
31The Earth’s Climate System
from both tidal gauges and satellite measurements worldwide, scientists can
say with condence that sea-level rise has increased during the twentieth
century. Based on data acquired from Australia’s Commonwealth Scientic
and Industrial Research Organization (CSIRO), data gathered from January
1993 to April 2008 shows that sea level has risen on average 3.3 mm/year
(Figure 1.8). Increased scientic knowledge has also claried some issues
that were not well understood previously, such as that the large polar ice
sheets are far more sensitive to surface warming than initially thought, with
signicant changes c