Princeton University has revealed how carbon is stored and transported by the intricate network of coastal and inland waterways. The study has important implications in enforcing carbon calculations as part of international climate agreements. The study was published in Nature journal.
Most global carbon-budgeting efforts assume that water flows in a straight line from the land and the sea. This ignores the interplay of streams, rivers, lakes groundwater, estuaries and mangroves. A study by climate scientist Laure Resplandy, an assistant professor in geosciences at Princeton University, examined how carbon is stored and transported via the complex interplay of inland waterways and coastal waterways.
The level of atmospheric carbon dioxide (CO2) is controlled by terrestrial and marine ecosystems. These ecosystems are often seen as being disconnected from one another, which overlooks the fact that carbon is transferred from land to open ocean through a complex network water bodies. This network includes streams, rivers and estuaries, as well as other bodies that transport water from land into the sea. The team of researchers from France, the United States, and Belgium discovered that the land-to-ocean aqua continuum (LOAC), contains significant amounts of carbon from anthropogenic sources (e.g., fossil fuels). This means that carbon not all of it is stored locally in the atmosphere, contrary to common belief. This has implications for global agreements that require each country to report its carbon inventories.
Researchers also discovered that the land-to ocean carbon transfer of natural origin was greater than previously thought. This has far-reaching implications on the assessment of anthropogenic CO2 uptake in the ocean and land. Pierre Regnier, a professor from the University of Brussels, co-led the study along with Resplandy.
Because of this complexity, important global carbon budgeting efforts, such U.N. Intergovernmental Panel on Climate Change or the Global Carbon Project, assume a direct “pipeline transfer” of carbon from river mouths into the open ocean. Another common assumption was the assumption that all the transported carbon is naturally occurring, ignoring the effects of human perturbations such as damming, coastal vegetation decimation, and other human disturbances on this aquatic continuum.
Researchers synthesized more that 100 studies on the various components of this continuum in this study. LOAC carbon budgets for two time periods were derived from this synthesis: the preindustrial period and the current day. The well-known “loop” of pre-industrial carbon was confirmed by their results. It is a loop in which carbon is taken up by terrestrial ecosystems from the atmosphere, transferred by rivers to oceans, and then released back to the atmosphere. Resplandy stated, “We find that the amount of carbon carried in this natural land–to-ocean loop is approximately 50% higher than previously thought.”
This loop also includes two smaller loops. One transfers carbon from terrestrial ecosystems into inland waters, and the other from coastal vegetation to the open sea. Resplandy stated that the ocean uptake anthropogenic CO2 from pre-industrial land to ocean carbon transport was greater than previously thought.
Regnier added, “The flip side is the overestimation of land uptake of anthrogenic CO2.” The study revealed that rivers carry anthropogenic CO2 and either release it back into the atmosphere, or store it in open ocean sediments.
Philippe Ciais is a researcher director at Laboratoire des Sciences du Climat et de l’Environnement. He was also a coauthor of the study. “This new view on the anthropogenic carbon dioxide budget may have a silver lining, because sediments or the ocean offer arguably more stable repositories that terrestrial biomass and soil carbon, which can be vulnerable to droughts, fires, and land-use changes.” The researchers also showed that humans have contributed to a decrease in atmospheric CO2 taken from blue-carbon ecosystems of up to 50%.
Raymond Najjar, an assistant professor at Pennsylvania State University, said that if the coast is not protected from pollution and sea-level rise, blue-carbon uptakes atmospheric CO2 will continue to decline and contribute to further climate warming. (ANI)
(This story was not edited by Devdiscourse staff. It is generated automatically from a syndicated feed.
