global warming and we need to curb it before it’s too late.