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Posted on 13 November 2013 by dana1981, Kevin C, robert way
A new paper published in The Quarterly Journal of the Royal Meteorological Society fills in the gaps in the UK Met Office HadCRUT4 surface temperature data set, and finds that the global surface warming since 1997 has happened more than twice as fast as the HadCRUT4 estimate. This short video abstract summarizes the study's approach and results.
The study, authored by Kevin Cowtan from the University of York and Robert Way from the University of Ottawa (who both also contribute to Skeptical Science), notes that the Met Office data set only covers about 84 percent of the Earth's surface. There are large gaps in its coverage, mainly in the Arctic, Antarctica, and Africa, where temperature monitoring stations are relatively scarce. These are shown in white in the Met Office figure below. Note the rapid warming trend (red) in the Arctic in the Cowtan & Way version, missing from the Met Office data set.
Met Office vs. Cowtan & Way (2013) surface temperature coverage and trends
NASA's GISTEMP surface temperature record tries to address the coverage gap by extrapolating temperatures in unmeasured regions based on the nearest measurements. However, the NASA data fails to include corrections for a change in the way sea surface temperatures are measured - a challenging problem that has so far only been addressed by the Met Office.
The Berkeley Earth Surface Temperature (BEST) project used a similar approach as NASA, but with a statistical method known as "kriging" to fill in the gaps by interpolating and extrapolating with existing measurements. However, BEST only applied this method to temperatures over land, not oceans.
Dr. Cowtan is an interdisciplinary computational scientist who recognized some potential solutions to this temperature coverage gap problem.
"Like many scientists, I'm an obsessive problem solver. Sometimes you see a problem and think 'That's mine, I can make a contribution here'"
In their paper, Cowtan & Way apply a kriging approach to fill in the gaps between surface measurements, but they do so for both land and oceans. In a second approach, they also take advantage of the near-global coverage of satellite observations, combining the University of Alabama at Huntsville (UAH) satellite temperature measurements with the available surface data to fill in the gaps with a 'hybrid' temperature data set. They found that the kriging method works best to estimate temperatures over the oceans, while the hybrid method works best over land and most importantly sea ice, which accounts for much of the unobserved region.
Both of their new surface temperature data sets show significantly more warming over the past 16 years than HadCRUT4. This is mainly due to HadCRUT4 missing accelerated Arctic warming, especially since 1997.
Cowtan & Way investigate the claim of a global surface warming 'pause' over the past 16 years by examining the trends from 1997 through 2012. While HadCRUT4 only estimates the surface warming trend at 0.046°C per decade during that time, and NASA puts it at 0.080°C per decade, the new kriging and hybrid data sets estimate the trend during this time at 0.11 and 0.12°C per decade, respectively.
These results indicate that the slowed warming of average global surface temperature is not as significant as previously believed. Surface warming has slowed somewhat, in large part due to more overall global warming being transferred to the oceans over the past decade. However, these sorts of temporary surface warming slowdowns (and speed-ups) occur on a regular basis due to short-term natural influences.
The results of this study also have bearing on some recent research. For example, correcting for the recent cool bias indicates that global surface temperatures are not as far from the average of climate model projections as we previously thought, and certainly fall within the range of individual climate model temperature simulations. Recent studies that concluded the global climate is a bit less sensitive to the increased greenhouse effect than previously believed may also have somewhat underestimated the actual climate sensitivity.
This is of course just one study, as Dr. Cowtan is quick to note.
"No difficult scientific problem is ever solved in a single paper. I don't expect our paper to be the last word on this, but I hope we have advanced the discussion."
The perceived recent slowdown of global surface temperatures remains an interesting scientific question. It appears to be due to some combination of internal factors (more global warming going into the oceans), external factors (relatively low solar activity and high volcanic activity), and an underestimate of the actual global surface warming.
How much each factor is contributing is being investigated by extensive scientific research, but the Cowtan & Way paper suggests the latter explanation is a significant contributor. The temporary slowing of global surface warming appears to be smaller than we currently believe.
For anyone who is interested there is a longer video abstract, a detail background document, and every single piece of code and data required to reproduce our results from scratch on the project website.
There's an object lesson here in terms of how we may forget that our public discussion can be perilously dependent on speculation without our pausing (!) to carefully consider what we fairly know. For all the sound and fury expended over "the pause" we didn't actually know what was happening, not enough anyway to get in a lather about it.
Now, suddenly, it appears "the pause" has shrunk rather dramatically, thanks to people who look while the rest of us leap. Sheepish looks should be the hangover, not that it's likely any of the more extreme hyperbole we've witnessed is going to be accounted for.
I'm truly surprised this previously gaping hole wasn't emphasized more in all the premature chatter. Particularly it's strange that people who should and do know better have gone on to formalize "the pause" in various embarrassing places.
Expanding a bit on Doug's point about public discussion - how do you present to a general audience the various decisions that are made in reconstructing temperature data? Obviously a discussion of kriging isn't really material for the local pub, but temperature curves published by the media get portrayed as "this is the temperature" not "this is the temperature we get from using stations with 85% global coverage and we suspect the other 15% would be warmer."
Nice work though. It's pretty clear the hybrid approach is better. I assumed that's what had already been done, unfortunately.
tmbtx: I assumed that's what had already been done, unfortunately.
Me, too, pretty much. With polar amplification being significant where a substantial part of the 16% of missing coverage lies and especially given the unexpected excursion of sea ice "up there," my assumption was that somehow, some way the gap was accounted for before banging on about a pause.
But when I think about it, I had no reason to assume. Which brings us back to the old saw about "ass u me." :-)
doug_bostrom: "But when I think about it, I had no reason to assume."
Yeah.... same here. I started to type a few other things about why I didn't know that and realized it was because I hadn't checked. You know, like 99.99% of all people whether or not they're informed on the issue overall.
But now there's a problem, even with well-intentioned media coverage, of having to explain why the temperatures are really going up faster without looking like we're cooking the books. *I* know the books aren't being cooked but how do I convince people of that?
The difficulties of scientific communication have never looked so intractable to me.
It's a nice reminder that every time you start looking for an explanation, you first need to be sure that there's an effect in need of one.
I'm curious to see how this research fits into other studies about the "pause" (AKA, "the paws"). Seems that Kosaka & Xie 2013 might be at odds with this finding since their POGA-H model had an excellent fit with the original temperature record.
That brings me to a question. When a model is compared with a temperature record, ¿do they use the same averagin method? It seems to me that if you are using an average observed temperature that doesn't include the Arctic, then you should construct an average model temperature with exactly the same converage. I don't know if that's customary but if that's what K&X did then there would be no problem.
The coverage issue is definitely something to be aware of when reading the literature or looking at blog discussions for models vs. observations - camparisons have to be made with the same masking of effective area to be informative.
I was looking at the briefing page in the link Kevin provided. When you look back at the curve comparisons to 1980 the agreement is good until the most recent 16 years.
Is it a well established finding that Arctic heating has accelerated more than the globe over the last decade or so?
tmbtx @12, the HadCRUT4 data set excludes large parts of Africa, and significant regions in the Middle East, Central Asia, the Amazon Basin and Australia. Most of these areas are not significantly effected by ENSO, with the result that HadCRUT4 is more sensitive to ENSO than other surface temperature indices. In particular, HadCRUT4 undersamples North Africa, the Middle East, and Central Asia, areas which experienced intense heat in 2010. These two facts combine to explain the relatively large corrections in 2010 and durring the very intense La Nina of 2011-2012. Consequently it is a mistake to focus solely on the Arctic.
On that point, the video does say that most of the change in trend comes from including the Arctic. It is not obvious to me that that is the case. I would be very interested if one of the authors would explain how that was tested, and the portion of the change in trend due to infilling the Arctic compared to the change from infilling the rest of the globe.
Finally, there have been a number of indications that the pause is over-explained by the data, ie, that absent a number of different effects, there would have been an increased 16 year trend relative to the 30 year trend rather than a decrease. However, as the well known "alarmist" (irony intended) Stefan Rahmstorf writes:
"[I]f after all adjustments the global warming trend shows some acceleration, this would probably get the data closer to the model-mean (rather than to a continued linear warming trend).
But it would probably not be statistically significant, so <b>interpreting an acceleration into 15 years of data would be as ill-founded as finding a slowdown</b>.”
(See first comment at preceding link, my emphasis.)
Tom - thanks for that reply. Let me broaden the question a bit then: If the station coverage bias has been there consistently, why is the descrepancy highlighted in the last 15 or so years? The agreement prior to the "pause" interval is pretty good, by which I mean the corrections of the hybridized model seem smaller.
Michael Tobis at Planet3.0 points out something that I found took some of the "fun" out the finding:
There’s another aspect to this, though, and it may be a bigger deal than might at first be apparent. It adds up to a pretty scary situation.
That’s because the “slowdown” or “hiatus” has also had a number of alternative explanations. Decreased solar activity. Increased volcanic activity. A prevalence of cool-phase El Nino oscillations. Increase in aerosol loading from rapid and dirty Chinese industrial expansion. Heat export to deeper ocean layers.
To be sure, we are somewhat at risk of post hoc reasoning here. If there had been no sign of a “hiatus”, it is likely that less effort would have gone into explaining it! But all of these explanations appear individually to be sound, and with the possible exception of the last, [un]likely to be reversed at any time. What that would mean is that in reality the underlying rate of warming is still accelerating.
I notice a considerable drop during the 1998 El Nino on the adjusted hybrid record - not at all surprising, as missing polar and mid-African regions are known to be less affected by ENSO than much of the world. It looks to me like this downward shift in the earlier part of the record is just as important WRT the trend as the faster global temperature rise in the later part of the 16 year period.
Interesting and ingenious approach. I've reserve full praise until I've read through the paper, but the detail and care that went into the accompanying figures and presentations are quite impressive in and of themselves.
Excellent work. It appears as if the HADCRUT and GISTEMP series may converge if they start to use the Cowtan & Way hybrid or kriging corrections on the HADCRUT data.
In the figure below I overlaid the GISTEMP series to their supplementary figure S6 to show how closely they match. Also shown is the CSALT model which takes into account CO2, SOI, Aerosol, LOD, and TSI variability.
Like almost everyone, I am thrilled at the novelty of this work.
I am sure it will be closely critiqued (no doubt it has been already), but the implications are quite large.
Estimates of climate sensitivity based on recent warming like those of Otto et al will have to be revisited.
Climate modellers will be smiling.
The publications that ascribed the "pause" to volcanoes, ozone, deep ocean warming or ENSO will have to be also revisited. But we do understand the role of the ocean in global climate a lot better now.
The scientists involved must be simultaneously thrilled and annoyed!
Given the uncritical attention the "hiatus" received, there is still no sign of a news media report of this paper AFAIK. We can watch the BBC Science and Technology page, and the Economist with interest!
The trend calculator has a "hadcrut4 hybrid" option. Is that based on this work? Could you confirm? If it is a link on the calculator to this article in the datasource list would be helpful.
Most excellent work and great to see a formal study on this.
I have ranted about the negative bias from the poor Arctic coverage and the obvious huge warming up here for years, so that could not be a big surprise for those who work with this full time. On the other hand, the work with areas with low ENSO sensitivity that also had poor coverage is novel and highly interesting.
The MSM is going to be all over this and they will demand an explanation from the ''skeptics''.
Wow indeed. We always knew that the lack of Arctic coverage meant that the estimates there were questionable, but I never expected the difference to be this significant. That said, it helps explain the observed collapse of Arctic sea ice and the approach seems sound. We had been assuming that the reason measured estimates of deep ocean warming didn't quite cover the 'missing heat' was because we still weren't finding all of it. If this result holds up then the last of the 'missing heat' may finally have been found.
The fact that they used UAH satellite data to 'bridge the gap'... that 'popping' sound you hear is Roy Spencer's head exploding.
Esop, for a second there I thought you had suddenly become an impossibly naive optimist... until I got to the airborne pigs.
Unfortunately I think it will be all too easy for the "skeptics" to respond to this by working it into their epic fairytale about how climate scientists "manipulate" data whenever it doesn't "say" what they want it to. As though reams of tables of raw numbers had a way of opening their mouths and "speaking" for themselves if "statistics" would just keep its grubby hands off of them.
Wow raised to the wowth power. WebHubTelescope's CSALT overlay strengthens the urgent need for even stronger data driven science . A linearized CSALT slope over the past 33 years describes a1.8 C per century rate. Do the math.
It would be interesting to see a temperature curve just for the area within the Arctic circle over the past century or so. The error bars would be large at first but getting smaller and smaller with accumulating satellite data/
When I first read this about Kevin Cowtan's and Robert Way's paper a few things fell into place inside my mind.
We all hold evidence based science to be the way forward to better understanding of reality.
The only argument that scientists legitimately have is where the evidence is patchy or has large errors.
I can see how someone with a background in x-ray crystallography can see the way clearly to fill the gaps in the existing data by drawing together seemingly unrelated data. Having a bright young PhD student as a collaborator is also a major asset.
There is only one dogma in science. The ratio of signal to noise!
Do not forget though one scientist's noise can be another scientist's signal. Bert
I find it fascinating how the same paper is viewed at different sites dealing with Climate Change. Here it is considered a groundbreaking and immensely influential paper whereas others consider it to have very little that is of value. To paraphrase Bert @31 One site's accolades are often matched by another site's criticisms. As in these cases each site usually has input from reputable climate scientists it is often hard to discern what is the real situation.
This paper by Kevin and Robert does a magnificent job of collating disparate data sets to show that Global Warming has NOT hit any sort of hiatus.
Anyone who has faced a noisy three dimensional electron density map generated by noisy x-ray diffraction data to elucidate a three dimensional molecular structure of a complex molecule and has used all other evidence to arrive at a refined structure by reiteration has my deepest sympathy. Bert
Bert my apologies for saying I had paraphrased your comment. I can see by your somewhat intemperate language that tis irritated you. You ask about other siies and on Judith Curry's site there is a lot less adulatoin than there is here. However despite Professor Curry being a climate scientist with a solid publication record of more than 150 peer-reviewed papers on climate related topics and the Chair of The School of Earth and Atmospheric Sciences at Georgia Tech., Even though she is quite clearly not one of the scientific illiterati, I am aware that many climate scientists are not enamoured of her views. But does that make them wrong? Looking at the report of this paper on Real Climate, a site I would think not even you would criticise, the comments from some readers there are far more critical than those at this site. In addition the replies Gavin Schmidt and Stefan Rahmstorf are very helpful. Should you look at the comments on this paper on Real Climate you may find some that are relevant to your own comments here. Once again, my apologies.
"However despite Professor Curry being a climate scientist with a solid publication record of more than 150 peer-reviewed papers on climate related topics and the Chair of The School of Earth and Atmospheric Sciences at Georgia Tech., Even though she is quite clearly not one of the scientific illiterati, I am aware that many climate scientists are not enamoured of her views. But does that make them wrong?"
The responses by the authors to Curry's criticism make it clear that either she didn't read the paper in detail, or chose to ignore the various tests of the robustness of the paper's methodology that made her objections moot.
While she's not part of the scientific illiterati, she often acts as though she is. It is that, not her contrarian views, that cause knowledgeable people to disagree with her. It is not enough to be contrarian, you have to have sound arguments to back up your contrarian views to gain respect.
While congratulating Kevin & Robert (I need to note here that Kevin C recently mentioned few times of working busily on one important publication - now we can assume what publication it was :)
I have to warn the authors that thisk work falls into the area of "inconvenient science" where results are simple to undesrtand and likely to be denied by contrarians with encumbered agenda. I mean here, that your work, guys, falls into the same implicative category as e.g. the work of Mike Mann of Shaun Marcott, so expect lot of scientific scrutiny and denialist attacks. The former maybe a rewarding challenge, as I hope your results wthstand (i cannot be certain until I have time to read it) but the later may be unpleasant.
I continue to hold the opinion that "global warming" is an increase in ocean heat content, but I can see that the complexities of surface temperatures and their distribution is erudite science and must be useful, just not "global warming". Need more Argos (the new 18kg ones).
grindupBaker @38-with regard to your opinion that "global warming is an increase in ocean heat content", a new, peer reviewed paper by Chen , Feng and Huang (http://www.sciencedirect.com/science/article/pii/S0921818113002397)
suggests this may not be the case. Their bullet points are:
The global mean sea level started decelerated rising since 2004 with the rising rate 1.8 ± 0.9 mm/yr in 2012
Deceleration is due to slowdown of ocean thermal expansion during last decade.
Recent ENSO events introduce large uncertainty of long-term trend estimation.
In the Abstract they note that since 2004 the rate of rise in global mean sea levels has dropped from the 3.2±0.4 mm/year seen from 1993 to 2003 with the rate of rise in 2012 being 1.8±0.9mm/year. This fall in the rate of rise is thought due to "a slowdown in the rate of thermal expansion in the Pacific during the last decade as part of the Pacific decadal scale variability" . From their Figure 5b it looks as though the Pacific may have changed from gaining heat in the period 1993 to 2003 to losing heat from 2004 to 2012
00
Moderator Response:
(Rob P) - That's a very interesting paper, but off-topic here. It does, however, provide independent support for greater heat being mixed into the deep ocean and the increased upwelling of colder, denser, water at the equator - all part of the spin-up of the wind-driven ocean circulation, and results in a phenomenon known as cabbeling. Please find a more appropriate thread if you wish to discuss that paper further.
At RealClimate the OP clearly states that this paper is considered important and groundbreaking. Your suggestion in 35 that RC is not supportive in incorrect. Do not confuse scientists closely reading a paper to understand it better with Currie's criticism. In addition, there are several posters in the thread at RC who appear to be tone trolls.
The authors have countered Curries objections directly. Curry has not responded to these counters. The paper has been widely peer reviewed before publication. I personally doubt that Curry can find important issues in a single day of thought that the reviewers missed with much longer reflection. We will have to wait to see how the conclusions of this paper hold up.
Curry has in truth responded to the comments made by both authors at her blog although there is little more to learn from her responses except that she is not up to speed with the literature (or the authors' names). Probably has too little time to spare now she's a blog-mom.
Later in the comments thread she (curryja) dismisses the attempt to establish a 'global' surface temperature record, but rather considers the key issue to be a comparison of 'model simulations with observations' and again refers to the Ed Hawkins analysis. So, unless HadCRUT is revised by added coverage or by revised data, the inability of CMIP5 models to reflect Arctic amplification will be ignored by curryja and the 'pause' will remain. Yet this is strange as I don't remember this 'pause' being measured by comparing models & observations. It is surely always a regression of temperature observations alone with not a sniff of model simulation.
This past summer, the Arctic was somewhat cooler than it had been over the past few summers. As expected, the global average temp shot up to record tying level, further proving the negative bias provided by the non-measured heat bundled up in the Arctic over the past few years.
Passing ironic that my simple-minded note that OHC is the future and my lukewarm kudo for the sterling poster (actual posters) historical GMST (a "global warming" proxy) work drew only #39 Poster with an even more nebulous proxy that assumes I'm so ignorant that I think oceans at 0-4 Celsius will expand hugely if warmed a tad. I've done the simple math in the first few hours I first looked at this topic in spring. My moderation-resistant on-topic asides are Prof Muller BerkeleyEarth shows a smoother increasing temperature & derivative land-only data mean (? I've no time to study his available RMS? software) and that I disagree with Bert #43 about "venomous response" because I can only see this brilliant satellite infill analysis to correct (and warm-up) the data in recent years as increased polar warming renders simple interpolation (even modelled type) imprecise as being a much more accurate multi-sensor trick to hide the decline in polar GMST measuring quality that has evidently been happening with interpolation, so I see no basis for attack on the work or on my comment here for that matter.
We're perfectly OK acknowledging the differences in tables and graphs when someone asks directly why there is any difference at all between temperature measurements and trends from different organisations. See, look here, this crowd do it one way and these people do it another way and it's all perfectly reasonable that they come up with differing results. And everybody nods wisely.
As soon as this question is no longer front and centre, we blithely discuss "slowdowns" and "pauses" and heat sinks and various climate mechanisms as though the measurements and trends are entirely reliable, a mere background for other discussions. We should remind ourselves constantly that knowing about these features of the records is not like knowing times table or basic algebra as the unerringly solid foundation for simple calculations. We learn those things so that we don't have to think about them. These things do have to be thought about.
Keeping this work in the foreground for the next while should force us to keep the whole picture more comprehensively in mind.
adelady is quite correct. We all make the mistake of obsessing about the peripherals. This is where the deniers aim their missives.
As a simple first approximation our planet Earth is a simple sphere of solid rock with a layer of liquid water and then air.
If there is any imbalance of incoming radiation from the Sun compared to the blackbody radiation out to space of the whole Earth system, the air will heat up first. This is our early warning that something is wrong.
We know long term that more than 90% of the radiation heat imbalance ends up in the water. This is due to all sorts of complex mixings that is very difficult to model.
To then say that an 'hiatus' of air temperature increase indicates anything is absurd. It is even more absurd when you consider these air temperature measurements do not cover the full surface system.
This paper by Kevin Cowtan and Robert Way has shown how to measure the surface or 'air' temperature far better by filling in the important polar regions not well covered by surface measurements. This has shown there is no 'hiatus' in surface temperature rise.
The total ocean heat content increase is the final arbiter. By the time it is measured accurately and fully, it will be too late. Bert
Poster, in case you are interested, I just wrote my thoughts on the comments of Judith Curry (and Watts and Lucia).
Concluding, I see no problems with this paper. Like any work of science there is no certainty and we will have to see what future scientists will find. The comments by Judith Curry and Lucia point to interesting points for future research, but do not invalidate the study in any way.
Is it that the "ignorati" might disagree with us, or is it that scientifically minded people are logically superior and more fair? It took dacades for the scientific community to accept plate tectonics, now it is conventionial earth physiscs. People are passionate, since scientists are people they are passionate too.
It seems we have to do a better job of communicating to each other, to the media, and thus to the scientifically untrained. One of the ways is to be a little more humble about how fair we are. I am speaking from current experience trying to introduce a new concept to the scientific comunity. It is much hareder than one might think. But Thomas S. Kuns (the structure of scientific revolutions) would not be surprized.
"It took dacades for the scientific community to accept plate tectonics"
Plate tectonics was accepted quite quickly after the theory was developed to explain (among other things) observed sea-floor spreading.
Not only does it provide a satisfying explanation for the fact that the continents fit together roughly like jigsaw puzzle pieces, it was the final nail in the coffin for the proposed mechanisms underlying the continental drift hypothesis, all of which were physcially impossible and therefore properly rejected by mainstream science.
There is a reason why modern scientists speak of plate tectonics rather than continental drift ...
Arguments
This result is staggering. My congratulations to Kevin and Robert for a great piece of work.
Thanks Andy.
For anyone who is interested there is a longer video abstract, a detail background document, and every single piece of code and data required to reproduce our results from scratch on the project website.
Thanks, Kevin and Robert, and congratulations!
There's an object lesson here in terms of how we may forget that our public discussion can be perilously dependent on speculation without our pausing (!) to carefully consider what we fairly know. For all the sound and fury expended over "the pause" we didn't actually know what was happening, not enough anyway to get in a lather about it.
Now, suddenly, it appears "the pause" has shrunk rather dramatically, thanks to people who look while the rest of us leap. Sheepish looks should be the hangover, not that it's likely any of the more extreme hyperbole we've witnessed is going to be accounted for.
I'm truly surprised this previously gaping hole wasn't emphasized more in all the premature chatter. Particularly it's strange that people who should and do know better have gone on to formalize "the pause" in various embarrassing places.
Expanding a bit on Doug's point about public discussion - how do you present to a general audience the various decisions that are made in reconstructing temperature data? Obviously a discussion of kriging isn't really material for the local pub, but temperature curves published by the media get portrayed as "this is the temperature" not "this is the temperature we get from using stations with 85% global coverage and we suspect the other 15% would be warmer."
Nice work though. It's pretty clear the hybrid approach is better. I assumed that's what had already been done, unfortunately.
tmbtx: I assumed that's what had already been done, unfortunately.
Me, too, pretty much. With polar amplification being significant where a substantial part of the 16% of missing coverage lies and especially given the unexpected excursion of sea ice "up there," my assumption was that somehow, some way the gap was accounted for before banging on about a pause.
But when I think about it, I had no reason to assume. Which brings us back to the old saw about "ass u me." :-)
What Doug Bostrom said, at #4....we are inba much more dire sitation that any may have thought.
doug_bostrom: "But when I think about it, I had no reason to assume."
Yeah.... same here. I started to type a few other things about why I didn't know that and realized it was because I hadn't checked. You know, like 99.99% of all people whether or not they're informed on the issue overall.
But now there's a problem, even with well-intentioned media coverage, of having to explain why the temperatures are really going up faster without looking like we're cooking the books. *I* know the books aren't being cooked but how do I convince people of that?
The difficulties of scientific communication have never looked so intractable to me.
It's a nice reminder that every time you start looking for an explanation, you first need to be sure that there's an effect in need of one.
I'm curious to see how this research fits into other studies about the "pause" (AKA, "the paws"). Seems that Kosaka & Xie 2013 might be at odds with this finding since their POGA-H model had an excellent fit with the original temperature record.
That brings me to a question. When a model is compared with a temperature record, ¿do they use the same averagin method? It seems to me that if you are using an average observed temperature that doesn't include the Arctic, then you should construct an average model temperature with exactly the same converage. I don't know if that's customary but if that's what K&X did then there would be no problem.
Congratulations Kevin and Robert. Well done.
The coverage issue is definitely something to be aware of when reading the literature or looking at blog discussions for models vs. observations - camparisons have to be made with the same masking of effective area to be informative.
I was looking at the briefing page in the link Kevin provided. When you look back at the curve comparisons to 1980 the agreement is good until the most recent 16 years.
Is it a well established finding that Arctic heating has accelerated more than the globe over the last decade or so?
Congratulation Kevin & Rob. Very well done.
tmbtx @12, the HadCRUT4 data set excludes large parts of Africa, and significant regions in the Middle East, Central Asia, the Amazon Basin and Australia. Most of these areas are not significantly effected by ENSO, with the result that HadCRUT4 is more sensitive to ENSO than other surface temperature indices. In particular, HadCRUT4 undersamples North Africa, the Middle East, and Central Asia, areas which experienced intense heat in 2010. These two facts combine to explain the relatively large corrections in 2010 and durring the very intense La Nina of 2011-2012. Consequently it is a mistake to focus solely on the Arctic.
On that point, the video does say that most of the change in trend comes from including the Arctic. It is not obvious to me that that is the case. I would be very interested if one of the authors would explain how that was tested, and the portion of the change in trend due to infilling the Arctic compared to the change from infilling the rest of the globe.
Finally, there have been a number of indications that the pause is over-explained by the data, ie, that absent a number of different effects, there would have been an increased 16 year trend relative to the 30 year trend rather than a decrease. However, as the well known "alarmist" (irony intended) Stefan Rahmstorf writes:
(See first comment at preceding link, my emphasis.)
Tom - thanks for that reply. Let me broaden the question a bit then: If the station coverage bias has been there consistently, why is the descrepancy highlighted in the last 15 or so years? The agreement prior to the "pause" interval is pretty good, by which I mean the corrections of the hybridized model seem smaller.
Sorry, I meant to include the link to the image: http://www-users.york.ac.uk/~kdc3/papers/coverage2013/media_compare12.png
I see perhaps a similar correction around 1980 and then very little change until about 2000.
Hey, congrats to SKS for making it to the floor of the Senate!
Since there are no open threads here, I thought was a good a place as any...
Michael Tobis at Planet3.0 points out something that I found took some of the "fun" out the finding:
But see Stefan Rahmstorf's comment.
Wow. This is going to tweak a few folks who shall remain unnamed.
I notice a considerable drop during the 1998 El Nino on the adjusted hybrid record - not at all surprising, as missing polar and mid-African regions are known to be less affected by ENSO than much of the world. It looks to me like this downward shift in the earlier part of the record is just as important WRT the trend as the faster global temperature rise in the later part of the 16 year period.
Interesting and ingenious approach. I've reserve full praise until I've read through the paper, but the detail and care that went into the accompanying figures and presentations are quite impressive in and of themselves.
Excellent work. It appears as if the HADCRUT and GISTEMP series may converge if they start to use the Cowtan & Way hybrid or kriging corrections on the HADCRUT data.
In the figure below I overlaid the GISTEMP series to their supplementary figure S6 to show how closely they match. Also shown is the CSALT model which takes into account CO2, SOI, Aerosol, LOD, and TSI variability.
Like almost everyone, I am thrilled at the novelty of this work.
I am sure it will be closely critiqued (no doubt it has been already), but the implications are quite large.
The scientists involved must be simultaneously thrilled and annoyed!
Given the uncritical attention the "hiatus" received, there is still no sign of a news media report of this paper AFAIK. We can watch the BBC Science and Technology page, and the Economist with interest!
The trend calculator has a "hadcrut4 hybrid" option. Is that based on this work? Could you confirm? If it is a link on the calculator to this article in the datasource list would be helpful.
Most excellent work and great to see a formal study on this.
I have ranted about the negative bias from the poor Arctic coverage and the obvious huge warming up here for years, so that could not be a big surprise for those who work with this full time. On the other hand, the work with areas with low ENSO sensitivity that also had poor coverage is novel and highly interesting.
The MSM is going to be all over this and they will demand an explanation from the ''skeptics''.
Shortly after, pigs will be airborne.
Wow indeed. We always knew that the lack of Arctic coverage meant that the estimates there were questionable, but I never expected the difference to be this significant. That said, it helps explain the observed collapse of Arctic sea ice and the approach seems sound. We had been assuming that the reason measured estimates of deep ocean warming didn't quite cover the 'missing heat' was because we still weren't finding all of it. If this result holds up then the last of the 'missing heat' may finally have been found.
The fact that they used UAH satellite data to 'bridge the gap'... that 'popping' sound you hear is Roy Spencer's head exploding.
Esop, for a second there I thought you had suddenly become an impossibly naive optimist... until I got to the airborne pigs.
Unfortunately I think it will be all too easy for the "skeptics" to respond to this by working it into their epic fairytale about how climate scientists "manipulate" data whenever it doesn't "say" what they want it to. As though reams of tables of raw numbers had a way of opening their mouths and "speaking" for themselves if "statistics" would just keep its grubby hands off of them.
Wow raised to the wowth power. WebHubTelescope's CSALT overlay strengthens the urgent need for even stronger data driven science . A linearized CSALT slope over the past 33 years describes a1.8 C per century rate. Do the math.
It would be interesting to see a temperature curve just for the area within the Arctic circle over the past century or so. The error bars would be large at first but getting smaller and smaller with accumulating satellite data/
Holy Vostok Ice Cores, Batman, look at the difference in the trend calculator:
Old HADCRUT:
Trend: 0.52 ±1.55 °C/century (2σ)
HADCRUT Hybrid:
Trend: 1.33 ±1.83 °C/century (2σ)
(Naturally I started with 1998...cuz that's where "they" always start)
Hindsight is a wonderful thing.
When I first read this about Kevin Cowtan's and Robert Way's paper a few things fell into place inside my mind.
We all hold evidence based science to be the way forward to better understanding of reality.
The only argument that scientists legitimately have is where the evidence is patchy or has large errors.
I can see how someone with a background in x-ray crystallography can see the way clearly to fill the gaps in the existing data by drawing together seemingly unrelated data. Having a bright young PhD student as a collaborator is also a major asset.
There is only one dogma in science. The ratio of signal to noise!
Do not forget though one scientist's noise can be another scientist's signal. Bert
I find it fascinating how the same paper is viewed at different sites dealing with Climate Change. Here it is considered a groundbreaking and immensely influential paper whereas others consider it to have very little that is of value. To paraphrase Bert @31 One site's accolades are often matched by another site's criticisms. As in these cases each site usually has input from reputable climate scientists it is often hard to discern what is the real situation.
poster at @32 you did not paraphrase me but you did make a lot of crap up! You obviously are confused by subtle comment.
Show me a reputable site that refutes this refereed paper that is not run by the scientific illliterati. Bert
Just to make it clear to poster.
This paper by Kevin and Robert does a magnificent job of collating disparate data sets to show that Global Warming has NOT hit any sort of hiatus.
Anyone who has faced a noisy three dimensional electron density map generated by noisy x-ray diffraction data to elucidate a three dimensional molecular structure of a complex molecule and has used all other evidence to arrive at a refined structure by reiteration has my deepest sympathy. Bert
Bert my apologies for saying I had paraphrased your comment. I can see by your somewhat intemperate language that tis irritated you. You ask about other siies and on Judith Curry's site there is a lot less adulatoin than there is here. However despite Professor Curry being a climate scientist with a solid publication record of more than 150 peer-reviewed papers on climate related topics and the Chair of The School of Earth and Atmospheric Sciences at Georgia Tech., Even though she is quite clearly not one of the scientific illiterati, I am aware that many climate scientists are not enamoured of her views. But does that make them wrong? Looking at the report of this paper on Real Climate, a site I would think not even you would criticise, the comments from some readers there are far more critical than those at this site. In addition the replies Gavin Schmidt and Stefan Rahmstorf are very helpful. Should you look at the comments on this paper on Real Climate you may find some that are relevant to your own comments here. Once again, my apologies.
Poster:
"However despite Professor Curry being a climate scientist with a solid publication record of more than 150 peer-reviewed papers on climate related topics and the Chair of The School of Earth and Atmospheric Sciences at Georgia Tech., Even though she is quite clearly not one of the scientific illiterati, I am aware that many climate scientists are not enamoured of her views. But does that make them wrong?"
The responses by the authors to Curry's criticism make it clear that either she didn't read the paper in detail, or chose to ignore the various tests of the robustness of the paper's methodology that made her objections moot.
While she's not part of the scientific illiterati, she often acts as though she is. It is that, not her contrarian views, that cause knowledgeable people to disagree with her. It is not enough to be contrarian, you have to have sound arguments to back up your contrarian views to gain respect.
jdixon1980@27,
I concur,
While congratulating Kevin & Robert (I need to note here that Kevin C recently mentioned few times of working busily on one important publication - now we can assume what publication it was :)
I have to warn the authors that thisk work falls into the area of "inconvenient science" where results are simple to undesrtand and likely to be denied by contrarians with encumbered agenda. I mean here, that your work, guys, falls into the same implicative category as e.g. the work of Mike Mann of Shaun Marcott, so expect lot of scientific scrutiny and denialist attacks. The former maybe a rewarding challenge, as I hope your results wthstand (i cannot be certain until I have time to read it) but the later may be unpleasant.
I continue to hold the opinion that "global warming" is an increase in ocean heat content, but I can see that the complexities of surface temperatures and their distribution is erudite science and must be useful, just not "global warming". Need more Argos (the new 18kg ones).
grindupBaker @38-with regard to your opinion that "global warming is an increase in ocean heat content", a new, peer reviewed paper by Chen , Feng and Huang (http://www.sciencedirect.com/science/article/pii/S0921818113002397)
suggests this may not be the case. Their bullet points are:
The global mean sea level started decelerated rising since 2004 with the rising rate 1.8 ± 0.9 mm/yr in 2012
Deceleration is due to slowdown of ocean thermal expansion during last decade.
Recent ENSO events introduce large uncertainty of long-term trend estimation.
In the Abstract they note that since 2004 the rate of rise in global mean sea levels has dropped from the 3.2±0.4 mm/year seen from 1993 to 2003 with the rate of rise in 2012 being 1.8±0.9mm/year. This fall in the rate of rise is thought due to "a slowdown in the rate of thermal expansion in the Pacific during the last decade as part of the Pacific decadal scale variability" . From their Figure 5b it looks as though the Pacific may have changed from gaining heat in the period 1993 to 2003 to losing heat from 2004 to 2012
(Rob P) - That's a very interesting paper, but off-topic here. It does, however, provide independent support for greater heat being mixed into the deep ocean and the increased upwelling of colder, denser, water at the equator - all part of the spin-up of the wind-driven ocean circulation, and results in a phenomenon known as cabbeling. Please find a more appropriate thread if you wish to discuss that paper further.
Poster:
At RealClimate the OP clearly states that this paper is considered important and groundbreaking. Your suggestion in 35 that RC is not supportive in incorrect. Do not confuse scientists closely reading a paper to understand it better with Currie's criticism. In addition, there are several posters in the thread at RC who appear to be tone trolls.
The authors have countered Curries objections directly. Curry has not responded to these counters. The paper has been widely peer reviewed before publication. I personally doubt that Curry can find important issues in a single day of thought that the reviewers missed with much longer reflection. We will have to wait to see how the conclusions of this paper hold up.
michael sweet @40.
Curry has in truth responded to the comments made by both authors at her blog although there is little more to learn from her responses except that she is not up to speed with the literature (or the authors' names). Probably has too little time to spare now she's a blog-mom.
Later in the comments thread she (curryja) dismisses the attempt to establish a 'global' surface temperature record, but rather considers the key issue to be a comparison of 'model simulations with observations' and again refers to the Ed Hawkins analysis. So, unless HadCRUT is revised by added coverage or by revised data, the inability of CMIP5 models to reflect Arctic amplification will be ignored by curryja and the 'pause' will remain. Yet this is strange as I don't remember this 'pause' being measured by comparing models & observations. It is surely always a regression of temperature observations alone with not a sniff of model simulation.
This past summer, the Arctic was somewhat cooler than it had been over the past few summers. As expected, the global average temp shot up to record tying level, further proving the negative bias provided by the non-measured heat bundled up in the Arctic over the past few years.
What this work shows is how to start to merge all the data from physically different sensors.
My prediction is that one day ocean temperatures will also be better mathematically linked.
How long have the masses/ignorati cried out 'how do you measure the temperature of a whole planet?'
These criticisms are legitimate? from people who know nothing of science. The fact that they are totally ignorant of the complexities is very sad.
As night follows day this paper will be a focus for the ignorati for the most venomous response.
It has already started. Bert
Jos Hagelaars made a figure comparing these new Cowtan and Way data to the CMIP5 model ensemble (and to HadCRUt4 for reference).
Blogpost: http://ourchangingclimate.wordpress.com/2013/11/15/cowtan-and-way-global-average-temperature-observations-compared-to-cmip5-models/
Figure: http://ourchangingclimate.files.wordpress.com/2013/11/cowtan_way_hadcrut_rcp85-jos-hagelaars-2013.png
Passing ironic that my simple-minded note that OHC is the future and my lukewarm kudo for the sterling poster (actual posters) historical GMST (a "global warming" proxy) work drew only #39 Poster with an even more nebulous proxy that assumes I'm so ignorant that I think oceans at 0-4 Celsius will expand hugely if warmed a tad. I've done the simple math in the first few hours I first looked at this topic in spring. My moderation-resistant on-topic asides are Prof Muller BerkeleyEarth shows a smoother increasing temperature & derivative land-only data mean (? I've no time to study his available RMS? software) and that I disagree with Bert #43 about "venomous response" because I can only see this brilliant satellite infill analysis to correct (and warm-up) the data in recent years as increased polar warming renders simple interpolation (even modelled type) imprecise as being a much more accurate multi-sensor trick to hide the decline in polar GMST measuring quality that has evidently been happening with interpolation, so I see no basis for attack on the work or on my comment here for that matter.
Great work, guys. Made me think.
We're perfectly OK acknowledging the differences in tables and graphs when someone asks directly why there is any difference at all between temperature measurements and trends from different organisations. See, look here, this crowd do it one way and these people do it another way and it's all perfectly reasonable that they come up with differing results. And everybody nods wisely.
As soon as this question is no longer front and centre, we blithely discuss "slowdowns" and "pauses" and heat sinks and various climate mechanisms as though the measurements and trends are entirely reliable, a mere background for other discussions. We should remind ourselves constantly that knowing about these features of the records is not like knowing times table or basic algebra as the unerringly solid foundation for simple calculations. We learn those things so that we don't have to think about them. These things do have to be thought about.
Keeping this work in the foreground for the next while should force us to keep the whole picture more comprehensively in mind.
adelady is quite correct. We all make the mistake of obsessing about the peripherals. This is where the deniers aim their missives.
As a simple first approximation our planet Earth is a simple sphere of solid rock with a layer of liquid water and then air.
If there is any imbalance of incoming radiation from the Sun compared to the blackbody radiation out to space of the whole Earth system, the air will heat up first. This is our early warning that something is wrong.
We know long term that more than 90% of the radiation heat imbalance ends up in the water. This is due to all sorts of complex mixings that is very difficult to model.
To then say that an 'hiatus' of air temperature increase indicates anything is absurd. It is even more absurd when you consider these air temperature measurements do not cover the full surface system.
This paper by Kevin Cowtan and Robert Way has shown how to measure the surface or 'air' temperature far better by filling in the important polar regions not well covered by surface measurements. This has shown there is no 'hiatus' in surface temperature rise.
The total ocean heat content increase is the final arbiter. By the time it is measured accurately and fully, it will be too late. Bert
Poster, in case you are interested, I just wrote my thoughts on the comments of Judith Curry (and Watts and Lucia).
Is it that the "ignorati" might disagree with us, or is it that scientifically minded people are logically superior and more fair? It took dacades for the scientific community to accept plate tectonics, now it is conventionial earth physiscs. People are passionate, since scientists are people they are passionate too.
It seems we have to do a better job of communicating to each other, to the media, and thus to the scientifically untrained. One of the ways is to be a little more humble about how fair we are. I am speaking from current experience trying to introduce a new concept to the scientific comunity. It is much hareder than one might think. But Thomas S. Kuns (the structure of scientific revolutions) would not be surprized.
PluviAL:
"It took dacades for the scientific community to accept plate tectonics"
Plate tectonics was accepted quite quickly after the theory was developed to explain (among other things) observed sea-floor spreading.
Not only does it provide a satisfying explanation for the fact that the continents fit together roughly like jigsaw puzzle pieces, it was the final nail in the coffin for the proposed mechanisms underlying the continental drift hypothesis, all of which were physcially impossible and therefore properly rejected by mainstream science.
There is a reason why modern scientists speak of plate tectonics rather than continental drift ...