• How inland and coastal waterways influen

    From ScienceDaily@1:317/3 to All on Wednesday, March 16, 2022 22:30:42
    How inland and coastal waterways influence climate

    Date:
    March 16, 2022
    Source:
    Princeton University
    Summary:
    Most global carbon-budgeting efforts assume a linear flow
    of water from the land to the sea, which ignores the complex
    interplay between streams, rivers, lakes, groundwater, estuaries,
    mangroves and more. Climate scientists now detail how carbon is
    stored and transported through the intricacy of inland and coastal
    waterways. The work has significant implications for enforcing the
    carbon calculations that are part of international climate accords.



    FULL STORY ========================================================================== "Streams to the river, river to the sea." If only it were that simple.


    ==========================================================================
    Most global carbon-budgeting efforts assume a linear flow of water from
    the land to the sea, which ignores the complex interplay between streams, rivers, lakes, groundwater, estuaries, mangroves and more. A study
    co-led by climate scientist Laure Resplandy, an assistant professor
    of geosciences and the High Meadows Environmental Institute (HMEI)
    at Princeton University, details how carbon is stored and transported
    through the intricacy of inland and coastal waterways. Published in the
    current issue of the journal Nature, the work has significant implications
    for enforcing the carbon calculations that are part of international
    climate accords.

    Terrestrial and marine ecosystems have a powerful influence on climate
    by regulating the level of atmospheric carbon dioxide (CO2). These
    ecosystems, however, are often viewed as disconnected from each other,
    which ignores the transfer of carbon from land to the open ocean through
    a complex network of water bodies -- the continuum of streams, rivers, estuaries and other bodies carrying water from land to the sea.

    In a detailed analysis, the team of researchers from Belgium, the United
    States and France discovered that this land-to-ocean aquatic continuum
    (LOAC) carries a substantial amount of carbon of anthropogenic (e.g., fossil-fuel) origin.

    Thus, the carbon removed from the atmosphere by terrestrial ecosystems is
    not all stored locally, as is commonly assumed, which has implications
    for global agreements that require countries to report their carbon inventories. The researchers also found that the land-to-ocean carbon
    transfer of natural origin was larger than previously thought, with far-reaching implications for the assessment of the anthropogenic CO2
    uptake by the ocean and the land.

    "The complexity of the LOAC, which includes rivers, groundwater, lakes, reservoirs, estuaries, tidal marshes, mangroves, seagrasses, and waters
    above continental shelves, has made it challenging to assess its influence
    on the global carbon cycle," said Pierre Regnier, a professor at the
    University of Brussels who co-led the study with Resplandy.

    Because of that complexity, important global carbon-budgeting efforts,
    such as those of the U.N. Intergovernmental Panel on Climate Change
    and the Global Carbon Project, typically assume a direct "pipeline"
    transfer of carbon from river mouths to the open ocean. Another common assumption is that all the transported carbon is natural, neglecting
    the impacts of human perturbations on this aquatic continuum, such as
    damming and the decimation of coastal vegetation.



    ==========================================================================
    In this study, the researchers synthesized more than 100 individual
    studies of the various components of the continuum. From this
    synthesis, LOAC carbon budgets were developed for two time periods:
    the pre-industrial period and the present day. Their results confirm the well-known pre-industrial carbon "loop" in which carbon is taken up from
    the atmosphere by terrestrial ecosystems, transferred by rivers to the
    ocean, and then outgassed back to the atmosphere.

    "We find the amount of carbon carried by this natural land-to-ocean
    loop, 0.65 billion tons per year, is roughly 50% greater than previously thought," Resplandy said.

    Furthermore, this loop is comprised of two smaller loops, one that
    transfers carbon from terrestrial ecosystems to inland waters and
    another from coastal vegetation (so-called "blue carbon ecosystems")
    to the open ocean.

    "A larger pre-industrial land-to-ocean carbon transport implies that the
    ocean uptake of anthropogenic CO2 previously inferred from observations
    was underestimated," Resplandy said.

    "The flip side is that the land uptake of anthropogenic CO2 was
    overestimated," added Regnier.

    The study demonstrates that anthropogenic carbon carried by rivers is
    either outgassed back to the atmosphere or eventually stored in aquatic sediments and the open ocean.

    Philippe Ciais, a research director at the Laboratoire des Sciences du
    Climat et de l'Environnement and a co-author of the study explained:
    "This new view of the anthropogenic CO2 budget may have a silver lining
    because sediments and the ocean offer arguably more stable repositories
    than terrestrial biomass and soil carbon, which are vulnerable to
    droughts, fires and land-use change." The researchers also have shown
    that humans have decreased the uptake of atmospheric CO2 from blue-carbon ecosystems by up to 50%. "If left unprotected from sea-level rise,
    pollution and coastal development, blue-carbon uptake of atmospheric
    CO2 will further decline and contribute to additional climate warming,"
    said Raymond Najjar, a professor from the Pennsylvania State University
    who also co-authored the study.


    ========================================================================== Story Source: Materials provided by Princeton_University. Note: Content
    may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Regnier, P., Resplandy, L., Najjar, R.G. et al. The land-to-ocean
    loops
    of the global carbon cycle. Nature, 2022 DOI:
    10.1038/s41586-021-04339-9 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220316120818.htm

    --- up 2 weeks, 2 days, 10 hours, 50 minutes
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)