Which cities will sink into the sea first? Maybe not the ones you expect

[nitpicker]

https://www.theguardian.com/commentisfree/2018/oct/01/cities-sink-sea-first-earth-submerge-coastline

Which cities will sink into the sea first? Maybe not the ones you expect

Mark Miodownik

Mon 1 Oct 2018 06.00 BST Last modified on Mon 1 Oct 2018 08.16 BST

Better scientific understanding of global warming makes the discussion about its geopolitical consequences increasingly urgent. Put simply, there are going to be winners and losers: hotter places and colder places; wetter places and drier places; and, yes, places that disappear under the sea. But the reality is a bit more complicated. In particular, are sea levels going up or down? The answer seems clear when you consider that Antarctica has lost 3 trillion tonnes of ice in the last 25 years.

Yet to understand what is going on we first have to recognise that the Earth isn’t solid. It started life as a ball of hot liquid about 4.5bn years ago and our planet has been cooling ever since. Right at the centre of the Earth is a solid core of metal made of iron and nickel at a temperature of approximately 5,000C. But this core is surrounded by an approximately 2,000km-thick ocean of molten metal, again mostly iron and nickel. Surrounding this is a layer of rock called the mantle that is between 500C to 900C, and at these red-hot temperatures the rock behaves like a solid over short periods of time (seconds, hours, and days) but like a liquid over longer time periods (months to years) – so the rock flows, even though it is not molten. On top of the fluid mantle floats the crust, which is like the skin of the Earth. It is a relatively thin layer of cool rock that is between 30 to 100km thick and contains all the mountains, forests, rivers, seas, continents – our world.

Since the crust is floating on the fluid mantle, if you increase its weight by, for instance, building up kilometres of ice on top of it, then it sinks further into the mantle. This is what has happened to the landmasses of Antarctica and Greenland, which are both covered in 2km to 3km of thick ice. If global warming were to cause all that ice to melt, then the sea level of the oceans would rise by more than 50 metres, submerging all the coastal cities of the world and making hundreds of millions of people homeless. This seems obvious. What is less obvious is how it might unfold.

If the whole ice sheet covering Antarctica melts, the release of its weight will destress the rocks below, which, because they float on the mantle, will bob up. This is called post-glacial rebound. The position with Greenland is similar: the crust below it is being weighed down by the 3 million trillion litres of water held in the ice sheet, and if that ice sheet all melts then parts of the North American tectonic landmass will rise up. If the resulting increase in the height of the continent is bigger than the sea level rise, then major flooding may be avoided. Working out which scenario is more likely is vitally important for future generations, because one of these results will start to play out if global warming intensifies.

What we know is this: the global mean sea level has risen 20cm since the beginning of the 20th century. Some of this has been owing to the water thermally expanding as the oceans have got hotter – since hotter liquids take up more volume (this is how liquid thermometers work). Some of the rise in sea level has been due to the Greenland and Antarctic ice sheets melting, and some due to other glaciers melting. The rising sea levels are global: they affect everyone with a coastline, from tiny Pacific islands that would be entirely submerged to a huge country such as Bangladesh, for which a one-metre rise in sea levels would result in nearly a fifth of the country being submerged and 30 million people being displaced. But while rising sea levels affect everyone, the post-glacial rebound affects only the coasts connected to parts of the Earth’s crust weighed down by the Greenland and Antarctic ice sheets.
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[PaulX2]

1. Drill Baby Drill Says Rocket Scientist

Sarah Palin!

[Hermit-The-Prog]

2. Reagan and 'Daddy' Bush

3 trillion tonnes in 25 years, eh?

Maybe something should have been done way back when:

Reagan, Bush 41 memos reveal sharp contrast with today’s GOP on climate and the environment
https://www.washingtonpost.com/news/energy-environment/wp/2015/12/03/reagan-bush-41-memos-reveal-how-republicans-used-to-think-about-climate-change-and-the-environment/?utm_term=.88de7cea82a1

The memos, stamped “confidential” and kept under wraps for years, portray a White House eager to assert U.S. leadership on climate change. Global warming will have “profound consequences,” one document warns, and the United States “cannot wait” until all scientific questions are resolved before taking action.

The source of the memos: Not the Obama White House, but policy advisers to President George H.W. Bush.

The memos were among several formerly classified documents from the Bush and Reagan administrations obtained under the Freedom of Information Act and released on Wednesday by the National Security Archive. The documents portray senior officials in the two Republican administrations pressing for an aggressive response to international environmental issues of the day — including, during Bush’s term, climate change.

[LuvNewcastle]

3. Good article

Articles about climate change can be pretty dense sometimes, but this article explains the issues surrounding climate change in a clear, direct way.

[N_E_1 for Tennis]

4. Rebounding has been happening...

in the Great Lakes region for quite a while and affecting the lake levels being noticed today.
The Nordic countries saw massive changes in their coastlines also. Sometimes looking at something that will happen globally is best understood looking at smaller parts of the action.

https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/p/Post-glacial_rebound.htm

I live in Northern Michigan close to the shores of Lake Huron. This reaction has been closely monitored for quite a long time. Being a peninsula surrounded by the Great Lakes the changes can and do affect the tourism industry along the coastline of my beautiful state.


https://www.freep.com/story/news/local/michigan/2018/03/02/michigan-great-lakes-ice-age/363316002/