
Causal feedbacks in climate change - gtt
http://www.nature.com/nclimate/journal/v5/n5/full/nclimate2568.html
======
DennisP
As far as I can tell from reading the abstract, this process was described in
Hansen's book _Storms of My Grandchildren_.

Sometimes, he wrote, we do get temperature increases in the geological record
right before we see the CO2 go up. Historically, that's happened on a regular
basis due to orbital variations. The fact that CO2 goes up afterwards is not
reassuring, it's a positive feedback that drives the temperature even further.

That's why climate change is so worrisome; it's not just the direct heating
effect of our emissions we have to worry about, but the additional heating
from the extra CO2 released by the planet.

~~~
danieltillett
Yes our ignorance about how the climate will respond to all the GHG release is
a cause for worry. The only area I can agree with the deniers is our climate
models are not very good and the error bars quite high - this is not a cause
for compliancy, but great concern.

~~~
adrianN
Exactly. There more we move away from "0° warming" the more likely we are to
encounter some nonlinearity that our current models completely miss.

------
mirimir
tl;dr

> In conclusion, our analysis provides direct confirmation that internal Earth
> system mechanisms rather than orbital forcing have controlled climate
> dynamics over the Pleistocene cycles. Moreover, they demonstrate the
> existence and importance of a feedback effect of temperature variability on
> GHGs in driving the dynamics (Fig. 1b). This confirms the existence of a
> positive feedback operating in climate change whereby warming itself may
> amplify a rise in GHG concentrations. As CCM infers causality directly from
> the time series, the consistency of our results with elaborate mechanistic
> analysis represents remarkable empirical confirmation and, moreover,
> provides a clock for the response times involved. We suggest that this new
> and powerful approach may also help to assess causality behind the numerous
> other time series we have for the Earth system.

~~~
semi-extrinsic
So, we all know that correlation does not imply causation. Yet it sounds like
this paper does some fancy dynamical systems theory stuff to prove causation
based on correlation. Can anyone shed some light on how this works?

~~~
mirimir
Well, it's explained in Methods, but over my head. I gather that instead of
just looking at correlation between X and Y, they first map X to a ‘shadow
attractor manifold’. Then they fit a relationship between this transformed X
and Y.

They cite Sugihara, G. et al. Detecting causality in complex ecosystems.
Science 338, 496–500 (2012) for this.

------
cryptoz
Here is some additional information about this paper:

"Direct evidence for a positive feedback in climate change: Global warming
itself will likely accelerate warming":
[http://phys.org/news/2015-03-evidence-positive-feedback-
clim...](http://phys.org/news/2015-03-evidence-positive-feedback-climate.html)

~~~
xyzzy4
Then why would an ice age ever happen?

~~~
arcadius
A very interesting topic is how the details of Earth's orbit at any one time
affect the change in global temperature. You can read more about it here:
[https://en.wikipedia.org/wiki/Milankovitch_cycles](https://en.wikipedia.org/wiki/Milankovitch_cycles)

~~~
cossatot
Milankovitch cycles are thought to be a major factor, by everyone from climate
scientists to oil companies (who have refined the history of these cycles
exquisitely to help identify petroleum in particular rock units deposited
during rising or falling sea levels).

Another, much longer term factor (tens to hundreds of millions of years) has
to do with the positions of the continents on earth, which affects how well
ice can be stored. If there is considerable landmass near the poles and it's
cold, then ice sheets can form, which increase the amount of reflected solar
radiation (albedo) and decrease the amount of heat stored in the oceans (which
have less volume due to ice sheet storage, and because sea level falls, the
warm shallow seas that hold a lot of heat are much smaller). This can help
cooling feedbacks. When the continents are arranged such that there is little
polar landmass, these situations are reversed which leads to heating.

------
TrainedMonkey
Here is PDF link to the paper:
[http://deepeco.ucsd.edu/~george/Publications/15_causal_feedb...](http://deepeco.ucsd.edu/~george/Publications/15_causal_feedbacks_climate.pdf)

edit: article -> paper

~~~
danieltillett
Here is the link to reference 8 which is the key method used in this analysis.

[http://www.uvm.edu/~cdanfort/csc-reading-group/sugihara-
caus...](http://www.uvm.edu/~cdanfort/csc-reading-group/sugihara-causality-
science-2012.pdf)

------
nonbel
As far as I know it remains controversial whether causality is a topic for
philosophy or science (ie do any of our most successful physical laws require
the concept of causality, I think not).

It irks me to see that term mixed into scientific discussions, because I am
sure it will just be assumed that everyone knows what they mean by "casual"
and accepts it as a useful scientific concept.

~~~
nerdponx
It sounds to me like you're arguing that we should never try to prove that
anything causes anything because we don't have a good definition of causality.

I hope that's not what you're saying, because it's absurd.

~~~
nonbel
>"we should never try to prove that anything causes anything"

I don't know about never, but the "c-word" gets thrown around way too freely
in my opinion. But yea, I am saying that the most successful science has had
little to nothing to do with causality. You see the focus on causality is more
common in the less successful endeavors such as the social sciences, perhaps
it is time to consider that the causality concept is a red herring (at least
when it comes to science).

To be sure, I am far from the first to entertain such thoughts: "Causality in
physics has had bad press in philosophy at least since Russell’s famous 1913
remark: “The law of causality, I believe, like much that passes muster among
philosophers, is a relic of a bygone age, surviving, like the monarchy, only
because it is erroneously supposed to do no harm” (Russell 1913, p. 1).
Recently Norton (2003 and 2006) has launched what would seem to be the
definite burial of causality in physics. Norton argues that causation is
merely a useful folk concept, and that it fails to hold for some simple
systems even in the supposed paradigm case of a causal physical theory –
namely Newtonian mechanics." [http://philsci-
archive.pitt.edu/4690/1/CausalFundam.pdf](http://philsci-
archive.pitt.edu/4690/1/CausalFundam.pdf)

~~~
tlarkworthy
Causality is central to hard science.

Its why we have concepts like dependent and independent observations. We split
observable dimensions into these groups so we can change the independent
variable and find out their causal effect on the dependent variables. The
whole reason we have "experiments" is so an experimenter can deliberately
change the system in a focused way, outside of its normal dynamics, to reveal
the causal structure of the system under observation. You can't do this by
passively observing the system. This is why we have experiments. This is core
to the scientific method.

~~~
nonbel
I don't think your argument addresses the concerns here. Here is an example:

"However short we make the interval t, something may happen during this
interval which prevents the expected result. I put my penny in the slot, but
before I can draw out my ticket there is an earthquake which upsets the
machine and my calculations. In order to be sure of the expected effect, we
must know that there is nothing in the environment to interfere with it. But
this means that the supposed cause is not, by itself, adequate to insure the
effect. And as soon as we include the environment, the probability of
repetition is diminished, until at last, when the whole environment is
included, the probability of repetition becomes almost nil.

In spite of these difficulties, it must, of course, be admitted that many
fairly dependable regularities of sequence occur in daily life. It is these
regularities that have suggested the supposed law of causality; where they are
found to fail, it is thought that a better formulation could have been found
which would have never failed. I am far from denying that there may be such
sequences which in fact never do fail. Ic may be that there will never be an
exception to the rule that when a stone of more than a certain mass, moving
with more than a certain velocity, comes in contact with a pane of glass of
less than a certain thickness, the glass breaks. I also do not deny that the
observation of such regularities, even when they are not without exceptions,
is useful in the infancy of a science: the observation that unsupported bodies
in air usually fall was a stage on the way to the law of gravitation. What I
deny is that science assumes he existence of invariable uniformity of sequence
of this kind, or that it aims at discovering them." [http://www.hist-
analytic.com/Russellcause.pdf](http://www.hist-analytic.com/Russellcause.pdf)

~~~
tlarkworthy
But modern physicists now say, I have done this experiment n times and can
claim with 6 sigmas of certainty this is how the universe works. We are able
to quantify noise in our signals, and sure, the end result is that nothing is
100% certain, but we still tease out causalities from the patterns in our
noisy world. Uncertainty in measurement doesn't prevent us from observing
causality.

------
eximius
I would be interested to know if they are claiming that

1) it will be harder to undo the changes we caused or 2) greenhouse gas
changes occurred as a result of temperature change

or some other combination of things.

~~~
neltnerb
It claimed by time series analysis for different variables that temperature
rises release greenhouses slowly while greenhouse gas concentration rises
increase temperature nearly instantaneously (geologically speaking).

i.e. positive feedback loop, but with drastically different time scales.

