Vandstanden ved Tuvalu...

Og bekymringen for de små øsamfund kan nok være berettiget, men ikke på grund af havstigninger....
På Tuvalu er der ikke observeret nogen stigning over de seneste 16 år.

If the depression of the 1998 cyclone is ignored, there was no change is sea level at Tuvalu between 1994 and 2009: 14 years. The recent slight fall would probably be related to the recent earthquake.

Executive Summary

A SEAFRAME gauge was installed in Funafuti, Tuvalu, in March 1993. It records sea level, air and water temperature, atmospheric pressure, wind speed and direction. It is one of an array designed to monitor changes in sea level and climate in the Pacific.

This report summarises the findings to date, and places them in a regional and historical context.

The sea level trend to date is +5.1 mm/year but the magnitude of the trend continues to vary widely from month to month as the data set grows. Accounting for the precise levelling results and inverted barometric pressure effect, the trend is +4.7 mm/year. A nearby gauge, with a longer record but less precision and datum control, shows a trend of +0.9 mm/year.

Variations in monthly mean sea level, air and water temperatures are dominated by seasonal cycles and were affected by the 1997/1998 El Niño.

The seasonal sea level cycle shows a peak early in the year, a time when Funafuti frequently experiences flooding.

Since installation, at least two cyclones have passed through Tuvalu, but only one, Tropical Cyclone Gavin, was registered as extreme low pressure on the SEAFRAME at Funafuti.

The SEAFRAME at Funafuti, Tuvalu has recorded 16 separate tsunami events since its installation. The largest tsunami signal of trough-to-peak height 8 cm was recorded after an earthquake of magnitude Mw8.3 that occurred near Kuril Islands on 15th November 2006.

kfl skrev:
Opdatering af og uddybning af mit indlæg om Tuvalu:

Opdateret Tuvalu info

kfl skrev:
Det er utroligt, at du dels kan link til gamle artikler og dels til jubelidioten Niels Axel Mörner. Kan du ikke dbedre ?

Det er korrekt af kappekonvektion virker på længere tidsskala (>100000 år), men man kunne sagtens forestille sig at fx vulkanudbrud kunne forårsage hurtige ændringer. Sådanne ændringer ville også forventes på atoller, som jo netop ligger ovenpå lokale magmatiske-anomalier. Når man lægger sedimentation, som følge af bølgeaktivitet, oven i så giver det på ingen måde mening at bruge havniveau på atoller som en proxy.

Derfor er passive kontinentale marginer at foretrækker, men igen skal man så huske på at der sker variationer som følge af isostatisk landhævning i tidligere glaciale områder (som fx Danmark).

Studiet i Science viser dog at selv ved såkaldte passive kontinentale marginer sker der ændringer som følge af dyb kappekonvektion

kfl skrev:
Jeg har ud fra PSMSL's tabel med GIA udarbejdet en tabel med GIA mm/år og rate mm/år for Bredde 0 - 20S og Længde 140V-280V svarende til den centrale del af Stillehavet.

Denne tabel viser at området synker lidt, medens vandstand vokser på de flest tidevandstationer.

Igen er spørgsmålet hvorfor ?

kfl skrev:
Nils Axel Mörner er ikke annerkendt som forsker, men derimod for det modsatte.

Det kan du åbenbart ikke fatte!

kristofferszilas skrev:
Der er for nyligt publiceret et review om dette emne:

Stammer, D., Cazenave, A., Ponte, R. M., & Tamisiea, M. E. (2013). Causes for Contemporary Regional Sea Level Changes. Annual Review of Marine Science, 5, 21-46.

Ahmed Shaig: Climate Change Vulnerability and Adaptation Assessment of the Maldives Land and Beaches.

3.2. Worst Case Scenario
If the predicted climate change becomes a reality with the maximum changes while sea level continues to rise as predicted and the geological forces fail to adapt to sea level rise, Maldives most likely would cease to exist as a nation within the next 150-200 years. Frequent inundations of land and damage to island hydrology could make the islands virtually uninhabitable.

...efter korrektion for lufttryk og verticale bevægelser af tidevandstationen

»En større gruppe af geofysikere har undersøgt verdens havniveau 4.000 år tilbage i tiden og har fundet en effekt på stort set nul på havet ved Maldiverne. Havet her bevæger sig ikke mange millimeter om året, og hvis det bevæger sig, er det nedad,« mener Nils Finn Munch-Petersen.

Coral reef islands across the world could naturally adapt to survive the impact of rising sea levels, according to new research.

The increased flooding caused by the changing global climate has been predicted to render such communities — where sandy or gravel islands sit on top of coral reef platforms — uninhabitable within decades.

However, an international study led by the University of Plymouth (UK) suggests that perceived fate is far from a foregone conclusion.

The research, published in Science Advances, for the first time uses numerical modeling of island morphology alongside physical model experiments to simulate how reef islands — which provide the only habitable land in atoll nations — can respond when sea levels rise.

The results show that islands composed of gravel material can evolve in the face of overtopping waves, with sediment from the beach face being transferred to the island's surface.

Når havet stiger, oversvømmes en atol oftere. Ved oversvømmelser skylles der nyt sand mv. op på toppen af atollen, så den vokser i højden, i takt med havstigninger. Når havet falder i niveau blæser vinden toppen af atollen, så den mindskes i højden. Derfor er atoller altid nogle få meter høje over havets overflade, uanset havniveau.

Jeg faldt så over flg. fra National Geographic 13. februar 2015:

Will Pacific Island Nations Disappear as Seas Rise? Maybe Not

They found that reef islands change shape and move around in response to shifting sediments, and that many of them are growing in size, not shrinking, as sea level inches upward. The implication is that many islands—especially less developed ones with few permanent structures—may cope with rising seas well into the next century.

Nå, forskerne fandt så langt om længe ud af, hvad Darwin fortalte os for snart 200 år siden!?

Lidt historie her: Climate Experts Catching Up With 200 Year Old Science

Maldiverne er atoller, ikke klippeøer. Alle atoller i verden rager maksimum få meter op over havniveauet, og det selvom havet er steget ca. 120 meter siden sidste glaciale periode. Hvordan kan det være? Det er fordi atoller vokser og bliver lavere i takt med havniveauet.

Når havet stiger, oversvømmes en atol oftere. Ved oversvømmelser skylles der nyt sand mv. op på toppen af atollen, så den vokser i højden, i takt med havstigninger. Når havet falder i niveau blæser vinden toppen af atollen, så den mindskes i højden.

Forklaringen blev første gang givet af Charles Darwin.

Så lad nu være med at gentage det nonsens med, at atoller forsvinder i havet, når havet stiger. Det er latterlige påstande, og derfor ikke værd at gentage. Mennesker bliver ikke tvunget til at forlade hverken Maldiverne, Tuvalu eller de andre eksempler, man hiver frem.

Og så falder snakken på ø-staten Tuvalu, som man mener drukner i havstigninger. Det er et sygdomstegn for Niels Bohr Institutet, at en professor hopper med på dette nonsens. Tuvalu består af atoller, som vokser i højden, når havet stiger, og som bliver lavere, når havet falder. Dette blev beskrevet så langt tilbage som af Charles Darwin. Se f.eks. dette blogindlæg af Tony Heller med referencer:

Climate Experts Catching Up With 200 Year Old Science

Tony Heller skrev:
Climate experts are the ultimate anti-science buffoons, having to re-discover 200 year old science before they begin to understand how stupid they are.

kfl skrev:
Vandstanden ved Maldiverne - opdateret april 2013

Der er kommer ny forskning vedr. overlevelse af de lavtliggende koraløer som følge af vandstandstigningerne i verdenshavene:

Islands Might Not Actually "Drown" As Sea Levels Rise – Here's Why

Coral reef islands across the world could naturally adapt to survive the impact of rising sea levels, according to new research.

The increased flooding caused by the changing global climate has been predicted to render such communities — where sandy or gravel islands sit on top of coral reef platforms — uninhabitable within decades.

However, an international study led by the University of Plymouth (UK) suggests that perceived fate is far from a foregone conclusion.

The research, published in Science Advances, for the first time uses numerical modeling of island morphology alongside physical model experiments to simulate how reef islands — which provide the only habitable land in atoll nations — can respond when sea levels rise.

The results show that islands composed of gravel material can evolve in the face of overtopping waves, with sediment from the beach face being transferred to the island's surface.

Jeg skal have studeret artikel i detaljer.

Tuvalu in the Pacific is often said already to be in the flooding mode. The tide-gauge record (Fig 7) for the last 25 years does not show any rise, however. The truth seems to be that a Japanese pineapple industry had subtracted too much freshwater by that forcing saltwater to invade the subsurface.

...according to a growing body of evidence amassed by New Zealand coastal geomorphologist Paul Kench, of the University of Auckland's School of Environment, and colleagues in Australia and Fiji, who have been studying how reef islands in the Pacific and Indian Oceans respond to rising sea levels.

They found that reef islands change shape and move around in response to shifting sediments, and that many of them are growing in size, not shrinking, as sea level inches upward.

Their analysis, which now extends to more than 600 coral reef islands in the Pacific and Indian Oceans, indicates that about 80 percent of the islands have remained stable or increased in size (roughly 40 percent in each category). Only 20 percent have shown the net reduction that's widely assumed to be a typical island's fate when sea level rises.

Some islands grew by as much as 14 acres (5.6 hectares) in a single decade, and Tuvalu's main atoll, Funafuti—33 islands distributed around the rim of a large lagoon—has gained 75 acres (32 hectares) of land during the past 115 years.

Besides the damage inflicted by sea-level rise itself—coastal erosion, surface flooding, and saltwater intrusion into soil and groundwater—they will suffer from increasingly frequent and severe weather extremes (droughts and cyclones) and die-offs of their coral reefs through ocean warming and acidification, leading to potential collapse of marine ecosystems that provide food and livelihoods for island dwellers.

But from what I could see, in 2004 it was business as usual in Funafuti.

In November 2014, armed with Kench's findings, I returned to Tuvalu to see whether anything had changed. The first thing I noticed was that Fongafale was even more crowded than before. According to the 2012 census, Fongafale's population had increased by 1,500 since my earlier visit, to more than 6,000. So much for the shutting down of a nation.

On atoll islands, fresh groundwater occurs as a buoyant lens-shaped body surrounded by saltwater derived from the sea, forming the main freshwater source for many island communities. A review of the state of knowledge of atoll island groundwater is overdue given their susceptibility to adverse impacts, and the task to address water access and sanitation issues within the United Nations' Sustainable Development Goals framework before the year 2030. In this article, we review available literature to summarise the key processes, investigation techniques and management approaches of atoll island groundwater systems. Over fifty years of investigation has led to important advancements in the understanding of atoll hydrogeology, but a paucity of hydrogeological data persists on all but a small number of atoll islands. We find that the combined effects of buoyancy forces, complex geology, tides, episodic ocean events, strong climatic variability and human impacts create highly dynamic fresh groundwater lenses. Methods used to quantify freshwater availability range from simple empirical relationships to three-dimensional density-dependent models. Generic atoll island numerical models have proven popular in trying to unravel the individual factors controlling fresh groundwater lens behaviour. Major challenges face the inhabitants and custodians of atoll island aquifers, with rising anthropogenic stresses compounded by the threats of climate variability and change, sea-level rise, and some atolls already extracting freshwater at or above sustainability limits . We find that the study of atoll groundwater systems remains a critical area for further research effort to address persistent knowledge gaps, which lead to high uncertainties in water security issues for both island residents and surrounding environs.

kfl skrev:
Kære Ulrike

Du har ikke sat dig ind i, hvad Nils Axel Mörner siger og skriver. Prøv at undersøge dette og kom så tilbage. Du vil så nå frem til, at han er en fusker og bedrager på linje med mange andre klimaskeptikere, der bl.a. er samlet i Klimarealisterne og på Klimadebat.

Det generer mig, at man sjælden møder kvalificerede klimaskeptikere, der kan deres kram/fag og ansporer til alternative analyser og synspunkter. En af dem er Judit Curry, som er dygtig og vidende, men svømmer i olie og kulpenge. Nogle gange går hun for langt ud af tangenten.

En diskussion med klimaskeptikeren ender altid i konspirations-teorier og person angreb. jfr Frank Lanser, Helios, Kosmos, John Niclasen, Jens Morten Hansen,.....,jf "Hokus pokus katte gør æg"

Du er en undtagelse, idet du altid holder en god tone og forsøger at forstå tingene.