No, climate change is not experiencing a hiatus. No, there is not currently a “pause” in global warming.
Despite widespread such claims in contrarian circles, human-caused warming of the globe proceeds unabated. Indeed, the most recent year (2014) was likely the warmest year on record.
It is true that Earth’s surface warmed a bit less than models predicted it to over the past decade-and-a-half or so. This doesn’t mean that the models are flawed. Instead, it points to a discrepancy that likely arose from a combination of three main factors (see the discussion my piece last year in Scientific American). These factors include the likely underestimation of the actual warming that has occurred, due to gaps in the observational data. Secondly, scientists have failed to include in model simulations some natural factors (low-level but persistent volcanic eruptions and a small dip in solar output) that had a slight cooling influence on Earth’s climate. Finally, there is the possibility that internal, natural oscillations in temperature may have masked some surface warming in recent decades, much as an outbreak of Arctic air can mask the seasonal warming of spring during a late season cold snap. One could call it a global warming “speed bump”. In fact, I have.
Some have argued that these oscillations contributed substantially to the warming of the globe in recent decades. In an article my colleagues Byron Steinman, Sonya Miller and I have in the latest issue of Science magazine, we show that internal climate variability instead partially offset global warming.
We focused on the Northern Hemisphere and the role played by two climate oscillations known as the Atlantic Multidecadal Oscillation or “AMO” (a term I coined back in 2000, as recounted in my book The Hockey Stick and the Climate Wars) and the so-called Pacific Decadal Oscillation or “PDO” (we a use a slightly different term–Pacific Multidecadal Oscillation or “PMO” to refer to the longer-term features of this apparent oscillation). The oscillation in Northern Hemisphere average temperatures (which we term the Northern Hemisphere Multidecadal Oscillation or “NMO”) is found to result from a combination of the AMO and PMO.
In numerous previous studies, these oscillations have been linked to everything from global warming, to drought in the Sahel region of Africa, to increased Atlantic hurricane activity. In our article, we show that the methods used in most if not all of these previous studies have been flawed. They fail to give the correct answer when applied to a situation (a climate model simulation) where the true answer is known.
We propose and test an alternative method for identifying these oscillations, which makes use of the climate simulations used in the most recent IPCC report (the so-called “CMIP5” simulations). These simulations are used to estimate the component of temperature changes due to increasing greenhouse gas concentrations and other human impacts plus the effects of volcanic eruptions and observed changes in solar output. When all those influences are removed, the only thing remaining should be internal oscillations. We show that our method gives the correct answer when tested with climate model simulations.
Estimated history of the “AMO” (blue), the “PMO (green) and the “NMO” (black). Uncertainties are indicated by shading. Note how the AMO (blue) has reached a shallow peak recently, while the PMO is plummeting quite dramatically. The latter accounts for the precipitous recent drop in the NMO.
Applying our method to the actual climate observations (see figure above) we find that the NMO is currently trending downward. In other words, the internal oscillatory component is currently offsetting some of the Northern Hemisphere warming that we would otherwise be experiencing. This finding expands upon our previous work coming to a similar conclusion, but in the current study we better pinpoint the source of the downturn. The much-vaunted AMO appears to have made relatively little contribution to large-scale temperature changes over the past couple decades. Its amplitude has been small, and it is currently relatively flat, approaching the crest of a very shallow upward peak. That contrasts with the PMO, which is trending sharply downward. It is that decline in the PMO (which is tied to the predominance of cold La Niña-like conditions in the tropical Pacific over the past decade) that appears responsible for the declining NMO, i.e. the slowdown in warming or “faux pause” as some have termed it.
Our conclusion that natural cooling in the Pacific is a principal contributor to the recent slowdown in large-scale warming is consistent with some other recent studies, including a study I commented on previously showing that stronger-than-normal winds in the tropical Pacific during the past decade have lead to increased upwelling of cold deep water in the eastern equatorial Pacific. Other work by Kevin Trenberth and John Fasullo of the National Center for Atmospheric Research (NCAR) shows that the there has been increased sub-surface heat burial in the Pacific ocean over this time frame, while yet another study by James Risbey and colleagues demonstrates that model simulations that most closely follow the observed sequence of El Niño and La Niña events over the past decade tend to reproduce the warming slowdown.
It is possible that the downturn in the PMO itself reflects a “dynamical response” of the climate to global warming. Indeed, I have suggested this possibility before. But the state-of-the-art climate model simulations analyzed in our current study suggest that this phenomenon is a manifestation of purely random, internal oscillations in the climate system.
This finding has potential ramifications for the climate changes we will see in the decades ahead. As we note in the last line of our article,
Given the pattern of past historical variation, this trend will likely reverse with internal variability, instead adding to anthropogenic warming in the coming decades.
That is perhaps the most worrying implication of our study, for it implies that the “false pause” may simply have been a cause for false complacency, when it comes to averting dangerous climate change.
[Response: In all fairness Robert, no, I’m afraid you’re missing the point. There is no amount of shifting of global mean temperature or interpolation of Arctic temperatures that is going to explain away…]
I did not bring up coverage bias – in fact I believe it to be a small contributor not a major one, something that kevin and I have tried to make clear. I think you’re implying something when you make a comment like that which is no one’s argument. At the time I began speaking about this project with Kevin I had spent years compiling old environment Canada weather records because I was interested in data rescue in the Arctic. When Kevin started this work there was no intention of ‘explaining’ some pause or anything of the sort – in fact at the time we thought it was a reasonably obscure problem that wasn’t likely to garner much interest at the time of submission. By the time it was in press there had been a number of articles on a so-called pause which had been published in Nature and Science and other leading journals because it was a high profile issue by then. For us, we were more interested in robustness than attention and that is why we went directly to a specialist journal where we would be sure to get heavy scrutiny from those whose record we were using. When we realized it was going to be in the media we prepared materials to help people understand the work and its limitations. Hence the four online supplements we have added in the time since (The last of which shows an anomalous cooling in GISTEMP’s Arctic data that explains much of why they’re cooler than our record). The idea that you believe we tried to ‘explain away’ anything is unfortunate.
[…we have seen anomalous increase in tropical Pacific trade wind strength, sustained tendency for La Nina-like conditions, and enhanced tropical Pacific ocean heat burial, over the past decade+. There is a healthy body of research, as you know (and as is cited in our article) showing that these factors have contributed to a slowing of global-mean warming over the past decade+. That is what our article (and several others by England et al, Risbey et al, etc) are investigating. I think we explain this pretty clearly in the article and in the blog post, so I’m rather perplexed that the point is being lost…]
The point is not being lost – I’ve always been certain that the conditions in the pacific are contributing to a reduced rate of warming as a result of the predisposition towards la nina conditions and deep ocean heat story. There is no doubt about that. My point is that when you’re trying to directly quantify the magnitude and relative importance of the multidecadal variability to recent temperatures you need to have an accurate estimate of the role of external forcing over the past decade. Most if not all of the models that you’re using in your study would show lower temperatures over the past decade if they had updated forcings for volcanic activity and the weak solar cycle. This would result (with your methodology) in a more positive AMO and a less negative PDO which in term would reduce the total role of multidecadal variability.
As I pointed out above – the updated forcings are relevant and a few of Santers paper show that – not to mention Schmidt et al (2014) which shows the updated forcings playing as large a role in the discrepancy as the phase of ENSO.
Santer et al (2014)
“…We show that climate model simulations without early 21st century volcanic forcing overestimate the tropospheric warming observed since 1998…”
Ridley et al (2014)
“…Finally, the SAOD above 15km most noticeably underestimates the total SAOD at high latitudes following an eruption, particularly a high-latitude eruption…. “
Santer et al (2015)
“Our findings show that the hiatus is not due to internal variability alone…Of particular interest is our positive detection of volcanic cooling signals in observed tropical SST data… Volcanic cooling signals are therefore aliased into the observed tropical SST changes specified by Kosaka and Xie [2013]… While prescribed SST simulations are useful for many purposes [see, e.g., Gates et al. , 1999], our study shows that they cannot reliably quantify the contributions of individual factors to the “warming hiatus.””
You demonstrate in this contribution and the supplemental materials what appears to be a reasonable method for discriminating between forced and unforced variability and that itself deserved to be published in a specialist journal for covering the period where we have known forcings. The section post-2005 is where you have the least certainty in the forced response and external forcings and I just don’t see that reflected in the analysis, error bars and conclusions.
I genuinely feel that when updated model runs are available and this analysis is repeated it will show a reduced contribution of multidecadal variability because many models include a stronger solar cycle and virtually no volcanism. But we can disagree on that.
"... a comment like that which is no one’s argument ..."Important caution there — hard argument ain’t easy.
Worse on blogs. Misunderstandings propagate faster here.
You know that “blind guys and the elephant” story?
Our elephant is the size of the planet — our elephant _is_ the planet.
Some can see better than others.
But we’re all damned small, and see partially.
Thanks to the scientists willing to do this kind of argument on blogs where we in the peanut gallery can read it, knowing it’s harder and riskier.
This is very interesting, but I hope the RC team develops a strategy to effectively share these kinds of clarifications with the American public. For every lay person like me who is intrigued by climate science, there must be hundreds who do not even get the opportunity.
I have written to the New York Times public editor on this subject, specifically requesting that Mike or someone of similar talents be given a regular climate column. The fact that Times readers are currently getting their information from Andy Revkin is unconscionable. Their regular general columnists are mostly indifferent on the subject, so apart from occasional news stories Times readership is not being well informed. If that changed, it’s possible that other news organs would follow.
[Response: Thanks Mike! –Mike]
How did #49, by goldmund52 not make it into the borehole. It is utter falsehood and mis-(dis?)information from beginning to end. Clearly the poster is utterly ignorant of how climate models are constructed.
t marvell 48: The bedrock of time series analysis is now stationarity and cointegration. As far as I can tell, it is little used in climate studies.
BPL: I used it for my studies of drought fraction, dT, and the influence of the SOI. I think climate scientists who use time series analysis are very aware of it. Try tamino’s blog, “Open Mind” at tamino.wordpress.com.
goldmund 49: The problem is not just that relevant “factors” are unknown, unmeasurable or badly measured. It’s that the “factors” landscape is itself necessarily a chosen post hoc construction at a chosen point in time, from which it then deforms going forward in time.
BPL: You never heard of “analysis of variance,” did you?
Thanks for the contribution, and others elsewhere. It’s helpful and informative. Plus there’s no doubt about the point. The point is to avert dangerous climate change. So your analysis is done with that in mind. Not many authors of any kind can be so comprehensive, concise, and current all at once.
[Response: Thanks Patrick, much appreciated :-) –Mike]
Thanks for this wonderful piece. I see that the issue has been picked up at ClimateCentral now, too.http://www.climatecentral.org/news/warming-spurt-looms-will-it-change-minds-on-climate-change-18716
Looking back at your article from about a year ago in Scientific American that you link to above, I note that you mentioned volcanism and slight decreases in solar activity as possible contributing factors to the ‘faux pause.’ Here you emphasize the role of the ocean, which seems to be a bigger and more certain affect.
Are there other temporary phenomenon that might have played a small but significant role? Aerosols from China’s incredible largely-coal-powered growth spurt? The energy needed to melt some 10,000 cubic kilometers of Arctic sea ice mostly in the last 15 years (and to melt the equal or greater quantities of terrestrial glaciers that melted in place or after flowing into the sea)?…
Some of these have been studied individually, but has anyone put all these together to try to estimate how much influence each may have had, which are minor, which major…?
And if you could also clarify one other thing from that SA article. I have seen some posters online interpret the graph to mean that, if there is a equilibrium climate sensitivity of 3, we should expect global surface temperatures to exceed 2 degrees by 2036. But do you instead mean that by that year we will have reached atmospheric levels of CO2 that _commit_ us to eventually warming to that level?
Thanks ahead of time for any clarifications and for all your work and bravery.
[Response: Thanks for the kind words and thoughtful comments Wili :-) Ideally we would have discussed the various potential contributors (errors in both natural and anthropogenic forcing) in more detail, but we were only able to discuss briefly in the article (and the blog post). I see these as complementary, rather than competing mechanisms. Most likely the “faux pause” is a combination of a number of factors which include (i) potential underestimation of actual warming due to data gaps, (ii) forcings that are not quite accounted for in the CMIP5 forcing protocol (i.e. unaccounted for contributions to radiative forcing over last decade including persistent background volcanic forcing, small dip in solar forcing, possible increase in anthropogenic aerosols), and (iii) internal variability. In my view, only mechanism (iii) can likely explain the dominant role that the Pacific has played, but all three factors likely contributed to the temporary slowdown in surface warming. –Mike]
49, goldman42: Time series analysis doesn’t work for climate modeling because a non-linear dynamical system is formally unpredictable. – See more at: https://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/comment-page-1/#comments
That is pretty silly. There is no reason why scientists can not come up with models that are accurate enough over defined time periods for meaningful functionals: mean, variance, 1st and 99th percentiles and such. The test of the model is with respect to out-of-sample data. There are lots of examples in the published literature of chaotic phenomena that are reasonably well approximated by chaotic mathematical models over at least a few oscillatory cycles: heart beat, neurophysiological rhythms and others.
Matthew @59: An interesting example lies in the not unrelated field of global weather modelling — the ultimate home of the “formally unpredictable” butterfly. Despite its undoubted influence, weather model skill continues to improve, year after year. GFS has just managed another substantial step change, particularly with hurricane tracks.
Wow!! Thanks for the prompt response, Professor Mann. I see this is getting coverage in the LA Times now (linked at SkS): http://www.latimes.com/science/sciencenow/la-sci-sn-ceres-bright-spot-dwarf-planet-nasa-dawn-20150225-story.html
[Response: Thanks again Wili. Yes, was surprised that this got as much coverage as it did, particularly since there have been numerous other articles on the “faux pause” in recent months (our work would have seemed even more novel a year ago, it spent a long amount of time in several rounds of review, w/ a particularly stubborn “reviewer #3”. –Mike]
Thanks Mike (and colleagues) for this interesting piece of research.
I notice on figure herein (likely coming from Fig. S5 – not sure) the large spike in both AMO & PDO from ~ 1940-1950, a time of significant cooling followed by a flat plateau in thermometer records, until ca 1970.
The Lewadowsky’s piece you linked to in earlier comment, shows good agreement of Cowtan & Way 2013 temp series with model runs closest to El Niño – La Niña, but only from 1960 to 2010.
Have you anyone else looked at the first part of 20th century data? Your opinion/conclusion, that PMO explains surface temp hiatus does not explain the 1940-1960 period of largest hiatus ever recorded in AGW trend – according to Fig. S5 we should have seen surface warming at that time. So what does?
[Response: Thanks Chris. So our study basically just partitions the instrumental record into a “forced” component and an “internal variability” component. The former is shown in Fig 1. The two, by construction, must add up to give the full observational record, so the feature you describe has to be contained in or the other or both. However Fig 3 shows only the low-frequency component (the “PMO”) of the estimated internal variability, so variations as short as a decade or so will not be captured by that. I would argue that the feature you describe is likely a manifestation of shorter-term internal variability. –Mike]
Correcting typos, I think, on Response to #31: adding ) where it seems to read better, and s to paper
[Response: Time series analysis (a topic on which I’ve published dozens of times) alone provides no physical insight. Using climate models allows us to introduce some actual physics into the problem. As someone who has worked in the area of time series analysis for two decades now, I’m painfully aware of the shortcomings in relying entirely on such approaches when it comes to establishing causal relationships. There are papers that have used precisely the approach you’re suggesting, and they’ve been found wanting. –Mike] – See more at: https://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/?wpmp_switcher=desktop#sthash.CDlMzA8U.dpuf
@50 R. Gates says: “Multiple studies have shown the TOA energy imbalance to be something around 0.6 to 0.9 w/m2.”
How does that correlate with the recent report from the LBNL of the first-ever direct observation and measurement of C02-specific radiative forcing?
– From Abstract: “Radiative transfer models calculate that the increase in CO2 since 1750 corresponds to a global annual-mean radiative forcing at the tropopause of 1.82 ± 0.19 W m−2… The time series both show statistically significant trends of 0.2 W m−2 per decade (with respective uncertainties of ±0.06 W m−2 per decade and ±0.07 W m−2 per decade) and have seasonal ranges of 0.1–0.2 W m−2.”
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14240.html
Prof Peter Wadhams prediction of nil summer sea ice this year may well eventuate. The polar sea ice max is at record low levels for extent and not far behind for area as well. Does not look good for September at all! We have put into the atmosphere in the past 25 years 65% of all the anthropogenic CO2 that has ever been released since even before the industrial revolution. It takes roughly 40 years for the CO2 released today to physically affect the climate. Do the maths..we do not have time!!! I expect to see climate and environmental scientists bailing up politicians and industry leaders left right and centre. What do I see…zip! Come on people! Or do you already concede it’s way too late.
Shelama 63, you have have “total radiative forcing” confused with “radiative imbalance at top of atmosphere.” They are two different numbers. The first is a one-way measurement of one or more influences; the second is a net balance applied to all of them.
#65–Lawrence, I think you are a little overheated there. Though Arctic SIE is indeed low just now, we aren’t at maximum yet, and the evolution of the season is highly weather dependent. I’d say there’s very little prospect that we’re going ice-free this year–5% chance seems very, very generous, if you ask me. Though I do suspect that we’ll see a break in the trend of increases that we’ve had since the record low in 2012.
Professor Wadham’s annual prediction of total ice loss in the Arctic is doing him and us no good in a boy cried wolf kind of way. I agree things are not looking good, but this appears to be an emotional rather than evidentiary commitment. I think a proper looksee at actual conditions in the Arctic would produce a more realistic sense of the physical entity; I would not be surprised to see unusual breakup this summer, but that’s a relative thing in a vast area.
I would agree that we are all in bad case in terms of getting active in dealing with a real problem in real time, but statements like this contribute to the dismissive tone of those who claim there’s nothing to it.
Now, I’m firmly convinced that there is no magic bullet and that we all need to get busy doing everything possible a couple of decades ago, but wild posturing and exaggeration only leads to dismissal.
In addition, as far as I’ve been able to discern, manipulations of the atmosphere are more than likely to make things worse, as RayPierre says, “barking mad”.
http://www.slate.com/articles/health_and_science/science/2015/02/nrc_geoengineering_report_climate_hacking_is_dangerous_and_barking_mad.html
chriskoz @
The PDO:
Mid-century cooling using wood for trees: gistemp loti and Jiaso PDO index.
You can see why people fell for the stadium wave.
Michael, if your conclusion is natural cooling in the Pacific is a principal contributor to the recent slowdown in large-scale warming, then I submit forced burial of this heat below the ocean surface, using heat pipes to produce ocean thermal energy, is the approach we should be taking to address the warming/energy problem. This also could be the cheapest way to produce zero emissions energy per the following.
No.65: “Prof Peter Wadhams prediction of nil summer sea ice this year may well eventuate. The polar sea ice max is at record low levels for extent and not far behind for area as well. Does not look good for September at all!”
The reality: The september-min extent depends on february extent! (With R²=0,05… when one detrends both records from 1979 to 2014.) With monthly data of the NSIDC.
No. 67: +1
Aerosol emissions of ocean going vessels? A few years ago I read through all the papers (I could find) about how global shipping would affect radiative forcing. I also interviewed several of the authors. Conclusion was that aerosol emissions from shipping have direct and indirect (cloud seeding/whitening) cooling effect. Estimates ranged from minor to very significant cooling effect. Global shipping has been growing rapidly during last 2 decades and the emissions are spread on very wide areas across world’s oceans. Is there any reason to assume that this might be an issue which would need more attention and possibly explain in small part why surface has not warmed more? I’m interested in this topic because cooling effect of shipping is expected to be reduced during next decade due to new regulations.
Esko wrote: “I’m interested in this topic because cooling effect of shipping is expected to be reduced during next decade due to new regulations.”
Also due to ever larger container ships* being introduced, translating into fewer voyages required to move the same number of containers. (*Pushing well over 19,000 TEU now, compared to 1984 when 4,000 TEU was considered huge.)
#67 Susan Anderson said, Professor Wadham’s annual prediction of total ice loss in the Arctic is doing him and us no good in a boy cried wolf kind of way…. but wild posturing and exaggeration only leads to dismissal.
You are dismissing a forward-looking claim as “wild posturing and exaggeration.” Ironic, no? How can you possibly know? While I agree anyone claiming that over the last few years has been incorrect, but that is past, not future. At some point it will be true, and likely sooner than later for most’s tastes. Personally, seeing as how we are fighting natural reticence of science in the first place, having a tiny number of scientists (though the number seems to be growing rapidly) saying *anything* “alarming” is a welcome thing!
Also, bear in mind the definition of ice-free is more generally regarded to be on the order of 80% melt with old ice still along the archipelago. By that definition we’ve come closer than I’d like already.
Secondly, if the people reading about and interested in and/or concerned with climate and ASI can’t contextualize comments within the overall flow of information, are they really a key demographic just yet? Probably not. More likely they won’t be on board till the boat is nearly swamped.
We need to stop worrying about who is freaking out and worry about those who are ready to deal and work. The freakouts are not yet part of the solution.
Finally, the extremes determine the shape of a thing. There is no reason to dismiss Wadham’s unless you find some flaw in his math, etc. Seems the ASI could hit the 80% in any given year, so is his yearly expectation really all that wild? I do not think so.
[Response: Predictions should not be dismissed or accepted based on how you feel about the actual prediction. Instead, they should be judged on the methodology that is used, it’s track record and assessments of it’s credibility. On all counts, Wadhams’ (and Mieslowski’s) forecasts are woeful. Fitting negative exponentials (for which there is no physical support – as he admitted in the Q&A) is guaranteed to produce a dramatic crash, regardless of where you start; this doesn’t work in predicting GCM results or any other model, etc. – gavin]
@66 Barton Paul Levenson
Actually, I’m not confused so much as dumb and ignorant. I really didn’t know if – or how, when or why – they were related (or correlated) at all.
You’ve put me in the right direction and gotten me part way there (I think), thanks.
Still, do the findings of that Nature study have any relevance or possible contribution to this thread that might be worth a comment?
Regarding Dr. Wadhams, apparently the the latest iteration of the death spiral question is discussed here:
http://barentsobserver.com/en/arctic/2014/11/expert-predicts-ice-free-arctic-2020-un-releases-climate-report-04-11
So, he isn’t currently expecting a crash this year, but by 2020. He’d previously called it for this year, but has walked that back, and had been mocked for it by WUWT (which goes to support Susan’s point.)
Dr. Wieslaw Maslowski, of the US Naval Observatory–Gavin, was that who you meant when you wrote “Mieslowski”?–called it for 2016 +/- 3 years:
http://www.theguardian.com/environment/earth-insight/2013/dec/09/us-navy-arctic-sea-ice-2016-melt
Lost in most of the discussion, as is so often the case, were his caveats, notably:
“Regardless of high uncertainty associated with such an estimate, it does provide a lower bound of the time range for projections of seasonal sea ice cover.”
Of course, denialists have usually presented this as “Wasn’t the sea ice supposed to be gone by 2013?”
Personally, I still wouldn’t rule out a reasonably ice-free minimum before Maslowski’s ‘prediction window’ closes in September 2019. But the one thing I’ve learned over several seasons of watching the annual cycle is that the Arctic is very good at making fools of predictors–in the short term.
The long term, of course, is much more deterministic.
Apparently, Dr. Wadhams is no longer calling for a sea ice ‘crash’ this year; he has walked the extrapolation back to 2020. He was duly mocked for it by WUWT (which goes to Susan’s point.) For the former point, see:
http://barentsobserver.com/en/arctic/2014/11/expert-predicts-ice-free-arctic-2020-un-releases-climate-report-04-11
Dr. Wieslaw Maslowski of the US Naval Observatory–Gavin, was that who you meant by “Mieslowski”?–had originally called the first ice-free minimum for 2016 +/- 3 years:
http://www.theguardian.com/environment/earth-insight/2013/dec/09/us-navy-arctic-sea-ice-2016-melt
Denialists usually presented this as a prediction of ‘ice-free by 2013’, which for them is now yet another ‘failed prediction’ of the ‘warmists.’ Maslowski himself was of course much more nuanced, saying, inter alia:
“Regardless of high uncertainty associated with such an estimate, it does provide a lower bound of the time range for projections of seasonal sea ice cover.”
If I’ve learned anything by watching the last few melt seasons fairly assiduously, it is that the Arctic is very good at making fools of predictors–at least in the short term.
The long term, of course, is much more deterministic.
I know this doesn’t exactly belong on a science site, and discussion of the Arctic is OT, but in addition to Gavin’s always on the spot maths in his response, I was trying to add a common sense viewpoint. That’s all I can do in my math-challenged but scientifically rich situation.
What I’d like to see is people get a grasp of the vastness and inaccessibility of the pole. Every time we get hype it appears to be emotional, and I think our access to satellite pictures makes us lose the sense of what it might be like to actually be there, how big it really is. We have the same problem with geological time. We think in terms of lifetimes and places we go and reframe magnitude in terms we find more accessible. This is our loss, and leads to false conclusions as well.
I am a regular attendant at Neven’s Sea Ice Blog, and the more I look the more awed I am at the magnitude of the task of observing the grand scale of its entirety.
Flinging accusations about does not address what I was trying to say, which is, please think about it and avoid making shallow claims. Saying I am emotional is a cheap shot and actually misses my point, which is that before we oversimplify we should try to get a grasp of what we are simplifying.
Well I just hope that this does not make the powers that be go soft on emissions cuts thinking the oceans are going to suck up all the co2 and give us more time to react. We are already reacting too slowly, 0.8C already and 0.6C in the pipeline means we need to start cutting soon
GRL:
Pacific Sea Surface Temperature and the Winter of 2014
Dennis L. Hartmann
DOI: 10.1002/2015GL063083
http://onlinelibrary.wiley.com/doi/10.1002/2015GL063083/abstract
Abstract
It is shown from historical data and from modeling experiments that a proximate cause of the cold winter in North America in 2013-14 was the pattern of sea surface temperature (SST) in the Pacific Ocean. Each of the three dominant modes of SST variability in the Pacific is connected to the Tropics and has a strong expression in extratropical SST and weather patterns. Beginning in the middle of 2013 the third mode of SST variability was two standard deviations positive and has remained so through January of 2015. This pattern is associated with high pressure in the northeast Pacific and low pressure and low surface temperatures over central North America. A large ensemble of model experiments with observed SSTs confirms that SST anomalies contributed to the anomalous winter of 2014.
Oops, sorry for the double post–the first iteration appeared to vanish.
Apparently, it didn’t.
Post 65 says: “It takes roughly 40 years for the CO2 released today to physically affect the climate.”
Is that true – 40 years?
Lawrence Coleman:
You are asking too much of climate and environmental scientists. The failure of politicians and industry leaders to act isn’t because they don’t understand the science, it’s because public support for positive action isn’t enough to overcome the pushback from the people whose assets will be stranded if the climate cost of fossil-fuel consumption is internalized. Scientists have no more political power than the rest of the 99%, so the onus is (heh) on us, i.e. you, to shift the center of political gravity.
I personally don’t think it’s ‘way too late’ to act, but I don’t see a way to neutralize the power of fossil-fuel money, especially since so much of that money goes to keep public support for action from reaching critical mass in the first place. I’m willing to be surprised, though.
t 82,
No, it’s quite wrong. The greenhouse effect happens very nearly at the speed of light.
Re- Comment by t marvel — 2 Mar 2015 @ 4:13 PM, ~#82
T, without any parameters this 40 year statement is hard to understand. Check out the following:
https://www.realclimate.org/index.php/archives/2010/06/climate-change-commitment-ii/
https://www.realclimate.org/index.php/archives/2010/03/climate-change-commitments/
Steve
#67 Gavin said, Killian: Finally, the extremes determine the shape of a thing. There is no reason to dismiss Wadham’s unless you find some flaw in his math, etc. Seems the ASI could hit the 80% in any given year, so is his yearly expectation really all that wild? I do not think so.
[Response: Predictions should not be dismissed or accepted based on how you feel about the actual prediction. Instead, they should be judged on the methodology that is used, it’s track record and assessments of it’s credibility.
Which is why I said, There is no reason to dismiss Wadham’s unless you find some flaw in his math, etc. Being wrong isn’t a good enough reason.
As for woeful, I’ll stick with, Seems the ASI could hit the 80% in any given year, so is his yearly expectation really all that wild? I do not think so.
I had fun debates with a new climate scientist, Beckwith, who was in lock step with Wadhams the last two years. I came the conclusion new records were unlikely in both years, and last year being especially obvious. While you wouldn’t accept my methods, I continue to make pretty darned accurate guesses each year, so you’ll forgive me my continued willingness to believe my own eyes.
:-)
FWIW, this year looking a bit likely now of a lower total than the last two years, but I don’t think reliable guestimates are possible this early on, so…
Fitting negative exponentials (for which there is no physical support – as he admitted in the Q&A) is guaranteed to produce a dramatic crash, regardless of where you start; this doesn’t work in predicting GCM results or any other model, etc
Thanks. I will try to remember this when assessing predictions of whatever type, but my head is a sieve with numbers and formulas.
for t marvel (pasted your question into Google): first hit is:
http://www.skepticalscience.com/Climate-Change-The-40-Year-Delay-Between-Cause-and-Effect.html
P.S., of course do read the comments, some of which make it a bit clearer. Definitely don’t read just the headline and assume there’s a “Yes or No” about that. You won’t get “truth” from a simple one sentence summary of climate.
E.g. this, the last comment there to date.
#82–No, it’s not true. It’s a garbled version of something that *may* be true, in some sense. Here’s an example:
http://www.skepticalscience.com/Climate-Change-The-40-Year-Delay-Between-Cause-and-Effect.html
“A paper by James Hansen and others [iii] estimates the time required for 60% of global warming to take place in response to increased emissions to be in the range of 25 to 50 years. The mid-point of this is 37.5 which I have rounded to 40 years.”
But CO2 emitted to the atmosphere has an immediate radiative effect.
“It takes roughly 40 years for the CO2 released today to physically affect the climate.” Is that true.
T Marvel: I think this is an example of how oversimplification can lead to problems of understanding. If we were to look at the impact on global mean temperature to a unit impulse of CO2, the forcing would be immediate (i.e. the increase in downwelling IR is effectively instantaneous). That would quickly increase land surface temps -but not yet the air. Then we atmosphere will take a while to absorb and be saturated by the somewhat warmer surface. I’m guessing the equilibration time of the atmosphere is roughly a month (I hope someone like Gavin and jump in with some expert numbers here). Then of course we are also warming the ocean surface, but much of the excess heat will go to warming the bulk of the ocean, and this has much longer time scales than the atmosphere, probably several decades for the most important top few hundred meters. So you would have at least three time scales with different amplitudes. First is changing the temp of a dryland surface in rection to a change in the radiation balence. Then you have to heat the thermal mass of the atmosphere. All the while much of the excess energy is being buried in the oceans, which have even larger thermal mass. So I think its a dangerous simplification to assign some characteristic time to the process. Again, I’d love it if one of the sites sponsors could supply a few terms of a simplified linear lumped model (as Bern Carbon cycle does for CO2). It would be useful for gaining insight into policy/climate responses without having to run detailed climate models.
79: Susan Anderson, I understand what you say and also Gavin speaking from the standpoint of a ‘true’ scientist. However I still think we are nit picking short term dates, nil summer ice 80% or otherwise going to happen sooner than later, all projections lead to that conclusion. However what Prof Wadhams did mention which at least to me seems totally plausible is that as soon as we get a ‘open’ sea where ice once was situated we are rapidly going to get longer and longer periods of open sea in the summer and then before you know it during the spring and autumn as well. Due to the fact that as the ocean goes above 0C snow is going to find it very difficult to get a toehold and form compact ice as it melts faster than it falls. There is question I have which you might know which might give us a negative feedback breather. As the insulation of the sea ice disappears the sea surface will be subject to bitterly cold -20 -40C circum-polar winds, wouldn’t that chill the sea surface (provided the sea is relatively calm) to below 0C and provide an anchor for ice to form. That is partially the situation during winter of course. Or would the increasing solar ocean heating in the summer overcome the effect of the wind? Taking into account that the polar air temps are up to 4C warmer now. Thanks Susan.
90: Thomas, a bell curve of CO2 forcing vs time would be handy here. Then you also need to differentiate anthropogenic CO2 from natural and/or cyclical CO2. What I was saying in #65 was that 40 years is generally known to be the optimal time for peak CO2 radiative forcing. You are quite right regards time frames for surface – upper atmosphere – ocean uptake etc. E.g for every mole of CO2 released now the greatest percentage of that mole will be causing the most forcing globally in 40 years and then very slowly diminish over hundreds of years.
a quick browse at google indicates that the north pole’s mean summer temp is 0C and warming, I assumed it was less. So back to the pressing issue of how long it will take the ice to grow back during the arctic autumn. Why I’m hammering this point is due to the widespread ramifications for the global climate as I’m sure you are all well aware. Where can I find studies on the predicted decelerating rate of ice formation during the autumn/ spring periods in 10,20,50 years based on nil summer ice by 2020?
Any finger in the right direction will be appreciated.
You’re thinking of biogeochemical cycling taking CO2 out of the ocean and atmosphere? That’s a long, long, long, long time away, not a ‘bell’ curve.
Why?
What? Natural change is extremely slow compared to what we’re doing here.
And that’s clearly a misreading, as I found pointed out.
Do read the linked article and the comments.
Again, type your question into the Google search box — you’ll find what you think is “generally known” there, along with explanations why it’s wrong.
It’s a poor sort of memory that only works backwards — almost anything learned years ago has subsequently been improved on, if we look it up.
Lawrence, a couple of posts:
“…north pole’s mean summer temp is 0C and warming, I assumed it was less.”
Not much summer warming trend, because the ice melt tends to ‘clamp’ surface temps. Without sea ice, that will change. See, as analogue, this graph of the yearly lake/air temps at Buffalo, NY:
http://i1108.photobucket.com/albums/h402/brassdoc/2014%20Buffalo%20Air%20amp%20Water%20Temps.png
So that will be a positive summer feedback at some point, abetted of course by water vapor and albedo feedbacks.
“As the insulation of the sea ice disappears the sea surface will be subject to bitterly cold -20 -40C circum-polar winds, wouldn’t that chill the sea surface (provided the sea is relatively calm) to below 0C and provide an anchor for ice to form.”
Yes, that will be a negative winter feedback–I think it’s actually already shown to be occurring with decreased winter SI area. It’s complex, because of the “provided the sea is relatively calm” clause; without sea ice, you get not just surface turbulence due to wave action, which inhibits ice formation, but also more surface mixing, which warms the atmosphere but cools the ocean as a net. (Or so I think, at least.)
Seems there’s a whole lot of modeling work required to put all these various pieces together. But it’s pretty clear that the Arctic will be a very, very different place under BAU–and maybe under probable mitigation regimes, at this point.
I think its clear that global warming and climate change are happening, which is why I made this animation ‘The World Has Got A Problem’ to try and raise awareness of climate change; https://www.youtube.com/watch?v=UjUVWICiH44
A 40 year period for the effect of Co2 seems like it could be reasonably calculated as the average time for 50% of the effect to be felt, depending on model used etc. However I don’t think it at all represents what actually happens. To explore this further try googling terms such as instantaneous doubling co2 and climate transit response. The best I could find at the moment is http://kiwi.atmos.colostate.edu/rr/groupPIX/tommy/tommy1/tom1.html
Several diagrams down from the top shows the modelled temperature response over time after global Co2 levels are instantly doubled. After 30 years around 2.2 degrees of warming has occurred. The equilibrium sensitivity is often quoted as something like 1.5-4.5. Note that there are longer term factors such as ice sheet responses, the time for the deep ocean to fully warm up, and slow release of carbon from perma-frost etc that are expected to cause significant warming even centuries and millennia in the future. Also note that the fastest warming following the release of new Co2 into the atmosphere is instantaneous, but the slower warming rate years, decades and centuries after adds up to quite a large amount.
89, Kevin McKinney: A paper by James Hansen and others [iii] estimates the time required for 60% of global warming to take place in response to increased emissions to be in the range of 25 to 50 years. The mid-point of this is 37.5 which I have rounded to 40 years.” – See more at: https://www.realclimate.org/index.php/archives/2015/02/climate-oscillations-and-the-global-warming-faux-pause/comment-page-2/#comment-626432
How much time is required for 95% of the surface and tropospheric warming to occur?
What is this “kirjoitti” instead of “says”?
EG @#98 wrote: “What is this ‘kirjoitti’ instead of ‘says’?”
It’s Finnish for ‘writes.’ Where did you see it?