About this Research Topic
The North Pacific’s sensitivity to changes in climatic forcing and feedbacks to background climate are an important, but largely open question in assessments of global climate, both in the modern and geological past. More comprehensive and multi-disciplinary knowledge of physical, chemical and biological processes under past and present climate variations is crucial to separate between natural and anthropogenic forcing, and to enhance the reliability of future climate projections.
On a spatial scale, this region comprises major oceanographic patterns including large Western Boundary Current systems (Kuroshio, Oyashio, East Kamchatka Current, East Sakhalin Current, Alaskan Stream) and several important frontal regions (Subarctic Front, Kuroshio Bifurcation, Mixed Layer Front). In addition, complex exchange processes and interactions between the open North Pacific, its marginal seas (Sea of Japan, Okhotsk Sea, Bering Sea) and continental shelf areas (Gulf of Alaska, Bering Shelf) create a heterogenous region, with small-scale mixing and both temporal and spatial variations at atmospheric, as well as oceanic surface, subsurface and deep levels.
On a temporal scale, the region’s climate system today experiences widespread and complex changes on seasonal to multi-decadal timescales, based on information from relatively short, instrumental time-series. However, a multitude of nonlinear characteristics, due to the combination of a global warming background, interaction with other regions and internal processes, as well as superposed variability across different time scales, renders much-needed evaluation of natural vs. human contributions challenging in regional assessments of global change. Physical change in climate has caused fundamental modifications in the biogeochemical setting of the North Pacific in the past and continues to do so in the present, e.g. in ocean oxygen concentrations, ocean acidification etc. Inevitably, this affects marine ecosystems and the oceanic CO2 sink capacity. Proxy-based paleo-reconstructions as well as paleo-simulations with state-of-the-art models can extend our knowledge about these processes back in time to help inform us about the future.
With this Research Topic, we aim to increase the insight into North Pacific climate states, atmospheric and oceanic circulation, as well as corresponding biogeochemical characteristics across a variety of temporal and spatial scales. We welcome results based on instrumental, paleoceanographic proxy or paleoclimate modelling data from times of changing, in particular warming, climates throughout the Quaternary, from sub-annual to orbital timescales. We hope to provide a collection of original contributions and syntheses that foster the dynamic, four-dimensional, process-oriented understanding of the complex role of climate and oceanic modes in the North Pacific and its marginals seas in regulating biogeochemical cycles, ocean circulation, as well as the resulting ocean-atmosphere greenhouse gas exchanges. We also welcome both established and novel approaches to decipher variations in oceanic stratification, nutrient budgets and their utilisation, micronutrient (Fe) supply, marine productivity, and resulting remineralisation, as well as their effects on the oxygenation of intermediate and deep waters. This includes studies that link and mechanistically connect results from the North Pacific to both the Arctic domain as well as low-latitude Equatorial and South Pacific characteristics and teleconnections, or global large-scale climate and ocean circulation patterns.
Providing a Pacific paleo-based benchmark collection in what may constitute natural systemic boundary conditions under future global warming, these past climate scenarios can be used to create a framework for the identification of potential thresholds and extreme events in the current, warming Earth system.
Keywords: Paleoclimate, carbon cycle, teleconnections, meridional overturning circulation, biogeochemistry
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