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APPENDIX C 

 METHODS OF ESTIMATING SNOW AND ICE CONTRIBUTION 



This appendix reviews the results and methods used to gene- 

 rate the estimates of ice melting in the doubled CO2 experiments 

 with the GISS general circulation model (GCM) and presents the 

 methods used to estimate snow and ice contributions in the 

 scenarios . 



GLACIAL MASS BALANCE IN GISS GCM 



by Gary Russell 

 Goddard Institute for Space Studies 



The GCM doubled CO2 experiments imply a sea level rise of 

 13.5 mm/yr due to melting of land ice. The melting is caused 

 by a mean addition of heat of 3.27 Wm~ 2 to the surface of the 

 land ice. The increment of sea level caused by reduced snow on 

 the continents is insignificant compared to the glacial metling. 



The following is a short description of algorithms applied 

 to land ice in the GCM, tables of results from the control run 

 and the doubled CO2 experiment, and calculations based on those 

 tables. 



Precipitation that falls on the ground is calculated from 



the atmospheric conditions. Precipitation is snow if the first 



atmospheric layer temperature is below 0°C; otherwise it is rain, 



EPRCP (W/m 2 ) = if T 1 > Q. 



[LHM = 334000 ( J/kg ) ] 

 -PRCP*LHM if T 1 < 



PRCP is the precipitation in kg/m 2 5 



