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that we count on to 'Buffer' the effects of increasing, man made atmospheric CO2 content...they are fast becoming 'Saturated'...meaning that global temperatures will continue to accelerate...as Dr. Roy Spencer's recent data illustrates.

Because there are so many studies and papers, here's an AI synopisis of what's happening,

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AI Overview

While neither the ocean nor the boreal forest carbon sinks are fully saturated, their capacity to absorb atmospheric carbon dioxide (CO2) is showing clear signs of stress and decline. This weakening could accelerate global warming, as more CO2 would remain in the atmosphere.

Ocean CO2 uptake is weakening

The ocean is the largest and most persistent absorber of human-caused CO2, but a combination of climate-related factors is starting to hinder its efficiency.

Weakening efficiency: While the ocean is still absorbing anthropogenic CO2, the rate of uptake has slowed over the last decade. A 2025 study found that record-high sea surface temperatures in 2023 caused the global ocean to absorb about 10% less CO2 than expected, cancelling out the strengthening effect from a simultaneous El Niño event.

Reduced CO2 solubility: The amount of CO2 that seawater can dissolve decreases as the water warms, much like a warm carbonated drink loses its fizz faster.

Ocean stratification: As warming and increased rainfall create a warmer, fresher surface layer, it becomes less dense and mixes less easily with the cooler, more alkaline waters below. This stratification prevents CO2 from being transported to the deep ocean, allowing the surface water to become saturated.

Alkalinity feedback loop: A 2023 study found that intense warming in future scenarios could lead to a feedback loop where ocean stratification decreases surface alkalinity.

Since alkalinity influences how much CO2 the ocean can absorb, this effect further reduces the ocean's CO2 uptake over centuries.

Boreal forest carbon sink is under threat

Northern boreal forests have long been a crucial terrestrial carbon sink, but climate change and disturbances are jeopardizing this capacity.

Weakening sink capacity: A 2024 study revealed that the carbon sink capacity of Northern Hemisphere boreal forests, which hold over 50% of the world's soil carbon, has already declined by 36%.

Increased wildfires: Boreal forests are experiencing more frequent and severe wildfires due to warming temperatures and drought. These fires release vast amounts of stored carbon—including "legacy carbon" trapped deep in the soil for centuries—turning forests from a carbon sink into a source.

Permafrost thawing: As the Arctic warms faster than any other region, permafrost is thawing. This process releases large quantities of stored CO2 and methane, fundamentally altering the region's carbon balance. A 2025 study showed that nearly one-third of the Arctic boreal zone has already switched from being a carbon sink to a carbon source.

Accelerated decomposition: Warming temperatures also speed up the decomposition of organic matter in the soil, which releases more CO2 into the atmosphere.

Consequences of weakening carbon buffers

Amplified warming: The ocean and boreal forests currently absorb more than half of human-caused CO2 emissions. As their capacity diminishes, a larger fraction of CO2 will remain in the atmosphere, accelerating the rate of climate change.

Reduced predictability: Changes in these major carbon sinks introduce more uncertainty into climate projections, complicating the planning for mitigation and adaptation efforts.

Ecosystem damage: Besides absorbing CO2, these buffers provide vital ecosystem services. The decline of the ocean sink accelerates ocean acidification, threatening marine life, while the loss of forest habitat affects biodiversity.
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