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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.

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Comments 26801 to 26850:

  1. So what's really happening in Antarctica?

    According to Zwally's paper, not only is Antarctica gaining ice now, but as I understand it, has been for the last 10 millenia.  If everything else were equal, that would have meant at least a couple of meters of sea level drop.  But we haven't seen that, so what is the source of the water that has kept sea level relatively constant?

    If I've misunderstood something, or gotten some facts wrong, I'd appreciate learning where I went wrong.

  2. Tracking the 2C Limit - October 2015

    Tor B @1, the indices you reference are simple temperature indices.  That is, they plot the temperature in a small area of the tropical Pacific and use that as an index of ENSO states.  However, because they simply take the temperature of a small region, any increases in temperature due to global warming generates a bias towards stronger and more frequent El Nino states (and weaker and less frequent La Nina states).  Given that, we do not know to what extent the record values are a consequence of a strong El Nino, and to what extent they are directly due to global warming.

    One way of avoiding this problem is to use ENSO indices that either are not direct temperature measurements (the SOI) or which use a variety of different indices so that any purely global warming signal does not bias the result (the Multivariate ENSO Index or MEI).  Here are the recent values of the later compared to other historically strong El Ninos:

    As you can see, it is only the third strongest El Nino by the MEI since 1950.  The SOI shows the current ENSO value (-20.2) as  weaker than five months of the 97-98 El Nino (peak at -28.5), and six months of the 82-83 El Nino (peak at -33.3).

    There is no guarantee as to how El Ninos will develop.  The current El Nino may collapse and fall away towards neutral conditions, but current predictions are that it will remain strong for several more months.

    If it were to do so, it will not challenge either 97/98 or 83/83 as the strongest El Nino since 1950.  It is however possible that it will strengthen again.  If it does so, it may follow a similar pattern to the 82-83 El Nino and end up as the strongest since 1950.  Or not.  If it did, that would be grim news indeed.

    As it stands, the big news about this El Nino is that it so hot globally relative to 97-98 when the El Nino event is not as strong as 97-98.

  3. Tracking the 2C Limit - October 2015

    The most recent weekly Nino data (released today?) hit a new all-time record of 3.1.  The base line for Nino datasets was reset early in 2015, a baseline raised from the previous baseline (I think by about 0.1); this makes me think this and last weeks record values all the more significant.

    From the Arctic Sea Ice Forum's Consequences/El Nino? thread:  "... NOAA data show[s] that the Nino 3.4 is now +3.1, that both the Nino 1+2 and the Nino 4 increased, and the Nino 3 remained constant at +3.0."  Included is a table of recent week values of the several Nino regions.

    Moderator Response:

    [PS] Added link

  4. The Skeptical Science temperature trend calculator

    I see that some of my questions have actually been raised and answered already above.. Sorry about that..

    Considering that my own calculation essentially has been verified through the replication of Foster & Rahmstorf original numbers, and that I get quite close (about rounding error level) to SkS calculator with "well defined" time series, I think I have no urgent questions anymore.

    However, it still would be quite nice to have clear definition of exact data sources used, and the timestamp when SkS calculator has retrieved refreshed datasets. But I well understand the issue with time in a voluteer setup. 

  5. So what's really happening in Antarctica?

    Don Burrows @10.

    It is not a "redistribution" Zwally is arguing for. Rather it is a millennia-long accumulation he is proposing. The argument is that the snowfall today is not much changed from the snowfall over recent millennia. Prior to this, in the distant past, there was both less snow and less ice. The snow compacts to ice that then, with time, flows off the summits of Antarctica towards the oceans. But the arriving snowfall, while constant over the millennia, is greater than the ice flow. So ice continues to build up as it has over all those millennia.

  6. So what's really happening in Antarctica?

    I'm having a hard time comprehending the argument that an increase in precipitation 18,000 to 12,000 years ago could be seen as an increase in mass in recent years. Once a net gain has occurred then we're only talking about redistribution of the mass by ice movement.

  7. 2015 shatters the temperature record as global warming speeds back up

    Yet no mention of the satellite data which is not aggreeing with the tone of this article.  This particularly since Spencer & Christy rolled out UAH 6.0.  Now both RSS and UAH seem to show there is no warming to speak of in the lower troposphere.  Right?  So long as that is the case deniers see that as confirmation this is a big hoax.  I did find the comparison of RSS to RATPAC data in this link interesting:

    https://tamino.wordpress.com/2015/09/24/exogenous-redux/

    I don't know to what degree it is reliable, however.  It does explain a lot to me about what is going one the past 15 years. Satellite vs. Surface temps.

    Moderator Response:

    [PS] Fixed link. Please use link button in the editor to do this yourself.

  8. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    The chart Andy posted at #13 conspicuously rules out nuclear a priori. We are going to need all the tools available to meet this challenge, including new generations of nuclear technology. Again, its political ...

  9. Water vapor is the most powerful greenhouse gas

    Water vapour and CO2 at high altitude.

    The concentration of water vapour, a powerful greenhouse gas, at the earth's surface is usually tens of thousands of parts per million, which completely dwarfs the CO2's 400, let alone the changes in the concentration of the order of 100 parts per million. So say the skeptics.

    But this isn't the case at high altitudes. At 40,000 feet, at the top of the troposphere, the temperature is around -50C, and so the water vapour is frozen out, with a vapour pressure of about 4Pa, (1Pa at -60C). Atmospheric pressure at sea-level is about 100,000 Pa, and about 20,000Pa at 40000 feet. If I assume that the concentration of CO2 remains about the same, with a bit of turbulence stopping the heavy CO2 molecules settling out to lower altitudes, then the pressure of CO2 would be about 8Pa=20,000x(400/1,000,000)Pa, which is twice the pressure of the water vapour. So maybe an increase in the CO2 concentration does matter. We shall all get warmer, regardless of the height at which the heat flow into space is restricted.

  10. Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change

    PaulG

    Read part 1B for more on the distances over which one can interpolate. And as scaddenp said, Hansen & Lebedeff 1987 is important to read.

    Let me address why anomalies give better accuracy mathematically. This article at wikipedia on Accuracy & Precision is worth reading, particularly for the difference beteen the two terms.

    For any reading from an instrument, a thermomemeter for example, we know that the reading will consist of the true value of what we are interested in and some error in the measurement. In turn this eror is made up of the accuracy of the reading and the prcision of the reading. What is the difference between the two ideas.

    Accuracy is the intrinsic, built in error of the instrument. For example a thermometer might be mis-calibrated and read 1 degree warmer than the real value. In many situations the accuracy of a device is constant - built into the device

    Precision is how precisely we cane take the reading. So by eye we might only be able to read a mercury thermometer to 1/4 of a degree. A digital thermometer might report temperature to 1/100th of a degree.

    So if we take many readings with our instrument each reading will be:

    Reading = True Value + Accuracy + Precision.

    This image might illustrate that:

    So if we take the sum of many readings we will get:

    ΣReadings = ΣTrue Values + ΣAccuracy + ΣPrecision.

    And the Average of the Readings is the Average of the True values + the Average of the Accuracy + the Average of the precisions.

    But the more readings we take, the more the average of the precisions will tend towards zero. The average of a random set of values centered around zero is zero. So the more readings we take, the better the precision of the average. Mathematically, the precision of an average is the precision of a single reading divided by the square root of the number of readings.

    So if an instrument has a precision of +/- 0.1, an average of 100 readings has a precision of
           0.1 / sqrt(100) = 0.01
    10 times more precise.

    And the average of the accuracy (for an instrument with a fixed accuracy) is just equal to the accuracy.

    So the more readings we have, the more the average tends towards being:
    Average of Readings = Average of True Values + Accuracy.

    Now if we take an anomaly. When we take the difference between 1 reading and the average we get:

    Single Anomaly = (Single True Value + Accuracy + Precision) - (Average True Value + Accuracy)

    which gives us:

    Single Anomaly = (Single True Value - Average True Value) + Precision.

    So by taking an anomaly against its average we have cancelled out the fixed part of the error - the accuracy. We have effectively been able to removed the influence of built in errors in our instrument from our measurement.

    But we still have the precision from our single reading left.

    So if we now take the average of many anomalies we will get

    Average of Read Anomalies = Average of True Anomalies.

    Accuracy has already been removed and now the average of the precisions will tend towards zero the more anomaliess we have.

    So an average of the anomalies gives us a much better measure. And the remaining error in the result is a function of the precision of the instruments, not their accuracy. Manufacturers of instruments can usually give us standardised values for their instrument's precision. So we can then calculate the precision of the final result.

    But we have to abandon using absolute temperatures. They would be much less accurate. Since the topic is climate Change, not climate, anomalies let us measure the change more accurately than measuring the static value.

    There is one remaining issue which is the topic of parts 2A and 2B. What if our accuracy isn't constant? What if it changes? One thermometer might read 1 degree warm. But if that themometer is later replaced by another one that reads 1 degree colder, then our calculation is thrown out, the accuracies don't cancel out.

    Detecting these changes in bias (accuracy) is what the temperature adjustment process is all about. Without detecting them our temperature anomaly record contains undetected errors.

  11. Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change

    Is Paul G asking for thermometers to cover the face of the earth? What about the depths of the ocean??

  12. Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change

    PaulG - the way you do it, it take lots of thermometers at varying distances from each other and see how exactly the correlation of anomalies vary with distance. That would be the Hansen and Lebedeff 1987 paper referenced in the main articles.

  13. Of Averages and Anomalies - Part 1A. A Primer on how to measure surface temperature change

    Okay, I read the explanation that averaged anomalies at nearby locations will typically show less change than will average measured temperatures. That sort of makes sense.  I am not sure how less change means more correct.

    And I understand the idea of teleconnection.  What I don't understand is how you can generalize, or interpolate, in areas where you don't have any measurements.

    It seems to me that you won't be able to determine the correlation coefficients resulting from teleconnection unless you have all of the temperature measurements in the first place.

    How can you determine the error in your averaging if you don't have all of the measurements to determine that error? The average of anomalies approach may intuitively feel better, but how is it mathematically justified?

    Sorry, this does not make sense to me.

  14. Satellites show no warming in the troposphere

    To add, bear in mind the denier mantra
    "Satellites are true and NOAA lies."
    is something I increasingly have trouble arguing against even considering the 10 positive indicators of a warming world show the idea we have not really warmed in 20 years makes no sense.  But, satellites don't lie, right? 

    Moderator Response:

    [Rob P] - It's informative to look at the satellite trend (for RSS) for the lower troposphere: 

    So the satellite data does in fact show a long-term warming trend. If one selects the super El Nino of 1997/1998 as a starting point it's possible to fool the uninformed, but that deceptive practice may soon come to an end with the current super El Nino likely to anomalously warm the lower troposphere in the next 4-5 months. 

  15. Satellites show no warming in the troposphere

    GregCharles is correct about UAH 6.0.  It also points out the need for several popular web sites to "get with the times".  Whatever the reason UAH 6.0 was adjusted, the effect was to make it nearly identical to RSS.  This improves "consistency", but begs the question why UAH thought RSS right and everyone else wrong.  Regardless, all the popular sites I visit still rely on older UAH 5.6 or thereabouts, and we are now left with the satellite data showing nearly no warming for the past 20 years, and the surface data sets with more significant warming.  The clear discrepancy between RSS & UAH 6.0 and the surface data (GISS, HadCrut4, Berkeley, etc) is something this site should address and I'm not seeing it.

  16. The Skeptical Science temperature trend calculator

    yes, but how do I find that series today and how is it different from NOAA? To my understanding both should be the same since last summer or so? So what is the difference here?

  17. The Skeptical Science temperature trend calculator

    The Karl et al 2015 paper that denier are objecting to is linked to on Tom's post. Another link here. 

    Full citation:Karl, Thomas R., Anthony Arguez, Boyin Huang, Jay H. Lawrimore, James R. McMahon, Matthew J. Menne, Thomas C. Peterson, Russell S. Vose, and Huai-Min Zhang. "Possible artifacts of data biases in the recent global surface warming hiatus." Science 348, no. 6242 (2015): 1469-1472.

  18. The Skeptical Science temperature trend calculator

    I found the code that Tamino used for their 2011 paper and the way they calculated standard error. Looks like I am now able to replicate quite well the slopes and confidence intervals produced by SkS calculator - at least for those series that are clearly identifiable like Berkeley Land, UAH (5.6), RSS (TLT 3.3), GISSTEMP and HadCRUT4..
    Unfortunately I still have some challenges with references like NOAA and Karl 2015 which I was not able to identify unambiguously. What I think they may mean (NCDC V3?) is not as close as I would have hoped for. Furthermore Berkeley global is a challenge for me as there my numbers deviate too much from SkS. It would be extremely helpful if the exact data sources (and last update time) were someplace visibe on the calculator page.
    (To avoid issues related to possible missing data point in 2015 I have made my calculations for period January 1979 - December 2014.)

  19. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    Michael: Yes, that is one of the articles that made me think it is possible to replace fossil fuels completely.  Then I read other articles saying in response that it's not so easy!  One thing glossed over is fuel for aircraft and ships.  I've heard of emission-free synfuels (synthetic fuels) for aircraft — whether or not they work for ships I don't know.

    The real blockage is of course political.

  20. So what's really happening in Antarctica?

    Just a note about the Zwally paper. Whilst it has been recently published, the research is much older and I first saw it as a conference paper listed on a NASA page, in 2012. It was also referenced in a Nature article that year. The conference paper had the same title and the same authors (apart from one).

  21. So what's really happening in Antarctica?

    Tried realclimate and got an immediate redirect to a screen saying

    "Offer
rdsa____.com"  (I'm not posting the full URL, which is spoofed anyhow, nor the actual link that was hidden behind that text, which was long, complicated and suspicious

    which changed immediately to

    "Win NHL Jersey
____"  (also not posting that URL which was also fake covering another long suspicious string of code)


    Beware -— looks like it's hidden layers of something rather nasty, hidden under what appears to be mere adware, I think.

  22. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    Digby,

    This article shows that it is possible to build a completely renewable energy supply by 2050.  If a high carbon fee was instituted so that carbon paid for all the damage it causes, investors would build out the renewable energy we need.  It would save everyone money and result in better health.  The primary block is political due to the influence of fossil fuel companies who stand to lose trillions of dollars.  

    Fossil fuels are only cheap because they make everyone else pay for the damage they cause.  Obama's clean power plan is completely justified by the health savings, the climate benefits are not considered.

  23. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    There are actually two aspects to my "subversive thought".  Firstly, is it physically possible to find ways to cope with declining supplies of fossil fuel over a thirty-year period?  I don't know.  From what I read, sometimes I think it is, sometimes I think it isn't.  I just don't know.  That's why I asked.

    Secondly, how should declining supplies of fossil fuel be allocated between countries?  This is the aspect you've latched onto, but this is a different problem altogether.  It is a problem the world would've had to face if we'd really passed peak-oil and supplies really were declining.  My subversive thought was to suppose the decline was imposed, not natural.

    Another way to look at the second aspect is this:  We're aiming to induce a decline in fossil-fuel use in the face of a plentiful supply.  Well, good luck with that!  Whatever methods are used, I'll believe them only when I see fossil-fuel production declining in reaction to declining demand.  I fear that, as you imply, the threat needs to be immediate and life-threatening before this will happen.

  24. 2015 shatters the temperature record as global warming speeds back up

    sauerj @10.

    If you examine NOAA OHC data, you'll see a strong El Nino signal in the 0-100m Pacific record with OHC rising during El Nino. The signal reverses for 0-700m data but becomes far less obvious. So when global 0-2000m OHC data is examined there is nothing really left to see.

    BC @9.

    The 0-2000m OHC data does indeed record OHC reduced from 2015Q2 to 2015Q3. But the same thing happened in both 2014 and 2013 when it showed even greater reductions but without an El Nino. Indeed, in the post the "400 million atomic bomb detonations (27 zettajoules, or 27 billion trillion Joules)" figure for ΔOHC in 2015 appears to be the annual figure for 2015Q3 - 2014Q3 which is 27.6 Zj. Over the last 8 quarters the annual ΔOHC averages 22 Zj.

    One comparison not made in the post but which I consider more interesting that numbers of bomb-equivalents is the global energy imbalance required to add, say, 22 Zj/year to the oceans. That would be 1.37W/m2 or according to IPCC AR5 Table AII.1.2 equal in size to the increase in all the positive human climate forcings 1978-2011 which, with these OHC figures, would thus still be up there warming away despite the level of AGW we have witnessed since that date. That's a rather scary equivalent.

  25. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    Digby: Suppose fossil-fuel producers were "forced" to cut production at the above rate. Would the free market coupled with human ingenuity find ways to cope?!

    One question that springs to mind: how would the cuts be allocated, between countries and among fuel types? Also, this would drive prices up, so who would benefit, the producers or would governments have to institute some kind of windfall profits tax? It would also be regressive, so some form of compensation to the poor would be needed.

    Perhaps a less regressive policy would be to ration fossil fuel use at the consumer level. But until there is a widespread consensus that we are facing a an urgent existential crisis, I can't see that being politically feasible.

    Far better would be a cap and trade policy. After all, the goal should be to lower emissions, not necessarilly to reduce fossil fuel use. Even better than that, in my opinion, anyway, would be a steadily rising carbon-tax-and-dividend policy.

  26. 2015 shatters the temperature record as global warming speeds back up

    It appears the rise in ocean heat content rate is trending up. Since 1990 (25 years), it appears to have increased ~21x10^22 J (15,668 atom bombs/hr), based on an atom bomb = 17x10^9 watt-hrs. In contrast, since 2008 (7 years), heat content appears to have increased ~8.5x10^22 J (22,650 atom bombs/hr).
    Article notes the 2015's El-Nino driven spike in heat content amounting to 50,400 atom bombs/hr (14/sec).
    I'm a bit preplexed: I had thought that in El-Nino years that the stored-up ocean heat content was expelled (more than avg rates) to the surface, causing spikes in land & ocean surface temps, and also causing a slight decrease in the rate-of-ocean heat content (compared to avg) due to this more aggressive expulsion of heat from the ocean. ... Opposite effect in La-Nina years, that the rate-of-rise of ocean heat content would be more than average. So, I'm surprised to see OHC rate-of-rise increase in 2015's El-Nino year. I obviously have something wrong here.

    Moderator Response:

    [Rob P] This years super El Nino has yet to really leave its mark on ocean heat content. The data for ocean heat content end in September and we're only reaching the peak of El Nino now. The next two quarters of OHC may tell a different story.

     Time-series of globally-averaged (60°South to 60°North) ocean temperature anomaly from the monthly mean, versus depth in metres (pressure in dbar).(b) Time?series of globally-averaged sea surface temperature anomaly (black, °C), ocean temperature at 160 metre depth (blue), and the Nino3.4 regression estimate for SST (red). From Roemmich & Gilson (2011)

     

  27. 2015 shatters the temperature record as global warming speeds back up

    I would have thought that higher surface temperatures would have resulted in more infra red radiation out to the atmoshpere and space and less accumulation of heat in the oceans. That is, wouldn't there be more accumulation in cooler surface temp /La Nina years and less in El Nino years? Maybe that's why there's a downward turn at the end of the graph, which only goes to June 2015. That downward turn may continue while the El Nino unfolds.

  28. So what's really happening in Antarctica?

    @ 5, where did you get this quote from: "If we knew the snowfall history perfectly then there wouldn’t be any controversy!" ?

  29. 2015 shatters the temperature record as global warming speeds back up

    A little birdy told me government departments expect ice free Arctic summers by 2050. Talk about conservative..

    I think we will see a lot of divestment into clean energy for good reason before 2020: the same people admit multi-year sea ice in the Arctic is looking very very ill!! 

  30. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    The scenario linked to is interesting, thanks.  It seems to match the back-of-envelope estimate I've made in the meantime:  If fossil-fuel use remains at 30 Gt per year until 2020 and thereafter declines at 1 Gt per year for almost 30 years one uses 585 Gt of the budget.  That leaves a residue of 15 Gt to play with.  Being so precise is a bit silly really, considering all the uncertainties involved.  However, the overall effect does seem to match the "WWW and Ecofys" scenario, even to the small tail of fossil-fuel use from 2050 onwards.

    As you point out, feasibility is a different story altogether.  In this regard, let me offer a subversive thought:  Suppose fossil-fuel producers were "forced" to cut production at the above rate.  Would the free market coupled with human ingenuity find ways to cope?!

  31. So what's really happening in Antarctica?

    Morgan01944 @5, the full context of your final quote reads:

    "One other thing is certain: West Antarctica has been losing mass at an increasing rate since the 1990s and, irrespective of what is happening further East, that trend looks set to continue. Going to the other end of the Earth, the Greenland ice sheet has also been losing mass at an accelerating rate since around 1995. Greenland is now the single biggest source of mass to the oceans. These trends at both poles are huge signals that are unequivocal and uncontested."

    West Antarctica is indeed at one pole, as Greenland is at another.  Further, their trends in ice loss are indeed both huge and uncontested (including by Zwally et al).  That it is not clear as to the trend in the East Antarctic Ice Sheet has no bearing on that claim.  Ergo, your juxtaposing this quote with the two others, which discuss the reasons for lack of clarity in Eat Antarctica, shows at best careless reading - not a problem with the OP.

  32. So what's really happening in Antarctica?

    Not one of your more convincing posts:

    "If we knew the snowfall history perfectly then there wouldn’t be any controversy!"

    "So what is really happening? One thing that Zwally’s study does highlight is how difficult it is to nail what is happening in East Antarctica because the signal is small and contaminated by unwanted effects that are as large or even large"

    " trends at both poles are huge signals that are unequivocal and uncontested."

    Moderator Response:

    [DB] Note that this article is a repost.  Please refrain from arguments from your personal incredulity, like you have done here. 

    If you have substantive issues with the content of the article, please cite those specific issues along with a link to a published analysis or examples from the primary literature that support your contentions.

  33. So what's really happening in Antarctica?
    Looks like realclimate DNS is down/subverted, i have informed Prof. Schmidt. The majority of nameservers that i checked claims no authoritative nameserver exists, a minority redirect to IP 208.91.197.217, which is also returned by directly querying the listed authoritative nameservers. whereat resides a spoof site claiming the domain has expired, and inviting one to buy it. A whois check is more illuminating, i have sent the results on to Prof. Schmidt also.
  34. So what's really happening in Antarctica?

    The "issue" with RC manifests itself primarily on weekends, as also appears to be the case here.

    So it's simply a regular server mainteance or they don't run a server on weekends. No surprise, climate scientists usually don't have too much volunteer money to spare to maintain their ageing server. RC has been running for over 10y with the same graphical appearance which is quite impressive in those days of constant (and not necessarily useful) technology changes.

  35. G R A P H E N E

    Ed Wiebe @ 3 icorrectly points out that Superconductivity of Graphene coated with Lithium is achieved at K5.9, not room temperature.

    The sentence: ‘When coated with Lithium it becomes a superconductor, having no resistance to an electric current at room temperature’ is wrong and the text has been modified to show deletion of the sentence.

  36. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    Here's a scenario by WWW and Ecofys that does the job of getting rid of fossil fuels by 2050. You should note that the total energy consumed in 2050 is about one-third of the amount in the RCP2.6 scenario I referred to in my post. Also, the amount of renewables and non-BECCS bioenergy looks (eyeball) similar between the van Vuuren and WWF cases, somewhere around 200-250 EJ/year.

    This would be a huge challenge over 35 years and relies very heavily on energy efficiencies as well as aid to developing countries to allow them to grow their economies without increasing emissions. Much of the capital stock we have like power stations would have to be scrapped before its economic lifetime was up.

    To me, this scenario looks even less feasible than the one that relies on CCS and BECCS.

  37. So what's really happening in Antarctica?

    bwilson4web - I've noticed RealClimate has hosting issues from time to time for several years. I suspect this is just another hosting farble, and will be resolved in due course. 

  38. So what's really happening in Antarctica?

    Hi,

    I'm having difficulty reaching the "RealClimate" web site with symptoms suggesting the domain name may have been redirected to someplace else. Is there another source and/or an IP address of the server?

    Thanks, Bob Wilson, Huntsville AL

  39. 2015 shatters the temperature record as global warming speeds back up

    I think Cooper13 has a good point. Next year, 2016, will be the appropriate year to add to the chart under the category of El Nino years. It should be empahasized that 2015 will be a record, even before the large influence of the strong El Nino is felt. 

  40. 2015 shatters the temperature record as global warming speeds back up

    I predict we'll have 20 years of people claiming "global warming stopped in 2015 - now it's for real!"

  41. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    Andy: I was using my mark-one eyeball to estimate the changes in gas and oil use from the thicknesses of the blue and orange bands.  Gas use seems hardly to change at all up to 2030 or so.  Oil use does decline somewhat.  But even with the large decline in coal use, the overall rate of decline in fossil-fuel use for the next two decades still does not seem drastic enough to me.  It would help to see some numbers!

    It's a bit of a worry when you say the scenario "still overshoots the carbon budget".  Also, talk of "negative emissions" raises my eyebrows — I'll believe it when I see it!

    What I'd really like to see is a graph showing the way fossil-fuel use has to decline in order to satisfy the 600 Gt budget — without any CCS.  I would love to see such a graph compared with RCP 2.6.  Any chance of that?

  42. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    Digby: In the second and third graphs, I think it's clear that fossil fuel use without CCS peaks in 2020, followed by a decline, with, for example, no coal without CCS after 2060. Although that's a very ambitious mitigation scenario, it still overshoots the carbon budget, requiring net negative emissions after 2060, as shown in the first figure in my original post. That's where the BECCS is needed.

    The 600Gt CO2 budget number that Flannery mentions is a lot lower than the figure of 1000Gt that you would find in the IPCC AR5 reports for a 66% chance of staying below 2 degrees. However, the lower number is more appropriate as a go-forward budget for fossil fuel use from now, because you have to subtract the three years or so of emissions since AR5, as well as make allowance for cement and land-use emissions over the rest of the century. 

  43. The Road to Two Degrees, Part One: Feasible Emissions Pathways, Burying our Carbon, and Bioenergy

    Andy Skuse: That sums it up well: to "rely on sequestration as the main response to the climate crisis" would be to face "a gigantic problem".  Some sequestration would help but it cannot be used as an excuse not to cut the burning of fossil fuel.

    With regard to the latter, I'm busy reading Tim Flannery's "Atmosphere of hope" and find it difficult to reconcile his comments on our "carbon budget" with the graph showing RCP 2.6 fossil-fuel use.  He states that we have a budget of 600 Gt of carbon dioxide remaining and are currently emitting just over 30 Gt annually from burning fossil fuel.  At current rates we'll use up the budget by 2028.  Even if the rate is capped at 30 Gt, that still extends the deadline to 2035 only.

    I've seen similar figures elsewhere but I've also seen comments disparaging the whole idea of trying to quantify a carbon budget — the uncertainties are large.  If we accept the budget of 600 Gt, then we can carry on as usual for about two decades and then we have to stop burning fossil fuel completely.  If the rate of fossil-fuel use declines considerably, then we can continue for longer.

    Now, if I look at the above graph, I see the use of oil and gas declining only slightly over the next two or three decades.  Coal use declines a lot and is compensated for by the use of gas plus CCS.  However, the overall reduction in fossil-fuel use does not seem in any way sufficient to meet Flannery's requirement.  Have I misinterpreted things?  Has Flannery erred?  Is the RCP 2.6 graph only part of the picture?

  44. SBC Energy Institute Climate Factbook

    enSKog @1, the claim on page 8 is not so much wrong as oversimplified.  As shown in this image from Wild et al (2012), the net effect of reradiation is that there is a 342 W/m^2 back radiation, so that back radiation is 86% of upward IR radiation at the surface:

     

    More importantly, IMO, only 239 W/m^2 escapes to space, so that the Outgoing Longwave Radiation is only 60% of the upward IR radiation at the surface.  The difference between the two (158 W/m^2) is the "Total Greenhouse Effect".  The difference between the upward IR radiation at the surface and the total IR radiation from the atmosphere (ie, 239+342-397 = 184 W/m^2) is made up for by other energy inputs into the atmosphere, specifically 79 W/m^2 of absorbed solar radiation, 85 W/m^2 from evaporation (including the release of H2O associated with photosynthesis, ie, transpiration), and 20 W/m^2 associated with convection (sensible heat).  

    As a side note, the same diagram is uses by the IPCC AR5 as Fig 2-8 except that upward IR radiation is given as 398 W/m^2 and evapo/transporation is given as 84 W/m^2 with no other changes, except related changes to bracketed figures, ie, the uncertainty ranges.

    If we take a more detailed look, we note that energy absorbed by a single molecule (from any source) and then emitted as radiation has an equal chance of being emitted in any direction.  This is sometimes glossed as "LWR is absorbed but then radiated in ALL directions", but of course individual molecules emit single photons on reradiation, each of which must have a specific direction.

    It might be supposed that this must result in a collection of molecules radiating equally in all directions, but again this is not true.  If we consider a parcel of air defined by vertical planes perpendicular to the surface with top and bottom boundaries defined by concentric shells around the Earth's center, then the air in the top of the parcel will be thinner and (in the troposphere) cooler than that in the bottom of the parcel of air.  As the parcel of air has measurable thickness, some of the IR radiation from the air at the bottom of the parcel going upward will be reabsorbed by air in the parcel above it, and vice versa.  Because of the difference in temperature, the air in the upper portion of the parcel will reradiate at a slower rate than that in the lower portion, with the net effect that the upward radiation from the parcel will be less than the downward radiation from the parcel.  This difference is the core reason why the greenhouse effect exists.

    The point is that the booklet's claim and your gloss both represent simplifications of a more complex process.  Both can be made true by appropriate qualification and or change in wording, but only by adding significant complexity.  The same is also true to a lesser extent of my explanation above.  In any teaching situation, you have to make these tradoffs between absolute accuracy and keeping things simple enough for people new to the subject to understand the concepts.  Unfortunately, those same tradeoffs result in potential misunderstandings, which are often exploited by deniers to spread confusion and doubt.  (For your gloss, the confusion is that outgoing LWR must equal the downard IR radiation at the surface - something I have seen argued by deniers.)  So, while I would have preferred to see an explanation of the importance of the temperature gradient in the atmosphere to the greenhouse effect, and the use of the word "net" on the page you discuss, overall the booklet is very good and the "errors" are only those of approximation needed to keep things simple in a teaching context.

  45. SBC Energy Institute Climate Factbook

    Looks pretty good but on page 8 they say

    "90% of the upwardly directed LWR is
    absorbed by GHGs and radiated back
    downwards, ...."

    90% of up LWR is absorbed but then radiated in ALL directions!

    Is it too late to get this corrected? Don't want to give the denialists anything to pick at.

  46. Climate's changed before

    It might help to quote some reliable sources from an earlier period before climate change became a political issue. For example: was rapid temperature change thought to be a or the cause of mass extinctions in the 80's or 90's? 

  47. 2015 shatters the temperature record as global warming speeds back up

    If 2015's high average temperature is in part influenced by a strong El Nino, then it is likely that several of the succeeding years will be cooler (even as the underlying trend remains unequivocally upward). This will surely lead to new claims that global warming has stalled, a cooling trend is upon us, there is no link between warming and CO2 concentrations etc etc  And yes, these claims will be repeated in major newspapers, albeit mainly in the 'comment' sections, where scientifically illiterate 'skeptics' are given free rein to spout whatever nonsense they like without any need to reference the facts.

  48. 2015 shatters the temperature record as global warming speeds back up

    With all these precise temperature measurements of known El Niño, La Niña events, plus volcanic influences, how far are we away from determining the climate sensitivity for a doubling of CO2?

    Moderator Response:

    [AS] Spelling of La Niña corrected

  49. 2015 shatters the temperature record as global warming speeds back up

    Foster Brown - I think that depends on what you mean by "deep". The Peruvian cold upwelling should be say "very deep". I think the article would be more correct if it said "deeper" (<500m) rather than deep.

  50. 2015 shatters the temperature record as global warming speeds back up

    Please correct me if I am wrong,  but  the phrase "During El Niño events, hot water is transported from the deep ocean layers to the surface" doesn´t seem accurate.   The typical situation in the Pacific Ocean off the Peruvian coast is upwelling of cold, nutrient-rich water that maintains a highly productive ecosystem.   El Niño tends to reduce this upwelling and its corresponding cold subsurface water.  

    Moderator Response:

    [Rob P] The post by Dana Nuccitelli is correct although, as Phil Scadden points out, "deeper ocean layers" would be a better description. The thermocline (the depth where there is a sharp contrast between the warmer well-mixed surface layers and the cooler layers beneath) across the tropical Pacific is 'tilted'; shallower in the eastern Pacific where a lot of upwelling occurs, and deeper in the western tropical Pacific.

    The westward tropical trade winds pile up warm water in the west - which is why sea level is higher in the west than in the east. This also drives an accumulation of warm water which extends well below the surface and thus displaces the thermocline to greater depth. This is known as the western Pacific warm pool.

    When the trade winds relax, buoyancy and the pressure gradient force (a response to gravity) take over and the warm water travels not only eastward (in pulses known as Kelvin waves), but also surfaces. This greater-than-normal exchange of ocean heat with the overlying atmosphere is why the global surface temperature spikes with El Nino. The other part of the equation, as you point out, is a shutdown of the cold water upwelling as the subtropical gyres spin down temporarily.         

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