Open AccessObservation‐based global biospheric excess radiocarbon inventory 1963–2005
Author(s) -
Naegler Tobias,
Levin Ingeborg
Publication year - 2009
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008jd011100
Subject(s) - radiocarbon dating , environmental science , biosphere , sink (geography) , atmospheric sciences , atmosphere (unit) , carbon cycle , flux (metallurgy) , climatology , meteorology , physics , chemistry , geology , geography , ecosystem , paleontology , ecology , cartography , organic chemistry , astronomy , biology
For the very first time, we present an observation‐based estimate of the temporal development of the biospheric excess radiocarbon ( 14 C) inventory I B 14, E , i.e., the change in the biospheric 14 C inventory relative to prebomb times (1940s). I B 14, E was calculated for the period 1963–2005 with a simple budget approach as the difference between the accumulated excess 14 C production by atmospheric nuclear bomb tests and the nuclear industry and observation‐based reconstructions of the excess 14 C inventories in the atmosphere and the ocean. I B 14, E increased from the late 1950s onward to maximum values between 126 and 177 × 10 26 atoms 14 C between 1981 and 1985. In the early 1980s, the biosphere turned from a sink to a source of excess 14 C. Consequently, I B 14, E decreased to values of 108–167 × 10 26 atoms 14 C in 2005. The uncertainty of I B 14, E is dominated by uncertainties in the total bomb 14 C production and the oceanic excess 14 C inventory. Unfortunately, atmospheric Δ 14 CO 2 from the early 1980s lack the necessary precision to reveal the expected small change in the amplitude and phase of atmospheric Δ 14 C seasonal cycle due to the sign flip in the biospheric net 14 C flux during that time.