
Even 50-year-old climate models correctly predicted global warming - aazaa
https://www.sciencemag.org/news/2019/12/even-50-year-old-climate-models-correctly-predicted-global-warming
======
svara
Svante Arrhenius got it basically right in 1896 [1]. There is no scientific
controversy and there never has been.

Unfortunately, arguing about this might just reinforce the mistaken view that
there are different valid "sides" to this.

[1]
[https://en.m.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_...](https://en.m.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_effect)

Edit: That doesn't detract from the article's more subtle point about the
_precision_ of climate models in the past, I was reacting to the comments here
viewing this in the light of a fictive controversy.

~~~
vmchale
Supposedly Fourier had some insight as well.

------
ekianjo
Where is the story hère though? So they looked retroactively and found some
models in the past that fitted with current observations even though they had
no clue that China would become such a powerful force in terms of CO2
emissions?

If you run random models and wait long enough you will always be able to find
at least one model that predicted the current observations. That does NOT mean
the models were right, it means that you are basically ignoring all the other
models that made bad predictions. So in order to make a headline out of this
you would need to make a extensive review of all the models we had back then
and found out HOW MANY were actually not bad.

Would not make that much of a headline because you would find most models were
bad. Anyone involved with forecasting will know what I mean.

~~~
starpilot
Yeah, this could be survivorship bias:
[https://motls.blogspot.com/2017/03/selection-of-climate-
mode...](https://motls.blogspot.com/2017/03/selection-of-climate-model-
survivors.html)

As someone who's written basic fluid dynamics codes, I'm blown away by the
complexity of climate models. The errors I ran into in debugging my relatively
straightforward codes were incredibly subtle. Like pressures, velocities still
"looking right" but still being wrong, due to numerical viscosity and other
artifacts of the inexact solutions to Navier-Stokes. This is for flow in a box
in a steady state. For an entire planetary atmosphere at a time scale of
decades, I can't even imagine how they can track down every error without duct
taping "corrections" (overfitting) on everything.

~~~
IanCal
Doesn't this partly fall into the weather Vs climate difference? I can't run
fluid dynamics in my head but no matter how much you shake up the box once
it's on the table I can say "I think the water/oil/honey will end up at the
bottom".

But also yes, it's complex, that's why independent groups dedicate huge
amounts of time researching and building them and then models are compared
against each other.

~~~
telotortium
> Doesn't this partly fall into the weather Vs climate difference? I can't run
> fluid dynamics in my head but no matter how much you shake up the box once
> it's on the table I can say "I think the water/oil/honey will end up at the
> bottom".

Not in the slightest. For example, the output of a numerically unstable [1]
algorithm, run on 64-bit floats, can diverge arbitrarily from the output of
the same algorithm run on real numbers with infinite precision (which
computers can't do). Often this will lead to obviously wrong outputs, but not
always. There are numerically-stable versions of most of the workhorse linear
algebra algorithms, but (1) sometimes it's possible to use a faster,
numerically unstable algorithm, and this is a matter of judgment that can be
mistaken and (2) it's easy to introduce numerical instability via subtle bugs,
or even via the exact arithmetic steps you use to calculate a result (in
particular, trying to add or subtract two numbers of very different orders of
magnitude is a big no-no).

[1]
[https://en.wikipedia.org/wiki/Numerical_stability](https://en.wikipedia.org/wiki/Numerical_stability)

~~~
irq11
This is not a rebuttal to the parent. They’re talking about stability of
prediction of aggregate properties, and you’re fixating on numerical precision
errors and algorithm bugs in particular implementations. The one has little to
do with the other.

Numerical instability leads to obvious, wildly inconsistent errors. It isn’t
subtle. Literally no climate simulations are going off the rails because of
these kinds of first-year grad-student code problems.

------
jml7c5
I'm not sure if he'll pop in here, but one of the co-authors (Henri Drake) has
a comment thread on /r/science if anyone wants to ask any questions:
[https://www.reddit.com/r/science/comments/e63ic5/of_17_clima...](https://www.reddit.com/r/science/comments/e63ic5/of_17_climate_models_published_between_the_early/f9no11k/)

EDIT:

Here is some of the code used in the paper:
[https://github.com/hausfath/OldModels](https://github.com/hausfath/OldModels)

Here is a blog post on the paper, written by one of the authors:
[http://www.realclimate.org/index.php/archives/2019/12/how-
go...](http://www.realclimate.org/index.php/archives/2019/12/how-good-have-
climate-models-been-at-truly-predicting-the-future/)

EDIT AGAIN:

The "supporting information" .docx at the bottom of this page has a lot more
detail, for those (like me) who can't get past the paywall ( :-/ ):
[https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019...](https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL085378)

~~~
aidenn0
When Henri was suggesting to use specific models for specific predictions, he
added this note:

> Note to reader: I was going to use Arctic sea ice in 2100 as an example, but
> there probably won’t be any lol

~~~
huffmsa
There has been sea ice in the Arctic for well under 50% of the planets
history.

Life thrived

The Sahara desert was a grassland 5000-10000 years

Life thrived.

~~~
gowld
Most people are interested in a particular subset of life thriving.

~~~
huffmsa
You don't think we will?

Perhaps not as many of us. But that's part of the problem isn't it? Too many
humans, chopping down forests, over fishing, sucking melted dinosaurs out of
the earth.

~~~
MagnumOpus
If I undertand right, your proposed alternative solution to cutting carbon
emissions is to let a few billion people die in famines and resource wars?

I kinda question that the living quality and wealth of the survivors ends up
better in your scenario...

------
starpilot
It does seem like survivorship bias could be a factor. The article talks about
how some of the old models were off until they "corrected" them. All right,
and did they apply the same scrutiny to the apparently "correct" ones? "All of
the models predicted this (except for the ones that didn't.)

~~~
henrifdrake
The correction is based on physics is really quite straightforward...

~~~
refurb
If it's so straightforward, why wasn't it accounted for in the first place?

Honest question.

------
refurb
I’m confused as hell to be honest. A few years ago they said there was a
global warming pause.[1]. They seemed so sure it was happening that Nature
devoted a whole issue to it.

Then they came back and said “actually it never happened”.[2]

Shouldn’t it be pretty straightforward to tell whether there was warming or
not?

[1]
[https://www.nature.com/collections/sthnxgntvp](https://www.nature.com/collections/sthnxgntvp)

[2] [https://insideclimatenews.org/news/18122018/global-
warming-h...](https://insideclimatenews.org/news/18122018/global-warming-
hiatus-pause-never-happened-studies-explain-climate-change-risbey-oreskes-
mann)

~~~
chrisbrandow
Most scientists didn’t think much of the idea of a pause, but skeptics started
beating the drum so consistently and loudly after a few years after 2001 that
the media began asking the question pretty consistently, and the climate
science community had to spend time answering the question.

There was never some broadly held idea that warming dynamics had paused.

~~~
refurb
My link has _dozens_ of papers that claim to explain the pause. It wasn’t we
_think_ there is a pause, they are already explaining _why_ there was one.

I’d say a full issue Nature dedicated to exploring why there was a pause,
suggests it was a broadly held idea.

That said, if there was no consensus, why is that? Why do some scientists
believe there was a pause, while others disagree? Isn’t figuring out whether
warning was happening pretty straightforward?

~~~
moultano
> Isn’t figuring out whether warning was happening pretty straightforward?

Not exactly. There are two ways that it can be ambiguous:

1\. We don't measure the entire earth to measure its temperature, and
combining the sensor readings from various sources to get a calibrated total
energy content can be difficult.

2\. It is difficult to take a time series, and with a short history, decide
whether something is a significant deviation from the trend or just random
variation. Humans instinctively underestimate how often a random sequence of
coin flips will have consecutive strings of heads of a given length, and the
same tendency causes us to see a "pause" as a deviation from the trend, when
it's really just random variation causing a bunch of consecutive heads.

------
s1k3b8
There were dozens and dozens of "climate models" which predicted everything
from global cooling to a fiery wasteland and everything in between. Of course
you could go back and find a model that "predicted" correctly because every
possibility was predicted.

That's like dozens and dozens of "stock price models" predicting FB stock to
go up, down and stay the same. Of course one is guaranteed to be correct.

What is "scientific" about this? It's simply people who want to prove
something and then narrowly searching for the data to prove that point and
ignoring everything else.

This is so disappointing coming from something calling itself a sciencemag.

~~~
jointpdf
This comment is just completely nonsensical and intellectually dishonest. This
is not _at all_ what this paper did, nor what any remotely credible scientific
study ever does.

~~~
s1k3b8
> This comment is just completely nonsensical and intellectually dishonest.

I'm sorry you feel that way. Would be interested to find which parts you felt
was "nonsensical and intellectually dishonest" so I expand on it and clarify
it for you. Hard to respond to an ad hominem.

> This is not at all what this paper did, nor what any remotely credible
> scientific study ever does.

It's exactly what it did. How about this. If a "anticlimatemag" opposed to the
climate change agenda had an article titled "Even 50-year-old climate models
were wrong about global warming", would you be defending it as vigorously?

~~~
jointpdf
No, that was a statement of fact. The core problem is that your comment
(ironically) commits the very offense that you are falsely projecting onto the
authors. Namely, you are redefining concrete terms to fit the meaning that you
want them to have (=nonsense) and generating your own set of easily-
disprovable "facts" and stating them as truth (=intellectual dishonesty). I
_feel_ exasperated and exhausted from spending my evening responding to
shallow anti-science trolling (note: not an _ad hominem_ since I'm addressing
your words and not you as a person), which led to my response. But since you
asked politely, let's walk through a fiery wasteland of mangled logic.

> _There were dozens and dozens of "climate models" which predicted everything
> from global cooling to a fiery wasteland and everything in between._ > _What
> is "scientific" about this? It's simply people who want to prove something
> and then narrowly searching for the data to prove that point and ignoring
> everything else._

The paper clearly states their methodology, which included a literature review
to find all published climate models that produce a numeric forecast for
future average temperatures. I quoted the relevant section in a different
comment. If they missed or ignored _dozens and dozens_ of other published
climate models, then find them and show us. Otherwise, you're explicitly
accusing the authors and publishers of peer-reviewed science of committing
research malpractice.

> _Of course you could go back and find a model that "predicted" correctly
> because every possibility was predicted._

The output of a climate model (in this context) is an expected value (i.e. a
single real number) of the global mean temperature at time _t_ (in years). It
is true that if the support of a random variable is the real numbers, then
every outcome in (-inf, +inf) is weighted by some probability density (and yet
any _particular_ outcome in the set of reals occurs with zero probability!).
But it is decidely untrue that the model predictions analyzed by this study
(or produced by climate scientists in the time period considered by the study)
contained the set of all possible outcomes. It data evaluated is _one_
temperature value per model per year are published right here--take a look:
[https://github.com/hausfath/OldModels/tree/master/references](https://github.com/hausfath/OldModels/tree/master/references)

> _That 's like dozens and dozens of "stock price models" predicting FB stock
> to go up, down and stay the same. Of course one is guaranteed to be
> correct._

Effectively the same fallacy as above, but with a discrete number of outcomes.
The point of probabilistic forecasts is not to be correct (this goes against
the definition), it's to estimate the likelihood that a certain outcome will
occur in the future given information known up until the current time (ideally
--but not necessarily--so that some rational decision can be made). Laypeople
often incorrectly redefine prediction to meaning the black-or-white selection
of a particular future outcome. I could go on, but I suggest you read this
masterpiece instead: [https://fivethirtyeight.com/features/the-media-has-a-
probabi...](https://fivethirtyeight.com/features/the-media-has-a-probability-
problem/) (or _Thinking, Fast and Slow_ for the human psychology lens on this
problem of misunderstanding the nature of uncertainty).

> _If a "anticlimatemag" opposed to the climate change agenda had an article
> titled "Even 50-year-old climate models were wrong about global warming",
> would you be defending it as vigorously?_

Um, no? I do not and will not defend blatantly false anti-science regardless
of the source or agenda. That is extra true of anti-science that supports an
avoidable existential threat to half of all species, countless current and
future human lives (especially in the developing world, who bear most of the
costs while contributing a negligible amount to the problem), and perhaps to
civilization and the era of an inhabitable Earth itself.

But as the essential quote goes, "All models are wrong, but some are useful".
It's always possible for disingenous headlines like the hypothetical Climate
models are useful because they enable us to (quite accurately, it turns out)
estimate risks to our single most precious resource, which then allows us to
take rational action to minimize that risk (and other models, e.g. those
produced by environmental economists, suggest ways to balance the costs of
mitigative action).

Your comments, on the other hand, are not useful (so far...).

------
yters
What about the 50 year old models that predicted a looming global cooling? Why
were they wrong?

~~~
tzs
Those predictions were based upon projections that we would not address the
growing levels of smog and other particulates, and the cooling effect from
those would be larger than the warming effect from greenhouse gases.

We did address smog. Without growing smog, those models predicted warming.

~~~
yters
Would increasing particulates be an effective way to stop global warming?

~~~
hatmatrix
That's one proposal for geoengineering (either sulfate particles in the
stratosphere, or marine particles over the oceans). More for a "pause" or slow
down rather than a solution to stop it.

------
acje
I never doubted our capability to predict short term (10s of years)
temperature change from CO2 levels.

I'm also 100% sure we aren't capable of predicting the consequences of these
temperature changes, because they are going to be complex. This will be an
interesting ride and the train has left the station. We may want to find more
diverse controls than just the CO2 emissions. How about manipulating not just
land but also the oceans to run more efficient photosynthesis? Dangerous
perhaps?

------
ev0lv
I find it absolutely disastrous that we spend more time talking about the
environmental impacts of humans, than we do about the inevitability that one
of the Sun's CMEs completely decimates our power grid and can cause warming of
several orders of magnitude higher than the human footprint.

------
ltbarcly3
This reminds me of the models I made a few years ago to predict where a
Frisbee will land after you throw it. I made about 14 different models, some
of them _correctly predict where the Frisbee will land_. That's right, I have
a model that can tell you where the Frisbee you are about to throw will land,
it correctly predicts Frisbee throws.

Here is how it works: You input all the factors of your Frisbee throw. Then
you throw the Frisbee, and that's it! Well, I guess there is one more step,
since all 14 models make wrong predictions about where the Frisbee will land.
But you can just go back and adjust the models and input better data after you
already know where the Frisbee actually ended up, and then some of them
correctly predicted where it will land!

Don't down-vote me, this is definitely what the phrase 'correctly predicted'
means, and I'm not being misleading at all.

------
metasj
The clearest models should be: what the world looks like when all ice and
permafrost are melted, and how we plan now to be able to cope then.

------
nanis
Some time ago, I got curious about the sources of data in the period where
humans were measuring temperature using thermometers. When we talk about
predictions from fifty years ago matching today (also I read the linked
article and I didn't really see proof that a model that was specified at that
time being explicitly benchmarked), it matters how the distribution of sources
of surface temperature data varied since then.

I haven't been motivated enough to do another one of these animations, but
this video[1] shows locations of all temperature stations in GHCNv3[2] (I see
that GHCNv4[3] is out). Notice how where humans measure temperature depends so
much on what living conditions humans seek or find acceptable. I find this
visualization interesting in terms of the number of modeling questions it
poses. If you are interested, it shouldn't take much to replicate something
similar with current hardware/software.

As another note, it makes little sense to say model predictions are not
statistically significantly different from each other. What is the population
from which these models are being drawn? What is the measure of variability
among models? The article[4] is behind a paywall, so I can't see what they
did.

[1]:
[https://www.youtube.com/watch?v=h95uvT67bNg](https://www.youtube.com/watch?v=h95uvT67bNg)

[2]: [https://www.ncdc.noaa.gov/data-access/land-based-station-
dat...](https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-
based-datasets/global-historical-climatology-network-monthly-version-3)

[3]: [https://www.ncdc.noaa.gov/data-access/land-based-station-
dat...](https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-
based-datasets/global-historical-climatology-network-monthly-version-4)

[4]:
[https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019...](https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019GL085378)

------
garchee
We didn't listen.

~~~
dmead
we didn't listen!!

~~~
hkt
_We_ listened..

~~~
dmead
oh sharon!

------
ropiwqefjnpoa
And yet other 50-year-old climate models in-correctly predicted global
cooling.

~~~
hcknwscommenter
No. No they did not. This is wrong.

~~~
sambull
They aren't wrong technically, but the papers relied on key mechanisms that no
longer are as big of a issue thus negated. Particulate matter, the effect is
now actually being considered as a method of 'geoengineering' a cooler climate
to combat the warming by businessmen like Bill Gates [0].

[0] [https://www.cnbc.com/2019/09/07/bill-gates-funded-solar-
geoe...](https://www.cnbc.com/2019/09/07/bill-gates-funded-solar-
geoengineering-could-help-stop-global-warming.html)

------
mysterydip
When I was growing up we had a set of encyclopedias from the 70s. They were
predicting a new ice age coming if we didn't change our ways. Anyone else
remember this? I doubt I can find them online but I'll look.

~~~
pragmar
There was a paper by Rasool and Schneider in 1971 that was behind this, I
think. "Our ways" would've been industrial particulate pollution, where a 4x
increase, sustained, risked kicking off a new ice age. Schneider later
retracted the findings in 1974.

~~~
mysterydip
Ah, thanks for explaining the (possible/likely) origin!

------
nabla9
These climate models can also correctly predict the climate on other planets.
Planetary scientist use the same models, modified to it to match conditions in
Mars, Venus and run them to get more coarse but essentially correct climate.

------
huffmsa
Its almost like they're predicting that we're a few thousand years into the
process of coming out of an ice age.

More at 11.

~~~
lukifer
I don't think there's any disputing the overall trendline, which far predates
the Industrial Revolution. Yet that doesn't mean that human activity isn't
also meaningfully impactful. Though it's hardly scientific, from a layperson's
perspective, I find xkcd's climate history megacomic instructive:
[https://xkcd.com/1732/](https://xkcd.com/1732/). That rapid-ish spike after
1900 is by no means a smoking gun, but it's a hint that there may be more
going on than a ten-thousand-year gradual geological process (which I don't
think any climate scientist disputes the presence of).

I know of at least a few cases, where skeptics have changed their minds due to
new evidence (Richard Muller [0] comes to mind). I'm curious if there are any
instances of reputable scientists with sufficient training in the relevant
fields, who went from true believers to significant skepticism of
anthropogenic influence.

[0] [https://www.nytimes.com/2012/07/30/opinion/the-conversion-
of...](https://www.nytimes.com/2012/07/30/opinion/the-conversion-of-a-climate-
change-skeptic.html)

~~~
huffmsa
I'm mostly concerned about the scale were looking at. A 50-100 year uptick is
nothing on the timescales that the planet operates on.

Even 20k years is miniscule.

~~~
lukifer
No dispute. And yet, I don't see any other instances of the a near-45-degree
angle spike over the last 20k years (with the obvious caveat that our data on
the past is imperfect).

Like I said, not a smoking gun; just a clue that it's worth digging into. And
from a Bayesian perspective, one must ask: what are the odds that that rising
temperature would happen to correlate with CO2, for entirely unrelated
reasons?
[https://www.youtube.com/watch?v=Sme8WQ4Wb5w](https://www.youtube.com/watch?v=Sme8WQ4Wb5w)

Don't get me wrong, I find Greta-style alarmism and claims of "extinction" to
be counter-productive. But given how difficult it is to get nerds to agree on
_anything_ , the fact that there are so few credible scientists on the other
side of the issue gives me pause. Pure groupthink? Maybe. Hardly
unprecedented. But we've been examining the data and improving the models for
decades (including from those with a strong financial incentive to debunk
AGW), and yet the scientific consensus continues trending in one direction.
Skepticism is a good thing, but the evidence for AGW can't merely be handwaved
away by causal narrative.

~~~
huffmsa
By no means do I want to hand wave it, I'm just personally not convinced of
the presented outcomes.

I know that alarmism is the best way to get attention, but its also the best
way for me to think you're a zealot who should be ignored.

------
m0zg
That's not "prediction". Prediction is when you say something will happen and
then it does, at least somewhat reliably. Better yet, if you have some skin in
the game, such as your scientific reputation. I.e. if you say there won't be
any polar bears by 2020, their population better not quadruple to thwart your
prognostications.

[https://fee.org/articles/the-myth-that-the-polar-bear-
popula...](https://fee.org/articles/the-myth-that-the-polar-bear-population-
is-declining/)

It's very easy to find a model that predicts this retrospectively. It's also
completely worthless. Predicting the future is much harder.

That's my main beef with climate science: not only do they do this kind of
hand picking retroactively and claim they're able to "predict", they also
sometimes go back and _tweak the input data_ to fit the models better, or make
it up entirely where coverage is inadequate. This is not how science is done
in any other field. This also doesn't feel like it's being treated as an
existential threat would be treated, in terms of scientific rigor. I
understand it's a very complex problem, sure, but that doesn't give you a
license to take arbitrary liberties with scientific method or ground truth
data.

------
beatpanda
"Well of course the models were right", you say to yourself. Who is still
arguing about this? The evidence has piled up to the extent that being
"skeptical of the science" is unacceptable in educated, elite spaces (such as
Hacker News and the tech industry generally).

But now, as you can already see proliferating in the comments to this piece,
the new acceptable contrarian take on climate change is that _of course_ its
happening, but since life thrived on the planet during other climactic
conditions there's nothing to worry about.

The message is the same as it's always been: trying to do anything in response
is foolish, and we should all continue to just focus on making as much money
as possible.

But the real issue with climate change is and has always been that it will
_socially and politically_ de-stabilize the planet, because quite a few people
live in places that will become less livable in the near future, and those
people will want to go somewhere else.

Those people will have a quite strong claim on land and resources in wealthy
countries that emitted most of the pollution and have lots of mostly empty and
more habitable land. This will cause global conflict on a scale beyond any
that exists in living memory.

Yes, "life" will survive. Our societies in their current configurations will
not, and decisions we make now will determine how messy or violent (or not)
that transition will be.

Pedantic retorts about geological time should embarrass you in the face of the
leaders of the tech industry evidently using their immense wealth to prepare
for social collapse[1].

And although these people are clearly willing to spend money to prep for
climate change, I _still_ can't get a single one of the recruiters who cold-
call or email me about HOT NEW SILICON VALLEY OPPORTUNITIES to find me a
single credible company working on anything climate or energy adjacent. I can
just hear their jaws slackening every time I bring it up.

1\. [https://www.theguardian.com/news/2018/feb/15/why-silicon-
val...](https://www.theguardian.com/news/2018/feb/15/why-silicon-valley-
billionaires-are-prepping-for-the-apocalypse-in-new-zealand)

~~~
codingslave
Science is not a religion, its continuing integrity hinges on unbridled
skepticism.

