Temperatures in Polar Ice Caps

Abstract

DECREASE in temperature with depth which was first observed by Sorge¹ in the top 20 m. of ice at Eismitte in Greenland has since been confirmed for much deeper strata there^2,3 and in Antarctica^4,5. Sorge thought that the negative temperature gradient could have been created by a secular rise in air temperature. Independent evidence exists for such a trend in Greenland but not in Antarctica⁶. Moreover, the much greater depth to which a steady decrease in temperature in the ice has now been traced would require a surface warming extending over very long periods. In these circumstances it seems necessary to consider first the effects of the warming of the ice-cap surface connected with the decrease in its height during the outward movement of the ice. By geometrical reasoning Robin⁷ deduced that in the absence of heat conduction this movement (of velocity v) coupled with a net surface accumulation v leads to the temperature gradient: where α is the surface slope and λ the vertical gradient of the annual mean air temperature along the ice cap surface. A more complete treatment of the problem, taking into consideration heat conduction as well as advective temperature changes, now shows the relation (1) to have a deeper significance.