RECENT SEA LEVEL CHANGE RATES IN THE NORTH PACIFIC AND IMPLICATIONS FOR THE FUTURE

Satellite measurements of sea surface height since the early 1990s show substantial regional variability in the rate of sea level change. In the North Pacific, rates in the western half of the basin are up to 5 times larger than the global mean rate of ~3 mm/yr. In contrast, rates along the Pacific North American coast are small and even negative. Understanding these recent rates in the context of historical measurements from tide gauges is important for long-term coastal planning. We show that the recent long-term rates of change in the eastern (western) North Pacific represent a deceleration (acceleration) relative to previous decades. Furthermore, the changes in rates across the basin are linked via long-term changes in the large-scale wind patterns over the basin associated with internal modes of climate variability, such as the Southern Oscillation and the Pacific Decadal Oscillation.

The implications of these findings are two-fold. First, as internal modes of pacific climate variability change sign, we expect sea level trends along the boundaries of the North Pacific to change sign as well. This implies an acceleration of the sea level change rate along the Pacific North American coast in the coming decades. Second, it is apparent that internal climate variability is an important driver of regional sea level change. Accounting for these dynamic variations is of utmost importance for determining accelerations in the global rate, and perhaps most importantly, the errors in such calculations.