Mapping Forest Carbon Cycles

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Mapping how much carbon forests hold and their role in the carbon cycle is critical to understanding climate change. A recent research project that has included NASA scientists has now provided a way to better assess the role that forests play in the global carbon budget.

This new map and system could also be used in future years, allowing a better way to measure the efficacy of policies used to protect forested landscapes. 

In addition to understanding the role of forests in the carbon cycle, scientists were also able to distinguish the role that different forest types in this cycle play. Their research has confirmed that tropical forests play the largest role in the carbon cycle among forests. Tropical forest absorb the most carbon and release the most carbon when there is deforestation.

Quaking Aspen grove, Kobuk Valley National Park, NPS, public domain.
Trees capture and store billions of metric tons of carbon dioxide from the atmosphere each year. Quaking Aspen grove, Kobuk Valley National Park, NPS, public domain.

Currently, forests around the world collectively absorb around 15.6 billion metric tons of carbon dioxide from the atmosphere each year over the last decade.

On the other hand, deforestation, fires, and disturbances to forest habitat released about 8.1 billion metric tons of carbon dioxide per year over that same time.

Flames rising up black spruce, Lake Clark National Park and Preserve.
Forest fires and deforestation contribute to carbon dioxide being released into the atmosphere. Flames rising up black spruce, Lake Clark National Park and Preserve. Photo: NPS / Yasunori Matsui, public domain.

Overall, forests absorb about 7.6 billion metric tons per year, which means our current forests act as a carbon sink that can absorb about 1.5 times the annual emissions from the United States.[1] 

Data also suggest that about 27% of the world’s net forest carbon sinks are from protected areas, in particular national parks. This emphasises the need to further protect forests landscapes, which provide a disproportional benefit in carbon absorption around the world.[2]

Using Geospatial Technology and Data to Map Carbon Flux in Forests

This ability to now better monitor forests is made possible by the combination of numerous data sources, which including on-the-ground measurements and reports, aerial data and measurements, and satellite data used to measure wide areas.

A view of the tropical forest from a USGS Amazon forest study site near Santarém, Brazil.
Tropical forest absorb the most carbon and release the most carbon when there is deforestation. A view of the Tapajós National Forest from an Amazon forest study site near Santarém, Brazil. Photo: Dennis Dye, USGS, public domain.

Effectively, the research was able to better calibrate satellite data using on-the-ground measures to effectively make a global framework that can better estimate carbon flux, specifically variation between how carbon is absorbed and released as forests are destroyed.

There is some uncertainty with the data, but as on-the-ground measures are better calibrated relative to near-orbit observations, then scientists should be better able to create even more accurate maps of carbon flux in coming years.

World map showing forested regions that are sources of carbon emissions (purple) and where they are carbon sinks (green). Credit: Harris et al. 2021 / Global Forest Watch / World Resources Institute
World map showing forested regions that are sources of carbon emissions (purple) and where they are carbon sinks (green). Credit: Harris et al. 2021 / Global Forest Watch / World Resources Institute via NASA.

Additionally, the Carbon Monitoring Systems Biomass Pilot, which is the project used to combine satellite and field data to improve carbon and vegetation change estimates, will utilise NASA’s ICESat-2 and the Global Ecosystem Dynamics Investigation (GEDI), which uses laser data to records three-dimensional topographic data for forests, to provide further data on carbon removal for forest landscapes. These also will improve overall data quality.[3]  In fact, GEDI data have been available over the last couple of years and scientists have begun to look at canopy measurements for forested landscapes.[4]

What the new research also highlights is we now have better tools to gauge the efficacy of policy used to protect forested landscapes. The researchers highlight the fact that we now have a geospatial monitoring framework that supports climate policy development and monitoring. The framework can be used to create an alignment and transparency in how effective forest preserving measures are around the world.

Given the results, priorities should be focused on enabling more protected forested regions, where progress in forest-specific climate mitigation goals can be better understood. This will have global impact over the coming decades and puts greater urgency that global action is taken to protect vulnerable regions such as those that have tropical forests.

The new research has highlighted the carbon flux cycle and the disproportional role forests play in balancing our carbon cycle which affects climate change. Now that we can determine a relatively accurate estimate on how much carbon can be absorbed and lost by our forests, policy efficacy can also be better measured. This also puts greater urgency in protecting more forested regions, in particular tropic forests, as such regions have been shown to provide a high portion of carbon absorption. 

References

[1]    The specific article that publishes this new research on forests’ roles in the carbon cycle can be found here:  Harris, N.L., Gibbs, D.A., Baccini, A., Birdsey, R.A., de Bruin, S., Farina, M., Fatoyinbo, L., Hansen, M.C., Herold, M., Houghton, R.A., Potapov, P.V., Suarez, D.R., Roman-Cuesta, R.M., Saatchi, S.S., Slay, C.M., Turubanova, S.A., Tyukavina, A., 2021. Global maps of twenty-first century forest carbon fluxes. Nat. Clim. Chang. https://doi.org/10.1038/s41558-020-00976-6.

[2]    For more on a NASA story on the new carbon maps to measure carbon flux, see: https://climate.nasa.gov/news/3063/nasa-satellites-help-quantify-forests-impacts-on-global-carbon-budget/.

[3]    For more on measuring forests using 3D mapping of forested landscapes using on-board lasers, see: https://climate.nasa.gov/news/2825/a-new-hope-gedi-to-yield-3d-forest-carbon-map/

[4]    For more on GEDI measurements for forests, see:  https://www.nasa.gov/feature/goddard/2020/nasa-forest-structure-mission-releases-first-data.

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