The effect of global change and long period tides on the Earth's rotation and gravitational potential

The effects of a possible global warming, in particular the rising sea level and melting glaciers, has been a topic of great interest. This thesis attempts to quantify the effect these changes and long period ocean tides have on the Earth's rotation and gravity.; Global averages of tide gauge data, after correcting for the effects of post glacial rebound on individual station records, reveal an increase in sea level for the years 1900-1979, of between 1.5 and 2.0 mm/yr. The global response of sea level to atmospheric pressure is found to be inverted barometer at periods greater than two months.; Tide gauge data are fitted to numerically generated tidal data to show that the 18.6 year lunar nodal tide and 14.3 month pole tide have amplitudes and phases that are consistent with a global equilibrium response. The large coherence at 437 days between pressure and sea level in the North Sea, Baltic Sea and the Gulf of Bothnia may be due to meteorological forcing.; The effects on the Earth's rotation and gravitational potential due to changes in annual mass balance for 85 glaciers in 13 mountain glacier systems for the years 1965-1984 are generally at or below detectable limits but the contribution to sea level rise for these glaciers is 0.14 mm/year.; Gridded accumulation data for the Antarctic ice sheet and for the Greenland ice sheet are used along with estimates of the rate of discharge from the ice sheets to estimate the contributions these two regions make to the Earth's gravity and rotation. The Antarctic contribution to the gravitational signal and to the displacement of the solid earth are found to be within the limits of detection by satellites.; The secular trends in the X and Y-components of observed polar motion excitation agree well with the Antarctic contributions, for a model where the interior portions of the ice sheet undergo thinning and the coastal regions thicken. Changes in polar or glacial ice do not agree well with observed changes in the length of day during the last 80 years.