Role of the biosphere in the carbon cycle

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6115014

Olson, J S

Analyses of ecosystem areas, carbon inventories and exchange rates confirm that biospheric processes affecting atmospheric CO/sub 2/ have been important but changeable. Only part of the world's land ecosystems has been a net source to the atmosphere (approx. 1 to 3 Pg or Gton C per year, probably mostly from the tropics) and perhaps only during parts of the past century. Simultaneously, some land ecosystems (especially Temperate and Boreal) and perhaps freshwater and near-shore marine ecosystems (with their sediments) recently have become net sinks for much of the carbon that cannot be accounted for by present models of absorption in the open ocean. Hence the net contribution of nonfossil carbon to the atmospheric CO/sub 2/ was probably significantly smaller than the prompt atmospheric inputs from forest clearing and burning, global shifts from woody to nonwoody vegetation, and delayed CO/sub 2/ inputs related to transfers from slowly to rapidly decomposing debris and humus. Despite recent doubts, inputs from fossil fuels now appear mainly responsible for the clear increase in excess CO/sub 2/ recorded by global monitoring since 1958, even though releases from vegetation and soil were relatively more important earlier in the century preceding that. A global ecosystem map has been useful in clarifying how overestimated forest pools may sometimes have led to overestimates of their input to CO/sub 2/. Remaining challenges are: (1) relating this map to climate, and to parameters like albedo that affect modeling of climate; (2) understanding exchange rates of CO/sub 2/, as affected by climate and disturbance; and (3) evaluating impacts of change on ecological resources.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6115014
• Report Number(s): CONF-811006-6; ON: DE82002886
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
510200 -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
520200 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
BIOMASS
CARBON COMPOUNDS
CARBON CYCLE
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CLIMATES
COMBUSTION PRODUCTS
EARTH ATMOSPHERE
ECOSYSTEMS
ENERGY SOURCES
FORESTS
FOSSIL FUELS
FUELS
GLOBAL ASPECTS
OXIDES
OXYGEN COMPOUNDS
POLLUTION SOURCES
RENEWABLE ENERGY SOURCES
SEAS
SINKS
SURFACE WATERS