Greenhouse gas emissions: Natural vs. manmade

on November 1, 2021

In nearly every discussion about carbon dioxide (CO2) and climate change, we talk about the ways in which our activities have affected the environment.

There’s good reason for this: the average human-driven CO2 emissions per year climbed 1.4% to 32.5 gigatons in 2017, according to the International Energy Agency. Every year, they release an annual survey of global carbon levels. Now, these are just numbers - what do they really mean?

To illustrate this increase, imagine a freeway that is already pretty full with cars. There’s a traffic jam brewing, and cars are moving at a snail’s pace - bumper to bumper. What kind of effect are these cars having on the environment? There is exhaust filling the air, pumping carbon dioxide into the atmosphere.

Now, add another 170 million cars to that freeway. That’s right: 170,000,000.

That’s the effect that this increase in human CO2 emissions has on our world today. That 1.4% bump - which doesn’t sound like much - is the equivalent of firing up 170 million cars and letting their engines run.

Certainly you can see the problem with this.

Where are these emissions coming from?

Manmade, or “anthropogenic” CO2 sources are usually from everyday activities that we don’t even think about.

Did you turn on the lights this morning? Or are you reading this on your fully-charged phone or laptop? Did you ride in a car or bus today?

Or how about eating? Have you had your vegetables or fruits? And did you pull those out of your refrigerator?

Power generation is a major contributor to man made CO2 emissions - and in fact, electric power generation is the greatest source of CO2 to the atmosphere.

But it’s nearly impossible to avoid generating CO2. Transportation, industry, petroleum production, even agricultural practices… these are all activities that usually burn fossil fuels to function. And as we all know, burning fossil fuels like coal, oil, and natural gas will lead to increased CO2 emissions as a byproduct.

Now, this isn’t meant to make anyone feel guilty about the CO2 emissions they might be causing. In today’s world, we can all do our best (and should), but fossil fuels are incredibly common, and it’s often impossible to account for all the fossil fuels that are burned that are out of our control.

But it is important to be aware of how our daily activities affect the environment. There are steps you can take to mitigate that, and awareness is the first step.

There is one factor in global CO2 emissions that some of us do not quite realize: natural sources.

Yes, while carbon dioxide is presented often as damaging to the environment, it is not all dangerous. There are many natural sources releasing carbon dioxide into the air, and in very large amounts.

Where are common natural sources of carbon dioxide?

The greatest source of carbon dioxide in nature are the oceans. Annually, oceans will produce more CO2 than any natural or manmade source, by far.

Carbon dioxide in the air is absorbed into the ocean, then is used by the life living in the ocean. Many organisms will use carbon dioxide in the water. But as living creatures and plant life die and sink into the deep water, carbon dioxide is released and then moves to the surface, being released into the air once again.

There are other major sources of CO2 in the atmosphere. As animals and plants breathe, they exhale CO2 into the air - just like humans, of course. Another source is the decomposition of organic matter. This, like breathing, is unavoidable and natural. Disasters can also release significant amounts of CO2, like forest fires and volcanic eruptions.

On top of all of this, there are layers within the Earth’s crust that contain naturally-occurring CO2 deposits.

With all of this natural CO2 in the air, you may wonder where the biggest concerns should lie. But not all CO2 is created equal.

Natural greenhouse gas emissions vs. manmade: what’s the difference?

Before the Industrial Revolution in the middle of the last century, the levels of CO2 in the atmosphere were rather steady. This was not a snapshot: they were steady for thousands of years.

That’s because natural CO2 is not static, meaning it is not simply in the air, sitting there. Naturally generated CO2 is a part of a very natural cycle in the atmosphere. That’s why the levels remained stable.

The carbon on land and in the ocean has stayed in balance. By measuring ice cores and using proxies, we have been able to study historic CO2 levels both directly and indirectly. The Earth has been able to generate, absorb, and cycle through carbon dioxide naturally for generations.

Now, consider what happens when manmade carbon dioxide sources begin their ascent. Yes, the natural cycle of carbon in the atmosphere has been handling 750 gigatons of CO2 every year. Our 32.5 gigatons seem paltry and inconsequential compared to that, right?

Well, not so much. Our world is made to handle the 750 gigatons naturally. Adding more than 30 gigatons is devastating because the land and the ocean do not have the capability to absorb that CO2.

Picture the Earth as a two-quart bowl. Now imagine it filled with exactly two quarts of water. The bowl can easily handle that two quarts. But now, take another cup of water and dump it into the bowl. Immediately, you see the problem: that cup of water is going to overflow the bowl.

There are some who consider naturally occurring sources of carbon dioxide to be proof that man-made CO2 isn’t that big of a deal. But think of that bowl: the problem isn’t that the bowl has two quarts of water in it — the bowl is designed to handle that much water. The problem is the extra cup of water.

The same is true for us: the problem isn’t the 750 gigatons of CO2 that our planet can already handle — it’s the extra CO2 that we’re releasing into the atmosphere that it can’t handle.

The Earth is doing its best: about 40% of the extra CO2 in the air is being absorbed. But what happens to the rest of the CO2? It sits in the atmosphere.

What is the effect?

Because greenhouse gases have increased 31% since the Industrial Revolution, there is an extra buildup of CO2 in the atmosphere.

That carbon dioxide traps heat in the atmosphere, causing global temperatures to increase.

Yes, natural carbon dioxide contributes to this. But human activities are devastating the carbon cycle. The National Center for Atmospheric Research predicts a 90% chance that human activities — like the fossil fuel burning we’ve discussed here — will cause an increase in global temperatures of 1.7 to 4.9 degrees Celsius by the year 2100.

Focus on what you can control

Instead of leaning on the natural sources of carbon dioxide and assuming that they are the problem, let’s band together to focus on moving as much of our activities to clean energy sources.

The more we can reduce our own carbon emissions, the faster we can restore the natural carbon cycle of the Earth and protect our planet from climate change in the process.

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