- 22 - 



As discussed, the downward movement of heat was projected 



with a simple box diffusion model. While this model does not 



represent the ocean circulation processes that actually 



transport heat, it is probably a good surrogate for the likely 



effects of such processes for the time span of 100 years. 



Nevertheless, to ensure the validity of the sea level rise 



estimates, we used different assumptions: 



o For the high assumption , a rate of heat diffusion 



compatible with higher estimates of observed movement of 

 chemical and radioactive tracers was used (1.9 cm^/sec). 



o For the low assumption , a rate of 1.18 cm 2 /sec was used, 

 which is compatible with a more conservative 

 interpretation of tracer studies. ££/ 



o For the mid-range assumption , the average of the high 

 and low assumptions (1.54 cm 2 /sec) was used. 



The expansion of the seas was then computed using known 



coefficients of expansion for the temperature, salinity, and 



pressure of each ocean layer. We did not disaggregate thermal 



expansion to reflect the geographical variation of ocean 



temperatures. Because water expands by different amounts at 



different temperatures, disaggregation would improve sea level 



rise estimates. However, the one-dimensional description of 



temperature and salinity provides a good first approximation. 



The Cryosphere 



Most discussions concerning sea level rise have focused 

 solely on the possible contributions of ice and snow resting 

 below sea level in West Antarctica moving into the sea ,-*-->/ 



