Indo-Pacific Sea Level as an Indicator of Climate Variability and Change

Abstract

The Indo-Pacific Ocean, particularly in Southeast Asia, directly affects an enormous coastal and island population, drives heat and moisture transfer across the globe, and provides a critical influence on future anthropogenic climate change. Natural variability in the climate system, acting in concert with global warming, leads to sea level changes that vary considerably across the region. Here we present three studies where sea level gradients in the Indo-Pacific are used to better understand variability and trends in global climate Satellite altimetry measurements have recently reached 25 years in length (1993 to 2017) providing a precise global sea level record to illuminate changes in ocean heat storage. The data shows that from 1993 to 2012 sea level in the western Pacific has risen up to four times faster than the global mean due to strengthening trade winds. To ensure robust results and extend the sea level record further our work includes data from state-of-the-art climate models, reanalysis products, sea level reconstructions, and ocean temperature databases. In Appendix A (published in Geophysical Research Letters), we quantify for the first time the relationship between fast sea level rise in the western Pacific and the observed slowdown of global average surface temperature from 1998-2012. In Appendix B (published in Water), we use the east-west sea level gradient in the Pacific as a metric for evaluating climate model skill in simulating variability. In Appendix C (in preparation for submission to Geophysical Research Letters), we show how the Indonesian Throughflow response to western Pacific sea level rise differs between reanalysis products and climate model simulations. In these three studies we utilize the newly available satellite altimetry record to better understand Indo-Pacific Ocean dynamics and how they are represented in the current generation of climate models.