Fossil and biological carbon: a tonne is not a tonne

The document asserts that fossil and biological carbon operate on fundamentally different timescales and cycles, making them non-fungible. While fossil carbon is permanent, biological carbon is subject to rapid fluxes and risks of reversibility from fires, pests, or rising temperatures. The author contends that relying on biological offsets to mitigate fossil emissions is scientifically unsound and practically limited by land area and nutrient requirements, concluding that emissions from both sources must be addressed in parallel rather than through offsetting.

• Fossil and biological carbon are not fungible because they operate on vastly different timescales: fossil carbon was sequestered millions of years ago and its return to the geosphere takes thousands to millions of years, whereas biological carbon fluxes occur over much shorter periods, allowing for rapid emissions via land use changes, fires, and temperature increases.
• Biological carbon stocks are vulnerable to rapid release, creating a risk of reversibility that does not exist with the permanent act of not burning fossil fuels. For instance, one study indicates that tropical forests, including the Amazon, could release 53 ±17 billion tonnes of carbon for every degree Celsius of warming.
• There are significant biogeophysical and practical limits to using biological carbon for offsetting, including land area requirements and nutrient shortages. Removing one gigatonne of carbon through tropical afforestation would require at least 7×1 06 ha yr−1 of land, as well as 0.09 Mt y−1 of nitrogen and 0.2 Mt y−1 of phosphorous.
• Market-based attempts to address the lack of permanence in biological offsets, such as the Clean Development Mechanism's (CDM) use of temporary Certified Emissions Reduction (tCER) credits, have been unpopular with investors; consequently, afforestation and reforestation (A&R) projects represent only 0.8% of total CDM projects to date.

APA

Carbon Market Watch (n.d.). Fossil and biological carbon: a tonne is not a tonne. https://carbonmarketwatch.org/wp-content/uploads/2015/11/Fossil-and-biological-carbon-a-tonne-is-not-a-tonne_final.pdf

Chicago

Carbon Market Watch. Fossil and biological carbon: a tonne is not a tonne. n.d. https://carbonmarketwatch.org/wp-content/uploads/2015/11/Fossil-and-biological-carbon-a-tonne-is-not-a-tonne_final.pdf.

Wikipedia

{{cite report |author=Carbon Market Watch |title=Fossil and biological carbon: a tonne is not a tonne |url=https://carbonmarketwatch.org/wp-content/uploads/2015/11/Fossil-and-biological-carbon-a-tonne-is-not-a-tonne_final.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{carbonmarketwatchndfossil, author = {{Carbon Market Watch}}, title = {{Fossil and biological carbon: a tonne is not a tonne}}, institution = {Carbon Market Watch}, url = {https://carbonmarketwatch.org/wp-content/uploads/2015/11/Fossil-and-biological-carbon-a-tonne-is-not-a-tonne_final.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }