Sometimes things shrink, and sometimes this is a problem, as reported in this 1997 study:
“Ice Cream Shrinkage: A Problem for the Ice Cream Industry,” U.K. Dubey and C.H. White, Journal of Dairy Science, vol. 80, no. 12, 1997, pp. 3439-3444. The authors, at Mississippi State University, report:
When ice cream is shipped from one altitude toanother, a change in atmospheric pressure can contribute to shrinkage of the product. Although few recent references exist regarding the problem of shrinkage caused by changes in altitude or pressure, several pertinent articles were published in the 1940s and 1950s.