Forests, with their incredible capacity to absorb and store carbon dioxide, have always been important in the battle against climate change.
However, a recent study based on data from ESA’s SMOS satellite mission has thrown a fascinating twist into this narrative. Young trees, contrary to prior beliefs, are truly the champions of carbon capture.
A critical aspect of understanding our complex climate system is knowing how much carbon is stored in different parts of the planet, particularly in land-based vegetation.
Historically, this has posed a challenge to scientists, leading to uncertainties in estimating the global carbon balance.
The new study, which is published in the journal Nature Geosciences, has provided much-needed clarity.
Scientists, funded by ESA, utilized observations from the SMOS satellite to directly observe terrestrial carbon stock changes on both regional and global scales.
The implications of these findings are significant. They offer a more accurate gauge to monitor the progress towards the net-zero goals by 2050, which is an essential part of the Paris Agreement.
The team, led by researchers from the French Laboratoire des Sciences du Climat et de l’Environnement (LSCE), discovered that from 2010 to 2019, land-based carbon stocks saw an increase of approximately 510 million tons per year.
Boreal and temperate forests were the major contributors, while tropical forests, affected by deforestation and agricultural interference, showed only minor carbon gains.
An unexpected outcome from the study, conducted under ESA’s Climate Change Initiative RECCAP-2 project, revealed that forests between 50 to 140 years of age were the heavy lifters in carbon absorption.
By contrast, forests over 140 years old were nearly carbon neutral, a finding that counters traditional vegetation model predictions.
“Vegetation models that predict terrestrial carbon stores do not represent forest demographics and tend to overestimate the carbon sequestration capacity of old-growth forests and underestimate of carbon absorbed by boreal and temperate forests,” explained Hui Yang, from LSCE.
“Using space-based observations we can track and better understand long-term variations in terrestrial living-biomass. Our study highlights the importance of forest age in predicting carbon dynamics in a changing climate.”
“Delaying and decreasing the harvesting of timber from young forests could be a way forward for climate-friendly forest management.”
ESA’s SMOS satellite, orbiting since 2009, uses its interferometric radiometer to capture “brightness temperature” images. These images are instrumental in deriving global maps depicting soil moisture and ocean surface salinity levels.
Thanks to recent advancements, the satellite can now produce robust measurements of L-band microwave vegetation optical depth (L-VOD) which, in turn, aids in the diagnosis of global changes in terrestrial carbon stocks.
Philippe Ciais, also from LSCE, elaborated on the immense value of L-VOD data: “Using L-VOD data from SMOS has provided valuable insights into global terrestrial carbon storage.”
“The study’s findings have important implications for climate change mitigation efforts, as they contribute to a more accurate estimation of the global carbon balance which is needed to inform and track progress towards achieving the Paris Agreement goals.”
ESA’s upcoming Earth Explorer mission named Biomass, launching next year, is poised to provide more comprehensive insights into forest carbon.
Equipped with an innovative P-band synthetic aperture radar, it will enhance our understanding of forests’ role in the carbon cycle.
“The use of SMOS to understand more about carbon capture by forests is another example of one of our Earth Explorer research missions surpassing expectations,” said Simonetta Cheli, ESA’s director of Earth Observation Programmes.
“With the carbon cycle so fundamental to our climate system and to the health of our planet, we are busy preparing the Biomass Earth Explorer mission, which is dedicated to measuring forest height and biomass.”
“Information from this upcoming mission will not only shed new light on the carbon cycle, but also contribute to international efforts to reduce carbon emissions from deforestation and land degradation.”
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