Carbon dioxide (CO₂) plays a complex role in Earth's climate and ecosystem. As the foundation of photosynthesis, CO₂ is vital for plant growth, supporting food production and maintaining soil moisture through healthy vegetation. However, CO₂ is also a prominent greenhouse gas—its molecules trap heat in the atmosphere, warming the planet and making Earth habitable. Problems arise when CO₂ concentrations increase rapidly, primarily due to the burning of fossil fuels since the Industrial Revolution. This surge has caused present-day levels to reach their highest values in millions of years, far above the pre-industrial era.
High CO₂ levels amplify the greenhouse effect, raising global temperatures, melting ice caps, and increasing sea levels. If atmospheric CO₂ were drastically reduced, Earth’s climate could cool excessively; history shows that past glacial periods coincided with lower CO₂. Yet, in today’s era, CO₂ is not at a minimum but at a significant peak, and further increases pose risks including more frequent extreme weather events. Therefore, while CO₂ is indispensable for life, its balance is crucial—too little can trigger glaciations, too much drives global warming. Managing CO₂ levels is key to ensuring both climate stability and ecological health
Dear Suraj Kapoor ,
Greetings, interesting and thought-provoking question! My humble opinion would be that there is a distinction between naturally-arising CO2 and human-made CO2. I'd say that the former perhaps is more always sustainable, or that either way it changes at longer time scales, whereas the current abundance of CO2 is due to the human-caused (emitted) CO2 which has managed to mess up the planet in roughly 100-120 years (a virtual moment in planetary terms) and which threatens our own very human existence on Earth - the rest of the Earth may well survive or rebuild, it's just that the mantle of civilisation may be passed to more intelligent and street-wise creatures :-)
Best Wishes,
Haris
Suraj Kapoor
Carbon dioxide (CO₂) is a key component of the atmospheric system with a dual impact on the biosphere and climate. On one hand, it is an essential gas for the process of photosynthesis, enabling the production of organic matter and the release of oxygen, directly supporting primary productivity and agricultural systems. The presence of CO₂ in optimal concentrations contributes to the maintenance of vegetation cover, soil moisture retention, and overall ecosystem stability.
On the other hand, CO₂ is the most significant long-lived greenhouse gas, with a strong capacity to absorb infrared radiation, directly influencing the rise in global temperatures. The anthropogenic increase in CO₂ concentrations, primarily due to the combustion of fossil fuels, has led to an unprecedented climate imbalance in recent geological history. Today’s atmospheric CO₂ levels (~420 ppm) exceed all recorded values in the last 3–5 million years.
Excess CO₂ amplifies positive feedback mechanisms in the climate system—including ice melt, reduction in surface albedo, methane release from permafrost, and disruptions in oceanic circulation—which further accelerate global warming. Historical data from paleoclimate records confirm the correlation between low CO₂ levels and glacial periods, as well as between high concentrations and warm periods, clearly establishing its central regulatory role in climate dynamics.
Therefore, precise management of CO₂ emissions is essential for limiting global warming, stabilizing climate conditions, and preserving ecosystem functionality. CO₂ is neither inherently "harmful" nor "beneficial"—its impact depends on its atmospheric concentration and the rate of change, which current anthropogenic pressures have made unsustainable. The scientific consensus clearly shows that further increases in CO₂ pose exponential risks to planetary stability.
Suraj Kapoor I disagree with your enthusiasm about 'the CO2 paradox'. Take any compound, such as sugar, alcohol, heavy metals, or serotonin, and you can observe a transition from stimulation to suppression, depending on the concentration. Ancient people already knew about it. Modern systems science involves constructing a holistic picture of the studied natural phenomena by identifying key processes and so-called drivers (factors that affect the observed patterns). The number of drivers is never limited to a single factor. Atmospheric CO2 is a very convenient measure of the Earth's global status; nevertheless, it would be highly naive to interpret it as the only essential environmental driver. Yes, 30-50 years ago, it was a 'hot topic' when physicists recalled the Arrhenius greenhouse effect (19th century) and 'discovered' plant photosynthesis for themselves (what biology students knew 150 years ago). Today, the systems paradigm is the primary approach.
Dear Nicolai S Panikov ,
At the same time, wouldn't you agree that CO2 is quite an important driver? I struggle to understand your point here. Just because it was known 150 years ago, does it mean that it's not important anymore?
Best Wishes,
Haris
Dear Haris Shekeris, thank you for the question and comment. The root of the problem is that CO2 is not a completely independent variable, unlike solar radiation, soil moisture, water salinity, or oceanic pH. Let me explain this with a simple example. Even a short drought (2-3 days) can have a significant impact on the soil-plant community, including the respiratory release of CO2 and the reduction of plant photosynthesis. Generally, a drought-stressed community will increase CO2 efflux to the atmosphere; however, a resulting temporal rise in ambient atmospheric CO2 will have a negligible effect due to the high gas diffusivity and the enormous volume of the atmosphere. In this example, water content and temperature are independent factors that affect the CO2 fluxes. The changes in ambient CO2 are typically too small and can be safely neglected. Of course, there are anthropogenic CO2 sources (industry, transportation, coal/oil mining, and agriculture), and potentially two CO2 sources (anthropogenic + native evolutionary trends) could cause a slow rise in the global average CO2 level. It means that the ambient CO2 could be recognized as a genuine independent factor directly affecting the rate of photosynthesis and other biological and abiotic reactions. However, the laboratory and field CO2 manipulation experiments demonstrated that these effects are significantly smaller than well-known environmental perturbations, such as land use changes, desertification, N deposition, flooding, and many others.
Dear Nicolai S Panikov ,
Many thanks for this, it's super helpful for me to understand what we're talking about, and you seem to know much more than me on the topic. However, a question still remains in me, are you saying that for example all of the measurements about CO2 parts per million from thousands and millions of years ago and the last 50 years where there was a clear increase (in the CO2 ppm content of the atmosphere) are inaccurate? You're referring to a slow rise in the global average CO2 level. However, most headlines (the mind wanders to Al Gore, for example) refer to a big rise, are you saying they are wrong? Or that they are simply insignificant and inconclusive? Are we in agreement that there is such a thing as anthropogenic climate change and that this is a very big danger to humanity?
Best Wishes,
Haris
Dear Haris Shekeris, the topic of greenhouse effect is a highly politicized issue. It requires a more objective and unbiased approach. The bias comes from grant money and other aspects of governmental and international support. Many Earth researchers view the chronological signatures of the ice-entrapped gases not as a stable trend upward, but rather as oscillations over geological time. The timescale is measured in millennia, making it difficult to obtain reliable data. Presently, I am not deeply involved in this agenda and prefer to follow more realistic goals in science. My brief answer to your question is that contemporary science can't resolve the Global Change enigma. Most probably, the observed global warming will soon stop, and we will face cooling. The impact of industrial/anthropogenic CO2 release is likely to be overestimated. Sorry if I have disappointed you. Let us keep our eyes open and try not to be misled by politicians.
Dear Nicolai S Panikov , so you regard the position that says otherwise to yours as politicized science but your own stemming only from the scientific facts and not politicized at all? I'd say they both have to either stand (be impervious to politics) or fall (be politicized) together. But then again, ok, i'm not an earth scientists so my position may be naive.
Best Wishes,
Haris
PS: No need to apologise, at least not to me! :-)
Nothing is totally disappointed.
Remember, the plants do absorb carbon dioxide for photosynthesis definitely the allotrophs. This CO2 is excretory products of most heterotrophs. So vegetative and non vegetative organisms are dependent on one another. CO2 is not worthless totally. It is used as fire extinguisher and some other purposes
. Important is to maintain a proper percentage of everything. No weapon against the nature. In fact nature is the Almighty. Khudos to Amazon Forest.
Pl read autotroph in place of allotroph as written by me few minutes ago as an answer to the question as asked. It was a slip of the type. Sorry for that.
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