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James Hansen is expecting a 20 meter sea level rise for every degree
of warming? It's already warmed a bit more than half a degree C
since the late 1800s. Where's our 12 meter sea level rise? In
contrast, sea level has risen about 0.2 meters in the same time
period. I understand that he isn't saying that we'll get all 20
meters at once.<br>
<br>
Googling around the web a bit comes up with about a 3.1 mm/year sea
level rise, which is the "accelerated" rate they are worried about
in recent decades.<br>
<br>
20 m * (1 yr / 0.0031 m) ~= 6450 yr<br>
<br>
This level should be reached at around year 8461 BCE, given the
current rate of sea level rise. I think we'll have time to deal
with it as it happens. And that's for one degree. If we get the
expected 3, which is a little conservative, then we'll get to that
level on or around 21365 BCE.<br>
<br>
If we got all 20 meters by 2100, then that would mean a sudden
acceleration to: 20 m / (2100 - 2011) yr = 0.225 m/yr. So we would
expect to see as much sea level rise, on average, every year that
we've seen so far since pre-industrial times for this to happen.<br>
<br>
As it stands, if the current rate of sea level rise continues, we
should expect a sea level rise of (2100 - 2011) * .0031 m = 0.276
m. A little more than a years worth of Hansen's figures. Just one
meter of sea level rise would mean that the current sea level rise
would have to almost quadruple in the next few years.<br>
<br>
And people wonder why I'm skeptical.<br>
<br>
Paul<br>
<br>
<br>
On 12/14/2011 04:06 PM, Ted Moffett wrote:
<blockquote
cite="mid:CAJ-QB6V1NWVJF_3NMzTtzpodJiTGb_1WQw+7-YSbKwj8gthToQ@mail.gmail.com"
type="cite">
<div>Monday Dec. 12, 2011 the "Lewiston Tribune" front page
headline read "Climate Deal Extends Status Quo." </div>
<div><a moz-do-not-send="true"
href="http://lmtribune.com/editors_pick/article_e889c1b8-bb55-5783-9fb1-4635ca902dee.html">http://lmtribune.com/editors_pick/article_e889c1b8-bb55-5783-9fb1-4635ca902dee.html</a>
</div>
<div>The article was sourced from "The Associated Press," authored
by Maxx and Ritter, so my comments do not directly apply to
"Lewiston Tribune" journalists </div>
<div> </div>
<div>The headline might have read, to address the magnitude of the
problem humanity is potentially facing, "No Substantive Climate
Deal Portends Meters of Sea Level Rise by 2100" if the article
was referencing credible peer reviewed science on this
issue ("Global sea level linked to global temperature" <a
moz-do-not-send="true"
href="http://www.pnas.org/content/early/2009/12/04/0907765106.full.pdf">http://www.pnas.org/content/early/2009/12/04/0907765106.full.pdf</a>
). Instead, the article meekly declared "Scientists say that if
levels of greenhouse gases continue to rise, eventually the
world's climate will reach a tipping point, with irreversible
melting of some ice sheets and a several foot rise in sea
levels."</div>
<div> </div>
<div>Several foot rise? How about potentially meters of sea level
rise by 2100? With more to follow as climate change continues
into the next century: </div>
<div>National Academies Press: "Beyond the Next Few Centuries:
Long-Term Feedbacks and Earth System Sensitivity"</div>
<div><a moz-do-not-send="true"
href="http://www.nap.edu/openbook.php?record_id=12877&page=217">http://www.nap.edu/openbook.php?record_id=12877&page=217</a></div>
<div> </div>
<div>Read this recent release from NASA's Goddard Institute for
Space Studies, regarding a paper now "in press" (abstract at
bottom):</div>
<div> </div>
<div><a moz-do-not-send="true"
href="http://www.giss.nasa.gov/research/news/20111208/">http://www.giss.nasa.gov/research/news/20111208/</a></div>
<h2>Research News</h2>
<h3>Paleoclimate Record Points Toward Potential Rapid Climate
Changes</h3>
<p class="byline">Dec. 8, 2011</p>
<div><b><i>Related NASA AGU news briefing materials may be found <a
moz-do-not-send="true"
href="http://www.nasa.gov/topics/earth/features/rapid-change.html">here</a>.</i></b></div>
<div><strong><em></em></strong> </div>
<div>
<p>New research into the Earth's paleoclimate history by NASA's
Goddard Institute for Space Studies director James E. Hansen
suggests the potential for rapid climate changes this century,
including multiple meters of sea level rise, if global warming
is not abated.</p>
<p>By looking at how the Earth's climate responded to past
natural changes, Hansen sought insight into a fundamental
question raised by ongoing human-caused climate change: "What
is the dangerous level of global warming?" Some international
leaders have suggested a goal of limiting warming to 2 degrees
Celsius from pre-industrial times in order to avert
catastrophic change. But Hansen said at a press briefing at a
meeting of the American Geophysical Union in San Francisco on
Tues, Dec. 6, that warming of 2 degrees Celsius would lead to
drastic changes, such as significant ice sheet loss in
Greenland and Antarctica.</p>
<p>Based on Hansen's temperature analysis work at the Goddard
Institute for Space Studies, the Earth's average global
surface temperature has already risen .8 degrees Celsius since
1880, and is now warming at a rate of more than .1 degree
Celsius every decade. This warming is largely driven by
increased greenhouse gases in the atmosphere, particularly
carbon dioxide, emitted by the burning of fossil fuels at
power plants, in cars and in industry. At the current rate of
fossil fuel burning, the concentration of carbon dioxide in
the atmosphere will have doubled from pre-industrial times by
the middle of this century. A doubling of carbon dioxide would
cause an eventual warming of several degrees, Hansen said.</p>
<p>In recent research, Hansen and co-author Makiko Sato, also of
Goddard Institute for Space Studies, compared the climate of
today, the Holocene, with previous similar "interglacial"
epochs — periods when polar ice caps existed but the world was
not dominated by glaciers. In studying cores drilled from both
ice sheets and deep ocean sediments, Hansen found that global
mean temperatures during the Eemian period, which began about
130,000 years ago and lasted about 15,000 years, were less
than 1 degree Celsius warmer than today. If temperatures were
to rise 2 degrees Celsius over pre-industrial times, global
mean temperature would far exceed that of the Eemian, when sea
level was four to six meters higher than today, Hansen said. </p>
<p>"The paleoclimate record reveals a more sensitive climate
than thought, even as of a few years ago. Limiting
human-caused warming to 2 degrees is not sufficient," Hansen
said. "It would be a prescription for disaster."</p>
<p>Hansen focused much of his new work on how the polar regions
and in particular the ice sheets of Antarctica and Greenland
will react to a warming world. </p>
<p>Two degrees Celsius of warming would make Earth much warmer
than during the Eemian, and would move Earth closer to
Pliocene-like conditions, when sea level was in the range of
25 meters higher than today, Hansen said. In using Earth's
climate history to learn more about the level of sensitivity
that governs our planet's response to warming today, Hansen
said the paleoclimate record suggests that every degree
Celsius of global temperature rise will ultimately equate to
20 meters of sea level rise. However, that sea level increase
due to ice sheet loss would be expected to occur over
centuries, and large uncertainties remain in predicting how
that ice loss would unfold.</p>
<p>Hansen notes that ice sheet disintegration will not be a
linear process. This non-linear deterioration has already been
seen in vulnerable places such as Pine Island Glacier in West
Antarctica, where the rate of ice mass loss has continued
accelerating over the past decade. Data from NASA's Gravity
Recovery and Climate Experiment (GRACE) satellite is already
consistent with a rate of ice sheet mass loss in Greenland and
West Antarctica that doubles every ten years. The GRACE record
is too short to confirm this with great certainty; however,
the trend in the past few years does not rule it out, Hansen
said. This continued rate of ice loss could cause multiple
meters of sea level rise by 2100, Hansen said.</p>
<p>Ice and ocean sediment cores from the polar regions indicate
that temperatures at the poles during previous epochs — when
sea level was tens of meters higher — is not too far removed
from the temperatures Earth could reach this century on a
"business as usual" trajectory.</p>
<p>"We don't have a substantial cushion between today's climate
and dangerous warming," Hansen said. "Earth is poised to
experience strong amplifying feedbacks in response to moderate
additional global warming." </p>
<p>Detailed considerations of a new warming target and how to
get there are beyond the scope of this research, Hansen said.
But this research is consistent with Hansen's earlier findings
that carbon dioxide in the atmosphere would need to be rolled
back from about 390 parts per million in the atmosphere today
to 350 parts per million in order to stabilize the climate in
the long term. While leaders continue to discuss a framework
for reducing emissions, global carbon dioxide emissions have
remained stable or increased in recent years. </p>
<p>Hansen and others noted that while the paleoclimate evidence
paints a clear picture of what Earth's earlier climate looked
like, but that using it to predict precisely how the climate
might change on much smaller timescales in response to
human-induced rather than natural climate change remains
difficult. But, Hansen noted, the Earth system is already
showing signs of responding, even in the cases of "slow
feedbacks" such as ice sheet changes.</p>
<p>The human-caused release of increased carbon dioxide into the
atmosphere also presents climate scientists with something
they've never seen in the 65 million year record of carbon
dioxide levels — a drastic rate of increase that makes it
difficult to predict how rapidly the Earth will respond. In
periods when carbon dioxide has increased due to natural
causes, the rate of increase averaged about .0001 parts per
million per year — in other words, one hundred parts per
million every million years. Fossil fuel burning is now
causing carbon dioxide concentrations to increase at two parts
per million per year.</p>
<p>"Humans have overwhelmed the natural, slow changes that occur
on geologic timescales," Hansen said.</p>
<h4>Web Link</h4>
<p>NASA/GISS Science Brief: <a moz-do-not-send="true"
href="http://www.giss.nasa.gov/research/briefs/hansen_15/">Earth's
Climate History: Implications for Tomorrow</a> </p>
<h4>Reference</h4>
<p>Hansen, J.E., and Mki. Sato, 2011: <a moz-do-not-send="true"
href="http://pubs.giss.nasa.gov/abs/ha05510d.html">Paleoclimate
implications for human-made climate change</a>. In <cite>Climate
Change: Inferences from Paleoclimate and Regional Aspects</cite>.
A. Berger, F. Mesinger, and D. Šijači, Eds. Springer, in
press.</p>
<p>----------------------------------------</p>
<p><a moz-do-not-send="true"
href="http://pubs.giss.nasa.gov/abs/ha05510d.html">http://pubs.giss.nasa.gov/abs/ha05510d.html</a></p>
<h2>Publication Abstracts</h2>
<h3>Hansen and Sato 2011, in press</h3>
<p>Hansen, J.E., and Mki. Sato, 2011: Paleoclimate implications
for human-made climate change. In <cite>Climate Change:
Inferences from Paleoclimate and Regional Aspects</cite>. A.
Berger, F. Mesinger, and D. Šijači, Eds. Springer, in press. </p>
<p>Paleoclimate data help us assess climate sensitivity and
potential human-made climate effects. We conclude that Earth
in the warmest interglacial periods of the past million years
was less than 1°C warmer than in the Holocene. Polar warmth in
these interglacials and in the Pliocene does not imply that a
substantial cushion remains between today's climate and
dangerous warming, but rather that Earth is poised to
experience strong amplifying polar feedbacks in response to
moderate global warming. Thus goals to limit human-made
warming to 2°C are not sufficient — they are prescriptions for
disaster. Ice sheet disintegration is nonlinear, spurred by
amplifying feedbacks. We suggest that ice sheet mass loss, if
warming continues unabated, will be characterized better by a
doubling time for mass loss rate than by a linear trend.
Satellite gravity data, though too brief to be conclusive, are
consistent with a doubling time of 10 years or less, implying
the possibility of multi-meter sea level rise this century.
Observed accelerating ice sheet mass loss supports our
conclusion that Earth's temperature now exceeds the mean
Holocene value. Rapid reduction of fossil fuel emissions is
required for humanity to succeed in preserving a planet
resembling the one on which civilization developed.</p>
<p>------------------------------------------</p>
<p>Vision2020 Post: Ted Moffett</p>
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