The Physics of Climate Change

Superfact 128: There are a lot of natural carbon emissions from the soil, rotting plants, animal and human respiration, and oceans, and a small amount from volcanoes. However, carbon is also absorbed by the oceans, and by plants via photosynthesis, etc., and this creates a balance that has existed for many thousands of years. This is called the carbon cycle. Despite the fact that the carbon emissions from our burning of fossil fuels are much smaller than some of the naturally occurring carbon emissions mentioned, they are what is behind the increase of carbon in the atmosphere because they are a new addition that disrupts the carbon cycle.

The carbon cycle in the picture shows that the terrestrial biosphere is absorbing 120 Gigatons of carbon from the atmosphere and emits 60 Gigatons to the atmosphere. It also adds 60 Gigatons of carbon to terrestrial soils. It also shows the Surface of the Ocean both emitting and absorbing 90 Gigatons of carbon to the atmosphere and both emitting and absorbing 90 Gigatons of carbon to the deep ocean. There are additional flows in the picture. It is complex but stable cycle. — The picture above was drawn by me and is an adaptation of Figure 3.1 on page 31 in the book “The Physics of Climate Change by Lawrence M. Krauss”.

Regarding the picture above, the units are in Gigatons of carbon, i.e. the weight of the carbon atom. To get the numbers in Gigatons of carbon dioxide multiply all numbers by 3.67. The numbers in yellow inside the blocks correspond to how much carbon is stored in the system. The numbers without units in the grey arrows correspond to the number of Gigatons of carbon per year. I can add that Lawrence M. Krauss is not a climate scientist but a prominent theoretical physicist focusing on cosmology and quantum physics. However, he took a deep dive into the physics of climate change.

This picture is the same as above with the addition of our recent carbon emissions at 10 Gigaton. Oceans and other systems are absorbing some of it resulting in a net increase of 5 Gigaton per year. — This is the same picture as above, but I added the contribution from our recent additional carbon emissions such as the emissions from the burning of fossil fuels. This is depicted at far right in yellow. Since this is not part of the original carbon cycle the amount of carbon in the atmosphere grew from 600 Gigatons (pre-industrial) to 900 Gigatons.

As you can see in the picture above the amount of carbon stored in the atmosphere was 600 Gigaton originally and now we have increased it to 900 Gigaton. We are adding 10 Gigatons of carbon from our emissions, chiefly from burning fossil fuels, which correspond to 37 Gigatons of carbon dioxide. About half of this is absorbed by the ocean and other systems, resulting in a net addition of 5 Gigatons per year. The carbon dioxide added and stored in the atmosphere will be there for hundreds or thousands of years.

The existence of the carbon cycle and how it explains what is going on is an important fact that is widely misunderstood and therefore a surprising fact. You quite often see or hear claims such as “animal and human respiration emit a lot more carbon dioxide than our burning of fossil fuels, and therefore human caused global warming is BS”. The first part of that sentence is true, but the rest ignores the carbon cycle and the balance that has existed for many thousands of years. Therefore, this is a super fact.

The diagram shows how carbon is emitted and absorbed between the various elements in nature and our planet. It shows animals, plants, the soil, and also emissions from factories. The text says “The Carbon Cycle is important because it helps keep the right amount of carbon in the air, water, and soil. Too much carbon in the air can cause problems for our Earth and its climate.” — This illustration of the Carbon Cycle is simplified but artistic. Shutterstock asset id: 2271978649 by GraphicsRF.com

More on the Carbon Cycle

This picture is the same as the one above where I included our recent emissions from burning fossil fuels. — Same as the picture above but notice the flows depicted by the arrows and the total amounts stored in each system.

The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. In the picture above you can see that the atmosphere, the oceans, the biosphere, and the soil, as well as deep Earth reservoirs and Marine Carbonate Sediments are all absorbing and emitting carbon (dioxide). For example, the terrestrial biosphere absorbs 120 Gigatons of carbon per year, chiefly through photosynthesis, and emits 60 Gigatons of carbon into the atmosphere, via for example, animal / microbial / human respiration, rotting plants, and it adds another 60 Gigatons of carbon to terrestrial soils. 120 Gigatons of carbon correspond to 440 Gigatons of carbon dioxide.

This is a fairly detailed picture of the carbon cycle from wikipedia. — Carbon cycle schematic showing the movement of carbon between land, atmosphere, and oceans in billions of tons (gigatons) per year. Yellow numbers are natural fluxes, red are human contributions, and white are stored carbon. The effects of the slow (or deep) carbon cycle, such as volcanic and tectonic activity are not included. Diagram adapted from U.S. DOE, Biological and Environmental Research Information System., Public domain, via Wikimedia Commons.

The carbon cycle was relatively stable until we started burning massive amounts of fossil fuels. Our burning of fossil fuels emits 10 Gigatons of carbon (37 Gigatons of carbon dioxide) into the atmosphere. About 30% of this carbon is absorbed by the oceans. This slows the warming but causes ocean acidification, which is another dangerous problem. In total 50% of the carbon emissions are absorbed by oceans, the soil, the biosphere, etc., according to “The Physics of Climate Change by Lawrence M. Krauss”. This is why I wrote Net 5 Gigatons per year in the picture above. You can read more about the Carbon Cycle here and here.

Another thing to pay attention to in the diagrams above is that not only are volcanoes part of the carbon cycle, but their contribution to carbon emissions is tiny compared to our emissions, which contradicts the many false claims you see on social media. You can read about that in my post “Volcanoes emit a tiny fraction of carbon compared to humans”.

Conclusion

Many of our Planet’s systems (oceans, biosphere, terrestrial soil, atmosphere, etc.) emit (and absorb) more carbon dioxide than our burning of fossil fuels does. However, the fact that they are part of the long existing carbon cycle makes them irrelevant to the rapid and sudden global warming phenomenon that we are witnessing. The recent rapid Global Warming is happening, and it is caused by us, chiefly because of our burning of fossil fuels. I am illustrating this using the two bathtub pictures below.