
Ice mass the size of Greenland overlooked in climate models - fraqed
http://www.latimes.com/news/science/sciencenow/la-sci-sn-climate-melt-20130624,0,4448493.story
======
zdw
Most people have a distorted idea of how big Greenland is - it's actually
about the size of Saudi Arabia
([http://en.wikipedia.org/wiki/List_of_countries_and_dependenc...](http://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area))
and gets distorted by most map projections to outlandish sizes (larger than
South America in some).

~~~
lquist
Most likely a result of the flaws of the Mercator projection
([https://en.wikipedia.org/wiki/Mercator_projection#Mathematic...](https://en.wikipedia.org/wiki/Mercator_projection#Mathematics_of_the_Mercator_projection)).

~~~
yellowbkpk
Saying it's a result of a flaw in the Mercator projection is like saying zero
being undefined is a flaw of the logarithm scale: it's not a flaw, it's a
property.

If the projection doesn't work for your usecase, don't use it.

~~~
minikites
Okay, but the Mercator projection is/was used very frequently in schools where
there's isn't a choice in the matter. It's such a widespread misconception and
most people aren't taught about how map projections work so it's a part of the
general public consciousness.

[https://www.youtube.com/watch?v=n8zBC2dvERM](https://www.youtube.com/watch?v=n8zBC2dvERM)

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pmorici
I don't understand the emphasis on 'global warming' / 'climate change' as a
marquee issue to drive action on environmental protection. The science behind
it seems complex and because it relies so heavily on modeling leaves
significant uncertainty in the mind of any lay person that reads about this
stuff. I would think a much better way to promote environmental protection
would be from the human health angle. Things like Erin Broncovich, Gas Land,
(or whatever the air pollution equivalent is) etc... where there is clear
documented proof about how environmental contamination is literally killing
people. Seems like those would be more compelling reasons to act than some
uncertain doom a century from now.

~~~
DanBC
> leaves significant uncertainty in the mind of any lay person that reads
> about this stuff.

Unfortunately that uncertainty is almost entirely created FUD from paid staff
- the same people who worked for years to protect tobacco from science.

~~~
pyre
Like how all of our models of the universe were confirmed by probes like
Voyager 1, and we learned nothing new. You're right. Models have no
uncertainty (and scientists are always expert statisticians, while we're at it
;).

I'll at least say that the politicization of the issue hasn't helped the media
to accurately report things about global warming.

~~~
scarmig
It's important to put out that the politicization wasn't two sided: it neither
started political nor is inherently political, but was made political by a
campaign of disinformation by corrupting special interests.

Of course, now that politicization does exist, and that corruption has
worsened the quality of discourse among legitimate scientists. They're still
functioning decently, but it'd be nice to know how to build a stronger
scientific ecosystem.

~~~
pyre

      | politicization wasn't two sided
    

Maybe at the start, but nowadays there are plenty of people on the opposite
end of the spectrum spewing things like:

\- Hurricane Katrina is proof of Global Warming.

\- "There wasn't enough snow last winter. Global Warming!"

\- "There was more snow this year than last year. Global Warming!"

\- "There was a drought this year. Global Warming!"

\- "There was too much rain this year. Global Warming!"

There's also this idea that the climate has ever reached any sort of
equilibrium state. With as many variables go into something like the global
climate, I find it hard to believe that we can say anything with any
certainty. E.g.

How do deep sea methane pockets affect the climate? Do we know how often any
of these might be released into the atmosphere? Do we know if any of these had
any affect on any sort of ancient climate change that we only know about from
ice core samples?

~~~
scarmig
Yes, the "it's a hot day in summer therefore climate change" annoys me as much
as "it's a cool day in winter therefore no climate change." Any given year, or
even span of a couple years, isn't enough, let alone a day in a particular
region.

As for your questions, dealing with them individually with some level of
certainty isn't too bad: I've certainly read convincing discussions of them.
It's when dealing with things not in isolation that things become tricky. Most
(though not all) feedbacks point in the positive direction, so all together
they are almost certainly positive, even if that's not mathematical proof. But
the magnitude of that positivity is very much up in the air.

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brittohalloran
TLDR; Since the historical ice models, driven by fossil based sea level
readings in Barbados, failed to account for the way the Earth's crust bends
under the weight of a massive ice sheet on top of it, there was actually much
more ice than previously thought. The exact implications aren't given, but it
is implied that global warming is worse than we thought (has melted more ice).

~~~
tezza
Not sure I get the same conclusion you do from the same article.

Worse than we thought?:

"It allows for the possibility that there is significant melting of the East
Antarctic Ice Sheet," Rowley said. "Or it allows for a simple interpretation
of no melting."

There is a simple interpretation of no melting.

Also, previously in the article they show that the models used to predict
melting are suspect. The historical link of 'melt' being caused by CO2, may in
fact be flattening caused by crust flexing.

~~~
Retric
The crust flexes in response to freasing or melting but it don't not
significantly buldge without reason.

~~~
philhippus
With that sentence you are either a rather prodigious 6 year old or a
grammatically challenged adult.

~~~
tome
Or a non-native English speaker?

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yread
> The highly accurate dating and long time span of those fossils have allowed
> scientists to estimate fluctuations in sea level, and thus ice content, by
> extrapolating from variations in the ratio of oxygen isotopes

How do they estimate sea level from the ratio of oxygen isotopes? I've found
just this
[http://en.wikipedia.org/wiki/Δ18O](http://en.wikipedia.org/wiki/Δ18O) but it
talks only about temperature, salinity and amount of evaporation

~~~
kaybe
The Rayleigh process describes the continous depletion of a reservoir through
a fractionationing process - evaporation. It comes from the fact that heavier
isotopes need slightly more energy for a phase change and thus get enriched in
the fluid phase. In the case of water, it is mainly the stable O18 (as opposed
to the abundant O16).

\- Lighter isotopes evaporate easier and precipitate down on land. If they
don't return to the ocean for a long time due to freezing and glaciation, the
ocean has a higher ratio of heavy to light isotopes. More ice means lower
ocean level, and since the ratio in the ocean is dependent on the missing
water mass, calculations directly give the sea level.

Now how do we know what the isotope ratio was in the past?

In the oceans, there are those small animals (foraminifera) that build the
oxigen from water into their shells. The Wikipedia article you found discusses
this. (Another fractionation process, add more calculations here. Additional
temperature dependance.) When they die, they float to the ocean floor and, in
time, form sediments and eventually lime rock, which can be drilled for
probes.

Furthermore, different kinds live in different depths, giving us even more
information. This can be used for the past 70 million years, since that's the
age of the oldest ocean floors. Almost (!) everything older has been subducted
again. However, it is not easy to disentangle the temperature effect from the
ice volume effect.

You can check those out, if you're interested, they explain more thoroughly
than the wikipedia article:

shorter lecture script: [http://www.iup.uni-
heidelberg.de/institut/studium/lehre/Aqua...](http://www.iup.uni-
heidelberg.de/institut/studium/lehre/AquaPhys/docMVEnv3_13/AqSysSkript_part2_chap1.pdf)

long looooong version (read this and become a hydroscientist long):
[http://www-naweb.iaea.org/napc/ih/IHS_resources_publication_...](http://www-
naweb.iaea.org/napc/ih/IHS_resources_publication_hydroCycle_en.html)

~~~
yread
Thanks for this comprehensive response (I didn't expect any less from HN ;)

I understood the part about O18 ending up less in the glaciers but I couldn't
really grasp that if the water is in glaciers it isn't in the sea. I also
thought it would be impossible to get rid of influence of the temperature
(gradient with depth, latitude, ocean currents, ...) but it's probably not
impossible, just difficult.

Also for anybody who doesn't click in the "loooooong" version has 6 volumes...

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josephlord
At a plain reading this seems worthy science but not that newsworthy.
Scientists do more (presumably good) work and adjust estimate of ice last ice-
age by 10%, climate models may need minor tweak (direction not stated).

Did I miss something?

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TausAmmer
Change happens, all we can do is adopt, for now. Clear coastlines, clean low
river banks.

If anything, extremes are going to ramp up in count, adopt and build
infrastructure around it.

Paying gigantic amount of money to members that come together few times a year
do not solves anything.

~~~
gizmo686
>all we can do is adopt, for now.

You do realize that we are the first species to be the cause of a mass
extinction event. We are also the only species to seriously consider how to
terraform another planet [1]. What we need is the environmental movement to
stop saying that we are actively destroying the world and the only thing we
can do is stop, to one that says we have the ability to control the
environment of our own world, and we should do so intelligently.

Keep in mind that we are not the first mass extinction event (the
Permian–Triassic extinction event killed 96% of all species), but we are the
first species to be able to exercise intelligent control over the climate.
Also, while the environment will flourish after just like after every other
extinction, it won't happen quickly enough for our scientist to be able to
study life in the same way that they can with our pre-extintion bio-diversity.

[1]
[http://www.users.globalnet.co.uk/~mfogg/zubrin.htm](http://www.users.globalnet.co.uk/~mfogg/zubrin.htm)

------
binderbizingdos
temperatures of the last 12'000 years:
[http://en.wikipedia.org/wiki/File:Holocene_Temperature_Varia...](http://en.wikipedia.org/wiki/File:Holocene_Temperature_Variations.png)

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snowwrestler
I think this headline (which comes from the article) is a bit misleading.

The total mass of the overlooked historical ice is about the mass of the
Greenland ice sheet, but it was not all in one place like Greenland is. The
article says's it's actually about a 10% error in a global historical
reconstruction.

In addition, when I see the phrase "climate models", I think of the global
simulations that scientists use to try to predict the future effect of climate
change. This article seems to instead be about an historical reconstruction of
a past climate.

~~~
lftl
_In addition, when I see the phrase "climate models", I think of the global
simulations that scientists use to try to predict the future effect of climate
change. This article seems to instead be about an historical reconstruction of
a past climate._

But aren't the two extremely tightly coupled? I know nothing of climatology,
but it's hard for me to imagine how you would construct a future model that
didn't rely massively on our picture of how the Earth reacted historically to
different pressures. It would seem to me that adding a rather large chunk of
ice, and changing past sea level measurements would have a large effect on the
predicted future response of the system.

~~~
snowwrestler
Not as much as you might think. Models simulate a small range of time centered
around the present, and are constructed by combining measurable physical
quantities with physics equations. Basically, they attempt to simulate "the
truth" starting from first principles.

Historical reconstruction is about really advanced ways of observing,
estimating, and proxying data. The end product is a story of past climates,
not a simulation or prediction.

It's sort of like the difference between an evolutionary biologist
experimenting on fruit flies, and a paleontologist. You need both to get a
complete picture of life, but neither's work depends much on the other.

In this case I'd be surprised if there is much impact on near-term climate
predictions, because isostatic rebound is really slow at century timescales.

