Climate change, teleconnection patterns, and regional processes forcing marine populations in the Pacific

Climate change impacts in large marine ecosystems (LMEs) are driven by global climate variability, often communicated over large distances by atmospheric teleconnections, and modified by the dominant local and regional ocean processes. The focus of this paper is to summarize the key processes and features that characterize the major coastal LMEs of the Pacific, as part of a greater effort to understand the role of past and future global climate change in driving (possibly synchronous) fluctuations in marine populations. The physical setting of five LMEs – the Humboldt Current System (HCS), California Current System (CCS), Gulf of Alaska (GOA), Kuroshio Current System (KCS), and Oyashio Current System (OCS) – and the mechanisms and impacts of climate variability on these systems are described. Because of their pivotal role in linking and perhaps synchronizing climate variability in disparate LMEs, we also review teleconnections and analyze past global atmospheric teleconnections and regional ocean response patterns. The major Pacific eastern boundary current systems, the CCS and HCS, feature similar dominant processes (e.g., coastal upwelling), and share atmospheric forcing from common teleconnection patterns that vary together. Sea level pressure variations forcing the KCS and OCS systems on climate scales, however, are not strongly teleconnected to the CCS and HCS. A common factor analysis of sea surface temperature (SST) within these ecosystems provides an example of how LMEs have responded to past climate variability. All LMEs display a persistent warming tendency since 1900, with multi-decadal fluctuations superimposed. However, SST fluctuations in the western Pacific lag those in the east by about a decade. Global synchrony in climate forcing is modulated by distinct processes within each LME, which reduce the correlation between long-term fluctuations.