Daily Earth Science Environment Repost

Forests as a pathway for terrestrial carbon sequestration

Science is a critical tool in environmental decision making, but scientific analysis is only as good as the data supporting it. So, how do we determine the current and future roles of forests as pathways for terrestrial carbon sequestration? Step one is to determine the present-day state of affairs. 

Currently, there are two primary data sources providing information on global tree loss. Global Forest Watch (GFW) uses satellite images and limited on-site observations for quality control. However, the second major source, Global Forest Resources Assessment (FRA), depends on registered land-use records.

A fundamental conflict exists between the analyses and conclusions reached by each of these groups. Last year the GFW estimated tree cover loss at 72.6 million acres. FRA, on the other hand, estimated that loss at 8.2 million acres. This difference is close to a ten-fold increase (1000%) between the two estimates. Why are they so different?

Flaws in each system

FRA is at the mercy of government classifications, and thus if a country chooses to hide its forest loss, it can do so. On the surface, the GFW system appears reliable since it uses visual or optical inspection of Landsat images, seemingly a more exacting process for analysis. But, life is never simple. Land classified as forest by a government may be cleared by logging but replanted. Satellite imagery only sees the missing forest and does not account for the planned regrowth. So these two analyses can produce very different interpretations of the data.

Efforts are underway to reconcile and refine the modeling process. Recent work published in Science Magazine (Curtis, et al.), looked at the drivers of forest loss. They concluded: “Our results indicate that 27% of global forest loss can be attributed to deforestation through permanent land use change for commodity production. The remaining areas maintained the same land use over 15 years; in those areas, loss was attributed to forestry (26%), shifting agriculture (24%), and wildfire (23%). Despite corporate commitments, the rate of commodity-driven deforestation has not declined. To end deforestation, companies must eliminate 5 million hectares of conversion from supply chains each year.

Deforestation is a complex issue. Continuing research into the causes and effects of deforestation will eventually yield more consistent results, but that leads us to a second barrier in understanding terrestrial carbon sequestration. None of these studies provide any definitive analysis of how deforestation ties back into carbon sequestration. 

Carbon uptake in forests.

The base level of uncertainty regarding carbon uptake in global forests is significant. Recent investigations at the DOE indicated that CO2 uptake in the Amazon rainforests is up to 50% less than previously modeled. The previous models have not accounted for the phosphorous-depleted soils in the region.

Other research tells us that old, mature forest sequester less carbon than younger forest. Researchers speculate that immature forests support rapidly growing species that naturally fix larger amounts of carbon each year. Also, in the future, mid-latitude forests may be more critical carbon sinks that tropical rain forests.

The science supporting terrestrial carbon sequestration in the planet’s forests is immature, and more work is needed to understand the basic science before we can accurately predict the role of deforestation in fixing carbon into biomass. However, we can probably assume with some safety that less forested land does mean less ability to sequester CO2.

Unfortunately, the current trend of U.S government policy is to move away from climate science and environmental research. So, the answers we need will be slower in coming.   


Tree planting as a carbon sequestration plan (Source: ArcheanWeb) – https://archeanweb.com/2020/02/07/tree-planting-as-a-carbon-sequestration-plan/ Also:

Tongass National Forest: The good, the better, and the beautiful (Source: ArcheanWeb) – https://archeanweb.com/2020/02/24/tongass-national-forest-the-good-the-better-and-the-beautiful/ Also:

Extractive versus sustainable logging (Source: ArcheanWeb) – https://archeanweb.com/2020/02/25/extractive-versus-sustainable-logging/ Also:


Conflicting Data: How Fast Is the World Losing its Forests? (By Fred Pearce; Yale Environment 360) – https://e360.yale.edu/features/conflicting-data-how-fast-is-the-worlds-losing-its-forests Also:

Classifying drivers of global forest loss (By Philip G. Curtis, Christy M. Slay, Nancy L. Harris, Alexandra Tyukavina, Matthew C. Hansen; Science, 14 Sep 2018: Vol. 361, Issue 6407, pp. 1108-1111) – https://science.sciencemag.org/content/361/6407/1108 Also:

WHY NEW FORESTS ARE BETTER AT SEQUESTERING CARBON THAN OLD ONES (By MORGAN ERICKSON-DAVIS; Pacific Standard) – https://psmag.com/environment/young-trees-suck-up-more-carbon-than-old-ones Also:

Feature Image: Hoh Rain Forest, Olympic National Park, Washington State, 1992 (Michael Gäbler) (Modified) – https://commons.wikimedia.org/wiki/File:Hoh_Rain_Forest,_Olympic_National_Park,_Washington_State,_1992_-_Cropped_1.jpg  – This file is licensed under the Creative Commons Attribution 3.0 Unported license. – https://creativecommons.org/licenses/by/3.0/deed.en

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.