15. Legacy of the Past and Directions for Future Marine Policy in the North Pacific

1982 ◽  
pp. 493-510
Keyword(s):  
North Pacific ◽  
Marine Policy ◽  
The Past ◽  
The North ◽  
The North Pacific

Did a Beringian ice sheet once exist?

2020 ◽  
Author(s):  
Zhongshi Zhang ◽  
Qing Yan ◽  
Ran Zhang ◽  
Florence Colleoni ◽  
Gilles Ramstein ◽  
...  
Keyword(s):  
North Pacific ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Climate Modelling ◽  
Mountain Glaciers ◽  
The Past ◽  
The North ◽  
Paleoclimate Records ◽  
Glacial Landforms ◽  
The North Pacific

<p>Did a Beringian ice sheet once exist? This question was hotly debated decades ago until compelling evidence for an ice-free Wrangel Island excluded the possibility of an ice sheet forming over NE Siberia-Beringia during the Last Glacial Maximum (LGM). Today, it is widely believed that during most Northern Hemisphere glaciations only the Laurentide-Eurasian ice sheets across North America and Northwest Eurasia became expansive, while Northeast Siberia-Beringia remained ice-sheet-free. However, recent recognition of glacial landforms and deposits on Northeast Siberia-Beringia and off the Siberian continental shelf has triggered a new round of debate.These local glacial features, though often interpreted as local activities of ice domes on continental shelves and mountain glaciers on continents,   could be explained as an ice sheet over NE Siberia-Beringia. Only based on the direct glacial evidence, the debate can not be resolved. Here, we combine climate and ice sheet modelling with well-dated paleoclimate records from the mid-to-high latitude North Pacific to readdress the debate. Our simulations show that the paleoclimate records are not reconcilable with the established concept of Laurentide-Eurasia-only ice sheets. On the contrary, a Beringian ice sheet over Northeast Siberia-Beringia causes feedbacks between atmosphere and ocean, the result of which well explains the climate records from around the North Pacific during the past four glacial-interglacial cycles. Our ice-climate modelling and synthesis of paleoclimate records from around the North Pacific argue that the Beringian ice sheet waxed and waned rapidly in the past four glacial-interglacial cycles and accounted for ~10-25 m ice-equivalent sea-level change during its peak glacials. The simulated Beringian ice sheet agrees reasonably with the direct glacial and climate evidence from Northeast Siberia-Beringia, and reconciles the paleoclimate records from around the North Pacific. With the Beringian ice sheet involved, the pattern of past NH ice sheet evolution is more complex than previously thought, in particular prior to the LGM.</p>

Rapid climate variability in the North Pacific Ocean during the past 95,000 years

Nature ◽  
1995 ◽  
Vol 377 (6547) ◽  
pp. 323-326 ◽  
Author(s):  
A. T. Kotilainen ◽  
N. J. Shackleton
Keyword(s):  
Pacific Ocean ◽  
Climate Variability ◽  
North Pacific ◽  
North Pacific Ocean ◽  
The Past ◽  
The North ◽  
The North Pacific

Late Pleistocene History of the North Pacific: Evidence from a Quantitative Study of Radiolaria in Core V21-173

1973 ◽  
Vol 3 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Harvey Maurice Sachs
Keyword(s):  
Late Pleistocene ◽  
North Pacific ◽  
Transfer Functions ◽  
Near Surface ◽  
The Past ◽  
The North ◽  
History Of ◽  
The North Pacific ◽  
Oceanographic Conditions ◽  
Radiolarian Assemblages

AbstractObjective quantitative estimates of paleo-oceanographic conditions in the North Pacific can be made by analyses of radiolarian assemblages. With appropriate computation, transfer functions developed in a study of surface sediments can be used to estimate oceanographic conditions in cores containing late Pleistocene radiolarian faunas. Analysis of core V21-173 indicates that conditions as warm as the Holocene were rare during the past 800,000 yr, and that the region experienced marked near-surface temperature drops correlative with Caribbean and continental records for the past 250,000 yr. A major world-wide warm event at about 400,000 yr is also indicated.

Sea Surface Temperature Changes in the Northeastern Pacific Ocean during the Past 20,000 Years and Their Relationship to Climate Change in Northwestern North America

1996 ◽  
Vol 46 (1) ◽  
pp. 48-61 ◽  
Author(s):  
Ann L. Sabin ◽  
Nicklas G. Pisias
Keyword(s):  
Pacific Ocean ◽  
North America ◽  
North Pacific ◽  
Sea Surface ◽  
The Past ◽  
The North ◽  
Northeastern Pacific ◽  
Northwestern North America ◽  
The North Pacific ◽  
Continental Climate

Modern ocean–atmosphere interactions in the northeastern Pacific Ocean have a significant effect on the climate of the west coast of North America. We present radiolarian microfossil-based temperature reconstructions for the eastern North Pacific spanning the past 20,000 yr to examine possible correlations and linkages between continental climate change and changes in sea surface temperature (SST) in the northeastern Pacific Ocean on millennial time scales. The reconstructions indicate that the regional pattern of ocean circulation off the west coast of North America was further south 15,000 cal yr B.P. than it is today, and reached its present location 13,000 cal yr B.P. The North Pacific Drift and Transition Zone were further south as a result of a more southerly North Pacific high pressure cell prior to 13,000 cal yr B.P. While two continental paleoclimate records from northwestern North America show regional differences, they also can be correlated to the SST changes. A coastal site at 48°N shows similar patterns in summer temperatures, as observed in offshore marine records of SSTs. However, an inland continental record seems to reflect more-regional-scale changes in sea surface conditions showing a thermal maximum centered at 10,000 cal yr B.P which is observed in the marine transect south of 42°N. We conclude, based on the pattern of oceanographic change as reflected in radiolarian assemblages, that changes in the past latitudinal position of the North Pacific Drift played a significant role in controlling continental climate immediately to its east, as it does in the present environment. We also conclude that during the past 20,000 yr much of the evolution of oceanographic change is related to the migration of the atmospheric pressure cells (the North Pacific high and Aleutian low) of the northeastern Pacific.

226Ra evidence for the ecosystem shift over the past 40 years in the North Pacific Subtropical Gyre

2007 ◽  
Vol 52 (6) ◽  
pp. 832-838 ◽  
Author(s):  
JunHong Yang ◽  
Min Chen ◽  
YuSheng Qiu ◽  
YanPing Li ◽  
Qiang Ma ◽  
...  
Keyword(s):  
North Pacific ◽  
Subtropical Gyre ◽  
North Pacific Subtropical Gyre ◽  
The Past ◽  
The North ◽  
Ecosystem Shift ◽  
The North Pacific

Dust production and deposition in Asia and the north Pacific Ocean over the past 12 Myr

2000 ◽  
Vol 178 (3-4) ◽  
pp. 397-413 ◽  
Author(s):  
Thomas Pettke ◽  
Alex N. Halliday ◽  
Chris M. Hall ◽  
David K. Rea
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Dust Production ◽  
The Past ◽  
The North ◽  
The North Pacific

scholarly journals Changes of Subtropical North Pacific Radiocarbon and Correlation with Climate Variability

Radiocarbon ◽  
2001 ◽  
Vol 43 (1) ◽  
pp. 15-25 ◽  
Author(s):  
Ellen R M Druffel ◽  
S Griffin ◽  
T P Guilderson ◽  
M Kashgarian ◽  
J Southon ◽  
...  
Keyword(s):  
Surface Waters ◽  
North Pacific ◽  
Physical Mechanism ◽  
Vertical Mixing ◽  
Past Century ◽  
The Past ◽  
The North ◽  
North Pacific Gyre ◽  
The North Pacific

We show that high-precision radiocarbon (Δ14C) measurements from annual bands of a Hawaiian surface coral decreased by 7‰ from AD 1893 to 1952. This decrease is coincident with the Suess Effect, which is mostly due to the dilution of natural levels of 14C by 14C-free fossil fuel CO2. This decrease is equal to that expected in surface waters of the subtropical gyres, and indicates that the surface waters of the North Pacific were in steady state with respect to long term mixing of CO2 during the past century. Correlation between Δ14C and North Pacific gyre sea surface temperatures indicates that vertical mixing local to Hawaii and the North Pacific gyre as a whole is the likely physical mechanism to result in variable Δ14C. Prior to 1920, this correlation starts to break down; this may be related to the non-correlation between biennial Δ14C values in corals from the southwest Pacific and El Niño events observed during this period as well.

Radiocarbon and Stable Isotope Evidence for Changes in Sediment Mixing in the North Pacific over the Past 30 kyr

Radiocarbon ◽  
2017 ◽  
Vol 60 (1) ◽  
pp. 113-135 ◽  
Author(s):  
Kassandra M Costa ◽  
Jerry F McManus ◽  
Robert F Anderson
Keyword(s):  
Stable Isotope ◽  
North Pacific ◽  
Planktonic Foraminifera ◽  
Water Environment ◽  
Mixing Depth ◽  
Deep Sea Sediment ◽  
The Past ◽  
The North ◽  
Sediment Mixing ◽  
The North Pacific

AbstractDeep-sea sediment mixing by bioturbation is ubiquitous on the seafloor, and it can be an important influence on the fidelity of paleoceanographic records. Bioturbation can be difficult to quantify, especially in the past, but diffusive models based on radioactive tracer profiles have provided a relatively successful approach. However, a singular, constant mixing regime is unlikely to prevail in a region where dynamic oceanographic changes in the bottom water environment are a consequence of paleoclimatic variability. In this study, foraminiferal stable isotopes, radiocarbon (14C) dating, and 230Th fluxes are utilized to understand the sediment mixing history in the easternmost region of the North Pacific. In the uppermost sediment, a 12,000-yr offset between planktonic foraminifera species N. incompta and G. bulloides is observed that coincides with age plateaus at 2000–2500 yr for N. incompta and 15,000–16,000 yr for G. bulloides despite coincident glacial-interglacial shifts in δ18O of benthic species. These age plateaus, particularly for G. bulloides, are a result of changing foraminiferal abundance related to assemblage shifts and carbonate preservation changes since the last glacial period, providing a window into the extent of mixing in the past. The 14C and stable isotope results can be simulated using an iterative model that couples these changes in foraminiferal abundance with variability in mixing depth over time. The best-fit model output suggests that the deepest, or most intense, mixing of the past 30,000 yr (30 kyr) may have occurred during the Holocene. Even though changes in mixing affect the 14C and δ18O of planktonic species that have dramatically varying abundance, substantial age control is nevertheless provided by δ18O measurements on the more consistently abundant benthic foraminifera Uvigerina, thus allowing the construction of a reliable chronology for these cores.

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