The response of atmospheric CO sub 2 to changes in land use Page: 17 of 54
52 p.View a full description of this article.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
16
Oeschger, 1987; Keeling et al., 1989]. Again, interpretation of the residual flux as ter-
restrial biospheric exchange with the atmosphere is confounded by uncertainties in the
deconvolution, but the estimates that result are extremely useful as alternatives for com-
parison with the direct historical-ecological reconstructions. Furthermore, they provide the
additional benefit of allowing for the projection of future CO2 changes from current con-
centrations and rates of change since they are produced by simulations that are constrained
to reproduce these observations. Given the incompatibility of existing historical-ecological
reconstructions of past land-use CO2 release with conventional globally averaged one-
dimensional models of ocean-atmosphere CO2 exchange (Figure 5) [Eniing and Pearman,
1986; Enting and Mansbridge, 1987] and with at least the first generation of regional-
ized two-dimensional tracer-based models [Peng, 1986; Enting and Mansbridge, 1987] and
three-dimensional ocean general circulation models [Keeling et al. 1989], the constrained
atmosphere 'approach to simulating past CO2 changes is virtually indispensable for the
projection of future changes.
In Figure 6 we compare our constrained simulation with the historical record of past
changes in atmospheric CO2. We used a modification of the approach to constrained atmo-
sphere simulation used by Killough and Emanuel [1981], and we smoothed the simulation
by cubic splines to just maintain a monotonic increase in simulated CO2 concentration.
Note that the simulated history of CO2 is the same for each of the three models but that
the residual flux required to achieve that simulation varies inversely with the oceanic up-
take of the models (Figure 7). For example, the box-diffusion model simulates the smallest
net oceanic uptake and consequently generates the largest residual flux in producing the
simulation of Figure 6,
If the anthropogenic CO2 emissions driving the model simulations are limited to indus-
trial sources, the residual flux can be interpreted as the net exchange of carbon between the
atmosphere and the entire terrestrial biosphere (Figure 7a). If CO2 release from land-use
change is also included (e.g., the histories of Figure 3), the residual flux can be interpreted
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
King, A. W.; Emanuel, W. R. & Post, W. M. The response of atmospheric CO sub 2 to changes in land use, article, January 1, 1990; Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc1187253/m1/17/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.