Nature's ability to remove carbon dioxide (CO₂) from the atmosphere is significantly weakening. This has been confirmed by the latest analysis an international team of scientists who investigated long-term trends in so-called natural CO₂ sequestration using known data from the Keeling curve. The study builds on the authors' previous analysis and uses the latest available data up to the first half of 2024. The results were published in a recent scientific paper.

The key findings and conclusions are alarming. The researchers confirmed that the capacity of Earth’s ecosystems to naturally store carbon dioxide from the atmosphere peaked around 2008. Since then, this natural capacity has been declining markedly, today at a rate of about 0.25 % per year. This means that the natural potential for CO₂ absorption has been increasing in the past, increasing by about 0.8 % per year in the 1960s. If this positive trend had continued, today’s annual increases in atmospheric CO₂ could be more than 30 % lower than the currently observed increase.

According to a new report by scientists, this beneficial effect has disappeared. Today, just to compensate for nature’s declining ability to absorb CO₂, human society would have to reduce its global carbon dioxide emissions by about 0.3 % per year. This is a fundamental change – currently, global CO₂ emissions are steadily increasing by about 1.2 % per year. This means that the climate crisis will worsen unless this trend is urgently reversed.

Analysis of the Keeling curve, which records CO₂ concentrations annually at the Mauna Loa Observatory in Hawaii, plays a key role in this research. The scientists examined a parameter labeled d, which represents the annual seasonal decrease in atmospheric CO₂ levels due to absorption by vegetation during the Northern Hemisphere summer. The evolution of this parameter clearly signals that the natural sequestration capacity has begun to decline since 2008. According to the calculations, the decrease in the predicted natural sequestration capacity by 2024 will reach approximately 21 %, which means that the currently observed annual increase in atmospheric CO₂ concentrations is now 35 % higher precisely because the Earth's vegetation does not absorb carbon dioxide as intensively as before.

The authors' analysis also pointed to a serious disproportion between the volume of emissions emitted by humanity and the amount of CO₂ that remains in the atmosphere. In the period 1958–1982, when emissions increased 2.5 times, atmospheric additions increased "only" 2.31 times, which meant a significant help from natural sequestration. However, in the last 25 years (2000–2024), emissions have already grown 1.48 times and atmospheric additions even faster - 1.51 times, which means that the biosphere is no longer able to compensate for human greenhouse gas production as effectively as in the past.

Why does a relatively small decrease in the natural ability to absorb CO₂ have such a large effect on the total amount in the atmosphere? Scientists explain this by saying that two major processes in the atmosphere meet: a positive contribution (human emissions minus absorption by the oceans) and a negative contribution (sequestration by land). Even a relatively small change in one part of this balance can significantly affect the total amount of CO₂ that ultimately remains in the atmosphere.

"The results are a clear warning," the study authors warn. "The declining natural capacity to absorb carbon dioxide will significantly accelerate the pace of global climate change. This trend also demonstrates the very strong links between the climate and environmental crises."

The authors conclude that immediate and large-scale efforts to protect biodiversity and restore damaged ecosystems are more urgent than ever. According to the scientists, restoring and protecting the natural environment is key not only to halting biodiversity loss, but also to reversing the dangerous decline in the biosphere's ability to absorb CO₂ from the atmosphere. Spring

The study is published in the journal Weather.

Glossary of key terms

• Natural sequestration: The process of absorbing carbon dioxide (CO2) from the atmosphere by natural reservoirs, especially vegetation, through photosynthesis.
• Keeling Curve: Long-term measurements of carbon dioxide (CO2) concentrations in the atmosphere, recorded at the Mauna Loa Observatory in Hawaii, clearly show the increase in atmospheric CO2 and its seasonal fluctuations.
• Intra-annual dip: A seasonal decrease in atmospheric CO2 concentration, most pronounced in the Northern Hemisphere during summer, caused by intense CO2 absorption by vegetation.
• Anthropogenic emissions (Anthropogenic emissions): Emissions of substances into the atmosphere that result from human activity, particularly the burning of fossil fuels, deforestation and industrial processes.
• Biodegradation: The natural decomposition of organic matter by microorganisms. In the context of the article, it refers to the decomposition of dead vegetation, in which some of the absorbed CO2 is released back into the atmosphere.
• Quadratic regression: A statistical method of modeling the relationship between variables using a quadratic function (a second-degree polynomial).
• Gradient: The rate of change in the value of a function with respect to a change in its argument. In the context of the article, it refers to the rate of change in natural sequestration over time.
• Box model (Box model): A simplified model of a complex system in which the system is divided into several homogeneous "boxes" and the flows of substances or energy between them are monitored.
• Terrestrial biosphere: All living organisms on land, including plants, animals, and microorganisms, and their interactions with each other.
• Ecosystem services (Ecosystem services): The benefits that humans derive from ecosystems, such as water purification, crop pollination, and carbon sequestration.