124
emission of GHGs throughout this book. In this case, the two estimates represent an
attempt to harmonize the emissions used to drive the RCP scenarios with atmospheric observations of CH 4 and N 2 O.
15
Emissions of CH 4 , expressed as CO 2 -eq
using a 100-year time horizon, constitute about 80 % of the sum.
Figures 3.3b, c compare the RCP emissions of CH 4 and N 2 O, respectively, to
values from the Emissions Database for Global Atmospheric Research (EDGAR)
16
database (Rogelj et al. 2014). The two estimates for CH 4 are in very good agreement. However, they both use similar (or perhaps the same) measurements of the
atmospheric abundance of CH 4 versus time (Fig. 2.1 ) to guide the respective time
series. Both emission time series show that human release of CH 4 appears to have
stalled in the 1990s, before pickup up in the most recent decade. The precise reason
for this behavior is the subject of considerable uncertainty, perhaps best summarized by Kirschke et al. (2013), who in their abstract state:
Although uncertainties in emission trends do not allow definitive conclusions to be drawn,
we show that the observed stabilization of methane levels between 1999 and 2006 can potentially be explained by decreasing-to-stable fossil fuel emissions, combined with stable- to15 See http://www.pik-potsdam.de/~mmalte/rcps for further information.
16 Here and throughout, we use version 4.2 FT 2012 emissions from EDGAR.
0
5
10
15
Emission
(Gt CO
2
−eq yr
−1
)
N
2
O
CH 4
a
0
5
10
CH
4
Emission
(Gt CO
2
−eq)
b
RCP Potsdam
EDGARv4.2 FT 2012
1825
1850
1875
1900
1925
1950
1975
2000
0
1
2
3
N
2
O Emission
(Gt CO
2
−eq)
c
RCP Potsdam
EDGARv4.2 FT 2012
Fig. 3.3 Total global emissions of atmospheric CH 4 and N 2 O. (a) Emission of CH 4 (blue) and N 2 O
(green) expressed as CO 2 -equivalent (CO 2 -eq) from the RCP Potsdam database (Meinshausen
et al. 2011); (b) comparison of global emissions of CH 4 from the RCP Potsdam database and from
the Emissions Database for Global Atmospheric Research (EDGAR) version 4.2 FT2012 database
(Rogelj et al. 2014); (c) same as panel (b), but for N 2 O. See Methods for further information
3 Paris INDCs
emission of GHGs throughout this book. In this case, the two estimates represent an
attempt to harmonize the emissions used to drive the RCP scenarios with atmospheric observations of CH 4 and N 2 O.
15
Emissions of CH 4 , expressed as CO 2 -eq
using a 100-year time horizon, constitute about 80 % of the sum.
Figures 3.3b, c compare the RCP emissions of CH 4 and N 2 O, respectively, to
values from the Emissions Database for Global Atmospheric Research (EDGAR)
16
database (Rogelj et al. 2014). The two estimates for CH 4 are in very good agreement. However, they both use similar (or perhaps the same) measurements of the
atmospheric abundance of CH 4 versus time (Fig. 2.1 ) to guide the respective time
series. Both emission time series show that human release of CH 4 appears to have
stalled in the 1990s, before pickup up in the most recent decade. The precise reason
for this behavior is the subject of considerable uncertainty, perhaps best summarized by Kirschke et al. (2013), who in their abstract state:
Although uncertainties in emission trends do not allow definitive conclusions to be drawn,
we show that the observed stabilization of methane levels between 1999 and 2006 can potentially be explained by decreasing-to-stable fossil fuel emissions, combined with stable- to15 See http://www.pik-potsdam.de/~mmalte/rcps for further information.
16 Here and throughout, we use version 4.2 FT 2012 emissions from EDGAR.
0
5
10
15
Emission
(Gt CO
2
−eq yr
−1
)
N
2
O
CH 4
a
0
5
10
CH
4
Emission
(Gt CO
2
−eq)
b
RCP Potsdam
EDGARv4.2 FT 2012
1825
1850
1875
1900
1925
1950
1975
2000
0
1
2
3
N
2
O Emission
(Gt CO
2
−eq)
c
RCP Potsdam
EDGARv4.2 FT 2012
Fig. 3.3 Total global emissions of atmospheric CH 4 and N 2 O. (a) Emission of CH 4 (blue) and N 2 O
(green) expressed as CO 2 -equivalent (CO 2 -eq) from the RCP Potsdam database (Meinshausen
et al. 2011); (b) comparison of global emissions of CH 4 from the RCP Potsdam database and from
the Emissions Database for Global Atmospheric Research (EDGAR) version 4.2 FT2012 database
(Rogelj et al. 2014); (c) same as panel (b), but for N 2 O. See Methods for further information
3 Paris INDCs