

Climate Slowdown Means Extreme Rates of Warming 'Not as Likely' - rpm4321
http://www.bbc.co.uk/news/science-environment-22567023

======
rayiner
The thing that really put climate change in perspective for me was when a
professor pointed out that the last ice age was just 4-5C colder than today,
but that meant that the place where we were sitting, on the shore of Lake
Michigan in Chicago, was under a mile of ice.

~~~
glurgh
That seems like a (probably inadvertently) awful example. Chicago is right
smack in the middle of the 'tongue' of the Laurentide ice sheet that sticks
out way to the south - even today, without miles of ice the climate of NYC and
Barcelona are quite unalike while being at the same latitude. At the point of
maximum extent global mean temperatures were already rising, there were great
big gobs of the Pleistocene in which they were far lower.

'Mean surface temperature' is something that can be directly measured or
estimated from paleometeorologic proxies but without models for the underlying
mechanisms, it's pretty uninformative.

[http://en.wikipedia.org/wiki/File:WhereIsTheHeatOfGlobalWarm...](http://en.wikipedia.org/wiki/File:WhereIsTheHeatOfGlobalWarming.jpg)

And the linked references give some idea of how very misleading, taken at face
value, mean global temperatures can be.

Even just doing a bit of napkin physics - if one applied the energy needed to
heat the top meter of ocean by one degree to the first meter of air, it would
be like taking a blowtorch to the layer of air in question.

Examples like that are pithy but they're almost like walking up to a denialist
and saying 'I want you to hit me in the face, as hard as you can'.

~~~
rayiner
The point is that a relatively small change to the average can mean major
changes locally. It's irrelevant what the ice coverage in New York was. We
weren't in New York.

~~~
glurgh
The 'change to the average' is not small. Local changes exceed that all the
time, though. I never mentioned the ice coverage of New York.

It's an ass of an example. It's not like I'm calling you an ass for using it
but come on. It might have convinced you but it's bad. Many people with a
secondary education have airplane lift taught to them in terms of the
Bernoulli principle, even if, at the end of the day, it doesn't actually
explain lift.

------
hristov
I am going to quote the end of the article in order to make valiant attempt to
prevent a budding flame war:

\-----------

"Is there any succour in these findings for climate sceptics who say the
slowdown over the past 14 years means the global warming is not real?

"None. No comfort whatsoever," he said.

\-----------

So global warming is still real and it is still happening. It is just that the
rate of warming has slowed down somewhat.

~~~
sultezdukes
You're not trying to prevent a budding flame war, you're just trying to
preempt the "deniers" from denying.

And I guess you didn't get the memo. You can't call it global warming now. You
have to call it climate change. That way, no matter what happens and no matter
how cold it gets, evil man and evil capitalism can still be blamed.

~~~
btilly
_And I guess you didn't get the memo. You can't call it global warming now.
You have to call it climate change. That way, no matter what happens and no
matter how cold it gets, evil man and evil capitalism can still be blamed._

If you're trolling, that kind of trolling is not wanted around here.

If you're not trolling, then you didn't understand the article. This study
finds a rate of warming at 80% the consensus average of predictions from
several years ago, and well within the previous uncertainty bars. So evidence
of warming is getting stronger, not weaker, even though the exact predictions
of how fast it is warming are coming in on the conservative side of previous
estimates.

~~~
gwright
The dispute has not been about 'warming' in the abstract but about
'catastrophic warming'. So while the evidence for 'warming' may be getting
stronger, the evidence for 'catastrophic warming' would seem to be getting
weaker.

The longer we go without significant warming, the lower that growth rate will
get and the weaker the argument for a catastrophic warming will be.

~~~
btilly
Define catastrophic.

At current rates of change we are looking in near decades at changing rainfall
patterns that will result in regions and countries suffering permanent
drought, and others suffering regular flooding and other forms of extreme
weather. Among the areas predicted to have severe and permanent drought is the
southeastern USA.

Furthermore we are learning about new risks. For instance ocean acidification
has put us on a possibly irreversible path towards world-wide mass extinctions
of organisms that use calcium carbonate for protection. This includes coral
and shellfish. Nobody knows what resulting ecosystem changes will happen, or
what the consequences for commercial fisheries which are a critical food
supply for populations around the world.

The only way in which these things do not qualify as "catastrophic" is in
comparison to worse catastrophes that were within the realm of theoretical
possibility, but which now seem less likely. For the planet as a whole, and
for people on the planet, the current course bears a series of inevitable
catastrophes in our future.

~~~
gwright
It is all about the feedback. No one disputes the physics of warming created
by CO2 emissions. But that warming is insufficient to create the run-away
warming predicted in climate models.

The increases necessary to generate the catastrophic scenarios that you (and
many others describe) requires that there be an aggregate positive feedback
mechanism in the climate system to magnify the CO2 warming (the
anthropomorphic warming). If you read any of the literature you'll see this
refered to as the 'climate sensitivity'.

No one knows the actual climate sensitivity relative to CO2 concentrations. No
one knows what all the various positive and negative feedback mechanisms are.
These are all suppositions by climate scientists that are plugged into their
models in order to make the models accurate output the _historical_ record.
Then there is a grand leap of faith that says that the models will accurate
predict the _future_ record. Except that for the last 10-20 years, the models
have been _wrong_. CO2 has increased but the temperature has not changed
according to the models prediction.

The original article says:

 _The Intergovernmental Panel on Climate Change reported in 2007 that the
short-term temperature rise would most likely be 1-3C (1.8-5.4F).

But in this new analysis, by only including the temperatures from the last
decade, the projected range would be 0.9-2.0C._

So the models will be tweaked (for example by reducing the climate
sensitivity) in order to generate output that matches the new historical
record which has 10-20 years of no statistically significant warming.

The problem with all this is that the models can _always_ be tweaked to match
the historical record while at the same time generating whatever future
prediction you want. And if that doesn't work, you just tweak the model again.

I'll start to believe that the models are reasonable when they remain
unchanged for several decades while still tracking the actual observations.

~~~
btilly
First of all a note. I've made a substantial fraction of my living over the
last decade from my understanding of statistics. When I look at a projected
statistical range of 1.0-3.0 that later got refined to 0.9-2.0 I see that as a
fit. Sure, the bottom end of the new range moved out of the bottom end of the
old range. But if you watch an A/B test run, you'll see that this is entirely
expected. But the median prediction of the new range - the most likely outcome
- is 1.55 which is (assuming that the original range was a 95% confidence
interval) is inside of 1 standard deviation of the prediction.

Secondly when you say that the _warming is insufficient to create the run-away
warming predicted in climate models_ you're in disagreement with the vast
majority of people who have actually tried to run the numbers. Having just
seen you draw an incorrect "not a fit to the statistics" from something that I
know very well looks exactly in line with what I'd expect a fit to look like,
I'm going to trust that scientists understand their own numbers better than
you understand them.

Thirdly your claim that the new historical record has 10-20 years of no
statistically significant warming is just plain false. The article this
discussion started about finds that if you just use data from the last decade
and project that forward you get an average projection of increasing 1.55C in
a period that previous models had said would increase 1-3C. That doesn't look
to me like you're not warming.

And finally I'm glad that scientists don't let their models sit still for
decades. It is a fact that the models have huge error bars. I want them to
improve the models, to bring them down. And the fact that the new models are
in good statistical agreement with the old is confirmation that the old models
were reasonable (if less accurate than desired). Until we see a statistical
lack of fit between old and new data (which has yet to happen) - there is no
statistical reason to doubt the science.

In the meantime I'm concerned that the 10 years with the least arctic ice in
the summer all happened in the last 10 years. You may dismiss that data point.
But in all of the discussions about newly available oil drilling locations and
transport routes, it is worth noting that it is a very visible sign of a major
global phenomena.

BTW if you want to dig farther, I recommend
[http://onlinelibrary.wiley.com/doi/10.1029/2011GL048794/abst...](http://onlinelibrary.wiley.com/doi/10.1029/2011GL048794/abstract)
for a detailed energy budget of where heat appears to be going right now.

~~~
glenra
> _The article this discussion started about finds that if you just use data
> from the last decade and project that forward you get an average projection
> of increasing 1.55C in a period that previous models had said would increase
> 1-3C_

No, for some definitions of "the last decade" the trend line is cooling and
for others it really is flat.

If you define "the last decade" as the ten year period ending this month, the
temperature trend looks like this (slight cooling):

[http://www.woodfortrees.org/plot/wti/last:120/plot/wti/last:...](http://www.woodfortrees.org/plot/wti/last:120/plot/wti/last:120/trend)

(The "woodfortrees index" shown is built from an average of several standard
temperature series - if you like HADCRU or GISS or some other specific one you
can select it from the popup menu and hit the "plot" button to see that
instead.)

The 15-year trend _is_ rising, but just barely so:
[http://www.woodfortrees.org/plot/wti/last:180/plot/wti/last:...](http://www.woodfortrees.org/plot/wti/last:180/plot/wti/last:180/trend)

The 20-year trend is still positive, but the recent flattening is real and it
has already been flat enough long enough that it's starting to pose a serious
problem for the model predictions, hence articles like this one.

> _But the median prediction of the new range - the most likely outcome - is
> 1.55 which is (assuming that the original range was a 95% confidence
> interval) is inside of 1 standard deviation of the prediction._

Er, no. You're assuming the probability distribution is a normal distribution
with the median in the middle - it isn't. IIRC, some of the newer attribution-
based papers that have been forcing them to shift the window to the left have
a positive skew - the median peak is way on the left side and then there's a
"long tail" on the right. So depending on which papers they use it's actually
possible the new median could be outside the 95% confidence interval of the
old range.

~~~
btilly
Interestingly when I went looking I came up with
[http://www.guardian.co.uk/commentisfree/2008/jun/07/climatec...](http://www.guardian.co.uk/commentisfree/2008/jun/07/climatechange)
which is a prediction from 5 years ago citing two studies saying that there
would be several cooling years ahead.

But more fundamentally, the natural variation over a decade is +- 0.2 C. If
the warming trend for a century is 2 C, then the warming trend per decade is
also 0.2 C. Thus a flat decade is readily explainable by normal variation. If
the warming trend is instead 1.5 C per century, then a 15 year stall becomes
even more reasonable than a decade had been under a faster rise.

The golden question then becomes how this study found a 0.15 C rise in
temperature from data over the last decade. I have not read the study. But I
know that correctly modeling these things is far more complex than just
looking at a long-term average. And given that I know that detailed attempts
to produce actual heat budgets for where energy is going have consistently
found that the planet has been steadily absorbing large amounts of heat in
recent years, I'm inclined to believe their figures over an argument from a
temporary stall in global atmospheric temperature.

~~~
glenra
> The golden question then becomes how this study found a 0.15 C rise in
> temperature from data over the last decade.

In my skimming of the original article I didn't see where that claim was
presented. But if I had to guess, there are at least three ways somebody could
accidentally reach that wrong conclusion.

(1) Using something like the woodfortrees link, specify a "From date" year but
don't specify an "end date", so you plot, say, from 2002 to "today". The
leftmost point on your plot is in January; the rightmost point is in the
middle of summer because that's when it is now. Boom, you've got some instant
extra warming, assuming you picked a temperature trend influenced by surface
thermometer readings.

(2) Instead of looking at _actual temperatures_ , look at a heavily smoothed
_moving average_ of temperatures. Or average every decade into a single point
and then compare those points. This gives you a plausible excuse to ignore
much of the most recent data and the most recent trend ("Tamino" aka Grant
Foster often pulls this trick on the readers of his blog Open Mind.)

(3) Instead of looking at the most recent data, google up an old study that
ended in, say, 2000 and interpret all talk about "the last decade" as
referring to the last ten years shown in that study. :-)

UPDATE: I just thought of another:

(4) Timing. The annual temperature trend is pretty noisy, so over any given
ten-year period it might increase or decrease. If you're a "warmist", your
favored information sources are going to publish new studies and trumpet their
findings whenever the _most recent_ decade now seems to show a big jump
compared to the trend it seemed to show in prior years, with headlines like
"it's worse than we thought!". So any time this issue comes up, those are the
studies/stats that you'll remember and cite.

(the original Mac/PC debates had exactly this dynamic - both Mac fanboys and
PC fanboys were generally convinced that their platform was better in all the
ways that mattered; their certainty was almost entirely a matter of salience
bias and the timing of news release events.)

------
sethbannon
These two sentences summarize the article pretty well: "The authors calculate
that over the coming decades global average temperatures will warm about 20%
more slowly than expected. But when it comes to the longer term picture, the
authors say their work is consistent with previous estimates."

~~~
JeremyKolb
Thanks for the summary, I started reading but wasn't going to get far on this
one.

~~~
ramblerman
Why? I think climate change is happening personally,but why the need to cling
to it like religion.

If evidence comes out, look at it, revaluate, repeat...

~~~
btilly
The problem is that evidence has come out, been confirmed, etc multiple times.
Evidence is clear that if we want to avoid the consequences we need to act.
However we can't act, in significant part because a large portion of the
population is unwilling to believe that the consequences exist.

------
ankitml
Not sure what they wanted to achieve with this article, as the article paints
a picture different from the title.

1\. Likelihood in long term remains the same. (title betrays its readers) 2\.
In medium term likelihood of most extreme scenarios is less than what was
expected. (hey ho, extreme scenarios are not to account for, thats why they
are extreme) 3\. people should be exactly as concerned as before about what
climate change is doing

ANyway, the whole news-article is based on one publication. Meh. I would
rather ignore the details of one publication because minor difference in
details dont matter. The broad picture remains the same.

------
flagnog
in other words: we don't understand it, but we're still going to blame it on
mankind.

we can make short range predictions, but still don't know all of the variables
that are controlling the climate.

~~~
btilly
There is a form of argument which is essentially to take all incoming facts,
pattern match them against your existing beliefs, then spit out a matching
statement with no evidence of comprehension. This is very common in certain
subjects, including politics.

This form of argument is not wanted here. Please do not engage in it.

If you read the article with comprehension you'd find that global warming is
happening as predicted, but on the conservative side of those predictions.

Go out and investigate for yourself. You'll find that the error bars on those
predictions remain large. Though smaller than they were. And the conclusion
that it is human-caused has only become better supported with time.

~~~
ramblerman
> There is a form of argument which is essentially to take all incoming facts,
> pattern match them against your existing beliefs, then spit out a matching
> statement with no evidence of comprehension. This is very common in certain
> subjects, including politics.

This is very true on both sides of this argument though.

~~~
btilly
This is very true on both sides of any argument about anything that people
attach tribal identity to. Which includes politics, religion, sports, choice
of editor, one true indent style...

Knowing this I try to apply increased scrutiny on arguments from people that I
fundamentally agree with, because I know that if I don't do it consciously,
then I'll just nod in blind stupidity. I won't claim that I do a good job at
it. But I will say that the willingness to take the effort has resulted in my
changing opinions on a number of topics over the years.

But, in this case, taking an article that says, "We found warming at 80% of
previous average prediction, but well within previous predictions" and
concluding that climate science is all bunk clearly indicates a lack of
comprehension for what the article actually said.

~~~
flagnog
or we've been lucky so far with the predictions, or been able to fit our
predictions to match the data. This is just PREDICTIONS. it's not settled
science - meteorologists have been able to stretch their predictions out to a
couple of days, but the system is too chaotic for long-term predictions. It's
not all bunk, but it's not a perfectly accurate 'science', either, and
concluding that it's not indicates a lack of comprehension of the difference
between theory and settled fact.

Now, I'm not saying we should foul our nest, just that we don't know exactly
what is going to happen, given our current understanding of long-term climate
change.

~~~
btilly
The old "weather is chaotic so we don't understand climate" argument. Thereby
letting you dismiss what scientists agree on without even looking at their
evidence.

If you know the science, then you'll understand that predicting exactly what
the weather will be on one particular day in one month is fundamentally
impossible. But predicting what it is likely to average out to in June in Los
Angeles over the next decade is both possible, and routinely done (albeit with
significant error bars). There is absolutely no contradiction between these
two facts.

Let me illustrate with a good example showing how scientists can understand
both the predictability of climate and the unpredictability of weather at the
same time. I will illustrate with an important example that is not widely
understood by the lay public.

If you know what the Hadley cells are, you can predict at what approximate
latitude we'll have jet streams, and why. (Google that term if you don't know
what a Hadley cell is - they aren't that complex.) You'll also be able to
predict that the jet streams will cause weather to follow them, resulting in
(for instance) a general west to east flow of weather over much of the USA and
Canada. The fun part is that if you know more fluid mechanics, you can _also_
show that the exact location of the jet stream is chaotic. There will be bends
and kinks of with a predictable wavelength (about 2x the width of North
America if you are interested) and a generally predictable amplitude, but
entirely unpredictable location. Those bends will cause warm weather to be
pulled north in one place, and south in another. (Therefore when the East
Coast is unseasonably cold, the West Coast tends to be unseasonably warm, and
vice versa.) But you can't predict WHERE those bends will actually be.

So this tells us a lot about climate (for instance where it will be wet, where
you have rain shadows, etc). It tells us a lot about causes of significant
variation, including how big the variation tends to be. But it also says that
we can know nothing about which way the variation will go in New York City
next October.

Your argument boils down to, "You can't even tell me what New York City will
be like next October, you obviously aren't doing science here!" Which is
simply ridiculous, since in fact the mechanics, average, and average variation
are all understood along with the reasons why we cannot get more exact
answers!

Everything that I am describing is standard and has been known for decades. In
fact I learned it from my fluid mechanics text over 20 years ago.

Please stop using the, "We can't predict the weather so this can't be settled
science" fallacy. It is a cheap cop-out to avoid listening to what actually is
known by smart people who have devoted their lives to studying the subject.

(Oh, and you learned something kind of fun. The next time you look on a
weather map and see the jet stream, you'll know why it isn't running straight
across. And just watch - if you pay attention over the next few months you'll
notice unseasonable weather on one coast of North America that is the opposite
direction of unseasonable weather on the other. And on the weather maps you'll
see the jet stream, and know why it happened.)

~~~
flagnog
It's not a fallacy or a cheap cop out. You're of the opinion that what we know
about the weather now is all that we need to know, but it's not.

How does the orbit of the moon affect weather? What about changes in the
magnetic currents in the Earth's core? Earthquakes? Solar winds? Can you tell
me what solar activity will be like in 10 years?

"Everything that I am describing is standard and has been known for decades."
How many times have we heard this, just before big leaps in understanding have
occurred? Several times, just in my lifetime. It's hubris to believe we know
that much about the weather.

~~~
btilly
Comprehension time.

I never said that we know everything that we need to. I've repeatedly pointed
out that our models have big error bars on them, and there are long lists of
things that we need to improve, of which your list doesn't even hit on the
most important parts. But the fact that we have significant unknowns doesn't
mean that we can't put order of magnitude estimates on our uncertainty, plug
those into models, and come up with error bars. In fact that is how those
models are developed, and how we develop error bars.

 _"Everything that I am describing is standard and has been known for
decades." How many times have we heard this, just before big leaps in
understanding have occurred? It's hubris to believe we know that much about
the weather._

I said that after getting through a description of how the jet stream works,
and was clearly referring to that description. I did not say - nor did I imply
- that the jet stream is everything to do with the weather or climate.
Important? Yes. Everything? No.

It is certain that there will be major discoveries over the next 20 years
about how climate works. Why is Greenland showing far more melting than
expected? How does soot from China affect everything from arctic ice to
rainfall in the USA, and how does that affect climate? How much methane will
be released as permafrost melts, and what will the climate impact of that be?
These are all areas of active research.

But I'd be shocked if scientists 20 years from now disagree with scientists
from 20 years ago about how the jet stream works.

~~~
flagnog
Wow, speaking of comprehension - the last sentence that you quoted emphasizes
that I was talking about the weather, in general, not the jet stream. And
order of magnitude estimates are about as accurate as a neophyte programmers
time estimates.

