Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Twitter Facebook YouTube Pinterest MeWe

RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

New? Register here
Forgot your password?

Latest Posts


What has global warming done since 1998?

What the science says...

Select a level... Basic Intermediate

Every part of the Earth's climate system has continued warming since 1998, with 2015 shattering temperature records.

Climate Myth...

It hasn't warmed since 1998

For the years 1998-2005, temperature did not increase. This period coincides with society's continued pumping of more CO2 into the atmosphere. (Bob Carter)

Even if we ignore long term trends and just look at the record-breakers, 2015, 2014, 2010, and 2005 were hotter than 1998.

The myth of no warming since 1998 was based on the satellite record estimates of the temperature of the atmosphere.  However, as discussed in the video below by Peter Sinclair, even that argument is no longer accurate.  The satellites show warming since 1998 too.

There's also a tendency for some people just to concentrate on atmospheric or surface air temperatures when there are other, more useful, indicators that can give us a better idea how rapidly the world is warming. More than 90% of global warming heat goes into warming the oceans, while less than 3% goes into increasing the atmospheric and surface air temperature.  Records show that the Earth has been warming at a steady rate before and since 1998 and there is no sign of it slowing any time soon (Figure 1). 

Fig 1

Figure 1:  Land, atmosphere, and ice heating (red), 0-700 meter ocean heat content (OHC) increase (light blue), 700-2,000 meter OHC increase (dark blue).  From Nuccitelli et al. (2012).

Even if we focus exclusively on global surface temperatures, Cowtan & Way (2013) shows that when we account for temperatures across the entire globe (including the Arctic, which is the part of the planet warming fastest), the global surface warming trend for 1997–2015 is approximately 0.14°C per decade.

Ultimately, every part of the Earth's climate system is warming, and has continued warming since 1998.

This rebuttal was updated by Kyle Pressler in September 2021 to replace broken links. The updates are a result of our call for help published in May 2021.

Last updated on 29 September 2017 by dana1981. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

Further reading

Tamino further explores the warming trend since 1998 in Garbage is Forever and Wiggles.

I've kept my original treatment of the subject as other websites hotlink to the images. My original treatment uses similar arguments to Fawcett and Jones 2008 although their analysis is much more rigorous (as you'd expect in a peer-reviewed paper).

Further viewing


Prev  1  2  3  4  5  6  7  8  9  Next

Comments 251 to 300 out of 414:

  1. "What's wrong with this graph"?

    It's mislabeled.  WATTS and company can't add - that's 15 years, not 16.  It's also been shifted - the real data on that is from August 1997 to August 2012, not the beginning of 1997 and the end of 2012.  Also, the values have been altered.  The first one should be less than .5*C and the last higher.  It's been fudged, in other words. 

    "The Hadley Centre/CRU records show no warming for 18 years (v.3"

    False.  v.3 shows about .14*C of warming over that period globally. 

    "or 19 years (v.4),"

    Even more false.  The trend is bigger with v.4 - about .17*C of warming over the last 18 years and about .2*C over the last 19. 

    "and the RSS satellite dataset shows no warming for 23 years"

    Spectacularly incorrect.  RSS shows about .28*C of warming over the last 23 years. 

    "h/t to Werner Brozek for determining these values"

    Hat tip for feeding you false data?  Seriously?  Where's your skepticism? 

    "temps have been rising slowly since the middle ages"

    So, you're a LIA denier too? 

    "sorry gotta go catch ya later"

    Ah, hit and run.  Next time, why not come back with correct info?



  2. Warren, firstly your posts on SkS have demonstrated an argumentative rhetorical tone.  This is not conducive to discussion of science and is likely to irritate the other participants in the discussion, which reflects more badly on you than on anyone else.  Please give it a rest.

    So "What is wrong with the graph?"

    (i) It is an example of cherry picking start and end dates.  If you have a time series with an upward trend that is small in comparison to the magnitude of the noise, then it isn't surprising that you can choose start and end points where the noise temporarily masks the trend.  However that doesn't mean the trend has gone away.  This can be easily demonstrated by constructing a synthetic time series with an upward trend (so you know it is there by construction) and observing that you can still cherry pick periods where this trend is masked.

    (ii) Trends are not measured by noting the difference in temperature at the start point and the endpoint as this is to sensitive to the noise to have any statistical meaning.  Instead scientists use least-squares linear trends, often adjusted to take account of the autocorrelation. 

    (iii) The anlaysis makes no mention of statistical significance, nor of the statistical power of the test (which is very important if you want to claim that there has been no warming since 1998, I'd be happy to explain this in more detail when you respond to my post).


    [JH] I have deleted a number of Warren Hindmarsh's comments because they were off topic and/or slogannering. He definitely needs to loose the snarky tone. He also should read and adhere to the SkS Comments Policy. 

  3. Warren Hindmarsh - I've discussed this particular topic with Werner Brozek at some length, for example at Spencers blog. You, unfortunately, appear to have some of the same misconceptions regarding statistical significance - it's possible to cherry-pick an interval that shows any conclusion you wish, as long as you avoid using all of the data. But short periods are not statistically significant, there is insufficient data to make a claim one way or another. 

    As I have mentioned before on these threads: 

    For any of the instrumental series, over any time span ending in the present:

    • There is no period where warming is invalidated, against a null hypothesis of no warming.
    • Against a null hypothesis of the long term warming trend, there is no period where a "no warming" hypothesis is validated. None.
    • Over any period with enough data to show statistical significance, that data shows a statistically significant warming trend.

    Claims otherwise, such as your repetitions of 'skeptics' elsewhere, are demonstrably wrong. 

  4. Warren, well worth reading the Guardian's reporting on James Hansen's BBC R4 comments this mornng (here), in particular:

    Prof Hansen, speaking to BBC Radio 4's Today programme, rejected both arguments. "In the last decade it has warmed only a tenth of a degree compared to two-tenths of a degree in the preceeding decade, but that's just natural variability. There is no reason to be surprised by that at all," he said. "If you look over a 30-40 year period the expected warming is two-tenths of a degree per decade, but that doesn't mean each decade is going to warm two-tenths of a degree: there is too much natural variability."

  5. To further Dikran's point, consider the trend of 1992-2007.  Using Had4, the trend is 0.3C per decade.  That's approaching double the expected rate of warming. According to your logic, climate scientists should have declared that they had seriously underestimated the rate of warming.  No.  It's a short-term trend.  And it's a cherry-pick.  And it covers half of your 16-year period.  You can try to reconcile all that, or you could actually engage a critical thinking process and try to understand the forces at work that create the state of the surface temp -- like scientists do.

    One more thing, Warren: when you say "no warming" you immediately reveal yourself to be ignorant about the science.  You complained about the accuracy of the survey titling.  Now you want a free pass for using an insignificant portion of the thermal capacity of the climate system (the troposphere) to represent the whole shebang.  Ignoring OHC is deceptive . . . or ignorant.  Your response will determine my choice.

  6. For #40 and #50. Have you check Argo Project? It seems NO. Argo project the most serious study of the T and sea levels didn't observe increase in the T. It's true that it a new project (since 2005) but data is more accuracy.

  7. Chemasan, the methodology of Levitus et al. (2012) includes Argo data.  Go here to see the results.  If you choose Jan-Mar on any of the 3-month sets, you'll get up to 2013.  I strongly suggest using the 0-2000m set.  Here's global 0-2000m for all months:

    2005-3 8.972987
    2005-6 9.391529
    2005-9 9.681848
    2005-12 12.636982
    2006-3 11.932278
    2006-6 12.998004
    2006-9 12.264493
    2006-12 13.356965
    2007-3 13.49815
    2007-6 11.382808
    2007-9 12.277043
    2007-12 12.418795
    2008-3 13.305184
    2008-6 14.606297
    2008-9 13.024848
    2008-12 12.090649
    2009-3 12.614719
    2009-6 12.241169
    2009-9 13.816815
    2009-12 15.052814
    2010-3 15.881298
    2010-6 13.484779
    2010-9 13.959781
    2010-12 14.823184
    2011-3 15.215552
    2011-6 14.630487
    2011-9 16.870249
    2011-12 14.859973
    2012-3 17.308126
    2012-6 15.461417
    2012-9 15.34632
    2012-12 16.630146
    2013-3 19.332438

    The annual running average produces a linear trend of +1.74*10^21 joules added per year.  

  8. Could someone please respond to the peer-reviewed paper published yesterday in the International Journal of Modern Physics B by professor Qing-Bin Lu of the University of Waterloo, COSMIC-RAY-DRIVEN REACTION AND GREENHOUSE EFFECT OF HALOGENATED MOLECULES: CULPRITS FOR ATMOSPHERIC OZONE DEPLETION AND GLOBAL CLIMATE CHANGE?

    "Conventional thinking says that the emission of human-made non-CFC gases such as carbon dioxide has mainly contributed to global warming. But we have observed data going back to the Industrial Revolution that convincingly shows that conventional understanding is wrong,” said Qing-Bin Lu, a professor of physics and astronomy, biology and chemistry in Waterloo’s Faculty of Science. “In fact, the data shows that CFCs conspiring with cosmic rays caused both the polar ozone hole and global warming.”

    "Most conventional theories expect that global temperatures will continue to increase as CO2 levels continue to rise, as they have done since 1850. What’s striking is that since 2002, global temperatures have actually declined – matching a decline in CFCs in the atmosphere,” Professor Lu said. “My calculations of CFC greenhouse effect show that there was global warming by about 0.6 °C from 1950 to 2002, but the earth has actually cooled since 2002. The cooling trend is set to continue for the next 50-70 years as the amount of CFCs in the atmosphere continues to decline.”
    Quoted from Waterloo News, May 2013


    [DB] Refuted here:


    This is off-topic; please return the conversation to the topic of this thread.

  9. Thank-you and sorry for the misplacement (also the all-caps.) I note Lu made the claim in the quoted interview that there has been no warming since 2002.

  10. Why does the top video say "This video is private." ? It was playing okay a few weeks ago and I sorely need it right now for point of reference.  I'm confused.


    [DB] The video has been withdrawn to better enable updates and revisions to come.

  11. Hi; On the issue of the video being private. Any ETA on when the updated versin will become available? It's a really nice explanation and I'd love to pass it along to some friends for whom such visual representations are more compelling.


  12. For all the posts I read about the warming trend having apparently stabilized I don't find any arguments for enthalpy as a sink consuming vast amounts of excess atmospheric heat. I've only had a basic technical physics education so, while I feel a bit out of my class trying to contribute something substantive to the discussion, a review of the chapter on Properties of Heat and Heat Transfer in my physics text raised my eybrows relating to this topic.

    1 calorie of heat will raise the temperature of 1 gram of water 1 degree Celsius.

    Effect of Enthalpy - To raise a gram of water the degree across which it changes state from ice to liquid requires 80 calories in order to break down the crystaline structure of the ice.

    Eighty times as much is an enourmous increase in heat consumption and since enthalpy is taking place in the worlds ice packs it can be considered work that the global heat is doing. While it's somewhat valid for the denier to observe a levelling off global atmospheric temperature, wouldn't it be helpful to direct their attention to the fact that the world's ice has been melting at an alarming rate at the same time this "levelling" has been apparent? In my somewhat elementary view the world's ice is a great heat sink which, at its melting point, is consuming enormous amounts of excess heat from the atmosphere and from sea water. This is the work the heat is accomplishing. This is basic physics and I believe most deniers have the mechanical aptitude to wrap their minds around that concept. I haven't seen this accounted for in any climate science articles or graphs. I just think that, if my physics isn't off the mark, if enthalpy does account for a significantly stabilizing effect on global temperature, then it might be helpful to spin some easy to read and understand pictures about it.

    At any rate, I don't have the capability to scale the above argument up to the climate equation and am interested to know if it's valid and how significant is it? I don't like to think about what the temperature graphs will look like when the ice packs are gone.

  13. Can anyone point out the errors in this recent paper?

    For the most part it looks like another rehashing of the "we are actually cooling (or staying steady)" argument.

  14. I did some research and found out that the principle author, John C. Fyfe was a participant of the IPCC 4AR. So it would seem that he is not a denier, and is in fact a supporter. So I am not sure what to make of this comment: 


    The inconsistency between observed and simulated global warming is even more striking for temperature trends computed over the past fifteen years (1998–2012). For this period, the observed trend of 0.05 ± 0.08 °C per decade is more than four times smaller than the average simulated trend of 0.21 ± 0.03 °C per decade (Fig. 1b). It is worth noting that the observed trend over this period — not significantly different from zero — suggests a temporary 'hiatus' in global warming.

    So, my question is, has it gotten warmer in the last 15 years, or not? Does it matter? If it doesn't matter, then why is he bringing it up? He doesn't really make a big deal about it in the rest of the paper, which seems mostly focused on the models. I get that the model isn't important to whether or not climate change is real, so that is not what my question is about.

  15. MrGibbage, by what measure?  Ocean heat content shows no "hiatus" over the period, and it makes up 90%+ of the effective thermal capacity of the climate system.  Global ice mass loss makes up another 2-3%, and it has accelerated over the surface "hiatus" period.  Further, if you run a 30-year linear from 1975 to 1998, you get 0.163C per decade, and that doesn't factor in the lower transient response of the period's earlier years.  If you run 1975 to 2008, you get 0.19C per decade.  So when did the "hiatus" begin?  

    Further, could Fyfe not have written this in 1995?  The trend from 1981 to 1995 is 0.0879C per decade.  The trend for 1997 (capturing the full 97/8 El Nino) to present is 0.071C.  Not far apart.  The trend from 1981 to present is 0.161C per decade.

    All Fyfe is saying, to me, is "models are sketchy at projecting short-term surface temp fluctuations," which, of course, everyone already knows.  

    Now, has global warming "paused"?  Or has the surface temp trend "paused"?  Slow day at the Fyfe office, especially since five bajillion people have already covered the issue.  Have you read Kosaka & Xie 2013?  Does HockeySchtick provide fair and balanced coverage of it?

  16. DSL, thanks for replying. I know HockeySchtick is a typical denier website. But it has the full text of Dr. Fyfe's report for free. At the nature website where it was originally published, you have to pay for it.

    So I am not interested in the way that HockeySchtick is trying to use it. They are focused on the model inaccuracy--yeah yeah, I get it--the models are inacurate for short term, which is the point of the paper. I only have issue with the point that he made suggesting that the temperature hasn't increaded in fifteen years. Which to me is strange because he seems to be well regarded in climate science and even served on the IPCC.

    I am not a climate scientist--I'm just a guy that reads a lot of science stuff and I am trying to convince a denier friend of mine that climate change is real. He found this report (which is written by a real climate scientist) and found the line suggesting that there hasn't been any increase and is using it as evidence that there is no climate change. I feel like Dr. Fyfe is on our side, but when he drops a stat like that and doesn't go into any more detail, then I am confused. I am pretty sure he knows about ocean heat content making up 90% of the thermal mass. So I think the statement that the temperatures haven't changed in fifteen years actually means something other than how I am interpreting it.

    I don't know what Dr. Fyfe's motives are, but when he drops a line like that, it sure makes me think he is a denier, which just adds to my confusion.

    He has his email address on his bio page here:

    Maybe I should just email him and ask.

  17. MrGibbage,

    I think one should not automatically assume there something is wrong about the paper, or that the author is a denier; this is particularly so since this is a piece in Nature Climate Change (not some obsure Journal where the editorial standard may be questionable), and as you said John Fyfe is a respected climate scientist.

  18. @IanC, I tend to agree with you, which is what makes me think I am misunderstanding what he is saying there.

    I actually sent him an email. It will be interesting to see what (or if) he writes back.

  19. Oh, wow! I actually got a response from Dr. Fyfe. First my email to him and then his response below it.

    Hello Dr. Fyfe. I am sure you are very busy, but for a long shot, I thought I would try and just ask you about a question I have about your report

    Overestimated global warming over the past 20 years

    I am not a scientist, but I do like to read a lot of science papers and reports (mostly space stuff). I am a believer in climate change, but I have a friend that is a denier. I have a Master's degree in computer modeling and simulation, so I understand how models are supposed to work. I understand your point of the paper in that the CMIP model has been overestimating the global temperature for the last fifteen years, when compared to the actual temperature. The model needs fixing--I get that.

    What I don't understand is your statement:

    The inconsistency between observed and simulated global warming is even more striking for temperature trends computed over the past fifteen years (1998–2012). For this period, the observed trend of 0.05 ± 0.08 °C per decade is more than four times smaller than the average simulated trend of 0.21 ± 0.03 °C per decade (Fig. 1b). It is worth noting that the observed trend over this period — not significantly different from zero — suggests a temporary 'hiatus' in global warming

    All of a sudden it looks like (the typical denier sentiment) that the planet is not getting warmer at all. Now, I know this was not the point of the paper, but I am confused by it, and my friend is using it as evidence that climate change is not real. Maybe that *WAS* your point, in which case I may need to rethink my stance as well. Or maybe I am misunderstanding what you meant. Is the planet getting warmer or not?

    Anyway, if you have the time, perhaps you could explain it to me in somewhat layman's terms what that statement really means and how it should be interpreted.

    Thank you, Sir, for your time.
    Very Respectfully,

    Skip Morrow


    And Dr. Fyfe's reponse:

    Dear Skip,

    Thanks for your interest in our paper.

    That the rate of warming has recently slowed down is well known. Not so well known are the reasons for this, although several lines of evidence suggest that it combines cooling impacts from reducing solar radiation at the top of the atmosphere, increasing reflecting aerosols in the stratosphere, and decreasing tropical Pacific sea surface temperatures -- which together are temporarily masking the warming impact from increasing greenhouse gases. None of these cooling impacts are expected to carry on very much longer, at which point we expect a period of rapid warming back the path the planet had been following for the last 100-years or so.

    On a different topic, here is a new contribution of ours that was released today from the publishers of Nature.

    Best, John

    John C Fyfe, PhD
    Senior Scientist, Canadian Centre for Climate Modelling and Analysis
    Environment Canada

    Ocean, Earth and Atmospheric Sciences Bldg., University of Victoria
    off. 250-363-8236
    fax. 250-363-8247

    I think I understand now. It's a shame that so many denier websites are using this report to support their cause.

  20. Thanks for posting the email, MrGibbage.  The response clarifies Fyfe's position quite a bit.

  21. So, if the point of this page at SkepticalScience is to suggest that the planet hasn't been cooling since 1998, and has in fact been warming, then who do we believe? Dr. Fyfe, who suggests that it hasn't cooled or warmed, or Skeptical Science? Does this page need to be updated?

  22. Again, MrGibbage, the problem is in the wording.  Whenever scientists use "global warming" to refer to global mean surface temperature, confusion is the result.  I don't know why Fyfe did that in his published work.  Note that he says "warming" in his email. I take "global warming" to mean the entire climate system, including oceans.  One cannot talk about the future of GMST without factoring in the energy going into the oceans.  That energy MUST come back through the atmosphere, so it's ridiculous to say that the theory of anthropogenic global warming is _________ based on any analysis that ignores ocean heat content.

    In other words, when Fyfe says "global warming has paused," he's not saying that CO2 is suddenly not continuing to store more energy within the climate system.  He's just saying that the accumulating energy is not, over time, uniformly going into the various components of the climate system.  The top-of-atmosphere energy imbalance remains.

    So my question to you is "what is 'the planet'"?

  23. Hope this isn't considered political, but : Thank you for this site. As a "denier", it's nice to get answers to my questions without being called ignorant, stupid, or dishonest.  This site is convincing. Thank you.

  24. I'm no climate scientist andI like to keep things simple. Some things seem obvious. 

    Take a four-year rolling mean of the global surface temperature data. In the early 2000s it suddenly shoots off to the right. Let's assume the temperature rise has gone on holiday for a while, where did the heat go?

    Take a four-year rolling mean of the PIOMAS annual minimum volume data. From the late 1980s to the early 2000s there's a reasonably linear trend of around -250 km^3 of ice lost per year. From the early 2000s to the present there's a linear trend of around -700km^3 (equivalent to more than 2*10^20J) per year. 

    All that heat is being absorbed in a constant-temperature process (melting ice). The latter trend line hits zero around 2017 (mid rolling year), so the heat will have no-where to go without increasing temperature somewhere. I suspect Arctic (and possibly global) temperatures will rise until the Greenland ice sheet can be pursuaded to lose 700km^3 per year, resulting in another, longer, pause in temperature rise. 

    If the correlation of this amateur spreadsheed graph analysis has validity, we'll find out what happens to global crop production under these new conditions within five years. 

    A graph I found of the global glacial mass anomaly also appears to have a kink, but I lack the original data to play with.

    And no I don't know why a current four-year cycle seems to give a good fit.

    That's my tuppence worth.

  25. cpslashm @274, your theory is superficially attractive, but as it turns out the total energy going into ice melt is very small relative to the total energy being absorbed at the Earth's surface due to the enhanced greenhouse effect.  Most (approx 90%) of that excess energy is being absorbed by the ocean.  There is no reason why increased ice melt would draw that energy exclusively from the atmosphere, so it is very unlikely that your theory is correct.

    As it happens, base on a number of different lines of evidence, the major cause of the reduced rate of increase of global surface temperatures has been a switch from El Nino dominated conditions to La Nina conditions.  A further contributor, especially to the reduction in temperature indices that exclude the Arctic, has been a recent pattern of colder winters in mid-northern latitudes and warmer winters in very high latitudes.  Because the warmer high latitude winters are not included in the observations, this shows up as a reduced overall rate of warming.  There is an apparent connection to ice melt in this pattern, in that evidence suggests it is a lack of ice cover on the Arctic ocean causing this pattern.  Finally, some recent volcanoes, an increase in anthropogenic aerosol emissions and reduced solar radiation have also contributed to the reduced short term temperature trend.  

    The exact contribution of each of these factors has not yet been determined.  Indeed, there is some possibility that the combination of these factors explains more than the observed reduction in trend, ie, that the short term temperature trend would have accelerated were it not for this concatenation of factors.

  26. Tom Curtis @275, thanks for your response.

    Global surface temperature anomaly 4-year rolling mean


    4-year rolling mean from PIOMAS

    I was looking at the data from the opposite perspective: a sharp increase in energy going into melting ice from 2003. Is the trend real? Where is the extra energy coming from? What other part of the system is losing out? I am assuming that the bulk of the heat is being transported to the sea ice via the Arctic near-surface waters which then have less heat to pass up to the atmosphere. If this absorption of heat from Arctic waters by ice melt does not produce a corresponding loss of atmospheric heat input, I will have to look elsewhere.

    The amount of heat melting Arctic sea ice per average year since 2003 is minor but enough to raise the temperature of the top three metres of the Arctic Ocean by 1 degree C. I have not yet found a correlation with sea ice area minima which would be the case if the melting were due mainly to a progressive loss of albedo. I am not convinced of the relevance of sea ice extent in this case.

    To come back on topic, although minor compared to oceanic heat absorption, melting sea ice demonstrates that a lot of near-surface heating has been going on since 1998 which will not have contributed to a global surface temperature rise.

    The advantage with my hypothesis is that it can be proved wrong within the next four years - I hope!

  27. I like, or am scared by, the last two graphs. It would be nice to have them in a higher resolution.

    According to these graphs, yes, and the theory there has been a haiatus but that is because the heat has been melting ice, with potentially scarier postive-feedback calamitous potential if Polar Ice has a damping mechanism.

    > "The advantage with my hypothesis is that it can be proved wrong within the next four years - I hope!"

    I confess to being a bit of a sceptic, but I think that we are reaching a watershed. I guess a lot of people feel the same way. When the hiatus ends, the temperature is going to up or down. If it starts going up again, then I am going to junk my turbo charged car, and become a "realist".

    (I hardly ever drive my car, and I have had it for 16 years. I cycle and try to behave like a realist anyway.)

  28. CB... the IPCC alleges that of the most recent global warming ... non of it is natural and all of it is man made. ... do you agree with that hypothesis? 

  29. Donny... You're getting things wrong again. The IPCC states that the warming of the past 50 years is very likely primarily due to human activities. That's a very different statement. They make ample room for that to mean anything from 51% to over 100%, which they have to do because of uncertainties.

  30. Donny - The IPCC reports qualify the statement appropriately, but note that they have stated (AR5 SPM):

    It is extremely likely [i.e. 95% confidence] that human influence has been the dominant cause of the observed warming since the mid-20th century

    Various attribution studies indicate that the anthropogenic contribution is 90-170% of recent warming, with the >100% values being balanced by cooling influences of natural forcings - without which we would see even warmer temperatures. 

    Climate forcing attribution


    You appear not to agree with this conclusion, which quite frankly is far beyond hypothesis status at this point. Do you have any support whatsoever for a less than dominant anthropogenic contribution? Any attribution studies, for example? 

    I expect not, as your posts so far have primarily consisted of arguments by assertion and out-of-context numbers that in reality don't support your positions, but I'm more than happy to be surprised. 

  31. Donny, it appears you think that a significant part of the warming is natural? Perhaps you could tell us what data informs this opinion, given the flat or negative natural forcing data?

    You would also note the increasing warming of oceans consistant with the rise in CO2 (and after all that is where most of the extra surface radiation ends up).

  32. Why didn't it end up in the ocean during the 80s and 90s? 

  33. Donny, go to the top of this page. Look at the first graph. Notice that it shows warming in the oceans during the 80s and 90s.

    See the problem with your question?

  34. Update:

    "Varying planetary heat sink led to global-warming slowdown and acceleration"
    Xianyao Chen, Ka-Kit Tung

    Science 22 August 2014:
    Vol. 345 no. 6199 pp. 897-903
    DOI: 10.1126/science.1254937


    August 21, 2014
    Cause of global warming hiatus found deep in the Atlantic Ocean
    Hannah Hickey

    Following rapid warming in the late 20th century, this century has so far seen surprisingly little increase in the average temperature at the Earth’s surface. At first this was a blip, then a trend, then a puzzle for the climate science community.

    More than a dozen theories have now been proposed for the so-called global warming hiatus, ranging from air pollution to volcanoes to sunspots. New research from the University of Washington shows that the heat absent from the surface is plunging deep in the north and south Atlantic Ocean, and is part of a naturally occurring cycle. The study is published Aug. 22 in Science.

    Subsurface ocean warming explains why global average air temperatures have flatlined since 1999, despite greenhouse gases trapping more solar heat at the Earth’s surface.


    The results show that a slow-moving current in the Atlantic, which carries heat between the two poles, sped up earlier this century to draw heat down almost a mile (1,500 meters). Most of the previous studies focused on shorter-term variability or particles that could block incoming sunlight, but they could not explain the massive amount of heat missing for more than a decade.

    “The finding is a surprise, since the current theories had pointed to the Pacific Ocean as the culprit for hiding heat,” Tung said. “But the data are quite convincing and they show otherwise.”

    Tung and co-author Xianyao Chen of the Ocean University of China, who was a UW visiting professor last year, used recent observations of deep-sea temperatures from Argo floats that sample the water down to 6,500 feet (2,000 meters) depth, as well as older oceanographic measurements and computer reconstructions. Results show an increase in heat sinking around 1999, when the rapid warming of the 20th century stopped.

  35. Some images from the net which appear to originate from the Chen & Tung paper linked @284.


    Caption - Heat stored in the global ocean (top) and major oceans compared to the 1970 to 2012 average. Coloured lines show heat from the surface down to different depths (left scale). Black lines are average sea surface temperature (right scale) Source: Chen & Tung (2014)


    Caption - (Top) Global average surface temperatures, where black dots are yearly averages. Two flat periods (hiatus) are separated by rapid warming from 1976-1999. (Middle) Observations of heat content, compared to the average, in the north Atlantic Ocean. (Bottom) Salinity of the seawater in the same part of the Atlantic. Higher salinity is seen to coincide with more ocean heat storage. Credit: University of Washington


    Attribution - Xianyao Chen/Ka-Kit Tung




    I wonder if the so-called pause in global warming as expressed by surface atmospheric temperature can be quite easily explained as follows? The measured net atmospheric temperature was increasing at an annual rate of about 0.025º C prior to the late 90's. It then leveled off rather abruptly and increased at a much slower pace. Climate change deniers have been celebrating this as evidence that global warming has stopped and there's nothing to worry about. But what really happened? If increased atmospheric CO2 is trapping more energy, where is it going? What has changed? Andrew Shephard et al. in(Science, 2012, 338: 1183-1189 ), document a new phenomenon which began in the late 90's: significant net melting of arctic and antarctic land based ice. Greenland in particular and West Antarctica are losing about 400 gigatonnes per year (including allowances for increases of ice from increased snowfall in East Antarctica) as net ice melt. Prior to the late 90's there was no significant loss of land based ice mass. Their paper discusses the effect in terms of sea level rise (also measurable). But let's do the energy balance math. It appears that this recently arrived phenomenon of net ice melting coincides well with the abrupt change in the rate of atmospheric temperature increase. So, the energy required to melt 400 Gt of ice (its latent heat of fusion) is quite close to the amount of energy required to warm the earth's atmosphere by 0.025 º C. Wouldn’t such a newly arrived heat sink be taking up the so called missing energy? As has been widely reported, this “missing” energy is going into the oceans in the form of liquid water. So global warming has not paused at all! The earth is continuing to gain energy because of the increased energy absorption caused by the increased level of atmospheric CO2. Ice melting is accelerating and the atmosphere is still showing signs of warming. Thus we could rightly assume that global warming and its effects on climate are continuing and even accelerating as more and more energy is embedded in our global environment as we burn our way into a high risk future. Short term greed, instant gratification, discounting the future, delusional economics, and denial of reality are the hallmarks of humanity's dis-function and abuse of our only home.



    [RH] Snipped all caps (per policy) and resized font to standard size.

  37. Richard Hampton @286.

    I usually trot out the following levels of current annual ice loss - Arctic Ocean 300Gt, Greenland 450Gt, Antarctica 150Gt, Other 300Gt. Thise are far bigger numbers than last decade with today a total latent energy gain of 0.4 Zj pa. However that figure is a lot smaller than the extra annual increase in OHC which would be something like an extra 3Zj pa in just the measured bit of the oceans 0-2000m.

    So it is correct that more energy is being used melting ice but a whole lot more of the extra energy is ending up in the oceans. Further, if the atmosphere had been warmed significantly, most of that energy entering the oceans would be required to keep the atmosphere at the higher temperature and thus be radiating back into space.

  38. M. A. Rodger @287

    You are absolutely correct that the moderating effect of energy absorption by the oceans is much greater than the effect of melting glacial ice. However the ocean effect has been continuous and is reflected in the historical atmospheric temperature record. My point is that the newly active heat sink effect of arctic/antarctic net land ice melting coincides with the inflection in the atmospheric temperature record curve in both timing and energy balance. Direct cause and effect must be examined in the context of energy transfer mechamisms to develop a full understanding of the process. Nevertheless, whenever a continuing process (atmospheric warming) shows an inflection there has to be a coincidental cause. Here with arctic/antarctic ice melting we have a good fit in the data and therefore a strong candidate for a cause of the "pause".

  39. Richard Hampton @288.

    There certainly is a conicidence. 2007 was the year the global temperatures started showing signs of a pause and it was also the first starting melt year for Arctic Sea Ice.  And the energy fluxes are not dissimilar in size (although as ice loss continues to accelerate that equivalence will fail). Yet reasons for the 'pause' proposed by the climatologists, which are quite far reaching, to date don't include a diversion of heat from atmospheric warming to ice melting. I'd guess the main problem with the theory is how such a diversion would work in practice. And the 'pause' has symptoms that date back before 2007. So the changes in rate of surface warming and ice loss remain solely a coincidence.

  40. "I'd guess the main problem with the theory is how such a diversion would work in practice"

    I can think of one. Rain. The objection would be that we don't, as far as I am aware, see more rain yet on the ice. Yet.


  41. Looks like this handy rebuttal to a commonly expressed "skeptic" argument needs an update... where it states that the warmest 12 consecutive months on record are June 2009 - May 2010, this has just been surpassed according to NOAA, by the October 2013 - September 2014 interval. Time for a quick edit already!

  42. Excellent new post about the pause/hiatus (not) at RealClimate.

  43. Hello,

    I wonder if someone from the Skeptical Science team or commentators could give their opinion on the linked spreadsheet. (See below)

    It takes a different approach to de-bunking arguments such as "no warming for 15 years" or "AGW theory predicts an increase in CO2 should result in an increase in temperature". It does so by taking a qualitative description of some of the factors that affect atmospheric temperatures (CO2 concentration, solar cycles, IPO cycles and volcanic erruptions) and models them as simple algebraic functions.

    The intent is use this as de-bunking tool to show that (a) this qualitative description of factors affecting the atmospheric temperature record give rise to plausible looking temperature graphs and (b) the description does indeed predict short periods of "hiatus" or slowing in the temperature record, as well as accelerated periods too. It is not (obviously) an attempt to predict the Earths recent atmospheric temperature changes.

    The user can play with the relative strength of the various contributing factors by changing the "factors" in cells H3, I3, J3 and K3. The simple algebraic functions can be examined by looking at the formulae in cells C3-G3

    Link here.

    Suggestions, improvements, corrections welcome ...

  44. May need updating?  2014 now warmest year on record in several temperature databases.

  45. Hi. The year 1977 was the last year that the global temperature was ~the 20th century average of 13.9D C. - 21 years later, 1998 the gt was ~14.5. The 21st centruy average is so far 14.44D C. - 2005, 2010 and 2014 beat the 1998 temperature by a margin-total of just 0.1D C. -w/2014 being 14.6D C (warmest ever - with a measurement magin of error of 0.1D C ??)

    Today's rate of CO2 emissions has increased over the last century. The oceans of today that are "accumulating" heat existed back in the 20th century as well, yet the rate of change over 21 years was 0.6D C and the rate of change over the past 17 years (since) is only 0.1D C.

    2/3rds of the globe is ocean. Oceans are warming, per your statements, yet the 2/3rds of the planets atmosphere, above the oceans are only warming by 1/9th the rate, of previous warming.

    It would seem to this engineer in my 45th year as an engineer, that the atmosphere has reached a warming saturation and that all the heat trapping GHGs can't seem to provide any additiona warming in the atmosphere no matter how much the "plate" at our feet warms (accumulates) or how much CO2 enters the atmosphere.

    Something is not adding up. It would appear we need more heat-in to warm pass the curent highs we have been seeing. The highs can be beat by 0.01 or 0.03 degrees C but they will not increase by 0.6 without more heat input, it would seem.


  46. Albert, where are you getting your OHC figures?


  47. Albert H, for the following I have used the Berkely Earth Surface Temperature (BEST) as I consider it the best currently available surface temperature index.  That is because it is constructed using (by far) more temperature records in determining the series than any other temperature index, and also constructed with a less controversial method than any other temperature index.

    Using the SkS trend calculator, I find the trends are as follows:

    1977-1997: 0.11 C per decade

    1999-2014: 0.121 C per decade

    I notice that the 1999 onward trend is slightly greater than the 1977-1997 trend.

    Of course, if I use 1998 for a terminal and initial year respectively, if find trends of 0.126 C per decade (1977-1998) and 0.09 C per decade (1998-2014).

    I will note first that that is not so large a difference as to justify your conclusion.  Your conclusion, therefore, is based on using an alternative, unspecified, and objectively inferior temperature index.

    More importantly, your conclusion is shown to follow primarilly from using 1998 as your bridge year.  1998, however, is an unusual year in that it was the year of the strongest or second strongest El Nino event on record.  (Its only rival occured at the same time as a major volcanic erruption, with the effects of the two events on temperature essentially cancelling each other out.)  1998's unusual warmth, on which your claim relies, is therefore a consequence of short term internal variability, not radiative forcing.

    Finally, the trend over the whole period was 0.164 C per decade, within error of model predictions.

    So much for the technical discussion.  I notice as an aside you claim to be an engineer with 40 years experience.  As such you would clearly know certain basic principles of data usage:

    1) You would know to use trends rather than end points in analysing rates to avoid "endpoint effects";

    2) You would know to use clearly identified sources of data;

    3) You would know to use the best available data, or at least to justify your choice when you do not; and

    4)  You would know not to cherry pick end points for data analysis.

    You have clearly violated each of these principles.  I am therefore forced to conclude that your claim to tenuous authority (engineers often have very bad understanding of science, together with an over inflated belief in their understanding of science) is false; or that you have deliberately violated good practise to strengthen a very weak argument.  Which is it?


  48. Albert H...  That might seem like a logical assumption, but with all due respect to your engineering experience, the assumption would be wrong. There's far more that you should endeavor to learn about ocean-atmosphere coupling before coming to any conclusions. Here is a good place to start: LINK

    There are also many great informative articles here on SkS that you should take the time to read through. Nearly all of the articles here are fully cited with the relative current research which, if you have further questions, you should locate and read through.

  49. Albert H, you forget the possiblity of the ice sucking up the added heat content: it is my considered (lol, check me out: failed engineering student!!) opinion that the energy is going toward phase-change-mode.

    Politically the IPCC reports are by default conservative as all Governments involved have to agree as to what goes into them thus giving rise to my slightly panicked thoughts on this matter.

    The idea of 'diminishing returns' can be easily interpreted by the masses as wasted effort and the double-handling of matters tires us all. The need to Nip this problem of correlation with gap between rich and poor means climate denialism is over and the disinvestment campaign by the aroused consuming voter wins. What else is economics but a reason to get out of bed and do what needs to be done as the problem presents itself?

  50. It saddens me to agree with one of the specific comments regarding engineers as having a poor grasp of science. I failed Mechanical engineering and basically can't have a considered opinion by default but do know this: Mechanical engineers are the most variedly paid engineers, presumably meaning some barely passed and possibly took decades to finish just for the status involved with such a title.

     I have talked to retired engineers who simply don't accept CO2 as being mechanically forced into the closed system called our atmostphere even though that is exactly what they were involved with doing all those years: truly weird, I must admit, but seemingly not an uncommon phenomenon.


    The well paid would never talk like this, would they?

Prev  1  2  3  4  5  6  7  8  9  Next

Post a Comment

Political, off-topic or ad hominem comments will be deleted. Comments Policy...

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

Link to this page

The Consensus Project Website


(free to republish)

© Copyright 2022 John Cook
Home | Links | Translations | About Us | Privacy | Contact Us