<div dir="ltr"><div><div><div><br></div>I'm glad I'm old and not likely to live long enough to see the folly of ignoring this information.<br><br></div>Also see the rise of Measles again fuel by a parson who warned against the measles vaccine.<br>
<a href="http://www.nbcnews.com/health/measles-outbreak-tied-texas-megachurch-sickens-21-8C11009315">http://www.nbcnews.com/health/measles-outbreak-tied-texas-megachurch-sickens-21-8C11009315</a><br><br></div>Humankind, the only partially rational animal.<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Aug 26, 2013 at 8:52 PM, Ted Moffett <span dir="ltr"><<a href="mailto:starbliss@gmail.com" target="_blank">starbliss@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><h3><a href="http://www.realclimate.org/index.php/archives/2013/08/the-inevitability-of-sea-level-rise/#more-15633" target="_blank">http://www.realclimate.org/index.php/archives/2013/08/the-inevitability-of-sea-level-rise/#more-15633</a></h3>
<p>Academic website for Anders Levermann:<br></p><p><a href="http://www.pik-potsdam.de/~anders/" target="_blank">http://www.pik-potsdam.de/~anders/</a></p><p>---------------------------------------<br></p><h3>The inevitability of sea level rise</h3>
<div>Filed under: <ul><li><a href="http://www.realclimate.org/index.php/archives/category/climate-science/" title="View all posts in Climate Science" rel="category tag" target="_blank">Climate Science</a></li>
</ul> — stefan @ 15 August 2013 </div>
<p><em>Guest post by <a href="http://www.pik-potsdam.de/%7Eanders/" target="_blank">Anders Levermann</a> [via <a href="http://theconversation.com/the-inevitability-of-sea-level-rise-16871" target="_blank">The Conversation</a>]</em></p>
<p>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?<span></span></p>
<p>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 <a href="http://www.pnas.org/content/early/2013/07/10/1219414110" target="_blank">the inertia in the ocean and ice masses</a> on the planet. There are two major reasons for the perpetual response of sea level to human perturbations.</p>
<p>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 <a href="http://dx.doi.org/10.1073%2Fpnas.0812721106" target="_blank">for centuries or even millennia</a>. Of course, not cutting emissions would exacerbate the problem even further.</p>
<p>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. <a href="http://www.pnas.org/content/early/2013/07/10/1219414110.abstract" target="_blank">Our recent study</a>
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.</p>
<p><a href="http://www.realclimate.org/images//levermann2013.jpg" target="_blank"><img src="http://www.realclimate.org/images//levermann2013.jpg" alt="levermann2013" width="300"></a></p>
<p><em><strong>Graph:</strong> 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.<br>
</em></p>
<p>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.</p>
<p>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).</p>
<p>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.</p>
<p>Ben Strauss of <a href="http://www.climatecentral.org/" target="_blank">Climate Central</a> has <a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1312464110" target="_blank">considered</a> the different possible future pathways that society might take and computed which <a href="http://sealevel.climatecentral.org/" target="_blank">US cities are at risk</a>
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.</p>
<p>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.</p>
<p>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.</p>
<p><strong>Weblink:</strong> The New York Times has a good <a href="http://www.nytimes.com/2013/08/13/science/timing-a-rise-in-sea-level.html?_r=1&" target="_blank">current article</a> on this issue.</p>
<p><em><a href="http://www.pik-potsdam.de/%7Eanders/" target="_blank">Anders Levermann</a> is department head at the Potsdam Institute for Climate Impact Research, Germany</em></p><p><em>-------------------------------------------</em></p>
<p><em>Vision2020 Post: Ted Moffett<br></em></p>
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