Paleoceanography of the North Pacific

The North Pacific Ocean has undergone dramatic shifts in circulation, productivity and carbon storage over glacial–interglacial cycles. Proxy records from deep‐sea sediments, including isotopic compositions, trace‐metal concentrations and biogenic silica, reveal how changes in ice‐sheet extent, sea‐ice cover and atmospheric circulation have modulated nutrient upwelling, intermediate‐ and deep‐water formation, and hence global carbon dioxide levels. During warm intervals, strengthened westerly winds and reduced sea‐ice promoted enhanced upwelling of nutrient-rich subsurface waters, driving higher export productivity and releasing sequestered carbon. Conversely, expanded sea ice and intensified intermediate‐water formation during glacial maxima reduced vertical mixing and increased deep-ocean carbon storage. These processes are linked through variations in orbital forcing (precession and obliquity), tectonic boundary conditions such as the Bering Strait gateway, and millennial-scale events like Heinrich stadials. The resulting paleoceanographic framework has global significance for understanding the role of the North Pacific in past climate transitions and for projecting its response to ongoing warming.

Research from Nature Portfolio

High‐resolution sediment records spanning the last five glacial cycles demonstrate a pronounced interplay between ice-sheet dynamics and orbital precession in controlling subarctic North Pacific productivity. During peak boreal summer insolation, reduced ice‐cover allowed stronger westerlies to shift polewards, intensifying upwelling of nutrient- and carbon-rich waters and driving elevated biological export. Transient model simulations confirm that ice-sheet growth and decay are the primary controls on wind patterns that modulate carbon release from the subarctic Pacific.

Modelling studies of Heinrich Stadial 1 reveal that intensified formation of North Pacific Intermediate Water strengthened the vertical density gradient, thereby enhancing stratification between intermediate and deep waters. This process isolated abyssal carbon reservoirs during deglaciation and helped to prolong atmospheric CO₂ rise. The enhanced intermediate-water production also lowered salinity and raised temperatures at mid-depths, further reinforcing stratification and limiting deep-to-surface exchange.

Paleoceanography of the North Pacific publication trend

The graph below shows the total number of articles in paleoceanography of the north pacific across all publications each year (not limited to Nature Index journals).

Technical terms

Export productivity: The flux of organic material from the surface ocean to the deep sea, reflecting biological carbon uptake.

Precession: A ~20 000-year cycle in Earth’s orbital wobble that alters seasonal distribution of solar radiation.

North Pacific Intermediate Water (NPIW): A mid-depth water mass formed in the subarctic Pacific that influences nutrient and heat redistribution.

Meridional overturning circulation: A large-scale ocean circulation driven by density differences, transporting heat and carbon between low and high latitudes.

References

1. Ice sheet and precession controlled subarctic Pacific productivity and upwelling over the last 550,000 years. Nature Communications (2024).
2. Enhanced North Pacific deep-ocean stratification by stronger intermediate water formation during Heinrich Stadial 1. Nature Communications (2019).
3. Long‐Term Variability in Pliocene North Pacific Ocean Export Production and Its Implications for Ocean Circulation in a Warmer World. AGU Advances (2023).
4. Coupled climate and subarctic Pacific nutrient upwelling over the last 850,000 years. Earth and Planetary Science Letters (2019).
5. Closure of the Bering Strait caused Mid-Pleistocene Transition cooling. Nature Communications (2018).