O'Sullivan, M.O., Spracklen, D.V.,
Batterman, S.A., Arnold, S.R.,
Gloor, M. and Buermann, W.
2019
Have synergies between
nitrogen deposition and
atmospheric CO2
driven the recent
enhancement of the
terrestrial carbon sink?
Global Biogeochemical Cycles 33:
NOTE:
Net primary production (NPP)
is the net carbon that is "fixed"
( aka sequestered )
by a plant community,
or ecosystem.
NPP is the combined product of
climatic, geochemical, ecological
and human effects.
In recent years, there have been
concerns that global terrestrial NPP
is decreasing due to wildfires,
disease, pest outbreaks,
deforestation, and changes in
temperature and precipitation.
The United Nations' Intergovernmental
Panel on Climate Change, for example,
falsely claims the productivity
of the global biosphere is in decline
because of global warming.
In reality, the opposite is occurring.
Our planet is significantly 'greening'.
Biospheric productivity is increasing,
thanks to growth-enhancing, water-saving
and stress-ameliorating benefits of
atmospheric CO2 enrichment.
SUMMARY:
Claims of a
soon-to-be-collapsing
terrestrial biosphere
are false.
The world's land vegetation
has increased its robustness,
over the past twelve decades.
And the reason
is the increasing
use of fossil fuels.
The combustion of fossil fuels
is the principal driver
of increased atmospheric
CO2 and nitrogen deposition.
Green plants are "thankful"
for the use of fossil fuels !
The steady rise
in atmospheric CO2
was directly,
or indirectly,
responsible for 77%
of the simulated NPP
increase since 1901.
O'Sullivan et al. note that
the majority of the earth's
vegetated land surface
"increased net carbon uptake
over the historical period,
with the tropics, East Asia,
North America, and
northern Eurasia
dominating".
DETAILS:
O'Sullivan et al. (2019)'s six scientists
used the Community Land Model
version 4.5, which
"simulates biophysical, hydrological,
and biogeochemical exchange
processes between the land
and the ocean,"
to estimate changes in NPP
over the period 1901-2016.
As shown in Figure 1,
simulated NPP
"increased substantially
over the 20th century
to the present day from 56.2
(mean of 1901-1910)
to 66.0 Pg C/year
(mean of 2007-2016)
with positive contributions
from all drivers considered,
including rising CO2 concentrations
(referred to as CO2 fertilization),
nitrogen deposition, climate,
and carbon-nitrogen as well as
carbon-climate synergies."
The relative contribution
of these drivers to the
overall NPP increase
amounted to 60%
for CO2 fertilization,
15% for nitrogen deposition,
8% for climate,
8% from a combined
CO2 / nitrogen
deposition effect, and
9% for a combined
CO2 / climate effect:
A spatial display of the
changes in NPP
due to atmospheric CO2
enrichment over the period
of study is presented in Figure 2:
