Talk:Global warming hiatus

Some background re current thinking

http://scienceblogs.com/gregladen/2014/04/08/waving-good-bye-to-the-stadium-wave-model-about-that-global-warming-hiatus/

Karl et al.: Possible artifacts of data biases in the recent global surface warming hiatus

http://www.sciencemag.org/content/early/2015/06/03/science.aaa5632.abstract

Oh, and http://www.realclimate.org/index.php/archives/2015/06/noaa-temperature-record-updates-and-the-hiatus/

William M. Connolley (talk) 21:09, 4 June 2015 (UTC)

http://www.theguardian.com/environment/2015/jun/04/global-warming-hasnt-paused-study-finds --Nigelj (talk) 22:24, 4 June 2015 (UTC)

"A whole cottage industry has been built by climate skeptics on the false premise that there is currently a hiatus in global warming," said Mark Maslin, professor of climatology at University College London. "This important reanalysis suggests there never was a global warming hiatus; if anything, temperatures are warming faster in the last 15 years than in the last 65 years." (http://phys.org/news/2015-06-global.html) William M. Connolley (talk) 08:18, 5 June 2015 (UTC)

Nurture: http://www.nature.com/news/climate-change-hiatus-disappears-with-new-data-1.17700 William M. Connolley (talk) 16:38, 5 June 2015 (UTC)

New information casts doubt on hiatus.

This is a new study. So I wouldn't say the hiatus is discredited at this point(although the name is misleading). If this study holds up to scrutiny over time this page may need to be completely overhauled. In the meantime this information needs to be mentioned.

Article on NOAA website Study published in Science. — Preceding unsigned comment added by ErictheJacobson (talk • contribs) 01:19, 5 June 2015 (UTC)

A place to start: treat it as a hypothesis. [1]. I'm not sure a "complete overhaul" will be necessary, since the article's definitions relate more tob periodic "pauses", and much of the controversy will remain as currently documented. Yakushima (talk) 12:43, 5 June 2015 (UTC)

Judith Curry casts doubt on Karl et al.: Has NOAA ‘busted’ the pause in global warming?.

"My bottom line assessment is this. I think that uncertainties in global surface temperature anomalies [are] substantially understated. The surface temperature data sets that I have confidence in are the UK group and also Berkeley Earth. This short paper in Science is not adequate to explain and explore the very large changes that have been made to the NOAA data set. ... "

Given her (and other) criticisms, and the newness of this paper, might be best to back this one out. Or at least put in some qualifiers. Too new to tell if it will be a significant study. --Pete Tillman (talk) 23:16, 5 June 2015 (UTC)

Curry can "cast" as much doubt as she wants. Her blog rambling has zero weight. — TPX 00:36, 6 June 2015 (UTC)

Quoted in NYT article,

"The change prompted accusations on Thursday from some climate-change denialists that the agency was trying to wave a magic wand and make inconvenient data go away. Mainstream climate scientists not involved in the NOAA research rejected that charge, saying it was essential that agencies like NOAA try to deal with known problems in their data records.

"At the same time, senior climate scientists at other agencies were in no hurry to embrace NOAA’s specific adjustments. Several of them said it would take months of discussion in the scientific community to understand the data corrections and come to a consensus about whether to adopt them broadly."

NewsAndEventsGuy (talk) 01:03, 6 June 2015 (UTC)

Update the graphs for 2015?

The graph attributed to GISS annual data does not look current. Since they depend directly on the NASA data why not use the maintained graphics from http://data.giss.nasa.gov/gistemp/graphs_v3/ If the article needs its own graph, perhaps it should be updated to include recent data?

In R it might be something like:

library(ggplot2); library(reshape2) ; library(scales)

giss<-read.table(
'http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.txt',
  skip=4,nrows=2015-1880+1,na.strings='*',col.names=c('Year','Annual','Avg_5y'))

p <- ggplot(melt(giss,id='Year',value.name='C'),
       aes(x=Year,y=C,colour=variable))+
       geom_line()+
       theme(legend.justification=c(0,1), legend.position=c(0,1))+
       ggtitle("Global Land-Ocean Temperature Index (C)\n (Anomaly with Base: 1951-1980)") +
       scale_colour_discrete(name="Time Series of annual anomalies",
         breaks=c("Annual","Avg_5y"),labels=c("Annual Mean","5-year_Mean"))+
       scale_x_continuous(breaks=pretty_breaks(n=20))
  ggsave("GISS_Global_Land_Ocean_Index_201505.svg",plot=p,width=10, height=8)

... which gives the graph below. Drf5n (talk) 16:07, 5 June 2015 (UTC)

I help maintain a multilingual SVG graph of the GISS 'Fig A2' dataset at https://commons.wikimedia.org/wiki/File:Global_Temperature_Anomaly.svg, which is widely used across Wikipedia. I never understood why this article had to have its own graph. It seems a bad way to ensure that the data is always out of date, and allows for errors to be introduced without so many eyes on the job to notice. I'd be much happier with that graph in this article as elsewhere where the data needs understanding. --Nigelj (talk) 17:27, 5 June 2015 (UTC)

I have [boldly] made the change. --Nigelj (talk) 17:37, 5 June 2015 (UTC)

Cool. My R+ggplot graph was kinda fun, but referring to a graph with a good maintenance plan is a better solution. Drf5n (talk) 18:39, 5 June 2015 (UTC)

These findings have drawn criticisms from both sides of the climate debate

I took that out. The LA Times does indeed say it, but its not a reasonable thing to say: presented here, its false balance; there, its just lazy journalism. Also, if we're going to quote people on what this study is about, the balance-of-quotes needs to reflect the balance-of-scientific response; which means quoting only Curry is, like, way out maan William M. Connolley (talk) 06:28, 6 June 2015 (UTC)

Actually, the NY Times made much the same point, as N&EG pointed out in the discussion about this paper, @ "New information casts doubt on hiatus", above. Why didn't you post this comment there?

Perhaps we should combine the two news articles. We can't just ignore significant RS press commentary, especially on a brand-new primary-source paper. --Pete Tillman (talk) 21:53, 6 June 2015 (UTC)

You mean that it says that senior climate scientists said it would take months of discussion for the scientific community to come to a consensus about whether to adopt the new data broadly?[2] That's not a criticism of the research, that's a description of how scientific consensus works. — Preceding unsigned comment added by Nigelj (talk • contribs) 22:12, 6 June 2015‎

For once, the Graun seems to have got it righter: "Dr Peter Stott, head of climate monitoring and attribution at the UK’s Met Office, said Noaa’s research was “robust” and mirrored an analysis the British team is conducting on its own surface temperature record. 'Their work is consistent with independent work that we’ve done. It’s within our uncertainties. Part of the robustness and reliability of these records is that there are different groups around the world doing this work,' he said. But Stott argued that the term slowdown remained valid because the past 15 years might have been still hotter were it not for natural variations." Moere from others, including NASA. The LAT looked a bit rubbish, seems to have failed to read AR5 and just got a mangled version from somewhere. . dave souza, talk 23:02, 6 June 2015 (UTC)

Since when is "new" research accepted as gospel? The is one study, which rightly has been criticized, plus it doesn't vibe with the other measurments. I am going to return the criticism for balance. Arzel (talk) 16:37, 8 June 2015 (UTC)

Err, its not taken as gospel. The text now says "hypothesised", not "discredited". And its been widely accepted; the crit has come from a small number of the usual suspects, who as usual have been largely ignored; so should we William M. Connolley (talk) 16:42, 8 June 2015 (UTC)

Our description of this new paper (published online June 4) is a paraphrase of the abstract, and (naturally) is pretty sunny re the authors conclusions: with "improved adjustments", the supposed "slowdown" disappeared! Others have pointed out that the adjustments are unproven and perhaps dubiuos, and that time will tell. These concerns need to be here, for NPOV, which is not optional.

It's also noteworthy that this study was added to our article on June 5, one day after online publication. One might speculate on how quickly it would have been added here, were its conclusions different. WP:RECENT suggests caution. Pete Tillman (talk) 14:00, 10 June 2015 (UTC)

Others have pointed out that the adjustments are unprove William M. Connolley (talk) 14:09, 10 June 2015 (UTC)

Also for "it doesn't vibe with the other measurments": an unreliable source reports that the NOAA record is now more in line with other datasets; from 1998-2012 it's increased from 0.039°C +/- 0.082 to 0.086 °C +/-0.075, but this tool apparently shows GISTEMP as 0.066°C +/- 0.156, Berkeley: 0.108 °C +/- 0.152 and a HadCRUT4 hybrid (of Cowtan and Way): 0.136 °C +/- 0.181. Can someone with more expertise check this out? . . dave souza, talk 18:15, 10 June 2015 (UTC)

2015 study?

"A 2015 study reanalyzed the temperature data which had formed the basis of IPCC's assessment" looks a bit wrong, since the reanalysis was already under way in 2008: see Smith et al. (2008) p. 2290: "Because ships tend to be biased warm relative to buoys and because of the increase in the number of buoys and the decrease in the number of ships, the merged in situ data without bias adjustment can have a cool bias relative to data with no ship–buoy bias.... The increasing negative bias due to the increase in buoys tends to reduce this recent warming. This change in observations makes the in situ temperatures up to about 0.1°C cooler than they would be without bias. At present, methods for removing the ship–buoy bias are being developed and tested." So, it's really a 2015 paper reporting long term work refining NOAA's temperature data. . dave souza, talk 18:01, 10 June 2015 (UTC)

That's a bit picky. Papers or works are generally referred to by their year of publication; that the actual work was done earlier is understood William M. Connolley (talk) 20:30, 10 June 2015 (UTC)

the basis of IPCC's assessment that had apparently confirmed the hiatus

What's the cite for that? We don't seem to have one. We seem to be taking it for granted that the IPCC did indeed do so. Did it? William M. Connolley (talk) 15:48, 10 June 2015 (UTC)

Not sure offhand, so I removed the claim for now. If anyone has a source discussing the IPCC's assessment, we can review it and ensure its being summarized accurately.   — Jess· Δ♥ 15:52, 10 June 2015 (UTC)

Noticed that too. Thanks for writing it up! Cheers, Pete Tillman (talk) 18:19, 10 June 2015 (UTC)

Missing cite might be AR5 WG1 Tech Summary, page 37 (as printed by publisher) "Despite the robust multi-decadal warming, there exists substantial interannual to decadal variability in the rate of warming, with several periods exhibiting weaker trends (including the warming hiatus since 1998)" (Parenthetical in original)

NewsAndEventsGuy (talk) 18:33, 10 June 2015 (UTC)

Also note, for example, "Trends for short periods are uncertain and very sensitive to the start and end years. For example, trends for 15-year periods starting in 1995, 1996, and 1997...." and much more in Box TS.3 pp. 61–63. For the pdf see ref. 1. in the article. . . dave souza, talk 19:48, 10 June 2015 (UTC)

Yes, Box TS.3 | Climate Models and the Hiatus in Global Mean Surface Warming of the Past 15 Years is probably the most useful bit. I'm dubious that does anything as strong as "confirms" it though... for example, there is Even with this ‘hiatus’ in GMST trend, the decade of the 2000s has been the warmest in the instrumental record of GMST (note the quotes around hiatus, though that's the only time they do it) William M. Connolley (talk) 20:35, 10 June 2015 (UTC)

While we're on TS.3, they also say In summary, the observed recent warming hiatus, defined as the reduction in GMST trend during 1998–2012 as compared to the trend during 1951–2012, which does actually provide a definition, one which arguably contradicts the one this page uses. Should we update ours? William M. Connolley (talk) 20:37, 10 June 2015 (UTC)

Oh, and here is the TS link for convenience: [3] William M. Connolley (talk) 20:37, 10 June 2015 (UTC)

I think this page (A) defines the general notion of a hiatus and (B) talks about the recent one as an example. Regarding your question and item (B), sure we should use IPCC's def. NewsAndEventsGuy (talk) 21:05, 10 June 2015 (UTC)

However, the notion lies within natural variability: the interest is in seeing how far decadal modeling is possible, see below. . . dave souza, talk 21:52, 10 June 2015 (UTC)

Actually... I think its more complex than that. If you look in Chapter 2, which would be the natural place to find this stuff, the word "hiatus" doesn't occur at all. Instead we have:

Much interest has focussed on the period since 1998 and an observed reduction in warming trend, most marked in NH winter (Cohen et al., 2012). Various investigators have pointed out the limitations of such short-term trend analysis in the presence of auto-correlated series variability and that several other similar length phases of no warming exist in all the observational records and in climate model simulations (Easterling and Wehner, 2009; Peterson et al., 2009; Liebmann et al., 2010; Foster and Rahmstorf, 2011; Santer et al., 2011). This issue is discussed in the context of model behaviour, forcings and natural variability in Box 9.2 and Section 10.3.1. Regardless, all global combined LSAT and SST data sets exhibit a statistically non-significant warming trend over 1998–2012 (0.042°C ± 0.093°C per decade (HadCRUT4); 0.037°C ± 0.085°C per decade (NCDC MLOST); 0.069°C ± 0.082°C per decade (GISS)). An average of the trends from these three data sets yields an estimated change for the 1998–2012 period of 0.05 [–0.05 to +0.15] °C per decade. Trends of this short length are very sensitive to the precise period selection with trends calculated in the same manner for the 15-year periods starting in 1995, 1996, and 1997 being 0.13 [0.02 to 0.24], 0.14 [0.03 to 0.24] and 0.07 [–0.02 to 0.18] (all °C per decade), respectively

so then I have to go to chapter 10. Page 870 then repeats the hiatus defn quoted already. Further on: GMST warmed strongly over the period 1900–1940, followed by a period with little trend, and strong warming since the mid-1970s (Section 2.4.3, Figure 10.1)... Since 1998 the trend in GMST has been small (see Section 2.4.3, Box 9.2). There may be more, but I didn't find it. Overall, I'd say they aren't very interested in it William M. Connolley (talk) 21:06, 10 June 2015 (UTC)

Chapter 01 has "In summary, the trend in globally averaged surface temperatures falls within the range of the previous IPCC projections. During the last decade the trend in the observations is smaller than the mean of the projections of AR4 (see Section 9.4.1, Box 9.2 for a detailed assessment of the hiatus in global mean surface warming in the last 15 years
Which leads to Chapter 09 Box 9.2 | Climate Models and the Hiatus in Global Mean Surface Warming of the Past 15 Years. . . dave souza, talk 21:52, 10 June 2015 (UTC)

Point to note: the AR5 refers to HadCRUT4, a journalist notes the recent update to Had which should be interesting when it's combined with CRUT. . . dave souza, talk

Just to note that there's now a post on RC (http://www.realclimate.org/index.php/archives/2015/06/debate-in-the-noise/) that mentions this specific point:

Some media reports even gave the impression that the IPCC had confirmed a “hiatus” of global warming in its latest report of 2013, and that this conclusion was now overturned... The IPCC thus specifically pointed out that the lower warming trend from 1998-2012 is not an indication of a significant change in climatic warming trend, but rather an expression of short-term natural fluctuations. Note also the uncertainty margins indicated by the IPCC.

- See more at: http://www.realclimate.org/index.php/archives/2015/06/debate-in-the-noise/#sthash.jcqIuTXj.dpuf

Chris Mooney's Mother Jones essay, 2013

WMC reverted this edit diff, commenting "however, that one isn't reasonable; asserting or iplying that its only CM is clear bias". Can you unpack that, starting with "CM"?

Here's the edit:

In an essay for Mother Jones magazine, Chris Mooney wrote that climate skeptics argue that global warming has stopped since the record-breaking warm El Niño year of 1998: an example appeared as an opinion piece in the Daily Telegraph in 2006, and was rebutted at the time. These arguments were given new prominence in media reporting in March 2013. Research explaining the issue was after the deadline for inclusion in the IPCC Fifth Assessment Report, and a leaked draft of the report was publicised by the press in August with assertions that scientists were struggling to explain the hiatus. When the full report was published that November[,] the wording was clarified. Mooney wrote that the IPCC's communication record is "pretty poor". [cite Mooney, 2013 opinion essay in MJ)

-- which does need a couple of tweaks[ ], I see. Perils of late-night edits!

Thanks, Pete Tillman (talk) 17:43, 12 June 2015 (UTC)

Just to assist, CM might perhaps be not unconnected to Chris Mooney, since it's being used for checkable facts rather than opinion, and so attributing this mainstream view to one author fails NPOV. The section needs reorganised, it would work better as a history of this so-called "hiatus", showing the mainstream context. . . dave souza, talk 20:20, 12 June 2015 (UTC)

New Karl et al adjustments raise past temps, hence decrease overall GW

I added this bit to Karl et al, from Justin Gillis's NYT report on same, rather an eye-opener:

The corrected data set also "makes the temperature increase of the past century appear less severe than it does in the raw data", by about 0.42 °F (0.23 °C), according to NOAA climate scientist Russell S. Vose. Cited to Global Warming ‘Hiatus’ Challenged by NOAA Research , New York Times, June 4, 2015.

WMC reverted, commenting "perfectly reasonable edits if in a different article. This isn't the intrumental temperature record article."

I submit that it's perfectly reasonable for here, too. If the Karl 2015 adjustments are accepted, the overall GW since 1880 decreases by about 20%, a substantial effect. It would seriously mislead our readers to imply that the only effect of the new NOAA adjustments was to make the Pause go away.

I agree it should be added elsewhere as well. Has anyone seen a more formal writeup of this change? Preferably with a before & after graph, 1880 to 2014? We should add that chart here, too, under the current one in the lede.

Incidentally, our cite of the Karl paper currently omits the 8 et als. Cheers, Pete Tillman (talk) 18:08, 12 June 2015 (UTC)

It would seriously mislead our readers to imply that the only effect of the new NOAA adjustments was... - this page isn't about the paper. Its been edited in recently, but don't get confused. Arguably this page shouldn't really even exist; it should just be a subsection of the temperature record William M. Connolley (talk) 19:48, 12 June 2015 (UTC)

Fair enough -- we can certainly cross-ref (and should ).

But, in the here-and-now, the page DOES exist. So, if we are discussing Karl et al, we need the GW implications too. This is pretty straightforward, WMC. Pete Tillman (talk) 19:52, 12 June 2015 (UTC)

The urgency of the matter is tied to climate sensitivity, and the implication of actual temp increase being lower than anyone previously thought is that climate sensitivity is higher than we thought. After all, we have multiple lines of evidence of warming from Retreat of glaciers since 1850 to thawing of Ötzi the ice man to Extreme weather to many others. Wherever we talk about actual temp increase being lower than thought, we shoul also mention that the system is that much more sensitive than we thought. Presumably there's RS for this, but I haven't gone looking for them yet. NewsAndEventsGuy (talk) 20:02, 12 June 2015 (UTC)

WMC being well aware of the context, he may have missed PT's confusion and hence the unjustified excitement: the clue is that Russell S. Vose didn't say that the new correction "makes the temperature increase of the past century appear less severe than it does in the raw data". Careful reading of the NYT is needed. . . dave souza, talk 20:23, 12 June 2015 (UTC)

b.t.w. a handy before-and-after graph showing the effect of the adjustments on earlier years is Figure 2.4. Not completely up to date, but shows the same principle. . dave souza, talk 20:37, 12 June 2015 (UTC)

• From The NYT:

However, Russell S. Vose, chief of the climate science division at NOAA’s Asheville center, pointed out in an interview that while the corrections do eliminate the recent warming slowdown, the overall effect of the agency’s adjustments has long been to raise the reported global temperatures in the late 19th and early 20th centuries by a substantial margin. That makes the temperature increase of the past century appear less severe than it does in the raw data.

If you just wanted to release to the American public our uncorrected data set, it would say that the world has warmed up about 2.071 degrees Fahrenheit since 1880,” Dr. Vose said. “Our corrected data set says things have warmed up about 1.65 degrees Fahrenheit. Our corrections lower the rate of warming on a global scale.”

Seems pretty straightforward, Dave. If the past was warmer, delta-T (1880-2014) is less. Unpack your remark, please. Thanks, Pete Tillman (talk) 22:40, 12 June 2015 (UTC)

Vose is reported in the NYT to say, "the overall effect of the agency’s adjustments has long been to raise the reported global temperatures in the late 19th and early 20th centuries by a substantial margin" (my italics). NOAA has been making adjustments to raw data for a long time. Dave said, "Vose didn't say that the new correction "makes the temperature increase of the past century appear less severe..."" (again my italics) It seems pretty clear to me. You just have to read all the words. --Nigelj (talk) 23:41, 12 June 2015 (UTC

Thanks Nigelj, the RC gospel on this covers the point well in the caption to Figure 2 from Karl et al (2015). Fig 2A shows that the total effect of the recent improvements is very small, to my eye 2B showing relationship of corrected data to raw data is very similar to Figure 2.4 from TAR (2001), though of course the newer paper shows about 15 more years of warming. Note that the text of the TAR shows reasons for corrections which have been repeated in reports on Karl et al. . . . dave souza, talk 06:46, 13 June 2015 (UTC)

Another example why we should work harder at following FAQ twenty-one NewsAndEventsGuy (talk) 02:20, 13 June 2015 (UTC)

---

Thanks to all for the comments. On carefully rereading it, Vose's statement is (to me) ambiguous, and who knows if the newspaper got all the details right. Bottom line: WMC was right that it doesn't belong here. It might be interesting to pursue in the history of adjustments to the temp record. Best, Pete Tillman (talk) 22:26, 13 June 2015 (UTC)

Misconceptions

I was considering adding something to do with the global warming hiatus over at List of common misconceptions. While I wasn't considering putting "there is no hiatus" or something so certain like that, There do seem to be a lot of misconceptions about this topic. So, I brought it up on the talk page, and the response was to be cautious about this, and to only proceed if the other editors here have a consensus on the existence of a common misconception. It doesn't even need to be that the hiatus itself is a myth, I think a misconception ABOUT the hiatus would also be a candidate. Thoughts? SarrCat ∑;3 05:30, 13 June 2015 (UTC)

Good idea! Thanks for your approach, too.

(A) Fact we have DS in place on the topic "climate change" means there is debate among Wikipedia editors. It does not indiciate anything (yes or no) regarding genuine scientific debate.

(B) It is indeed a common misconception that the hiatus means "no warming", or "global warming stopped". In the news lately is a genuine scientific debate whether the apparent hiatus may be due to biases in the data. We don't need that genuine scientific debate to finish in order to conclude that it is a misconception to think "'the global warming hiatus' means global warming stopped". Anyone who knows the scientific literature knows that's absurd for two reasons. First, the narrow meaning of "global warming" is strictly about surface temperatures, and to scientists the recent hiatus has been a period in which "surface temps are still rising, just not as fast". Second, to the lay public "global warming" means the overall story, which is about much more than just surface temps. It includes the climatological interactions between everything from sea floor muck to glacial base to upper atmosphere. The overall climate system is still taking in BTUs (i.e., it's warming) just as fast as ever, due to the imbalance of Earth's energy budget. There is some genuine debate regarding where that heat is going, but no debate at all for the fact we're taking it in and its going somewhere in the climate system. So yes, its a common misconception that "global warming hiatus means global warming stopped". Belief in that misconception is like fixating on the burning paint when your entire house is aflame.NewsAndEventsGuy (talk) 08:59, 13 June 2015 (UTC)

Second graph

I notice the second graph which used a shorter time frame and therefore showed the hiatus more clearly is gone Why is this? The subject of the article is this hiatus. The graph showing it more should be given preference not be excluded completely — Preceding unsigned comment added by 24.217.74.133 (talk) 05:27, 23 June 2015 (UTC)

Both of the previous graphs were out of date by well over a year. The present graph is updated regularly and used on dozens of articles. It is an SVG graph which means that if you click onto it you can zoom in to any area as much as you like. --Nigelj (talk) 08:16, 23 June 2015 (UTC)

File:GISS zoom 1970 2011 Temp.png was a cropped derivative of the main graph, it's now obsolete and appears only in Talk:Global warming controversy/Archive 11. The IPCC has defined the "hiatus" as the relationship between 1951–2012 and 1998–2012, Karl et al. extend that from 1950 to 2014. It would be helpful if we could have a cropped graph of the anomaly from 1950 to present and keep it updated: would that be possible? . . . dave souza, talk 10:18, 23 June 2015 (UTC)

If someone would like to code one up, and undertake to maintain it, I would have no objection. However, I'm not sure of the benefit when with an SVG graph any user can simply clink into it and use their browser's zoom controls to see all the detail that is there, in perfect graphical quality. I would be slightly worried about who would make the choice as to where to start the reduuced dataset - 1950, 1970, 1990 etc. We all know that by cherry-picking start and end points it is possible to show almost anything you like from noisy data, and I don't believe we can do better than display all that we have, and let readers make their own minds up. Lastly, it is possible, with papers like Karl et al, that the shape of all this will officially change in the near future and the whole issue will become of history-of-science interest only. --Nigelj (talk) 10:50, 24 June 2015 (UTC)

Ed Hawkins on Karl et al 2015

An interesting discussion at his Climate Lab Book: A spectrum of global temperature trends.

Karl et al.’s conclusion that the warming during the most recent 15 years compared to the second half of the 20th century ... is broadly correct, although I would suggest that ‘similar to’ is more appropriate than ‘at least as great as’.

But, there has clearly been a slowdown in the rate of warming when compared to other periods, e.g. those centred on the 1990s.

So, it's a criticism of detail, but then, it's pretty obvious that the timing of publication of Karl et al. had a political element. Good discussion, too.--Pete Tillman (talk) 02:32, 29 June 2015 (UTC)

Pete, once again this is your own political interpretation and doesn't follow the WP:TALK guideline, or indeed WP:NOTAFORUM policy: the blog isn't a reliable source, and the comments even less so. Got any reliably sourced proposals for article improvement? . . dave souza, talk 06:26, 29 June 2015 (UTC)

Hawkins is certainly RS under the expert exemption, as you know, Dave. And your postings are always so pure and ideology-free, right? Pete Tillman (talk) 17:31, 29 June 2015 (UTC)

I've not used RealClimate as a source here, but given your support for expert opinion in blogs I'll reconsider that. As for this brief post by Hawkins, you seem to be taking part out of context, and the "political element" is your speculation with no reliable source. As for ideology, you seem to be getting very WP:BATTLEFIELD: try to comply both with conduct policy and with policy on giving due weight to mainstream science. . . dave souza, talk 18:23, 29 June 2015 (UTC)

Natural Variability

I added a short paragraph to the section on Natural Variability, to better explain in the big picture how a short-term 'pause' resulting from climate variability is theoretically compatible with a long term warming trend (resulting from increased CO2). Some people seem confused and therefore put off by the concept, but it is really quite simple and intuitively graspable when properly summarized.Bdmwiki (talk) 21:26, 29 June 2015 (UTC)

...A 2013 study (supporting anthropogenic global warming over both solar activity and cosmic ray explanations) showed that the increase in CO₂ from the pre-industrialization level of about 280 ppm to the current level of about 400 ppm would theoretically, with the CO₂ greenhouse effect taken unrealistically entirely in isolation, result in a 6.6° Celcius atmospheric temperature increase... Nah, 6.6 oC isn't at all plausible William M. Connolley (talk) 21:27, 29 June 2015 (UTC)

Agreed, it's not plausible -- but it is taken in isolation, as noted. The general circulation models include the isolated simple model effect in addition to all the real-world effects. The math for the isolated simple model result is shown in the referenced study and ensues from accepted theory. This near parity of overall effects is good news, of course, for explaining common short-term pauses due to natural variability while maintaining a long term warming trend from increasing CO2. By contrast, if the simple model isolated result were drastically lower, say 0.85C vs the actual observed 0.8C, then it would be much less plausible/likely (or be an incredibly rare occurrence) for natural variability alone to explain a short term pause within a longer term warming trend resulting from increasing CO2.Bdmwiki (talk) 21:43, 29 June 2015 (UTC)

I've cut the para. I didn't believe your number, and it looks like you don't either. It was:

To understand how natural climate variability factors could in theory mitigate the warming effect of increases in CO₂ in the short-term, it is necessary to understand the relative impact of each. A 2013 study (supporting anthropogenic global warming over both solar activity and cosmic ray explanations) showed that the increase in CO₂ from the pre-industrialization level of about 280 ppm to the current level of about 400 ppm would theoretically, with the CO₂ greenhouse effect taken unrealistically entirely in isolation, result in a 6.6° Celcius atmospheric temperature increase. The reason for the lower actual increase of 0.8° Celsius is attributable to the real-world mitigating effects of "feedback mechanisms [both positive and negative] and all the other complications of the climate." Given the similar order of magnitude of these two groups of effects, even a small unexpected short-term change in real-world mitigating effects could slow-down, neutralize, or even overwhelm the incremental greenhouse effects of increased CO₂, thereby producing a hiatus; however, with such a short-term hiatus it is currently thought that the greenhouse forcing effects of increased CO₂ would nonetheless restore the warming trend in the longer term.

The number is so badly wrong that it hinders rather than helps understanding William M. Connolley (talk) 06:51, 30 June 2015 (UTC)

Produce a coherent account, complete with solid scientific reference, to show that this properly published paper, authored by well credentialed scientists, using established physics, arrived at an erroneous result with respect to their (not my) number that inexplicably offends you. That is how Wikipedia works -- not by someone just scribbling, "Nah, I don't buy some number don't think you do either, so I'm removing your whole edit."Bdmwiki (talk) 05:29, 1 July 2015 (UTC)