NEW CONSTRAINT ON ESTIMATION OF THE ANTHROPOGENIC CO_2 BUDGET : RELATIONSHIP BETWEEN CONCENTRATION AND δ^<13>C OF ATMOSPHERIC CO_2 DETERMINED FROM ICE CORE ANALYSIS

• Main Authors: カトウ キクオ, コマキ カオリ, Kikuo KATO, Kaori KOMAKI
• Format: Report
• Language: English
• Published: ABSTRACT 1997
• Subjects: Greenland; Antarc*; Antarctica; ice core; Polar meteorology and glaciology; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=4015; http://id.nii.ac.jp/1291/00004015/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=4015&item_no=1&attribute_id=18&file_no=1

Studies on ice cores from Antarctica and Greenland revealed variations in the concentration and δ^<13>C of ancient atmospheric CO_2. Since the Industrial Revolution, addition of anthropogenic CO_2 to the atmosphere has caused a significant increase in atmospheric CO_2,accompanied by a decrease in δ^<13>C of atmospheric CO_2. The relationship between them shows that the δ^<13>C value of CO_2 which remained in the atmosphere is significantly larger than -25‰ of that originated from coal burning and deforestation at mid-latitudes. So, we consider that the δ^<13>C value of CO_2 uptaken from the atmosphere should be small. Then we calculated the δ^<13>C value of CO_2 which remained in the atmosphere, obtaining a result of about -13‰. We considered that this fact would be useful as a new constraint on the anthropogenic CO_2 budget. On the other hand, IPCC 1994 reported the revised budget of anthropogenic CO_2 and emphasized that the problem of the missing sink of CO_2 was solved. So, as this budget is determined for carbon as an element (that is, ^<12>C), we examined the budget reported by IPCC for ^<13>C. In the anthropogenic CO_2 budget in IPCC 1994,for the sources the δ^<13>C values of 5.5Gt/yr of carbon which originates from emissions from fossil fuel burning, and 1.6Gt/yr from emission from deforestation in the tropical region may be given as -27‰ and -30‰, respectively. For the sinks, the δ^<13>C values of 3.2Gt/yr of carbon which remains in the atmosphere, 0.5Gt/yr in northern hemisphere forest regrowth and 1.4Gt/yr in additional terrestrial sinks may be given as -13‰, -25‰ and -30∿-25‰, respectively. Therefore, as the result of calculation, δ^<13>C of 2.0Gt/yr of carbon which is uptaken in the ocean became very small. -54∿-46‰. This result cannot be explained by the observed fractionations for CO_2 exchange between the atmosphere and the ocean, photosynthesis and formation of carbonate. This indicates that the anthropogenic CO_2 budget reported by ...