41Monthly mean CO 2 at SPO (red line) is based on data provided by NOAA
ESRL at:
http://scrippsco2.ucsd.edu/assets/data/atmospheric/stations/flask_co2/monthly/
monthly_flask_co2_spo.csv
Monthly (line) and daily (dots) observations of the O 2 /N 2 ratio are based on data
archived by SIO at:
http://scrippso2.ucsd.edu/sites/default/files/data/o2_data/o2_monthly/mloo.txt
http://scrippso2.ucsd.edu/sites/default/files/data/o2_data/o2_daily/mlooav.csv
Finally, monthly (line) and daily (dots)^13 δCO 2 is also based on data from SIO, at:
http://scrippsco2.ucsd.edu/assets/data/atmospheric/stations/flask_isotopic/
monthly/monthly_flask_c13_mlo.csv
http://scrippsco2.ucsd.edu/assets/data/atmospheric/stations/flask_isotopic/daily/
daily_flask_c13_mlo.csv
Figure 1.8 shows the difference between annual average CO 2 at MLO and CO 2
at SPO versus total anthropogenic emissions of CO 2. Here, we formed annual aver-
age CO 2 for each station from monthly mean values, based on in situ and flask
sampling archived by SIO at:
http://scrippsco2.ucsd.edu/assets/data/atmospheric/stations/in_situ_co2/
monthly/monthly_in_situ_co2_mlo.csv
http://scrippsco2.ucsd.edu/assets/data/atmospheric/stations/flask_co2/
monthly/monthly_flask_co2_spo.csv
The total anthropogenic emissions of CO 2 are annual tabulations, reflecting the sum
of combustion of fossil fuel (Boden et al. 2013 ) plus land use change (Houghton
et al. 2012 ), and originate from the Global Carbon Project archive described in
Methods for Fig. 1.6.
Figure 1.9 shows an estimate for the sources and sinks of atmospheric CH 4.
Numerical values of the CH 4 source for total humans (335 Tg year−1), total natu-
ral (218 Tg year−1), natural wetlands (175 Tg year−1), other natural (43 Tg year−1)
are from the top-down estimates for 2000–2009 given in Table 1 of Kirschke
et al. ( 2013 ). The apportionment of the human sources is based on Fig. 1 of
Conrad ( 2009 ). Numerical values of the total sink (550 Tg year−1) and the sink
due to soils (32 Tg year−1) are also based on the top-down estimates from table
1 of Kirschke et al. ( 2013 ), whereas the sinks due to chemical loss via reactions
with tropospheric OH (452.8 Tg year−1), reactions with tropospheric Cl
(21.4 Tg year−1), and stratospheric chemistry (43.7 Tg year−1) are based by scal-
ing the bottom-up estimates of these quantities given in Table 1 of Kirschke
et al. ( 2013 ) for the decade 2000–2009 by the ratio 518/604 = 0.8576, where
518 Tg year−1 is the total chemical sink found using the trop-down approach and
604 Tg year−1 is the total chemical sink found using the bottom-up approach.
The numbers have been combined in this manner to provide a self-consistent
estimate of the CH 4 source and sink terms by combining best available informa-
tion from several studies and approaches.
Figure 1.10 shows ΔRF due to CO 2 , CH 4 , N 2 O, and all anthropogenic GHGs
from the RCP 4.5 scenario (Meinshausen et al. 2011 ). The numerical values have
been obtained from the same file used to find ΔRF for Fig. 1.3. The figure also
1.3 Methods