scholarly journals Last Ice Age Millennial Scale Climate Changes Recorded in Huon Peninsula Corals

Radiocarbon ◽  
2000 ◽  
Vol 42 (3) ◽  
pp. 383-401 ◽  
Author(s):  
Yusuke Yokoyama ◽  
Tezer M Esat ◽  
Kurt Lambeck ◽  
L Keith Fifield
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
North Atlantic ◽  
Thermohaline Circulation ◽  
Sample Selection ◽  
Ice Age ◽  
Base Line ◽  
The North ◽  
Sequence Of Events ◽  
The North Atlantic

Uranium series and radiocarbon ages were measured in corals from the uplifted coral terraces of Huon Peninsula (HP), Papua New Guinea, to provide a calibration for the 14C time scale beyond 30 ka (kilo annum). Improved analytical procedures, and quantitative criteria for sample selection, helped discriminate diagenetically altered samples. The base-line of the calibration curve follows the trend of increasing divergence from calendar ages, as established by previous studies. Superimposed on this trend, four well-defined peaks of excess atmospheric radiocarbon were found ranging in magnitude from 100% to 700%, relative to current levels. They are related to episodes of sea-level rise and reef growth at HP. These peaks appear to be synchronous with Heinrich Events and concentrations of ice-rafted debris found in North Atlantic deep-sea cores. Relative timing of sea-level rise and atmospheric 14C excess imply the following sequence of events: An initial sea-level high is followed by a large increase in atmospheric 14C as the sea-level subsides. Over about 1800 years, the atmospheric radiocarbon drops to below present ambient levels. This cycle bears a close resemblance to ice-calving episodes of Dansgaard-Oeschger and Bond cycles and the slow-down or complete interruption of the North Atlantic thermohaline circulation. The increases in the atmospheric 14C levels are attributed to the cessation of the North Atlantic circulation.

Cuban stalagmite suggests relationship between Caribbean precipitation and the Atlantic Multidecadal Oscillation during the past 1.3 ka

The Holocene ◽  
2012 ◽  
Vol 22 (12) ◽  
pp. 1405-1412 ◽  
Author(s):  
Claudia Fensterer ◽  
Denis Scholz ◽  
Dirk Hoffmann ◽  
Christoph Spötl ◽  
Jesús M Pajón ◽  
...  
Keyword(s):  
North Atlantic ◽  
Little Ice Age ◽  
Rainfall Intensity ◽  
Thermohaline Circulation ◽  
Atlantic Multidecadal Oscillation ◽  
Ice Age ◽  
The Past ◽  
The North ◽  
Southward Shift ◽  
The North Atlantic

Here we present the first high-resolution δ18O record of a stalagmite from western Cuba. The record reflects precipitation variability in the northwestern Caribbean during the last 1.3 ka and exhibits a correlation to the Atlantic Multidecadal Oscillation (AMO). This suggests a relationship between Caribbean rainfall intensity and North Atlantic sea-surface temperature (SST) anomalies. A potential mechanism for this relationship may be the strength of the Thermohaline Circulation (THC). For a weaker THC, lower SSTs in the North Atlantic possibly lead to a southward shift of the Intertropical Convergence Zone and drier conditions in Cuba. Thus, this Cuban stalagmite records drier conditions during cold phases in the North Atlantic such as the ‘Little Ice Age’. This study contributes to the understanding of teleconnections between North Atlantic SSTs and northern Caribbean climate variability during the past 1.3 ka.

Rapid sea-level rise in the North Atlantic Ocean since the first half of the nineteenth century

The Holocene ◽  
2006 ◽  
Vol 16 (7) ◽  
pp. 949-965 ◽  
Author(s):  
W. Roland Gehrels ◽  
William A. Marshall ◽  
Maria J. Gehrels ◽  
Gudrún Larsen ◽  
Jason R. Kirby ◽  
...  
Keyword(s):  
Nineteenth Century ◽  
Atlantic Ocean ◽  
Sea Level Rise ◽  
Sea Level ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
The North ◽  
The North Atlantic

scholarly journals Spatial Variability of Sea Level Rise in Twenty-First Century Projections

2010 ◽  
Vol 23 (17) ◽  
pp. 4585-4607 ◽  
Author(s):  
Jianjun Yin ◽  
Stephen M. Griffies ◽  
Ronald J. Stouffer
Keyword(s):  
North America ◽  
Southern Ocean ◽  
Sea Level Rise ◽  
Sea Level ◽  
North Atlantic ◽  
North Pacific ◽  
First Century ◽  
The North ◽  
The North Atlantic ◽  
Twenty First Century

Abstract A set of state-of-the-science climate models are used to investigate global sea level rise (SLR) patterns induced by ocean dynamics in twenty-first-century climate projections. The identified robust features include bipolar and bihemisphere seesaws in the basin-wide SLR, dipole patterns in the North Atlantic and North Pacific, and a beltlike pattern in the Southern Ocean. The physical and dynamical mechanisms that cause these patterns are investigated in detail using version 2.1 of the Geophysical Fluid Dynamics Laboratory (GFDL) Coupled Model (CM2.1). Under the Intergovernmental Panel on Climate Change’s (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario, the steric sea level changes relative to the global mean (the local part) in different ocean basins are attributed to differential heating and salinity changes of various ocean layers and associated physical processes. As a result of these changes, water tends to move from the ocean interior to continental shelves. In the North Atlantic, sea level rises north of the Gulf Stream but falls to the south. The dipole pattern is induced by a weakening of the meridional overturning circulation. This weakening leads to a local steric SLR east of North America, which drives more waters toward the shelf, directly impacting northeastern North America. An opposite dipole occurs in the North Pacific. The dynamic SLR east of Japan is linked to a strong steric effect in the upper ocean and a poleward expansion of the subtropical gyre. In the Southern Ocean, the beltlike pattern is dominated by the baroclinic process during the twenty-first century, while the barotropic response of sea level to wind stress anomalies is significantly delayed.

Beyond Hurricane Sandy: What Might the Future Hold for Tropical Cyclones in the North Atlantic?

2014 ◽  
Vol 01 (01) ◽  
pp. 1450007 ◽  
Author(s):  
Radley M. Horton ◽  
Jiping Liu
Keyword(s):  
Tropical Cyclone ◽  
Sea Level Rise ◽  
Sea Level ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Hurricane Sandy ◽  
Economic Losses ◽  
The North ◽  
The Future ◽  
The North Atlantic

Coastal communities are beginning to understand that sea level rise is projected to dramatically increase the frequency of coastal flooding. However, deep uncertainty remains about how tropical cyclones may change in the future. The North Atlantic has historically been responsible for the majority of global tropical cyclone economic losses, with Hurricane Sandy's approximately USD$70 billion price tag providing a recent example. The North Atlantic has experienced an upward trend in both total tropical cyclones (maximum sustained winds > 18 m/s) and major hurricanes (maximum sustained winds > 50 m/s) in recent decades. While it remains unclear how much of this trend is related to anthropogenic warming, and how tropical cyclone risk may change in the future, the balance of evidence suggests that the strongest hurricanes may become more frequent and intense in the future, and that rainfall associated with tropical cyclones may increase as well. These projections, along with sea level rise and demographic trends, suggest vulnerability to tropical cyclones will increase in the future, thus requiring major coastal adaptation initiatives.

Redating the Global Abrupt Sea-Level Rise during Meltwater Pulse-1A and Implications for Global Ice Mass Loss

2021 ◽  
Author(s):  
Christian Turney ◽  
Nicholas Golledge ◽  
Paula Reimer ◽  
Tim Heaton ◽  
Alan Hogg ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
North Atlantic ◽  
Ice Sheets ◽  
Ice Sheet ◽  
The North ◽  
The North Atlantic ◽  
Global Sea Level ◽  
Age Range ◽  
Ice Sheet Modelling

<div><span>Model-based projections of ice-sheet thresholds and global sea-level rise are severely constrained by </span><span>instrumental observations being only decadal to century-long. As we improve our understanding of these processes, projections just a few years old are now considered conservative, raising concerns about our ability to successfully plan for abrupt future change. </span><span>Past periods of abrupt and extreme warming offer ‘process analogues’ that can provide new insights into the future rate of response of polar ice sheets to warming of the Earth system. The Last Termination </span><span>(20,000-10,000 years ago or 20-10 ka BP) </span>in the North Atlantic region was characterised by a series of abrupt climatic changes including rapid warming at 14.7 ka BP (the start of the “Bølling”, or GI-1 in the Greenland ice-core isotope stratigraphy) which was accompanied by an Antarctic Cold Reversal (ACR) in the south. Potentially important, during the onset of GI-1, warming persisted in the south for some 256±133 calendar years before the ACR, providing a period of time during which both polar regions experienced increasing temperatures. Sometime around the onset of GI-1 and the ACR, Meltwater Pulse 1A (MWP-1A) formed an abrupt sea level rise of ~15 metres, and was coincident with a period of enhanced iceberg flux in the Southern Ocean. It seems likely the majority of the sea level rise came from the Northern Hemisphere – up to 5-6 metres from the Laurentide Ice Sheet – though the timing remains uncertain. The contribution of Antarctic Ice Sheets (AIS) to global mean sea level (GMSL) rise during MWP-1A range from ‘high-end’ scenarios (>10 m contributing over half of the total GMSL rise), to ‘low-end’ (scenarios with little to no contribution). Here we report the results of a multidisciplinary study, with refined age and Antarctic ice-sheet modelling of the MWP-1A sea-level rise. With the recently released international radiocarbon calibration curve (IntCal20), our Bayesian age modelling of terrestrial ages from flooded mangrove swamps suggests global <span>sea level rose across a mean age range of 14.58 ka BP to 14.42 ka BP, with a mean rate of sea-level rise of 0.94 metres per decade (14.97 metres over 160 years). Because the calibrated age range at 95% confidence overlaps in this age model, it is possible the 15 metre rise during MWP1A could have taken place essentially instantaneously. Even the most conservative age modelling we have undertaken indicates an extraordinary rapid rate of sea-level rise; two orders of magnitude larger than the mean rate of global sea level rise since 1993 (0.03±0.003 metres per decade). Our ice-sheet modelling suggests a substantial and rapid loss of Antarctic ice mass (mostly from the Weddell Sea Embayment and the Antarctic Peninsula), synchronous with warming and ice loss in the North Atlantic. The drivers and mechanisms of the observed near-synchronous interhemispheric changes will be discussed, with implications for the future.</span></div>

7000 years of paleostorm activity in the NW Mediterranean Sea in response to Holocene climate events

2012 ◽  
Vol 77 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Pierre Sabatier ◽  
Laurent Dezileau ◽  
Christophe Colin ◽  
Louis Briqueu ◽  
Frédéric Bouchette ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
North Atlantic ◽  
Clay Mineralogy ◽  
Mediterranean Coast ◽  
Ice Age ◽  
Storm Activity ◽  
The North ◽  
Nw Mediterranean ◽  
The North Atlantic ◽  
Nw Mediterranean Sea

A high-resolution record of paleostorm events along the French Mediterranean coast over the past 7000 years was established from a lagoonal sediment core in the Gulf of Lions. Integrating grain size, faunal analysis, clay mineralogy and geochemistry data with a chronology derived from radiocarbon dating, we recorded seven periods of increased storm activity at 6300–6100, 5650–5400, 4400–4050, 3650–3200, 2800–2600, 1950–1400 and 400–50 cal yr BP (in the Little Ice Age). In contrast, our results show that the Medieval Climate Anomaly (1150–650 cal yr BP) was characterised by low storm activity.The evidence for high storm activity in the NW Mediterranean Sea is in agreement with the changes in coastal hydrodynamics observed over the Eastern North Atlantic and seems to correspond to Holocene cooling in the North Atlantic. Periods of low SSTs there may have led to a stronger meridional temperature gradient and a southward migration of the westerlies. We hypothesise that the increase in storm activity during Holocene cold events over the North Atlantic and Mediterranean regions was probably due to an increase in the thermal gradient that led to an enhanced lower tropospheric baroclinicity over a large Central Atlantic-European domain.

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