The Maritime Continent in the mid-Piacenzian Warm Period

: climate, and impacts of topographic change

Abstract

The Maritime Continent (MC) connects the Indian and Pacific Oceans, and influences both local and global climate systems. In the mid-Piacenzian warm period of the Pliocene (mPWP; 3.264 to 3.025 Ma) CO2 concentrations were ~400 ppm, and the land-sea distribution was different.


This study investigates the climate of the MC during the mPWP and explores the role of MC topography. Three main aspects are addressed; the climate and ocean circulation of the mPWP in the MC is explored and compared with proxies; the impact of model tuning on the simulated climate of the mPWP is identified; and finally the role of topography of the MC in the mPWP is investigated.


An ensemble of 17 simulations from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) reveals a 1.88 ℃ increase in sea surface temperature and wettening in the MC, and a lower sea surface salinity in the surrounding ocean in the mPWP compared to the preindustrial. 10 out of 15 models show an increased volume transport of the Indonesian Throughflow, likely associated with the closure of the Bering Strait.


Following PlioMIP2 protocols, a newly tuned version of HadCM3 is used to carry out mPWP simulations that aligns better with mPWP proxy reconstructions than the original version, due to improved representation of high-latitude warming.


Using the tuned HadCM3, sensitivity studies with modified topography in the MC region, reveal that these topographic changes influence sea surface temperature, freshwater flux, clouds, and the structure of the Timor flow. While the overall impact of MC topography on global temperature is relatively small, its influence on regional oceanic and atmospheric circulation is substantial.


This study not only helps with our understanding of MC climate in a warmer world but also offers a framework for evaluating how future changes in MC topography, driven by sea-level variations, could influence a future warming world.

Date of Award	13 May 2025
Original language	English
Awarding Institution	University of Bristol
Sponsors	H2020 Marie Skłodowska-Curie Actions
Supervisor	Dan Lunt (Supervisor) & Erica Hendy (Supervisor)