National Aeronautics and Space Administration

Forcings in GISS Climate Model

Well-Mixed Greenhouse Gases

Historical Data

Assumed histories of CO₂, CH₄, N₂O and other trace gases, are based on in situ measurements for the past few decades and ice core data for earlier times.

CO₂: For 1850-1953, Etheridge et al's ice core data were adjusted to account for the geographical distribution of CO₂ as a function of time. The means of data (SIO for 1958-1974 and CMDL in-situ data for 1975-1982) at sites (Mauna Loa and South Pole) were adjusted for the geographical inhomogeneity. For 1983-2002, means of data at CMDL CCCG sampling network were computed. The 2003 data is the mean of the increment of in-situ data at four sites (Barrow, Mauna Loa, American Samoa and South Pole) from 2002 to 2003 added to the 2002 global data. For 2004 amount an estimated increase of 1.5 ppm was added to the 2003 amount.

CH₄: For 1984-2003, we use E. Dlugokencky's global mean data. For 2004 amount, an estimated change of -1.03 ppb was added to 2003 data. Since the ice core data with interpolar difference modifications (Table 2 in Etheridge et al.) had always been used, no change was made to these data (except the ice core data were used through 1980 and linear interpolations were done between 1980 and 1984).

N₂O: CMDL's in situ GCs/CATS global data are used for 2000-2004, adding 0.7 ppb to the flask global mean data for 1978-1999 which had been used to match the data with the CATS data in year 2000.

CMIP5 Scenarios

In CMIP5, scenarios were based on representative concentration pathways (RCPs) with nominal radiative forcing from WM-GHGs at 2100 of 2.6, 4.5 6.0 and 8.5 W/m². For non-interactive runs, CH₄ levels are as specified in each RCP, but in simulations with interactive chemistry, methane levels are free to adjust to climate-related changes in reaction rates, water vapor etc. This figure is from Nazarenko et al., (2015).

Data for all scenarios (out to 2500) in the non-interactive (NINT) and interactive (TCADI) model versions are available as follows:

• 1850-2005: CO2, CH4, CFCs, N2O.
• RCP2.6: CO2, CH4, CFCs, N2O. Interactive: CH4
• RCP4.5: CO2, CH4, CFCs, N2O. Interactive: CH4
• RCP6.0: CO2, CH4, CFCs, N2O. Interactive: CH4
• RCP8.5: CO2, CH4, CFCs, N2O. Interactive: CH4

CMIP3 Scenarios

Scenarios used in the CMIP3 simulations were based on storylines developed by IPCC TAR. The figures an update of Fig. 2 in Hansen, et al. (2007)

Pre-CMIP3 scenarios

Scenario datasets used in the GISS 2004 GCM (last modified: 2004-06-15).

Related figures from Hansen and Sato 2004, "Greenhouse gas growth rates".

Contact

Please address scientific inquiries about these data to Dr. Makiko Sato.

References

Hansen, J., M. Sato, R. Ruedy, A. Lacis and V. Oinas 2000. Global warming in the twenty-first century: An alternative scenario. Proc. Natl. Acad. Sci. USA 97, 9875-9880.

Hansen, J., and M. Sato 2001. Trends of measured climate forcing agents. Proc. Natl. Acad. Sci. USA 98, 14778-14783.

Hansen, J., and M. Sato 2004. Greenhouse gas growth rates. Proc. Natl. Acad. Sci. USA 101, 16109-16114. Also see supplementary material.

Intergovernmental Panel on Climate Change 2001. Climate Change 2001. Eds. J.T. Houghton, Y. Ding, D.J. Griggs, et al. Cambridge University Press, Cambridge, U.K.

Nazarenko, L., G.A. Schmidt, R.L. Miller, et al., 2015: Future climate change under RCP emission scenarios with GISS ModelE2. J. Adv. Model. Earth Syst., 7, no. 1, 244-267, doi:10.1002/2014MS000403.

CO₂

• 1850-1953: Etheridge, D., L. Steele, R. Langenfelds, R. Francey, J.Barnola, and V. Morgan 1996. Natural and anthropogenic changes in atmospheric CO₂ over the last 1000 years from air in Antarctic ice and firn. J. Geophys. Res 101, 4115-4128, doi:10.1029/95JD03410.
• 1958-1974: C.D. Keeling and T.P. Whorf (UC SIO) http://cdiac.ess-dive.lbl.gov/trends/co2/sio-keel.html (last accessed 2018-07-16, formerly at http://cdiac.esd.ornl.gov/trends/co2/sio-keel.htm)
• 1975-1982 and 2003: P. Tans and K. Thoning (NOAA CMDL) ftp://ftp.cmdl.noaa.gov/ccg/co2/in-situ/
• 1983-2002: P.P. Tans and T.J. Conway (NOAA CMDL) ftp://ftp.cmdl.noaa.gov/ccg/co2/flask/
• 2004-2011: NOAA/ESRL/Global Monitoring Division ftp://ftp.cmdl.noaa.gov/ccg/co2/trends/co2_annmean_gl.txt

CH₄

• 1850-1980: Etheridge, D., L. Steele, R. Francey, and R. Langenfelds 1998. Atmospheric methane between 1000 A.D. and present: Evidence of anthropogenic emissions and climate variability. J. Geophys. Res. 103, 15979-15993, doi:10.1029/98JD00923.
• 1984-2010: E. Dlugokencky (NOAA CMDL, private communication).

N₂O

• 1850-1977: Machida, T., T. Nakazawa, Y. Fujii, S. Aoki, and O. Watanabe 1995. Increase in the atmospheric nitrous oxide concentration during the last 250 years. Geophys. Res. Lett., 22, 2921-2924.
• 1978-1999: NOAA CMDL Flask Data ftp://ftp.cmdl.noaa.gov/hats/n2o/flasks
• 2000-2011: G.S. Dutton, T.M. Thompson, J.W. Elkins and B.D. Hall (NOAA CMDL InSitu Data) ftp://ftp.cmdl.noaa.gov/hats/n2o/combined/HATS_global_N2O.txt

CFCs

• 1850-1977: IPCC 2001. Climate Change 2001, eds. J.T. Houghton, Y. Ding, D4J. Griggs, et al.
• 1978-1988 (CFC-11) and 1978-1987 (CFC-12): ftp://ftp.cmdl.noaa.gov/hats/cfcs/cfc11/flask/monthly, ftp://ftp.cmdl.noaa.gov/hats/cfcs/cfc12/flask/monthly
• 1989-1991 (CFC-11) and 1988-1991 (CFC-12): ftp://ftp.cmdl.noaa.gov/hats/cfcs/cfc11/insituGCs/global, ftp://ftp.cmdl.noaa.gov/hats/cfcs/cfc12/insituGCs/global
• 1992-2010 (CFC-11, CFC-12, CFC-113, HCFC-22, HCFC-141b,HCFC-142b, CCl4, CH3CCl3, H-1211, H1301) Update of S.A. Montzka, J.H. Butler, J.W. Elkins, T.M. Thompson, A.D. Clarke and L.T. Lock Nature 398, 690-694. ftp://ftp.cmdl.noaa.gov/hats/Total_Cl_Br
• 1970-2010 (CFC-114, CFC-115 and HCFC-123): IPCC 2001. Climate Change 2001
• 1995-2011 (HFC-134a, SF6) ftp://ftp.cmdl.noaa.gov/hats/ by S.A. Montzka, et al.
• All other OTGs: IPCC 2001. Climate Change 2001

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This page was written by Dr. Makiko Sato and Dr. Gavin Schmidt.

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