
Temperature chart for the last 11,000 years - deusclovis
http://kottke.org/13/09/temperature-chart-for-the-last-11000-years
======
rjdagost
For a little while I was interested in paleoclimatology and I started studying
how researchers developed these historical temperature reconstruction curves.
Basically you take “proxies” for temperature, things like tree rings, coral
growth, sediment layer thickness, etc. and you posit a relationship between
the proxy measurements and temperature. Measurements that better fit the
hypothesized model get more weight in the temperature reconstruction.

The main problem is that no one knows if the hypothesized models (temperature
vs. tree ring thickness, sediment layer thickness, etc.) have any validity.
Why should tree rings grow linearly with temperature- what about a huge number
of other variables? The temperature “signal” is at best very weak. Decoupling
the temperature signal from other variables (humidity, elevation, tree
species, CO2 concentration, etc.) is a hugely difficult multivariate
statistics problem and most of the researchers I've corresponded with do not
seem to appreciate this fact.

Another major problem is that proxies get weighted in the temperature
reconstruction based on how well they fit the hypothesized temperature model.
The weighting is where things get really shaky. Right away, you have biased
your results in such a way that that nonconforming data is discarded / de-
weighted. Note that there is not anything wrong with these nonconforming
samples that invalidates them; they just don't fit the proposed models very
well. Typically researchers develop their own methods for weighting samples in
the temperature reconstructions and many of these methods would make a
statistician cringe. Often during the weighting phase you find that a handful
of proxy samples (out of a sample size of hundreds) get the vast majority of
the weight in the temperature reconstructions. Sometimes the weight of a
temperature reconstruction in a location is almost completely computed from a
few proxy samples taken halfway around the world at a completely different
elevation.

If you try to discuss these fundamental problems with climate scientists
you'll typically get told that you're not a scientist (not true) or that
you're a "denialist" being paid by big oil (not true). I am convinced that
these temperature reconstructions are useless at best.

~~~
_delirium
It's definitely not the case that climate scientists are uninterested in
discussing methodological problems with paleoclimate proxies. A considerable
amount of the literature is taken up with doing precisely that, and it takes
up a good portion of the Paleoclimatology section of the IPCC report:
[http://www.ipcc.ch/pdf/assessment-
report/ar4/wg1/ar4-wg1-cha...](http://www.ipcc.ch/pdf/assessment-
report/ar4/wg1/ar4-wg1-chapter6.pdf)

~~~
rjdagost
I know that some folks in paleoclimatology are interested in these core
methodology problems. But these concerns are not conveyed to a wider audience.
When a temperature reconstruction graph is released to the public there is no
mention at all of these problems and one can easily get the impression that
these reconstructed temperatures can be known almost as accurately as going
outside and taking a reading from a thermometer.

~~~
TheCondor
Can the public understand that?

Excluding math, we use proxies for just about all science. With different
assumptions and different criteria. I don't deny that there are politics,
assumptions and margins of error but they do put effort in to minimizing them
and doing real science. Take a look at pharmaceuticals, they don't even know
why a lot of medicine works, in fact there is debate on if it even does... But
people still buy it and take it.

~~~
ddebernardy
The public can't understand that, but it certainly forms opinions based on it.
It votes, too...

~~~
Daishiman
The public is, honestly, incapable of understanding, or even caring, about
underlying issues in proxy temperature modeling. A large amount of the public
is incapable of distinguishing between weather and climate.

Proxy temperatures, statistical methods, atmospheric modeling, etc, are all
scientific areas whose knowledge can be gleamed at sufficiently well for a
person with some form of higher education in science or math education (but
only barely; remember that this stuff is being researched by people who have
devoted their entire lives to the scientific specialty). But that is an
astoundingly low proportion of the population. And even then it is clear that,
as methodological errors have diminished and methods for more accurate models
have appeared, that they all tend towards the same conclusion.

We should be worrying significantly more about the small but non-trivial (and
ever-increasing) probability of an extinction event within the next decades
rather than pretend that methodological errors, at this point, are a
significant issue in identifying the climate trends we have spotted in the
last decades.

------
_delirium
Sources,

The _Science_ paper:
[http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf](http://www.usu.edu/geo/physical/MarcottEtal_Science_2013.pdf)

Online supplemental material:
[http://www.sciencemag.org/content/suppl/2013/03/07/339.6124....](http://www.sciencemag.org/content/suppl/2013/03/07/339.6124.1198.DC1/Marcott.SM.pdf)

The figure itself is a new plot by Potsdam University researchers for
realclimate.org, though, using the same dataset, but not a graphic taken
directly from the paper (the paper's Fig. 1 has some alternate versions).

~~~
throwaway_yy2Di
I think this stinks. The _Science_ paper says their reconstruction is smoothed
and has low time resolution. They say it preserves no variability at all on
timescales <300 years, and attenuates even 1,000 year variations.
Superimposing this with the 30-year Hadley data seems misleading, because it
is on a very short timescale which is suppressed from the paleologic data.

(edit):

 _" Because the relatively low resolution and time uncertainty of our data
sets should generally suppress higher-frequency temperature variability, an
important question is whether the Holocene stack adequately represents
centennial- or millennial scale variability. [...] The results suggest that at
longer periods, more variability is preserved, with essentially no variability
preserved at periods shorter than 300 years, ~50% preserved at 1000-year
periods, and nearly all of the variability preserved for periods longer than
2000 years (figs. S17 and S18)."_

~~~
_delirium
The realclimate.org post discusses that as a potential issue, yes. See the
section following the sentence: _Because the proxy data have only a coarse
time resolution – would they have shown it if there had been a similarly rapid
warming earlier in the Holocene?_

~~~
throwaway_yy2Di
I read this as "no, it wouldn't show up".

 _" Had there been such a global warming before, it would very likely have
registered clearly in some of these data series, even if it didn’t show up in
the averaged Marcott curve."_

I'm not arguing their conclusions. I'm criticizing _the way they present this
data_. This composite reconstruction is so weak, that if you shifted 20th
century AGW back 5,000 years, it would completely erase it. That's how
powerful the smoothing is.

~~~
_delirium
I can buy that view, yeah. It presents conclusions that are probably true, but
the plot is a bit in the pop-science direction in doing so, in the sense that
the plot itself is not really a rigorous way of establishing those
conclusions. The paper doesn't include this kind of plot, probably for those
reasons.

------
rmrfrmrf
Throwing my hat into the ring here:

1) I think that we, as the human population, should actively move toward more
efficient, less destructive industry on principle, not just because of the
threat of climate change. I think making it about climate change gives too
many opportunities for argument derailment. Think about when "tree hugger" was
a pejorative term; i mean, who DOESN'T want to hug a tree? I think it's a lot
harder for people to argue against the idea of "leave a place as you found it"
than to find flaws a data set. It also allows for much broader regulation. For
example, we could then start focusing on legislation against pharm
manufacturers allowing meds to seep into the water supply rather than just the
air pollution they're producing.

2) I'm starting to wonder why we're not focusing more on adaptation to than
prevention of climate change. I've been watching a lot of TED talks lately
(thanks, Netflix!) about the impact of climate change, and the one that I'm
thinking of was a researcher who spent time in the arctic studying the
wildlife there, and made the case that we should prevent climate change so
that we can save arctic wildlife. But I wonder, if we were alive in the age of
dinosaurs, would we be saying that we need to clean up the atmosphere to
prevent the impact winter that would inevitably kill them? While I love
wildlife, I almost feel like it's not our responsibility as humans to tamper
with natural processes like extinction. In our prevention efforts, we may also
be preventing natural selection and, by extension, adaptation. It could be a
reality that we'll face an extinction event that wipes out all other non-
domesticated mammalian life. While we can all agree that an Earth like that
would suck, we know that, 600 million years from now, EVERYTHING will be wiped
out. People speculate that, at this time, humans themselves will either become
extinct or will have migrated off the planet. So, my question is, are we
prepared to jump ship if Earth becomes uninhabitable? Is it realistic to try
to change all 5,000,000,000,000,000,000 kilograms of atmosphere, or should we
starting thinking about building habitats for space living?

~~~
sliverstorm
_While I love wildlife, I almost feel like it 's not our responsibility as
humans to tamper with natural processes like extinction._

The fundamental premise is not that extinction is bad, but that extinction _we
cause_ is bad. If a fox tramples your neighbor's garden, that's too bad. If
_you_ trample your neighbor's garden, you should fix it.

~~~
rmrfrmrf
I used to agree completely with you, but now I realize that, given the second
law of thermodynamics, it's impossible to restore an entire ecosystem back to
a previous state. From what I hear, one goal of ending climate change is to
allow icecaps to re-form and to last longer throughout the year, which
ostensibly will end the suffering of polar bears "stranded" at sea. However,
even if we _did_ remove all excess amounts of greenhouse gases from the
atmosphere (which, as of today, is something that's _barely_ discussed
seriously), it's not going to suddenly reverse the adapted behavior of polar
bears. This is a totally hypothetical and unscientific story, but let's
pretend that the ice caps melted such that polar bears were forced inland and
began foraging for food in human-populated areas. In response, the government
of Canada single-handedly puts up the money to remove all excess greenhouse
gases from the atmosphere. Over a period of decades, the ice grows back, but:
do we really expect the polar bear population, which has now adapted to
foraging for garbage, to suddenly move _back_ to their initial habitat?
Chances are, food will be more plentiful for them in a human-populated area.
Now let's assume that polar bears play a significant role in seal population
control. Well, now that the polar bears have adapted and are now living
further inland, the seal population booms in the arctic region. In fact, it
gets so big, that now penguin populations are in rapid decline! So, at this
point, we've spent probably trillions of dollars, haven't really _helped_ the
polar bears at all, and have directly contributed to the endangerment of
penguins. _And this is all assuming that our plan even works!_ Not to mention
the fact that there may be other species that died off that played a huge
impact on balancing the ice-filled arctic ecosystem.

So, given that scenario, I think the better question to ask is, what benefit
would we, as humans, get from a return to a cooler Earth? IMO wildlife will
take care of itself: adapt, die off, etc. the same way it always has. BUT, I
think that too often the focus is put on sad-looking animals and melted
snowcaps, which makes it seem like global warming is just an
"environmentalist" issue rather than a serious threat to human life.

~~~
oinksoft
Oh, come on, are you trying to say that all endangered species will just adapt
to live amongst humans if their habitat is destroyed? Your idea about polar
bears foraging for human garbage is laughable: These creatures are (1) purely
carnivorous, and (2) incapable of living in warm climates. Polar bear
population has plummeted as their natural habitat has dwindled. Further, the
reason for wanting to save the polar bear is not just to save one species, but
that this animal's decline is a bellwether for the decline of the entire
arctic ecosystem. We can't say for sure what will happen if the arctic
ecosystem disappears.

The ongoing _massive_ extinction event driven by human activity is a real
thing. Do you want to live in a world where the only animals alive are ones
that humans raise as livestock, or that thrive amongst humans? Nothing but
pigs, chickens, pigeons, sparrows, cockroaches, bass and such. Sounds awfully
grim to me, but without serious efforts towards preserving wildlife, this is
precisely what the future holds.

~~~
dchichkov
It is purely a question of having the right technology. There is no law that
says that you can not engineer a polar bear that is _not_ purely carnivorous,
is capable of living in warm climate and very useful to humans in some way.
Same goes about every other species.

And it is not that sad. Well designed ecologies can be diverse and beautiful.
Even more diverse and beautiful than naturally evolved once.

~~~
djrobstep
[citation needed]

~~~
dchichkov
Well, I can't source precisely that phrasing. But imagine an engineered
ecology that is: less cruel than a naturally evolved one; as diverse; also
includes some 'dinosaur-killer-sized' asteroid impact aversion system that
prevents global scale mass extinctions. Wouldn't you find that ecology more
beautiful than a naturally evolved one (that we have now)?

~~~
mturmon
Given humanity's track record, my imagined idea of an engineered ecology is
not so rosy as yours. Who would do it, and what would their motivations be?

------
ctdonath
Temperature chart for the last 425,000 years:
[http://ctdonath.blogspot.com/2012/02/global-climate-
change-i...](http://ctdonath.blogspot.com/2012/02/global-climate-change-in-
context.html?m=1)

~~~
kolbe
Do you know why the original 11,000 year chart doesn't look anything like the
10,000 year chart in your link?

~~~
anon1385
His chart is based on a single data set (the vostok ice core) for the majority
of that period (plus modern temp records slapped on at the end, but it's not
visible in the 10,000 year graph) which is not representative of global
climate. Correlating proxy records with modern instrument records of
temperature is not trivial either (which becomes far more apparent once you
look at more than a single proxy record).

It's just cherry picked data to make a cheap political point. The scale of the
vertical axis makes it very hard to see what is happening during
interglacials, which is what we are in at the moment. If we were worried about
an ice age arriving in the next couple of centuries the choice of scale might
have some merit, to show how much colder it could possibly get. But we are
worried about rapid heating, which that scale does a good job of hiding.

~~~
sliverstorm
Why do people worry about the possibility of entering an ice age? That seems
like the sort of thing humanity is much more prepared to survive.

~~~
EdiX
We are more prepared to survive a 10 degrees drop than a degree and a half
increase?

~~~
sliverstorm
Not so much that a degree warmer is hard to survive, but the associated things
that either come along with or are implied by global warming seem more
damaging than colder weather and more ice, which we already know humans
survived no problem ages ago when they migrated through Siberia and Alaska.

------
crazy1van
My skepticism in climate change is based on a long history of censuses in the
scientific community that later proved to be completely wrong.

I'm not saying we should not try to understand the world. I'm saying we should
realize we have limits. The more complex the system we seek to understand, the
more we should be skeptical. The climate of the entire planet and to the
degree one particular species impacts it seems extremely complex to me. Hence,
I am highly skeptical.

~~~
leot
No one is saying that we should devote 100% of GDP to mitigating global
warming. Go ahead, factor in the uncertainty. What % of GDP should we spend to
avert the very real possibility catastrophic warning occurs? What % are we
spending?

~~~
crazy1van
If it were left up to me, I would say we should have zero forced spending and
an unlimited amount of voluntary spending to avert a potential global warming
catastrophe.

Let me remind you, that at any time you are free to donate any amount of your
own money to thwart global warming. That's not what some people really want
though. They don't want to spend their own money on the problem. They want to
spend other people's money on the problem. And I contend we don't know nearly
enough about the issue to cross that line.

~~~
tonyedgecombe
Really what you are saying is do nothing, at least be honest about it.

~~~
crazy1van
Only if you and all the other folks who are convinced of a need to act on
global warming choose to do nothing. The reality is that even among those who
think "we" need to act, most do not even have enough conviction on the matter
to volunteer to spend a dime of their own money on it.

~~~
leot
Because the world's climate is a public good, game theory predicts that this
kind of thing won't ever work.

We are semi-rational actors in a dynamic competitive system. We can all want X
to happen, and be willing to spend money to make X happen, but realize that
doing so would make our own lives worse because of the non-participation of
others, and so we contribute to making X happen not directly, but instead by
trying to put rules in place that enforce participation.

I refer you to:
[http://en.wikipedia.org/wiki/Public_good](http://en.wikipedia.org/wiki/Public_good)
[http://en.wikipedia.org/wiki/Tragedy_of_the_commons](http://en.wikipedia.org/wiki/Tragedy_of_the_commons)
[http://en.wikipedia.org/wiki/Game_theory](http://en.wikipedia.org/wiki/Game_theory)

------
brownbat
Out of idle curiosity, can anyone tell me more about what a 0.4 (0.6, 1, 2...)
°C anomaly _feels_ like, maybe with reference to cities that have climates
with differing annual averages? I mean, is it like shifting every city 5 ° in
latitude closer to the equator, or what?

(I know this wouldn't capture the whole story, I'm just curious.)

EDIT: I guess the state of New York has a range of annual average temperatures
from 4 °C to 12 °C, so maybe this isn't useful at all.
[http://en.wikipedia.org/wiki/Climate_of_New_York#Temperature...](http://en.wikipedia.org/wiki/Climate_of_New_York#Temperatures)

~~~
sethrin
Think of it more as extra energy being imparted to the global weather system.
This will have all sorts of fun and exciting effects, and as I understand the
warming will be greatest at the poles. Alaska has warmed by about 1.6[0] in
the last 60 years, and the interior of Alaska by 1.4° C in the last 100[1],
compared to a global temperature rise of .8° C over the same period. This has
resulted in the melting of thousands of cubic kilometers of glacial ice, with
this study[2] suggesting that this is the largest glaciological factor in
rising sea levels.

To the eyes of the native inhabitant, the glacial retreat is shocking, with
the lower altitude glaciers most affected. We've built glacier overlooks in
some places, where once the glacier was a stone's throw away, and now it's
barely visible, and in another few decades the only thing they'll be able to
show anyone there are photos. I've seen photos from the early 1900s of glacial
termini which towered over the masts of a sail-rigged steamer. Today there is
a fjord there, and the glacier is more than 13km away.

And you want to know what that feels like?

How about instead you imagine how it feels to watch the Arctic melting around
you, while an endless circus of millions deny that it's even happening.

[0]
[http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.ht...](http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.html)
[1]
[http://oldclimate.gi.alaska.edu/papers/Arctic62-3-295.pdf](http://oldclimate.gi.alaska.edu/papers/Arctic62-3-295.pdf)
[2]
[http://glaciers.gi.alaska.edu/material/arendt_phd.pdf](http://glaciers.gi.alaska.edu/material/arendt_phd.pdf)

~~~
brownbat
> And you want to know what that feels like? How about instead you imagine how
> it feels to watch the Arctic melting around you,

I said in the original comment that I was well aware this wasn't the entire
story.

There are some subjects where I really wish I could ask questions like someone
new to the topic and not immediately be branded as some kind of enemy.

~~~
sethrin
My apologies if you read any offense in my words; none was intended. Unless
you happen to have a heat ray and a hatred for H20 solids, I can't imagine
that you've had much of a personal hand in making it melty up here. I hope the
data I provided may serve you even if my rhetoric don't.

~~~
brownbat
Ah, sorry for reading too much into your comment.

While I've got you here, and while we're pushing the civil boundaries on the
topic, there's something on this subject I'm curious about, but have always
been afraid to ask...

Won't a more accessible / inhabitable taiga be kind of awesome?

I mean, low lying areas without hurricane protection swallowed by the seas,
algal blooms, the shutdown of the thermohaline cycle leading to a frozen
Europe, midwestern desertification, all these are well down the bad side of
the ledger. Harms are still outweighing the good. But isn't some of what's
going on up north good for humanity?

~~~
sethrin
I complain about glaciers, but they're really just the tip of the icefield.
Most of the ground here is some variety of permanently frozen (permafrost)[0],
so that's all going to melt at some point. Most of the population here does
not live on/near permafrost, despite that map. However, if you do happen to go
to Fairbanks or some more northerly hellhole, you'll find all the buildings
are built on stilts, elevated a few feet off the ground. If they were not, the
ground underneath would melt and sink (ice is less dense, remember), and
eventually you'd be making a nice cross-stitch for "Home Sweet Bog".

So there's that. There's no soil in most of Alaska; it's either been scraped
away by glaciers or the frozen layer is too close to the surface for much to
develop. In some places the pine taproots can only get a meter or so down, and
you'll have endless forests of man-high spindly pines. In many other places
there are no trees at all. This is generally what we call taiga. When the
permafrost underneath this melts, you're not going to have fertile soil left
behind, at least not for a really long time.

On the plus side, Alaskans are probably not going to complain a whole lot
about a warming trend, and the Northwest Passage is finally a thing. Maybe my
friend will finally be able to grow avocados? It's hard to come up with a lot
of other things that might be beneficial -- maybe we'll have more
opportunities for strip mining now that the glaciers are gone. Maybe in a few
million years the Alaskan Bog will be a good source of petrochemicals.

Really it's pretty hard to come up with good things, especially compared to
"most of the ground will melt". Siberia is likely to be much the same story,
as well as large parts of Canada -- you can find your own permafrost maps for
there. Oh, and we have problems with coastal storms here too, and are already
having to relocate whole villages (Newtok, Shishmaref, etc)[1][2]. Probably
the only really good thing is that not a lot of people live here now,
otherwise it'd be pretty easy to call the Arctic as the region most severely
affected by AGW.

[0]
[http://i1109.photobucket.com/albums/h427/m4135/ps9_zps5c9b1b...](http://i1109.photobucket.com/albums/h427/m4135/ps9_zps5c9b1bf0.jpg)
[1]
[http://en.wikipedia.org/wiki/Shishmaref,_Alaska](http://en.wikipedia.org/wiki/Shishmaref,_Alaska)
[2] [http://www.theguardian.com/environment/2013/aug/05/alaska-
ne...](http://www.theguardian.com/environment/2013/aug/05/alaska-newtok-
climate-change)

~~~
brownbat
Ah, thanks! I do appreciate the insight here...

------
exit
googling "industrial revolution averted iceage" returns a few conservative
blogs, smugly pleased with the possibility

the only credible commentary i can find is in a nytimes article:

"Scientists say that if natural factors were still governing the climate, the
Northern Hemisphere would probably be destined to freeze over again in several
thousand years. 'We were on this downward slope, presumably going back toward
another ice age,' Dr. Marcott said."

[http://www.nytimes.com/2013/03/08/science/earth/global-
tempe...](http://www.nytimes.com/2013/03/08/science/earth/global-temperatures-
highest-in-4000-years-study-says.html)

~~~
kaybe
I cannot cite the exact words, but in discussions professors have indeed
expressed the opinion that a next ice age won't be of concern for us.

Those charts, especially those going back further, are a good argument for why
we will need to control the climate at some point in the future (but please
not when we have not figured out how to without significant risk).

------
temphn
This plot compares an inferred model to the instrumental record. Here is the
study expressed in the words of Real Climate:
[http://www.realclimate.org/index.php/archives/2013/09/paleoc...](http://www.realclimate.org/index.php/archives/2013/09/paleoclimate-
the-end-of-the-holocene/)

    
    
      Over the last decades, numerous researchers have 
      painstakingly collected, analyzed, dated, and calibrated 
      many data series that allow us to reconstruct climate 
      before the age of direct measurements. Such data come e.g. 
      from sediment drilling in the deep sea, from corals, ice 
      cores and other sources. Shaun Marcott and colleagues for 
      the first time assembled 73 such data sets from around the 
      world into a global temperature reconstruction for the 
      Holocene, published in Science. Or strictly speaking, many 
      such reconstructions: they have tried about twenty 
      different averaging methods and also carried out 1,000 
      Monte Carlo simulations with random errors added to the 
      dating of the individual data series to demonstrate the 
      robustness of their results.
    

Marcott et al.'s graphic states that their model reflects historical
temperatures so accurately that it can measure the average temperature of the
entire globe continuously back to 8000 years ago, to within a small fraction
of 1 degree Celsius (i.e. the 1-sigma error bars). That is simply an
extraordinary claim given:

1) The "divergence problem". The lack of correlation between model inputs like
tree rings and the instrumental record over the last few decades is
acknowledged by all; climate scientists generally state that it is due to
anthropogenic factors, arguably assuming the consequent.

[http://www.skepticalscience.com/Tree-ring-proxies-
divergence...](http://www.skepticalscience.com/Tree-ring-proxies-divergence-
problem.htm)

2) Serious climate model prediction failures over the past 10 year period, as
acknowledged in Nature:

[http://www.nature.com/news/climate-change-the-forecast-
for-2...](http://www.nature.com/news/climate-change-the-forecast-for-2018-is-
cloudy-with-record-heat-1.13344)

In other words, key model inputs used in climate reconstructions do not
strongly correlate with the instrumental record over the last 30-40 years
("the divergence problem") and climate models have so far had a poor track
record over the last 15 years, with average temperatures winding up below the
envelope of model predictions. These predictive failures in the datasets we
can check bode ill for the prospect of hindcasting global average temperatures
to within 1 degree more than 8000 years ago.

~~~
asgard1024
In the same article, they explicitly mention that the study is not based on
tree ring proxies. In fact, all the global reconstructions are based on many
different proxies.

I also think you misrepresent the 2nd article. The question is what and on
what time scale are you trying to predict. I believe they are talking about
more precision more short-term models. Just like we can predict winter and not
predict weather, we can predict warming due to human forcing, but not the
specific details.

In the end, however, it's completely irrelevant to AGW if there was a higher
temperature in the past or not. The theory of AGW doesn't stand just on that
argument (nor any other single argument, for that matter).

~~~
thaumasiotes
Without trying to say too much, one big reason we can predict winter is that
we've had hundreds of thousands of years of experience with it.

------
nhoss2
Am I alone in finding the graph scary? This rate of change in temperature is
probably not something that would be easy to slow down, yet it feels like not
many people care about this.

------
moe
World population chart for the same timeframe:
[http://upload.wikimedia.org/wikipedia/commons/b/b7/Populatio...](http://upload.wikimedia.org/wikipedia/commons/b/b7/Population_curve.svg)

------
serichsen
It seems that the uncertainty is much higher at the end of the blue curve. I
wonder why.

It also seems that the red curve has no uncertainty data.

I would not dare draw any conclusion from these curves before I have
satisfying explanations for these two questions.

~~~
jellicle
It's probably because all the climate scientists in the world are trying to
trick you.

------
Gravityloss
"Worry about global warming impacts in the next 100 years, not an ice age in
over 10,000 years. "

[http://www.skepticalscience.com/heading-into-new-little-
ice-...](http://www.skepticalscience.com/heading-into-new-little-ice-age.htm)

Basically none of these memes are new. They often rely on misunderstanding of
context. (For those who didn't know, skeptical science rebuts these commonly
found arguments against global warming.)

------
microcolonel
Of note is that the chart's error bars fill the entire scale near the end, so
the measurements could really be anywhere there. It's anyone's guess whether
or not temperatures have somehow mysteriously skyrocketed or not.

My personal inkling is that the alarmist reports are wrong, and the changes
aren't as drastic as reported; since the same people publish results from
proprietary, rigged climate models.

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callmeed
Can someone please explain how we're able to know the temperature in 4,000 BC
with an accuracy of +/\- .2° C?

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kjackson2012
Global temperatures are basically flat for the last 17 years, and below every
single computer model of climate change. This is even more stark given the
fact that the most co2 has been produced in the last 17 years. I think the
theory is pretty much broken and they need to figure a better model.

[http://www.dailymail.co.uk/news/article-2420783/Worlds-
clima...](http://www.dailymail.co.uk/news/article-2420783/Worlds-climate-
scientists-confess-Global-warming-just-QUARTER-thought--computers-got-effects-
greenhouse-gases-wrong.html)

~~~
bjz_
[http://www.skepticalscience.com/global-warming-stopped-
in-19...](http://www.skepticalscience.com/global-warming-stopped-
in-1998-intermediate.htm)

The Daily Mail? Really?

~~~
kjackson2012
That's comparing apples to oranges. All the other data used to create the
original graph o calculate temperature such as tree rings, etc do not take
into account the temperature of the oceans, etc. There may be perfectly good
explanations as to why the temperature may be flat, but those same
explanations are not being fed into the graph that the OP posted.

~~~
anon1385
>All the other data used to create the original graph o calculate temperature
such as tree rings, etc do not take into account the temperature of the
oceans, etc

[https://en.wikipedia.org/wiki/Proxy_(climate)#Corals](https://en.wikipedia.org/wiki/Proxy_\(climate\)#Corals)

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dghughes
How much do we humans contribute to the heating of the world? The heat we
output from our bodies and population increases must mean more heat.

I say this because a friend has a small barn and in it two horses, two pigs
and some chickens. He said the barn doesn't use any heat source because the
heat from the two horses is enough to warm the barn. Even a bucket of water in
the barn won't freeze.

~~~
mturmon
A human uses about 100W. I don't know about horses, but depending on how well-
insulated the barn is, a few hundred watts would make a significant
difference.

About those humans heating the Earth -- the effect of the GHG's we emit is
tapping into solar insolation, which is huge, so it probably dwarfs the above
figures (see next paragraph). Also, the energy that powers us (food) would be
turned into heat by other processes anyway.

Order of magnitude: population of 7 billion * 100W/person = 9.7TW. Solar
insolation 1361 W/m^2, over the projected area of the earth, which totals
175,000,000 TW.

I just throw that figure (100W) as a useful order of magnitude estimate.

------
beloch
The cyclical recurrence of interglacial and glacial periods (we're technically
still in one of these) can theoretically be explained by cyclically evolving
properties of the Earth's orbit around the sun such as the precession of the
Earth's ratational axis (google Milankovitch cycles). This theory is
consistent with the gradual cooling trend observed thus far into the Holocene
epoch, and predicts it will continue for tens of thousands of years. The
linked graph shows this very nicely.

A sudden, full-blown glacial period would be far more disastrous for human
civilization than significant global warming. The latter would submerge
densely populated coastal areas and force humans to move to the new
coastlines, but the overall capacity of the Earth to support life would
increase, just as it did at the start of the Holocene. The former would result
in a large reduction in the Earth's carrying capacity and global famine.

Any change in the Earth's temperature is going to be disruptive to both human
civilization and the existence of other species on Earth. We have reversed the
effects of several thousand years of cooling in just a couple of centuries
and, assuming we are able to continue extracting and burning hydrocarbons at
an unabated pace indefinitely (dubious) we could significantly change the face
of the world, but it will still support our civilization, just in a very
changed state. Avoiding the pain of this change is ample incentive to curb the
use of hydrocarbons. (Edit: It has taken centuries and a significant portion
of the world's hydrocarbon reserves to produce less than a degree of warming.
At this rate, even if we evaded peak-oil for another thousand years the Earth
will still be in a glacial period.)

However, we should be much more aware of events that could trigger another
glacial period. Megaeruptions or large meteor impacts could plunge global
temperatures suddenly and catastrophically. These are far greater threats to
our species, but we are both incapable of adequately predicting them or
preventing them if we do predict them. The probability of this sort of event
happening in a single human lifespan is remote, while global warming is a
certainty, but these events will eventually occur with certainty. Managing
global warming is certainly a good idea for the comfort of our civilization,
but we should have more eyes on the bigger threats. (Edit: Even if we tried,
we would be unable to maintain global warming indefinitely simply by burning
hydrocarbons. In the ten-thousand year time-frame we will need to find other
ways to combat gradual cooling.)

~~~
magicalist
> Managing global warming is certainly a good idea for the comfort of our
> civilization, but we should have more eyes on the bigger threats

Orrrr we could do more than one thing at once?

In any case, a "sudden, full-blown glacial period" has never happened
according to any geological record we have. The most "sudden" have happened
over centuries. The actual, demonstrated suddenness of current warming trends
is a major part of the problem.

There are a bunch of problems in your post (I have no idea where you get the
idea that we're in a glacial period, these are just labels, but no one calls
the Holocene anything but an interglacial; it is well established that
Milankovitch cycles do not explain current trends; current atmospheric carbon
will be there for centuries to come and will not stop warming us even if we
were to stop all emissions today; you neglect ocean acidification, sea level
rise, etc), but the fact remains that its ridiculous to assert that "we should
have our eyes" on one threat instead of another, when we could have much more
scientists and funding for asteroid detection if someone would exert some
political will. _That_ is what's necessary, not trying to minimize other
threats with specious (at best) arguments.

------
codex
I don't think this chart comes close to proving that Obama was born in the
United States.

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jokoon
Sorry but I hear a lot of speculation, not real reports of hard actual life
threatening changes.

Maybe soft ones like the sea temperature and acidity, but most people can
still go out and food still grows.

------
crististm
Until you were there to measure the temperature, all you have is just the
output of a model. The model is not the world.

------
clubhi
Start burning tires folks. We need to save ourselves from an ice age.

------
JulianMorrison
Well, the upside is, we fixed the ice age that was trying to happen.

