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Title: Biogeochemical responses of the carbon cycle to natural and human perturbations: Past, present, and future

Abstract

In the past three centuries, human perturbations of the environment have affected the biogeochemical behavior of the global carbon cycle and that of the other three nutrient elements closely coupled to carbon: nitrogen, phosphorus, and sulfur. The partitioning of anthropogenic CO{sub 2} among its various sinks in the past, for the present, and for projections into the near future is controlled by the interactions of these four elemental cycles within the major environmental domains of the land, atmosphere, coastal oceanic zone, and open ocean. The authors analyze the past, present, and future behavior of the global carbon cycle using the Terrestrial-Ocean-aTmosphere Ecosystem Model (TOTEM), a unique process-based model of the four global coupled biogeochemical cycles of carbon, nitrogen, phosphorus, and sulfur. They find that during the past 300 yrs, anthropogenic CO{sub 2} was mainly stored in the atmosphere and in the open ocean. Human activities on land caused an enhanced loss of mass from the terrestrial organic matter reservoirs (phytomass and humus) mainly through deforestation and consequently increased humus remineralization, erosion, and transport to the coastal margins by rivers and runoff. Photosynthetic uptake by the terrestrial phytomass was enhanced owing to fertilization by increasing atmospheric CO{sub 2} concentrations and supportedmore » by nutrients remineralized from organic matter. TOTEM results indicate that through most of the past 300 yrs, the loss of C from deforestation and other land-use activities was greater than the gain from the enhanced photosynthetic uptake. Since pre-industrial time (since 1700), the net flux of CO{sub 2} from the coastal waters has decreased by 40%, from 0.20 Gt C/yr to 0.12 Gt C/yr. TOTEM analyses of atmospheric CO{sub 2} concentrations for the 21st century were based on the fossil-fuel emission projections of IPCC (business as usual scenario) and of the more restrictive UN 1997 Kyoto Protocol. By the mid-21st century, the projected atmospheric CO{sub 2} concentrations range from about 550 ppmv (TOTEM, based on IPCC projected emissions) to 510 ppmv (IPCC projection) and to 460 ppmv (TOTEM, based on the Kyoto Protocol reduced emissions).« less

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Hawaii, Honolulu, HI (US)
OSTI Identifier:
20006255
Resource Type:
Journal Article
Journal Name:
American Journal of Science
Additional Journal Information:
Journal Volume: 299; Journal Issue: 7-9; Other Information: PBD: 1999; Journal ID: ISSN 0002-9599
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; CARBON CYCLE; BIOGEOCHEMISTRY; HUMAN FACTORS; CARBON DIOXIDE; CARBON SINKS; GLOBAL ASPECTS; GEOLOGIC HISTORY

Citation Formats

Ver, L M.B., Mackenzie, F T, and Lerman, A. Biogeochemical responses of the carbon cycle to natural and human perturbations: Past, present, and future. United States: N. p., 1999. Web. doi:10.2475/ajs.299.7-9.762.
Ver, L M.B., Mackenzie, F T, & Lerman, A. Biogeochemical responses of the carbon cycle to natural and human perturbations: Past, present, and future. United States. doi:10.2475/ajs.299.7-9.762.
Ver, L M.B., Mackenzie, F T, and Lerman, A. Thu . "Biogeochemical responses of the carbon cycle to natural and human perturbations: Past, present, and future". United States. doi:10.2475/ajs.299.7-9.762.
@article{osti_20006255,
title = {Biogeochemical responses of the carbon cycle to natural and human perturbations: Past, present, and future},
author = {Ver, L M.B. and Mackenzie, F T and Lerman, A},
abstractNote = {In the past three centuries, human perturbations of the environment have affected the biogeochemical behavior of the global carbon cycle and that of the other three nutrient elements closely coupled to carbon: nitrogen, phosphorus, and sulfur. The partitioning of anthropogenic CO{sub 2} among its various sinks in the past, for the present, and for projections into the near future is controlled by the interactions of these four elemental cycles within the major environmental domains of the land, atmosphere, coastal oceanic zone, and open ocean. The authors analyze the past, present, and future behavior of the global carbon cycle using the Terrestrial-Ocean-aTmosphere Ecosystem Model (TOTEM), a unique process-based model of the four global coupled biogeochemical cycles of carbon, nitrogen, phosphorus, and sulfur. They find that during the past 300 yrs, anthropogenic CO{sub 2} was mainly stored in the atmosphere and in the open ocean. Human activities on land caused an enhanced loss of mass from the terrestrial organic matter reservoirs (phytomass and humus) mainly through deforestation and consequently increased humus remineralization, erosion, and transport to the coastal margins by rivers and runoff. Photosynthetic uptake by the terrestrial phytomass was enhanced owing to fertilization by increasing atmospheric CO{sub 2} concentrations and supported by nutrients remineralized from organic matter. TOTEM results indicate that through most of the past 300 yrs, the loss of C from deforestation and other land-use activities was greater than the gain from the enhanced photosynthetic uptake. Since pre-industrial time (since 1700), the net flux of CO{sub 2} from the coastal waters has decreased by 40%, from 0.20 Gt C/yr to 0.12 Gt C/yr. TOTEM analyses of atmospheric CO{sub 2} concentrations for the 21st century were based on the fossil-fuel emission projections of IPCC (business as usual scenario) and of the more restrictive UN 1997 Kyoto Protocol. By the mid-21st century, the projected atmospheric CO{sub 2} concentrations range from about 550 ppmv (TOTEM, based on IPCC projected emissions) to 510 ppmv (IPCC projection) and to 460 ppmv (TOTEM, based on the Kyoto Protocol reduced emissions).},
doi = {10.2475/ajs.299.7-9.762},
journal = {American Journal of Science},
issn = {0002-9599},
number = 7-9,
volume = 299,
place = {United States},
year = {1999},
month = {7}
}