The 100 Metre Line: 2009/12

2009/12/03

Major sea level rise likely as Antarctic ice melts - 1.4 metres by 2100

New studies find higher rates likely:

http://news.bbc.co.uk/2/hi/science/nature/8387137.stm

Quotes:

"Sea levels are likely to rise by about 1.4m (4ft 6in) globally by 2100 as polar ice melts, according to a major review of climate change in Antarctica.

"Conducted by the Scientific Committee on Antarctic Research (SCAR), it says that warming seas are accelerating melting in the west of the continent.

and from:

Rising sea levels: A tale of two cities

http://news.bbc.co.uk/2/hi/science/nature/8369236.stm

"Off the Netherlands, for example, sea levels rose by some 20cm in the last 100 years. But the country's national Delta Commission predicts they will increase by up to 1.3m by 2100 and by as much as 4m by 2200.

---

Thats not a bad fit with the curve...

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Welcome

There are many possible representations of the impact of climate change on humanity, but perhaps the most difficult to grapple with yet the easiest to show is that of sea level rise.

Have a look at the maps herein, and say: "This is how high the sea is going to get; how will that affect you and your grandchildren?"

We have the wonderful opportunity to pull together to save our planet from dangerous climate change by reducing CO2 levels, while at the same time we can be preparing prudently for what ever future nature may hand us.

Kind regards, Nigel and grandsons.

To view or post comments, click the word 'COMMENTS' below each blog. Write you comments in the box, then in 'Comment as:' select Name/URL to enter your name, or Anonymous if your wish. Then click either 'Post Comment' or 'Preview'.

Comment Moderation is OFF, so if you post it will appear. If its inappropriate or irrelevant it may be removed.

If you have posted merely to dump a link to your site into another blog it will be removed, so don't waste your time, or mine.

How to get your post published.

The purpose of this blog is to present information on the issue of sea level rise and The 100 Metre Line concept. We want to to share action stories on how The 100 Metre Line idea is being deployed around the world.

The 100 Metre Line is a unifying concept for deployment around the world to support ongoing action and information distribution.

If you have a story to tell about your 100 Metre Line actions in your neighbourhood let us know and we will publish it here to inform and inspire others.

This blog is not intended to be a forum for discussing the pros and cons of the climate change issue.

The blog is moderated. Be patient. Be nice. Thanks. N.

What to do.

Measure up from the high tide level to strategic locations that will be inundated by rising sea levels. Use Google Earth for height if thats more convenient.

Using that level difference read off the Date from the Date and Sea Level table.

Get a nice white banner. I suggest about a standard sheet size of 2.4m wide by 1.2m high, (8' x 4' for our imperial friends).

Paint a 100mm wide (4") black strip across it.

Above the line in big black letters write: HIGH TIDE

Under the line in big black letters write: 2100 AD (or what ever the year is from the table for that rise.)

Keep to that format so the sign becomes universally recognisable. Keep it simple black on white. Your brother's bed sheet would do!

Get permission from the land or property owner and occupier to erect the sign.

Erect the sign.

Repeat all the way from the coast up the hill to the 80 metre mark.

Mark the level outside iconic buildings and places.

If needed simply stand on-street out of the public road and footpath and hold up the sign for passer's by to view.

Be safe. Don't damage any property or annoy anybody.

Using Google Earth for elevation:-

The Christiansborg square in Copenhagen will be submerged about year 2100 AD.

Hamburg - mostly under water 2200 AD.

Berlin virtually all gone 2600 AD.

Greenpeace International HQ, Amsterdam. 2100 AD.

Arc de Triomphe, Paris. 2700 AD.

The gates of Buckingham Palace are gone about year 2300 AD.

The White House Lawn is under water about year 2200 AD.

The Sydney Opera House is gone about year 2100 AD.

Mildura 2600 AD.

Parliament House, Wellington New Zealand. 2300 AD.

Penrith, Sydney 2600 AD.

Perth International Airport gone 2350 AD.

Singapore mostly gone 2300 AD.

Tokyo gutted 2500 AD.

New York gutted 2150, gone 2500 AD.

Central Beijing 2700 AD.

Dhaka 2250 AD.

Amadabad 2700 AD.

Karachi 2700 AD.

Baghdad 2600 AD.

Cairo 2350 AD.

Vatican City 2400 AD.

Central Lisborn 2500 AD.

Dublin 2500 AD.

Montreal 2500 AD.

Buenos Aires 2350 AD.

Cape Town 2350 AD

The road on the way to my home is gone by 2100 AD.

The State Highway around New Zealand is cut in many places by 2100 AD.

Take the signs down when CO2 gets below 350ppm.

FAQ - What's it all about?

1 The 100 Metre Line is a blog enabling people to consider and present the issues raised by the sea level rise component of climate change.

2 Why The 100 Metre Line? See the section at the bottom of this page.

3 What is the scientific basis for The 100 Metre Line? See the section at the bottom of this page.

4 So? OK. The 100 Metre Line is intended to give you the tools you need to present a major signal about our climate-changed future in a way that can be understood by ordinary people, and by policy-makers and elected representatives.

5 The main things you will find here are:

A. Information about how high the ocean will be by various dates in the future.

B. Suggestions about how you can present this information to the public.

C. An action plan suggesting some ways you can use The 100 Metre Line to support your 350.com activities.

D. A moderated blog where I present postings by people and organisations about how they are using The 100 Metre Line for their 350 activities and for other landmark presentations of the sea level rise and climate change issue.

6 It is difficult to show the effect of climate changes such as temperature rise, increased flooding or desertification at specific locations and times. We can paint word-pictures of such futures, but these descriptions do not resonate in hearts and minds of people to the extent that they may consider a need for action to address the issues so described.

I believe that the most effective, tangible and ‘real’ indicator of the changes that are approaching is an indication of the date and level the ocean will reach among the communities we live in. The erection of temporary or permanent markers of likely sea levels at specific iconic locations nationally and at strategic sites around the world will provide citizens with a clear indication that change is coming, and will send an unambiguous message to policy makers and elected representatives about the need to attend to these most urgent matters.

If you live below the 100 metre line, then make sure you have a High Tide maker on your front lawn. It may not help your property values, but it will make the neighbours think!!!!

7. Is it 'accurate'? Nope. This is a best-guess at future sea levels. The only hard facts we have are that the sea is rising. It will rise by more than 2 metres and quite conceivably by up to 5 metres by 2100. Sometime later (a thousand years or so) all the ice will be melted and the coasts of the world will start to settle down again. I've just joined the dots of a sine-like curve connecting those points. Prove me wrong!!!

8. Who am I? Nigel Williams. Auckland. New Zealand. An ordinary citizen.

Dates and corresponding Sea Levels

Date Sea Level Rise above historic mean sea level. (metres)

Updated to take account of recent predictions of increased warming from 2 to 5 degrees Celsius by 2100. Thus my prudent 2100 prediction is shown as +5 metres sea level rise. (NJW 20090714)

Date (Year AD) SLR (m)
1800 0
1900 0.02
2000 0.2
2025 0.5
2050 1.4
2075 2.9
2100 5.0
2200 15.0
2300 27.0
2400 40.0
2500 52.0
2600 59.5
2700 63.5
2800 66.5
2900 68.5
3000 70.0
3100 71.0
4000 75.0
5000 77.5
7000 80.0

Interpolate levels and dates as required.

There are only three data points extant: About 140mm to 200mm rise last century, now about 5.0 m (previously about 2 m) by 2100, then melt-out over the next couple of thousand years. The curve is a best-fit S curve thru those points, allowing for the long 'tail' as the highest and most remote ice cooks off, and thermal expansion of the oceans reaches equilibrium.

The sharp upturn from today is driven by the 0.2m to 5.0m used for the coming century. It is now expected that we will get 5.2 C warming by 2100 thus in my view it is a sensible precautionary rate to adopt. The resulting melt-rate at 2100 is unlikely to suddenly ease off, hence the curve has a fairly constant slope over the next few hundred years.

See also:
http://the100metreline.blogspot.com/2009/07/five-degrees-and-five-metres-by-2100.html

The Scientific Basis

This is a very brief overview of the state of knowledge relating to climate change and hence to the expected degree of sea level rise.

You must do your own study and arrive at your own conclusions so that you can defend your stance to those who simply do not understand, and to those who would like to learn more. We cannot turn around those who do not want to hear or believe – that is for their conscience. We must work with the people in the middle ground and present them with clear and honest information that they in turn can use to make personal and political decisions about the futures of their own families.

The IPCC and many peer-reviewed papers have been and continue to give us clear warnings that we must reduce the forcings on the global climate or we will reach a point where change will become dangerous for all humanity.

The climate changes most evident to scientific observers are increases in greenhouse gases and the consequent increase in the average surface temperature of the globe. A direct effect of these temperature increases is already evidenced in increased rate of melt of snow fields, glaciers and ice sheets around the world. The scientific literature tells us that unless we reduce global temperatures this melting will continue until the ice is gone.

June 2008.

Global Warming Twenty Years Later: Tipping Points Near: James Hansen

http://www.columbia.edu/~jeh1/2008/TwentyYearsLater_20080623.pdf

“…if emissions follow a business-as-usual scenario, sea level rise of at least two meters is likely this century. Hundreds of millions of people would become refugees. No stable shoreline would be reestablished in any time frame that humanity can conceive.”

“…The disturbing conclusion, documented in a paper2 I have written with several of the world’s leading climate experts, is that the safe level of atmospheric carbon dioxide is no more than 350 ppm (parts per million) and it may be less. Carbon dioxide amount is already 385 ppm and rising about 2 ppm per year. Stunning corollary: the oft-stated goal to keep global warming less than two degrees Celsius (3.6 degrees Fahrenheit) is a recipe for global disaster, not salvation.”

And in May 2009:

"The new projections, published this month in the American Meteorological Society's Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius by 2100, with a 90% probability range of 3.5 to 7.4 degrees. This can be compared to a median projected increase in the 2003 study of just 2.4 degrees. "

http://globalchange.mit.edu/news/news-item.php?id=76

So: In May 2009 MIT scientists running a sophisticated and well-respected climate model tell us that there is a median probability that the Earth will be 5.2 degrees Celsius warmer by 2100.

And: In 2008 Hansen stated that even 2 degrees Celsius of global warming ‘…is a recipe for global disaster…’, and …if emissions follow a business-as-usual scenario, sea level rise of at least two meters is likely this century. … … No stable shoreline would be reestablished in any time frame that humanity can conceive.”

Thus: Given our practical inability to return CO2 levels below 350 ppm, and the new predictions of global temperatures by 2100, global sea level rise is both inevitable and unstoppable by mankind.

I don’t propose to offer any more ‘scientific’ information here. Please continue your education.

See the section above giving an estimate of the global sea level rise profile reasonably expected over the period from today until the ice is all gone and coastlines begin to stablise again: Dates and Corresponding Sea Levels.

Why the "100 Metre Line" - How High can it Go?

How High can the Oceans Rise?

How high the oceans will rise is a relatively straightforward and uncontroversial matter. The amount of ice in the ocean's snowfields, glaciers and ice sheets is well defined. The answers from various sources may vary a bit but a typical analysis is from Wikipedia:

"If small glaciers and polar ice caps on the margins of Greenland and the Antarctic Peninsula melt, the projected rise in sea level will be around 0.5 m. Melting of the Greenland ice sheet would produce 7.2 m of sea-level rise, and melting of the Antarctic ice sheet would produce 61.1 m of sea level rise.[2] The collapse of the grounded interior reservoir of theWest Antarctic Ice Sheet would raise sea level by 5-6 m.[3]"

Source:
http://en.wikipedia.org/wiki/Sea_level#Glaciers_and_ice_caps
http://en.wikipedia.org/wiki/Current_sea_level_rise

So:
0.5
+7.2 = 7.7
+61.1 = 68.8
+say 5.5=74.3

Thermal expansion of the ocean as it warms is likely to contribute up to half a meter to sea level rise over the next hundred years or so, and possibly over one metre as the deep oceans reach equilibrium temperature with the increased global surface temperatures.

The final addition to the eventual level of the ocean at a particular point is the effect of local tides. Around the world tidal ranges can vary from practically zero to over 17 metres. Typical coastal tidal ranges are around two to three metres.

http://en.wikipedia.org/wiki/Tidal_range

To determine the height of a future high tide at your location, add half the tidal range at each locality to the sea level rise figure.

Thus we can be fairly confident that the likely result of the melting of the available frozen water in the planet in response to warmer surface temperatures will result in the final high tide line settling at a level of between 75 to 80 metres above the mean sea levels of previous centuries.

So if the sea can only rise 75 metres, why refer to The 100 Metre Line?

Existing coastlines present many forms depending on the shape of the land adjacent to the coast. There are mangrove swamps, gently shelving beaches, and there are rough rocky shores and sheer cliff faces dropping into the sea.

Each of these coastal configurations has developed over thousands of years in response to the action of wave on land, and the resulting coastline represents the condition where the erosive power of the ocean has reached equilibrium with the nature of the soils and underlying bedrock the sea can reach.

In reaching this equilibrium the sea has chewed away at the land. Where it has been up against bedrock then the ocean’s activity results in sculptured cliffs that resist the advance of the ocean. Where the sea meets a gently sloping hill covered in topsoil and loam it will sweep the soil away seeking bedrock. What may start out as a low clay cliff with muddy sea at its base is transformed over time by erosion from sea, rain and wind to a stable bank or bluff perhaps with a beach at its foot.

In this process the sea causes the land to assume its natural sustainable angle of repose back from the reach of the ocean. In the majority of areas the land 80 metres above present sea level is comprised of well-weathered readily-eroded soils based on firmer material some metres below the existing ground level. So the process of the coast assuming some long-term stability at the eventual high tide mark will entail the horizontal erosion of the newly inundated ground back to bedrock at the high tide mark, followed by the collapse of unsound soils above that point and the erosion by land-side mechanisms such as rain fall and stream activity to eventually see the up-slope area reach the same state of long term stability you see along the coast today.

You can observe this process by looking any existing coastal strip where buildings and other developments are established and extrapolating the adjacent land-form out to sea to the point it where would naturally meet the present-day sea level. You can readily notice how far back the stable ground is in terms of both horizontal and vertical distance.

To get an impression of where the new ‘final’ coast will be you can locate a point on existing ground that is about 80 metres vertically above the present sea level, then either add these observed horizontal and vertical offsets away from the existing coast to locate a likely position of the new stable ground level.

An alternative is to extrapolate the current beach gradient to a point where it lies beneath the 80 m contour, and then re-paint the existing coast form (cliff, rolling hills etc) behind that new high tide mark to see how far back the stable ground will lie.

The exact location of stable ground will vary in each case, however I am suggesting that a vertical offset of about 20 metres above the 80-metre mark (and thus a distance back from the new high tide mark similar to that at the present coast line) will be a useful starting point for considering where to find land that is unlikely to be taken by the ocean as the new coast lines establish.

We have here considered the maximum possible sea level rise from melting ice, thermal expansion and tidal effects, and added a prudent minimum vertical offset to allow for the stabilization of the new coast.

From this I arrive and what I suggest is the lowest prudent platform elevation as the base upon which to establish our future civilization. This elevation is typically at about 100 metres above today's mean sea level, hence: The 100 Metre Line.

(Updated 20190306. NJW)

The 100 Metre Line

Our 80 metre Sea Level Rise Maps

2009/12/03

Major sea level rise likely as Antarctic ice melts - 1.4 metres by 2100

Welcome

There are many possible representations of the impact of climate change on humanity, but perhaps the most difficult to grapple with yet the easiest to show is that of sea level rise.

Visitors

Followers

Year vs Sea Level Chart

Blog Archive

Links to Watch

How to get your post published.

What to do.

FAQ - What's it all about?

Dates and corresponding Sea Levels

The Scientific Basis

Why the "100 Metre Line" - How High can it Go?

The 100 Metre Line

Our 80 metre Sea Level Rise Maps

2009/12/03

Major sea level rise likely as Antarctic ice melts - 1.4 metres by 2100

Welcome

There are many possible representations of the impact of climate change on humanity, but perhaps the most difficult to grapple with yet the easiest to show is that of sea level rise.

Subscribe To The 100 Metre Line

Visitors

Followers

Year vs Sea Level Chart

Blog Archive

Links to Watch

How to get your post published.

What to do.

FAQ - What's it all about?

Dates and corresponding Sea Levels

The Scientific Basis

Why the "100 Metre Line" - How High can it Go?