The Earth relies on natural processes and ecosystems to regulate the climate, with carbon sinks playing a crucial role. These include oceans, forests, and soils, which absorb about half of all human carbon emissions. One of the key processes is the daily migration of zooplankton and other marine organisms that feed on algae near the surface at night and return to the depths during the day. This vertical movement helps transport carbon to the ocean floor, contributing to the natural absorption of carbon.
However, there are growing concerns about the stability of these carbon sinks. The hottest year on record, 2023, highlighted some troubling signs. Preliminary findings showed a significant collapse in the land carbon sink, with forests, plants, and soils absorbing almost no carbon. Although this collapse may be temporary, it demonstrates the fragility of the ecosystems we rely on to regulate carbon levels. Rising temperatures, extreme weather, and droughts further stress these systems, threatening their ability to act as effective carbon sinks.
In the oceans, similar issues are emerging. Melting glaciers and Arctic ice disrupt ocean currents like the Gulf Stream, which reduces the oceans’ ability to absorb carbon. Changes in sea ice also affect the behavior of zooplankton, potentially disrupting their role in carbon sequestration. The overall warming of the oceans, which have absorbed 90% of the heat from fossil fuels, further weakens the ocean’s function as a carbon sink.
The situation is dire for land-based carbon sinks as well. While the Congo basin remains a robust carbon sink, other major forests, such as the Amazon, are experiencing severe droughts that limit their carbon absorption. Boreal forests across Russia, Scandinavia, and North America are also struggling, with their carbon absorption down by more than a third due to climate-driven factors like beetle infestations, wildfires, and deforestation.
Experts warn that many climate models fail to account for the rapid decline of these natural carbon absorption systems. Events such as severe wildfires, which release massive amounts of carbon, are not fully integrated into predictions, suggesting that models might be overly optimistic. There is a significant gap in understanding how various factors interact to affect the planet’s natural carbon storage capabilities, making it difficult to predict future changes accurately.
The weakening of natural carbon sinks could have profound implications for global climate targets. If these systems fail to absorb carbon as expected, nations will need to make even deeper cuts in emissions to compensate. Some countries, such as Finland, have already seen their once-substantial land sinks vanish, even as they make strides in reducing industrial emissions. This trend suggests that achieving net zero emissions is impossible without maintaining and protecting existing carbon sinks.
Ultimately, scientists emphasize the need to shift the focus toward safeguarding and restoring natural ecosystems. Cutting emissions, halting deforestation, and improving the health of forests, oceans, and other ecosystems are vital for maintaining their role as carbon absorbers. Despite advances in technology and new proposals to enhance carbon capture, the most immediate and effective strategy remains to protect the natural systems that have long balanced atmospheric carbon levels.