Shift in Pacific Sea Level Trends Will Affect the West Coast

<p>Coastal flooding worldwide causes the vast majority of natural disasters; for the UK costing &#163;2.2 billion/year. Fluvial and surge-tide extremes can occur synchronously resulting in combination flooding hazards in estuaries, intensifying the flood risk beyond fluvial-only or surge-only events. Worse, this flood risk has the potential to increase further in the future as the frequency and/or intensity of these drivers change, combined with projected sea-level rise. Yet, the sensitivity of contrasting estuaries to combination and compound flooding hazards at sub-daily scales &#8211; now and in the future &#8211; is unclear. Here, we investigate the dependence between fluvial and surge interactions at sub-daily scales for contrasting catchment and estuary types (Humber vs. Dyfi, UK), using 50+ years of data: 15-min fluvial flows and hourly sea levels. Additionally, we simulate intra-estuary (<50&#160;m resolution) sensitivities to combination flooding hazards based on: (1) realistic extreme events (worst-on-record); (2) realistic events with shifted timings of the drivers to maximise flooding; and (3) modified drivers representing projected climate change.</p><p>For well-documented flooding events, we show significant correlation between skew surge and peak fluvial flow, for the Dyfi (small catchment and estuary with a fast fluvial response on the west coast of Britain), with a higher dependence during autumn/winter months. In contrast, we show no dependence for the Humber (large catchment and estuary with a slow fluvial response on the east coast of Britain). Cross-correlation results, however, did show correlation with a time lag (~10 hours). For the Dyfi, flood extent was sensitive to the relative timing of the fluvial and surge-tide drivers. In contrast, the relative timing of these drivers did not affect flooding in the Humber. However, extreme fluvial flows in the Humber actually reduced water levels in the outer estuary, compared with a surge-only event. Projected future changes in these drivers by 2100 are likely to increase combination flooding hazards: sea-level rise scenarios predicted substantial and widespread flooding in both estuaries. However, similar increases in storm surge resulted in a greater seawater influx, altering the character of the flooding. Projected changes in fluvial volumes were the weakest driver of estuarine flooding. On the west coast of Britain containing many small/steep catchments, combination flooding hazards from fluvial and surges extremes occurring together is likely. Moreover, high-resolution data and hydrodynamic modelling are necessary to resolve the impact and inform flood mitigation methodology.</p>

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Pacific Sea Levels Rising Very Slowly and Not Accelerating

Quaestiones Geographicae ◽

10.2478/quageo-2019-0007 ◽

2019 ◽

Vol 38 (1) ◽

pp. 179-184 ◽

Cited By ~ 1

Author(s):

Albert Parker ◽

Clifford Ollier

Keyword(s):

Pacific Ocean ◽

Sea Level ◽

Relative Rate ◽

Tide Gauges ◽

Sea Levels ◽

The Past ◽

The Pacific ◽

The Pacific Ocean ◽

Long Term Trend

AbstractOver the past decades, detailed surveys of the Pacific Ocean atoll islands show no sign of drowning because of accelerated sea-level rise. Data reveal that no atoll lost land area, 88.6% of islands were either stable or increased in area, and only 11.4% of islands contracted. The Pacific Atolls are not being inundated because the sea level is rising much less than was thought. The average relative rate of rise and acceleration of the 29 long-term-trend (LTT) tide gauges of Japan, Oceania and West Coast of North America, are both negative, −0.02139 mm yr−1and −0.00007 mm yr−2respectively. Since the start of the 1900s, the sea levels of the Pacific Ocean have been remarkably stable.

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Coldspot of Decelerated Sea-Level Rise on the Pacific Coast of North America

Quaestiones Geographicae ◽

10.1515/quageo-2016-0024 ◽

2016 ◽

Vol 35 (3) ◽

pp. 31-37 ◽

Cited By ~ 7

Author(s):

Albert Parker

Keyword(s):

United States ◽

Sea Level Rise ◽

Sea Level ◽

San Francisco ◽

West Coast ◽

Average Rate ◽

The United States ◽

The West ◽

Sea Levels

Abstract We show here the presence of significant “coldspot” of sea level rise along the West Coast of the United States and Canada (including Alaska). The 30-years sea level for the area are mostly falling also at subsiding locations as San Francisco and Seattle where subsidence is responsible for a long term positive rate of rise. The 20 long term tide gauges of the area of length exceeding the 60-years length have a naïve average rate of rise −0.729 mm/year in the update 30-Apr-2015, down from −0.624 mm/year in the update 14-Feb-2014. Therefore, along the West Coast of the United States and Canada the sea levels are on average falling, and becoming more and more negative.

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Flora and Vegetation of Clipperton (La Passion) Atoll, North-Eastern Pacific Ocean: Three Centuries of Changes and Recent Plant Dynamics

Atoll Research Bulletin ◽

10.5479/si.0077-5630.623 ◽

2019 ◽

pp. 1-31

Author(s):

Xenia Jost ◽

Christian H. Jost ◽

Jean-Yves Meyer

Keyword(s):

Pacific Ocean ◽

Anthropogenic Activities ◽

Abiotic Factors ◽

Vascular Plant ◽

Plant Cover ◽

First Record ◽

Eastern Pacific ◽

Eastern Pacific Ocean ◽

The Past ◽

North Eastern

The terrestrial flora and vegetation of Clipperton (La Passion) atoll, a very remote and small (170 ha of land) French island located in the North-Eastern Pacific Ocean, at ca. 1,000 km west of the Mexican coast, have dramatically changed during the past three centuries. This paper, based on historical testimonies, previously published floristic studies, and an extensive plant inventory conducted during the “International Scientific Expedition PASSION 2015”, show that the atoll has experienced particularly active and rapid vegetation dynamics with alternating plant cover expansion and regression phases. Our results provide the first comprehensive assessment of vegetation cover and vascular plant species distribution based on georeferenced data and mapped with GIS software, as well as the first record of two newly established non-native weeds. The current composition and abundance of native and alien vascular plant communities (15 species including only 4 native taxa) appear to depend not only on abiotic factors (e.g. substrate and climatic events) but also on biotic interactions with animal communities (e.g. native seabirds and crabs). Anthropogenic activities and disturbances (e.g. coconut palm, pig, rat and weed introductions) that have occurred in the past 100 years have also played an important role in explaining the past and current floristic changes.

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Last interglacial sea-level proxies in the Korean Peninsula

10.5194/essd-2021-205 ◽

2021 ◽

Author(s):

Woo Hun Ryang ◽

Alexander R. Simms ◽

Hyun Ho Yoon ◽

Seung Soo Chun ◽

Gee Soo Kong

Keyword(s):

Sea Level ◽

West Coast ◽

Korean Peninsula ◽

East Coast ◽

Vertical Movement ◽

Last Interglacial ◽

The West ◽

Sea Levels ◽

Marine Terraces ◽

Data Points

Abstract. Like most of the world’s coastlines, the Korean Peninsula experienced higher-than-present sea levels during the Last Interglacial (LIG) otherwise known as Marine Isotope Stage (MIS) 5e. However, the expression of that highstand in sea levels differs across the eastern and western Korean Peninsula. The active east coast of the Korean Peninsula is characterized by broad uplifted marine terraces, while the stable west coast is characterized by tidal flats and rias. In this study, we used a standardized database template to review and extract the existing constraints on LIG sea levels along both the east and west coasts of the Korean Peninsula. A total of 62 LIG constraining data points were compiled including 34 sea-level indicators, 22 marine limiting records, and 6 terrestrial limiting records. The ages from these data points are based on 61 optically stimulated luminescence (OSL) measurements and 1 paleomagnetic-based age. Along the uplifted east coast, LIG sea-level indicators based on marine terraces are at elevations ranging from +9 to +32 m. The uplifted marine terraces are cut or otherwise deformed by faults developed under a compressional regime due to backarc closing of the East Sea since the early Pliocene. As a result, tectonic uplift likely contaminates the elevation of the east coast LIG shorelines. On the contrary, LIG sea-level constraints on the west coast of the Korean Peninsula are found at heights of between +2 and +5 m and include marine and terrestrial limiting records as well as true sea-level indicators. The LIG sea-level constraints along the west coast of the Korean Peninsula are likely uncontaminated by vertical movement or experienced minor subsidence during the Quaternary.

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Bowie Seamount. A Recently Active, Flat-topped Seamount in the Northeast Pacific Ocean

Canadian Journal of Earth Sciences ◽

10.1139/e71-064 ◽

1971 ◽

Vol 8 (6) ◽

pp. 676-687 ◽

Cited By ~ 15

Author(s):

R. H. Herzer

Keyword(s):

Pacific Ocean ◽

Shallow Water ◽

Sea Level ◽

Volcanic Activity ◽

West Coast ◽

Basaltic Magma ◽

The West ◽

Northeast Pacific ◽

Wave Erosion ◽

Northeast Pacific Ocean

Bowie Seamount, situated off the west coast of Canada at 53° 18′ N, 135° 39′ W, is a long northeast-trending, volcanic mountain comprising a series of intersecting ridges. These ridges may have grown from extrusions along intersecting fractures in the oceanic crust. Two terraces form the flattened summit of the volcano at approximate depths of 80 and 235 m. These are thought to be remnants of platforms produced by combined shallow-water vulcanism and wave erosion during Pleistocene and Recent times when sea level was lower than it is today. The last episode of volcanic activity on the summit occurred after the formation of the upper terrace which is probably no more than 18 000 years old. Samples dredged from the upper half of the volcano include: pillow fragments, fragments of non-pillowed flows, pillow breccias, bombs, tuffs, ash, and unsorted tephra. The rocks are mainly alkali olivine basalts, accompanied by a few intermediate rocks which are believed to have been derived by differentiation of the basaltic magma.

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