**Scientists say climate change is effectively irreversible on human timescales without large-scale carbon removal.**
The length of time carbon remains in the biosphere depends on the form of carbon, where it’s stored, and what processes are acting on it. Here’s a breakdown by reservoir:
1. Atmosphere:
Carbon dioxide (CO₂) released into the atmosphere from fossil fuels can persist for hundreds to thousands of years. About 40–60% is absorbed by oceans and ecosystems within a few decades, but a significant fraction (about 20–30%) remains for more than 1,000 years, and a small portion could persist for tens of thousands of years.
2. Biosphere (plants, animals, soils):
Carbon in living organisms cycles more quickly.
In plants and animals, it typically cycles over years to decades.
In forest soils or peatlands, carbon can remain stored for centuries to millennia unless disturbed (e.g., by deforestation or warming).
3. Oceans:
The ocean is a major carbon sink. Surface waters exchange CO₂ with the atmosphere on a decadal scale, but deep ocean carbon sequestration happens over hundreds to thousands of years.
4. Geological Storage (fossil fuels, CCS):
Carbon stored underground through natural processes or carbon capture and storage (CCS) can remain trapped for millions of years, assuming the geological formations remain stable.
The growing carbon debt, Climate Brink, article, June 2024
**https://www.theclimatebrink.com/p/the-growing-carbon-debt?utm_source=substack&utm_medium=email**
Carbon is forever, Nature magazine, 2008
**https://www.nature.com/articles/climate.2008.122**
Irreversible climate change due to carbon dioxide emissions, article, The Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS)