“Only around 3% of all CO₂ emissions are man-made, i.e. they come from the economy, heating and transportation. Around 97% of CO₂ emissions are of natural origin.” This is a claim made by Karsten Hilse, a climate spokesperson for Germany’s far-right party AfD, on his website. It’s a claim regularly used to downplay human responsibility for the climate crisis. But while the number might be accurate, it’s deeply misleading — and part of a long-standing strategy to cast doubt on climate science.
The claim, also circulating on social media, suggests that only a tiny fraction of global CO₂ emissions — about 3% — comes from human activity. Although the percentage is somewhat accurate, this claim doesn’t take into account the absorbance of CO₂-emissions through soil and oceans. At first glance, it may seem harmless, but it questions the foundation of climate science.
Fabricated number
Hermanni Aaltonen, climate-focused senior scientist from Finnish Meteorological Institute (FMI), says that the percentage mentioned by Hilse is in the right scale, but “fabricated”. Aaltonen, who works as the group leader of FMI’s Greenhouse gases research group, states that the comparison is usually made to falsely make audiences believe that climate actions made by people have little impact.
According to Aaltonen, it is possible to calculate the amount of human-made emissions and end up with a percentage somewhere between 0–10. However, the percentage of 3 cannot be properly used to describe the natural carbon cycle, and it therefore gives little information about the carbon cycle.
“Whether the percentage is 3, 5 or something else, the absolute amount of anthropogenic [human-made] emissions is nevertheless big”, Aaltonen says.
Aaltonen points out that the carbon dioxide coming from natural sources eventually returns to nature over time, which creates what one might call a “closed circuit” or “carbon cycle”. In fact, due to human-originated carbon dioxide adding up to this carbon cycle and making CO₂ more available for plants and oceans to absorb, nature even takes more CO₂ in than it puts it out.
”We really don’t get anywhere by comparing the human-made emissions to the ones from natural origin. The total amount of the human-made ones is what really matters.”
When asked about the solutions to fighting climate change and false communication about it, Aaltonen repeats that we should be looking at the fossil fuel emissions from traffic, industry and other human origins rather than making comparisons between calculative numbers.
“There has been a discussion going on, for example in Finland, about natural and technological carbon sinks. They do of course matter, but what we really should do is rapidly get the total amount of our carbon emissions, mainly from fossil fuels, down.”
The claim about human-made CO₂-emissions being only about 3 percent has been circulating on many occasions, mostly on social media, but also in press media. According to journalist for Catalonian fact check service Verificat, Marc Masip, one of the first instances to make the claim was US-owned, world’s biggest investor-owned oil company Exxonmobil in 1997. According to Masip, it is apparent that Exxonmobil was the instance to make the claim mainstream. The company made the claim in their then weekly advertorial for The New York Times, and it has since been used widely by climate denialists, politicians and public figures to demonstrate that human-made carbon emissions aren’t that much of a threat.
What the IPCC says
We asked Karsten Hilse from the AfD for his primary source. Hilse referred to a webpage from an independent German climate fact-checking program Klimafakten.
The fact check Hilse refers to is actually aimed to prove the opposite point than Hilse is trying to make – that human-made emissions are, though relatively small in numbers, a real concern. The Klimafakten article comes to the same conclusion that Hermanni Aaltonen from FMI points out – that human-made emissions add to the natural cycle of carbon dioxide. The scientific basis for Klimafakten’s fact check refers to a figure in the IPCC’s sixth assessment report. The fact check doesn’t show the real percentage of human made CO₂ emissions, but when we calculated the number we got percentage of 5. As already mentioned, the natural and human made emissions are hard to compare.
When you want to compare these numbers you must look at which time humans started to spread CO₂ emissions as shown in the figure. The yellow arrows represent the natural carbon fluxes in billions of tonnes of CO₂ that existed before 1750, the pre-industrial era. The yellow circles indicate the natural carbon stocks during that time. Year 1750 is commonly considered as a point in time when human-made emissions started drastically rising.
The pink arrows show the human-caused carbon fluxes between 2010 and 2019, while the pink circles represent all carbon stocks since 1750 that are of human origins.
These figures show that nearly all of the natural emissions are absorbed back into soil, ocean beds and vegetation mostly through photosynthesis and ocean-atmosphere gas exchange. Looking at the pink arrows, these figures also show that more human-made emissions return to oceans and soil than are emitted. The “Net land flux” and “Net ocean flux” parts show, how much land and oceans absorb carbon, but as it shows, carbon emissions from land-use and fossil fuel usage add to these fluxes, making the total carbon emissions positive.
The circle at the top of the figure shows how much CO₂ is in the carbon storage of the atmosphere. As shown, in the atmosphere’s carbon stock, natural carbon emissions are 591 petagrams (billion tonnes) and human-made are 279 petagrams. Calculation with these numbers shows that human-made emissions have increased the atmosphere’s carbon stock by 48 percent since the pre-industrial era.
Aaltonen says it is also important to notice this number. While it doesn’t count in the overall carbon storages, it does, however, give a good perspective on how emissions from human activity have increased. The carbon storage of the atmosphere is crucial also because this is the part of emissions causing the greenhouse phenomenon, which is responsible for the global temperature rise. When greenhouse gases such as carbon dioxide, methane and nitrous oxide accumulate in the Earth’s atmosphere, they trap the heat of the sun near Earth’s surface which causes the surface temperature rise.
Conclusion
The claim that only 3% of global CO₂ emissions come from human sources is often used to suggest that our impact on the climate is minimal. It’s a figure that has found political traction, and it has been widely used by political commentators such as Karsten Hilse from AfD.
But this number leaves out a crucial part of the picture: the balance of Earth’s carbon cycle. Natural emissions are typically offset by natural absorption. Human emissions, though smaller in volume, are not fully absorbed—and it is this excess that accumulates in the atmosphere.
In conclusion, focusing on a single percentage without context is misleading. Even small imbalances can have large, long-term effects. Scientific consensus holds that this additional CO₂ is a key driver of current climate change. Understanding the full picture is essential — especially when such claims shape public debate and influence decisions on climate policy.
RESEARCH | ARTICLE © Nane Fechtner, Luca Klostermann | Jade University of Applied Sciences, Wilhelmshaven, Germany, Sampo Lepistö | Haaga-Helia University of Applied Sciences, Helsinki, Finland
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