wAbstract
@Carbon dioxide is taken up by agricultural crops and released
soon after during the consumption of agricultural commodities.
The global net impact of this process on carbon flux to the atmosphere
is negligible, but impact on the spatial distribution of carbon
dioxide uptake and release across regions and continents is significant.
To estimate the consumption and release of carbon by humans over
the landscape, we developed a carbon budget for humans in the
United States. The budget was derived from food commodity intake
data for the US and from algorithms representing the metabolic
processing of carbon by humans. Data on consumption, respiration,
and waste of carbon by humans were distributed over the US using
geospatial population data with a resolution of `450~450 m. The
average adult in the US contains about 21 kg C and consumes about
67 kg C year-1 which is balanced by the annual release
of about 59 kg C as expired CO2, 7 kg C as feces and urine, and
less than 1 kg C as flatus, sweat, and aromatic compounds. In
2000, an estimated 17.2 Tg C were consumed by the US population
and 15.2 Tg C were expired to the atmosphere as CO2.
Historically, carbon stock in the US human population has increased
between 1790 and 2006 from 0.06 Tg to 5.37 Tg. Displacement and
release of total harvested carbon per capita in the US is nearly
12 of per capita fossil fuel emissions. Humans are using, storing,
and transporting carbon about the Earth's surface. Inclusion of
these carbon dynamics in regional carbon budgets can improve our
understanding of carbon sources and sinks.
Keywords: Agriculture; Carbon dioxide; Food consumption; Horizontal
carbon transfer; Population; Respirationx
Introduction
Methods of carbon accounting
@Consumption of carbon by humans
@Expiration of carbon by humans
@Excretion and secretion of carbon by humans
@Carbon stock of humans
@Geospatial distribution of human respiration
Results and synthesis
Acknowledgments
Open access
Appendix 1: Consumption of carbon by humans
Appendix 2: Excretion and secretion of carbon by humans
Appendix 3: Carbon stock of humans
References