[Vision2020] 8-15-13 "The inevitability of sea level rise" by Anders Levermann, Professor of Dynamics of the Climate System

Art Deco art.deco.studios at gmail.com
Tue Aug 27 07:06:53 PDT 2013

I'm glad I'm old and not likely to live long enough to see the folly of
ignoring this information.

Also see the rise of Measles again fuel by a parson who warned against the
measles vaccine.

Humankind, the only partially rational animal.

On Mon, Aug 26, 2013 at 8:52 PM, Ted Moffett <starbliss at gmail.com> wrote:

> http://www.realclimate.org/index.php/archives/2013/08/the-inevitability-of-sea-level-rise/#more-15633
> Academic website for Anders Levermann:
> http://www.pik-potsdam.de/~anders/
> ---------------------------------------
> The inevitability of sea level rise
> Filed under:
>    - Climate Science<http://www.realclimate.org/index.php/archives/category/climate-science/>
> — stefan @ 15 August 2013
> *Guest post by Anders Levermann <http://www.pik-potsdam.de/%7Eanders/>[via The
> Conversation<http://theconversation.com/the-inevitability-of-sea-level-rise-16871>
> ]*
> Small numbers can imply big things. Global sea level rose by a little less
> than 0.2 metres during the 20th century – mainly in response to the 0.8 °C
> of warming humans have caused through greenhouse gas emissions. That might
> not look like something to worry about. But there is no doubt that for the
> next century, sea level will continue to rise substantially. The
> multi-billion-dollar question is: by how much?
> The upper limit of two metres that is currently available in the
> scientific literature would be extremely difficult and costly to adapt to
> for many coastal regions. But the sea level will not stop rising at the end
> of the 21st century. Historical climate records show that sea levels have
> been higher whenever Earth’s climate was warmer – and not by a couple of
> centimetres, but by several metres. This inevitability is due to the
> inertia in the ocean and ice masses<http://www.pnas.org/content/early/2013/07/10/1219414110>on the planet. There are two major reasons for the perpetual response of
> sea level to human perturbations.
> One is due to the long lifetime and warming effect of carbon dioxide in
> the atmosphere. Once emitted carbon dioxide causes warming in the
> atmosphere over many centuries which can only be reduced significantly by
> actively taking the greenhouse gas out again. This is because both the
> amount of heat and carbon dioxide the ocean can absorb is reduced, and so
> the temperature stays up for centuries or even millennia<http://dx.doi.org/10.1073%2Fpnas.0812721106>.
> Of course, not cutting emissions would exacerbate the problem even further.
> The other reason is that both the ocean and the ice masses are very big
> and a warming of the surrounding atmosphere will only penetrate slowly, but
> inevitably, into them. As a consequence their sea level contribution
> continues even if the warming does not increase. Sea level rise over the
> last century has been dominated by ocean warming and loss of glaciers. Our
> recent study<http://www.pnas.org/content/early/2013/07/10/1219414110.abstract>indicates that the future sea level rise will be dominated by ice loss from
> the two major ice sheets on Greenland and Antarctica – slumbering giants
> that we’re about to wake.
> [image: levermann2013]<http://www.realclimate.org/images//levermann2013.jpg>
> *Graph: Sea level rise contributions over 2000 years from: ocean warming
> (a), mountain glaciers (b), Greenland (c) and Antarctic (d) ice sheets. The
> total sea level commitment (e) is about 2.3m per degree of warming above
> pre-industrial.
> *
> It is easier to understand a future world that has adjusted to a new
> equilibrium of higher temperatures than it is to understand the dynamic
> (perhaps rapid) transition from today’s world to a warmer one. That is why
> we used physical models for the ocean, the mountain glaciers and the big
> ice sheets to compute how the systems would be different if the world was
> warmer.
> What we found was that for each degree of global warming above
> pre-industrial levels the ocean warming will contribute about 0.4 metres to
> global mean sea-level rise while Antarctica will contribute about 1.2
> metres. The mountain glaciers have a limited amount of water stored and
> thus their contribution levels off with higher temperatures. This is
> over-compensated for by the ice loss from Greenland, so that in total sea
> level rises quasi-linearly by about 2.3 metres for each degree of global
> warming (see figure).
> How fast this will come about, we do not know. All we can say is that it
> will take no longer than 2,000 years. Thus the 2.3 metres per degree of
> warming are not for this century. They need to be considered as our sea
> level commitment – the sea level rise that cannot be avoided after we have
> elevated global temperatures to a certain level.
> Ben Strauss of Climate Central <http://www.climatecentral.org/> has
> considered <http://www.pnas.org/cgi/doi/10.1073/pnas.1312464110> the
> different possible future pathways that society might take and computed
> which US cities are at risk <http://sealevel.climatecentral.org/> in the
> long-term. He poses the question as to what year, if we continue with
> greenhouse emissions at current rates, we will have caused an inevitable
> sea level rise that puts certain cities at risk.
> According to his analysis, within the next few years Miami in Florida will
> be committed to eventually lie below sea level, while our future actions
> can still decide on whether we want to one day give up cities such as
> Virginia Beach, Sacramento, Boston, Jacksonville or New York City.
> This is a decision society has to take for future generations. We will
> need to adapt to climate change in any case, but some things we will not be
> able to adapt to. Society needs to decide whether we want to give up, for
> example, the Tower of London, or to put the breaks on climate change so
> that we don’t have to.
> *Weblink:* The New York Times has a good current article<http://www.nytimes.com/2013/08/13/science/timing-a-rise-in-sea-level.html?_r=1&>on this issue.
> *Anders Levermann <http://www.pik-potsdam.de/%7Eanders/> is department
> head at the Potsdam Institute for Climate Impact Research, Germany*
> *-------------------------------------------*
> *Vision2020 Post: Ted Moffett
> *
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Art Deco (Wayne A. Fox)
art.deco.studios at gmail.com
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