Every tree and every blade of grass in every forest, jungle, field and garden. What's up guys, welcome to my channel! My name's Rosh and today we'll be investigating exactly how much carbon human activity has produced. Over the last century, global temperatures have risen 10 times faster than at any point in the recent geological past. In my last video, we saw how this has been primarily driven by a geologically unprecedented spike in CO2, which has taken atmospheric carbon levels to their highest point in at least 3 million years.
But is this really due to us? Are we humans really capable of changing the entire global climate? Simple chemistry dictates that burning fossil fuels, which are predominantly made of hydrogen and carbon, releases CO2 and water.
And other industrial processes, like the production of cement, also release CO2. So it's clear that human activity does contribute some carbon to the atmosphere. But how much do we actually produce? And how does it compare to natural processes? Well, since the beginning of the industrial revolution, human activity has produced about 1.5 trillion tonnes of CO2, and our emissions have only increased year on year, accelerating alarmingly quickly in recent decades.
In fact, half of all our emissions have occurred since 1988, and we currently emit about 36 billion tonnes of CO2. every year. This may seem like a lot, but how does it compare to natural emissions?
Because natural processes are constantly releasing CO2 into the atmosphere as part of the global carbon cycle. Processes like volcanic activity, respiration and decomposition, and together they emit a whopping 750 billion tons of CO2 every year. This means that human activity contributes less than 5% to the total annual carbon emissions. Tiny, right? Insignificant, right?
Well, it would be if we totally ignored the fact that for every natural process which releases CO2, there is a natural process which also absorbs it. The carbon released by respiration, for example, is more or less cancelled out by the carbon absorbed by photosynthesis. If this wasn't the case, the concentration of CO2 in the atmosphere would keep rising forever, or at least least until all the carbon in the ground was in the air.
Because of these checks and balances within the natural system, on human timescales at least, the carbon cycle is in balance and the concentration of CO2 in the atmosphere remains stable, or at least it should. The trouble is that the carbon locked away in rocks, like fossil fuels, normally takes thousands or even millions of years to be released into the atmosphere, and it takes just as long to return to the ground. By burning billions of tons of the stuff, we are accelerating the release of carbon from the atmosphere.
from the geological reservoir far faster than it can be absorbed back. Some natural processes like photosynthesis have increased in response. And a lot of this excess carbon has been absorbed by the oceans. But there are no natural processes which can absorb the CO2 as fast as we are producing it. Because of this, even though human emissions are comparatively small, they are enough to tip the balance and cause atmospheric carbon levels to rise.
So it's likely that human activity has contributed to the recent rise in CO2. But how can we know for sure? And to what extent are we responsible?
After all, there are natural phenomena which have caused massive spikes in CO2 in the geological past, like flood basalt events. If you're not sure what that is, imagine a giant game of the floor is lava. Except it's not a game and the floor is literally lava expanding for as far as the eye can see. Other potential culprits include the mass melting of permafrost or forest fires on a colossal scale. The trouble is that there is no evidence that any of these is happening on the scale of...
required to raise CO2 to its current level. These events aren't exactly subtle either. If they had been pumping out CO2 for decades on end, someone really would have noticed. So we can rule out all known natural causes of rapid CO2 rise present in the geological record.
But can we really be certain that humans are responsible? Well, there's one final piece of evidence to add to our collection. The chemical signature of the carbon in the air is increasingly matching the chemical signature of fossil fuels. There are two stable types, or isotopes of carbon, carbon 12 and carbon 13. Carbon derived from living things, like that found in fossil fuels, is known as organic carbon and is enriched in carbon 12, compared to inorganic carbon, like that emitted by volcanoes. Isotope measurements of the carbon in the air show that it is increasingly enriched in carbon 12, which means it must be coming from an organic source.
Now while it's true that respiration releases organic carbon, we know that this is cancelled out by photosynthesis. This means that in order for carbon 12 to increase in in the air, a large source of organic carbon which doesn't normally interact with the atmosphere must be the culprit. If only we knew of a source of carbon which fit that description. Since we know for a fact that we have burnt billions of tons of organic carbon in the form of fossil fuels, it's pretty clear where the evidence is pointing. To really hammer home how much human activity has disturbed the system, let's remember how much CO2 we have released.
1.5 trillion tons. When we take away the weight of the two oxygen atoms which make up each molecule of CO2, this amounts to around 400 billion tons of pure carbon. To put that into perspective, All the carbon in all the plants on land on the planet. Every tree and every blade of grass in every forest, jungle, field and garden amounts to 600 billion tonnes of carbon. In other words, we have burnt the equivalent of two thirds of all the plants on land on the planet.
So there it is, the evidence that human activity is the primary cause of the recent rise in CO2 is overwhelming. Thanks for watching and if you enjoyed the video don't forget to like, comment and subscribe. I really appreciate it. Until next time, goodbye.