Reconstructing seafloor age distributions in lost ocean basins

Reconstructions of past seafloor age make it possible to quantify how plate tectonic forces,surface heat flow,ocean basin volume and global sea level have varied through geological time.However,past ocean basins that have now been subducted cannot be uniquely reconstructed,and a significant challenge is how to explore a wide range of possible reconstructions.Here,we investigate possible distributions of seafloor ages from the late Paleozoic to present using published full-plate reconstructions and a new,efficient seafloor age reconstruction workflow,all developed using the open-source software GPlates.We test alternative reconstruction models and examine the influence of assumed spreading rates within the Panthalassa Ocean on the reconstructed history of mean seafloor age,oceanic heat flow,and the contribution of ocean basin volume to global sea level.The reconstructions suggest variations in mean seafloor age of~15 Myr during the late Paleozoic,similar to the amplitude of variations previously proposed for the Cretaceous to present.Our reconstructed oceanic age-area distributions are broadly compatible with a scenario in which the long-period fluctuations in global sea level since the late Paleozoic are largely driven by changes in mean seafloor age.Previous suggestions of a constant rate of seafloor production through time can be modelled using our workflow,but require that oceanic plates in the Paleozoic move slower than continents based on current reconstructions of continental motion,which is difficult to reconcile with geodynamic studies.

Airesea coupling over the Tasman Sea intensifies the ENSO-related South Pacific atmospheric teleconnection

The ENSO-induced PacificeSouth America(PSA)pattern is an important atmospheric bridge in linking the Antarctic climate to the tropical Pacific.The AGCM simulated PSA-like responses to ENSO are evidently weaker than the observed in terms of its intensity due to the lack of airesea coupling processes.The Tasman Sea features active airesea interactions.However,how and to what extent the airesea coupling explains the deficiency of the AGCM responses to ENSO is unclear.In this study,the role of the airesea coupling elsewhere the tropical Pacific in shaping the ENSOeSouth Pacific teleconnection is first estimated by comparing the coupled tropical Pacific pacemaker experiments(PACE)derived from the Community Earth System Model version 1(CESM1)and the parallel Pacific OceaneGlobal Atmosphere experiments(POGA)with the same atmospheric component model of CESM1.Our results suggest that the airesea coupling elsewhere the tropical Pacific greatly intensifies the South Pacific atmospheric response to ENSO.Then the separated impact of airesea coupling over the Tasman Sea is stressed with another set of AGCM experiments forced with the PACE sea surface temperature(SST)outputs in the Tasman Sea.The results show that the atmospheric response to the SST anomalies in the Tasman Sea bears a remarkable resemblance to that due to the airesea coupling elsewhere the tropical Pacific,and explains about 30%of the intensified amplitude.This highlights a substantial contribution of the airesea coupling over the Tasman Sea to intensifying the extratropical South Pacific atmospheric responses to ENSO,and provides a new perspective on the connection between tropical Pacific and Antarctic climate change.