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Comments 44001 to 44050:
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rockytom at 04:30 AM on 8 July 2013The Consensus Project Update and Dana on Al Jazeera Inside Story
Dana, it was good to see you "in person." All the guests in the two shows in the post were knowlegeable and contributed wisely to the discussion.
My main concerns continue to be the irreversable limits we have already passed. Some are more obvious than others. The ice sheets and glaciers are melting and sea level is rising. Extreme weather events are increasing both in number and intensity. Ocean waters are becoming more acidic. We know that there is enough carbon already in the climate system "pipeline" to allow these processes to continue for some time. We should also be discussing these consequences and how much time the next generations will have to deal with them as we inevitably reduce carbon pollution. We don't have all the answers (i.e., all the potential consequences) but we have enough to begin discussions.
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Bob Loblaw at 01:17 AM on 8 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
william:
Further to chriskoz's comment about the naming of the cells (just the tropical one is the Hadley cell), the boundary between the Polar and Ferrell cells is a bit more complicated than the old three-cell visual.
Winds blow because of a difference in air pressure. We are used to looking at air pressure at the surface, but atmospheric circulation also depends on pressure at different heights in the atmosphere - and differences in pressure. The idea of the Polar/Ferrell/Hadley cell circulation fits the early knowledge of surface pressure and wind patterns, but the high-altitude winds are a bit different.
Even with the same surface pressure in two regions, different air temperatures would mean different pressures at altitude. Cold air is more dense than warm, so starting with the same surface pressure and moving upwards, the colder location will see pressure dropping more rapidly. (Pressure is just the weight of the overlying air.) Consequently, at high altitude there will be a lower pressure in the cold location than in the warm, so you have a high-altitude pressure difference, and thus can have high altitude winds even though the surface pressures are equal. The pressure relationship to temperature differences is call baroclinicity. Wikipedia has an entry on thermal winds, and one on baroclinicity.
There is a strong temperature contrast between the Polar and Ferrel cells. The resulting thermal conditions lead to the jet stream - high altitude baroclinic winds. Just as surface winds can be seen to follow the patterns of surface pressures, the jet stream can be seen to follow the patterns of the high-altitude pressures.
Just to confuse things, meteorologists do not draw maps of the pressure at a constant altitude for upper air analysis. Instead, they pick a constant pressure, and determine what altitude you find that pressure at. The map will have the same pattern of highs and lows, but it's a slightly diffeerent way of thinking of things. Here is the web page of Environment Canada showing some of the maps available for analysis, and here is the map for the 500mb (500 hPa in SI units).
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sylas at 01:09 AM on 8 July 2013No warming in 16 years
Richard... yes, sort of... though it doesn't mean much. The Earth is heating up, and most of the absorbed energy goes into heating the ocean. According to the figures; 93.4% of it. Of the rest, 2.1% is taken up as heating of continents, and 0.8% is taken up as melting Arctic sea ice. So you can divy up those numbers in various ways. I don't recommend it; it muddles much more than it reveals.
If the sea ice wasn't there to be melted, then everything changes; because it's a complex interacting system we are considering. For example, the loss of sea ice in summer is a significant feedback that contributes to the magnitude of all changes. You could consider a conterfactual in which melting ice isn't particularly endothermic, so that no energy was taken up, any excess energy would be taken up mostly in the ocean; meaning very little difference in land temperatures. We already know that when there's excess energy around, it goes mostly into the ocean.
The other issue is that temperature is not heat.
The temperature we get to is not determined by heat capcities; but simply by what temperatures will bring radiation emitted into balance with radiation absorbed. Heat capacities -- and the absorbing of excess energy -- is part of the process of getting back into balance.. and this is about how long it will take for temperature to stablize for a given atmosphere or forcing.
The energy figures are not really about temperature, but about the imbalance and the time it will take to get to balance again.... whatever temperature that happens to be. Getting rid of the capacity of melting ice to absorb heat would mean only we get to equilibrium temperature a tiny little bit faster. It makes no difference to the temperature we actually reach.
Moderator Response:[JH] I deleted your duplicate post of the above.
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Richard Lawson at 00:21 AM on 8 July 2013No warming in 16 years
Thanks Sylas. So is it possible and/or justifiable to calculate the surface heating that would have taken place had that 10^21 J gone into warming the atmosphere instead of into melting Arctic ice?
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sylas at 23:32 PM on 7 July 2013No warming in 16 years
Richard, your estimate looks good.
Skeptical Science have used 0.5 W/m^2 as the energy imbalance for Earth... this is the energy going into heating the planet. At 5.1e14 m^2 for Earth's surface, and 3.15e7 sec per year. and for a 16 year period of time, you have about 1.3e23 J of energy heating the Earth. Using 0.8% of this into Arctic Sea ice (from the diagram above) this corresponds to 10^21 J. Same as you have calculated.
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R. Gates at 22:35 PM on 7 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
This was a very interesting post and certainly displays that even two experts on the "consensus" side can disagree about the details of the disruptions caused by anthropogenic climate change. The contrast in perspectives between Dr. Trenberth and Dr. Francis is actually quite refreshing. I tend to personally favor Dr. Francis in this particular difference of opinion.
From a larger perspective, the high amplitude jet stream patterns we are see are yet one more global example of a positive feedback mechanism whereby the overall increase in energy in the Earth system is trying to balance between pole and equator. The meridonal advection of energy brought about by this pattern is enhanced such that we get more vigorous equator to pole mixing. We are seeing the exact same thing higher in the stratosphere and even the mesosphere with an enhanced Brewer-Dobson circulation.
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sylas at 22:27 PM on 7 July 2013No warming in 16 years
Richard, your estimate looks good.
Skeptical Science have used 0.5 W/m^2 as the energy imbalance for Earth... this is the energy going into heating the planet. At 5.1e14 m^2 for Earth's surface, and 3.15e7 sec per year. and for a 16 year period of time, you have about 1.3e23 J of energy heating the Earth. Using 0.8% of this into Arctic Sea ice (from the diagram above) this corresponds to 10^21 J. Same as you have calculated.
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francis at 21:57 PM on 7 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
The mechanism linking Arctic amplification (AA: increased sensitivity of the Arctic to global warming or cooling) to changes in the jet stream that Steve Vavrus and I proposed and demonstrated in our March 2012 paper involves more than just sea-ice loss. While the ice loss is the largest contributor to AA in fall and early winter, rapid Arctic warming is also driven by the pronounced negative trend in snow cover on high-latitude land in spring and early summer, and even more strongly by the increase in water vapor at high latitudes, which affects AA in all months. That water vapor warms the Arctic in all seasons in 3 ways: it is a greenhouse gas, it releases latent heat into the atmosphere when it condenses into clouds, and those additional clouds also trap heat below them. Most of the modeling studies to date that examine the Arctic’s effects on the large-scale atmospheric circulation have focused only on the influence of sea-ice loss. I believe this is the reason that most of those studies fail to find a robust response, while the real world (which DOES include all the contributions to AA) is responding more strongly.
As commentor #8 points out, most of the modeling studies also average over time and over many ensemble members, which would smear a signal of a more amplified jet stream if those meanders did not occur in the same location. Take March 2012 versus March 2013, for example. In both cases the jet stream was highly amplified, but in 2012 there was a trough over the western U.S. and a large ridge over the east, which led to the breaking of thousands of high temperature records. A year later, the trough-ridge location was opposite but equally anomalous. Averaging over the two years would produce no signal.
It is also important to note that AA has emerged from the noise of natural variability only in the last decade or two (challenging tests of statistical significance), it is strongest in the fall and near the surface (because of sea-ice loss), and it is now becoming evident in all seasons and through a deep atmospheric layer (because of increased water vapor). This must inevitably have a more pronounced effect on the polar jet stream as we continue to warm the planet by burning fossil fuels.
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Klaus Flemløse at 20:52 PM on 7 July 2013Nils-Axel Mörner is Wrong About Sea Level Rise
I think, I have found the stockmark picture mentioned in post 55. It can by found in the video: http://www.youtube.com/watch?v=gZS2eIRkcR0 after 7 minutes and 42 second. The logo originates fra Newsworld. There is a cut in the video so it is not possible to make sure it is the same tree.
8.june 2013, 11.00
Before the cut we can se the ocean with a clear horison without any ships. After the cut , there are many ships in the horison. This means it is two different sequence taken at different times and different angels. Prof. Mömer is standing close to the tree and we can't se the whole tree. Does this mean, that it is a case of another photo manipulation ?
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chriskoz at 19:06 PM on 7 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
william@7,
You understand the things correctly (but your "Polar Hadley cell" is just called "Polar cell"), it's worth quoting this excellent article by John Mason here based laregely on Francis 2012.
However that's not the primary point of contention between Kevin & Jennifer above. The point is, that Kevin looks to me like climate scientist who averages everything (i.e. colder conditions in Arctic mean slower heat transfer therefore no large T swings expected) denying the variability of weather where he does not seem to specialise. To which Jennifer (both climate & weather specialist) replies that heat transfer is not by convection but by fast blowing wind which is simple and modest and dead-on accurate in rebuting his claim.
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Richard Lawson at 18:38 PM on 7 July 2013No warming in 16 years
Another factor, or maybe a subset of the ocean heat uptake, is the meting of the Arctic Ice. It is noteworthy that the ice melt has speeddecades once 2001. I have calculated that some 10^21 Joules have gone into melting the ice since 1997. http://greenerblog.blogspot.co.uk/2013/07/how-much-heat-has-gone-into-melting.html
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chriskoz at 18:08 PM on 7 July 2013The Consensus Project Update and Dana on Al Jazeera Inside Story
If you think Arabic language + google translate = imperfect text, check for example this translation of AJ commenting on recent tornadoes in OK. I'm just shocked with surprise: apart from few obvious misnomers: lack of distinction tornado vs. hurricane (maybe due to Arabic language nuances that someone speaking that language can explain), the translation reads perfectly clear and accurate, far clearer than most Fox, CNN, WSJ nonsense, where language is not a barrier for English reader.
In particualer, everything what Mike Mann has said is quoted without misrepresentation after this double translation. Why? Because the sound and honest journalism by the author (Yasser Aerami) + impartial google translator can confuse some technical words but cannot distort the meaning. On the other side, a human translator can be very biased and can distort the meaning (as we've seen meny times from denialists) and produce the text so obfuscated as sometimes incomprehensible. The climate science became comprehensible to me only after I started to read SkS. In terms of Climate News, AJ stands among those Fox, CNN, WSJ obfuscators like SkS stands among WUWT and the like.
Dana, I cannot wait AJ launch in Amerika. Hopefuly they be able to stream something over internet because Im located in AUS. Let us know.
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sylas at 17:59 PM on 7 July 2013Agnotology, Climastrology, and Replicability Examined in a New Study
In the interactive comments for review of this paper, in a reply by Rasmus ("SC C292: 'Reply to Ellestad/Solheim/"klimarealistene"', Rasmus Benestad, 25 Jun 2013"), there is a reference to a scanned copy of a letter:
I will maintain that Ellestad and “klimarealistene” are engaged in a propaganda campain. On February 3rd 2012, Ellestad wrote a letter to the director at MET Norway in an attempt to gag me, after I had commented on the Humlum et al (2011) paper on the website of a Norwegian newspaper. (A scanned copy is available on-line: https://drive.google.com/?usp=chrome_app#folders/0B5ZHm1tjzEtDWjhWZmxIQzVVSWc)
The link provided does not work. Is the scanned copy still available anywhere? Thanks!
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basnappl at 15:00 PM on 7 July 2013CO2 effect is saturated
Hello Tom,
Thanks for the reply. I read through the preprint as best I could. I am unfamiliar with the models used and some of the terminology. Is it true that, in their analysis, the temperature profile of the atmosphere is the fitting parameter?
As far as how well I represented their claims, I will quote with some (perhaps unnecessary) context:
First quote, commenting on the difference spectra figure I included in my previous post:
"An initial inspection indicates that the processing of the data has not caused any major artifacts. In all cases the difference spectra are seen to have consistent and reproducible
features. The only sign of asymmetry (which could indicate a mismatch of wavenumber scales between the spectra) is in the CO2 (0110 → 1000) band at 720 cm-1, which may be due to its position on the very steep high frequency wing of the CO2 fundamental centered
at 667 cm-1."Second quote, in reference to the same:
"A negative brightness temperature difference is observed in the CO2 band at 720 cm-1 in the IMG–IRIS (1997–70) and the AIRS–IRIS (2003–1970) difference spectra, indicating increasing CO2 concentrations, consistent with the Mauna Loa record (Keeling et al. 1995). However, this channel in the difference is also sensitive to temperature, and we note that in the 2003–1997 difference, despite a growth in CO2 between these years, there is no signal at 720 cm-1."
Third quote is where the portion in my previous post comes from, now with context:
"The CO2 band at 720 cm-1, though asymmetric for the reasons stated earlier, nevertheless shows some interesting behavior, with strong negative brightness temperature difference features for 1997–1970 and 2003–1970: whereas, the 2003–1997 (a much shorter period, of course) shows a zero signature. Since we know independently that the CO2 concentration globally continued to rise between 1997 and 2003, we must conclude that the 2003–1997 result must be due to changes in temperature that compensate for the increase in CO2. This would mean a warming of the atmosphere at those heights that are the source of the emission in the center of this band. This is somewhat contrary to the general (small) cooling of the stratosphere at tropical latitudes." (emphasis mine, I'm only trying to show where my "explanation" came from)
Fourth quote, regarding differences between model results and observations:
"Finally, there exists a marked gradient in the simulated spectrum between 800 and 700 cm-1, which is absent in the observations. This coincides with the far wings of the strong CO2 band centered at 667 cm-1. In sensitivity tests, this gradient showed sensitivity to the amount of CO2, and is therefore related to the strong CO2 band, and may reflect reanalysis uncertainties in temperature."
The paper includes appendices detailing the temperature profiles used to coerce the models to the data.
I would appreciate some help digesting this.
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Tom Curtis at 11:23 AM on 7 July 2013CO2 effect is saturated
basnapple @232, I have difficulty reconciling your description of the "explanation" by Griggs and Harries with that which they offer in the preprint version of their paper.
Specifically, in that version they show (Fig 3 a&b) that two popular reanalysis products do not predict the observed changes in OLR. They also show, however, that there is a profile constrained by observations that does predict the observed changes in OLR (Fig 3 c). That means the observed changes in OLR are consistent with the expectations of radiative physics plus observed changes in gas and temperature profiles, even though the observations of those profiles is of insufficient resolution to permit accurate prediction of these small changes in OLR. As they put it,
"Simulations created using profiles merged from a number of datasets show that we can explain the differences seen in the CO2 and ozone bands by the known changes in the those gases over the last 34 years."
This contrasts sharply with your claimed "explanation", which is of course no explanation at all. Converting a claim that changes in OLR lie within those expected given known limits of observation, and hence that there is no discrepancy, to a claim that a discrepancy exists for which there is no explanation is very substantial. I doubt that editorial review would have forced so large a change on the paper. Nevertheless I ask that you quote the original sections of the paper as published to show that you have indeed fairly represented Griggs and Harries.
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basnappl at 10:05 AM on 7 July 2013CO2 effect is saturated
Sorry for my various typos. I should have read it over before submitting!
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basnappl at 10:03 AM on 7 July 2013CO2 effect is saturated
Hello,
I have a question that I was hoping might be answered here. I've read through the comments and admit that most of what is being discussed are not things I understand well. It seems that the results of difference spectra reported by Harries et al. are a smoking gun. IR measurements from space over time provide concrete, easy to interpret proof that the composition of the atmosphere has changed with time in such a way that more IR is captured.
In trying to understand the methodology better, I came across this more recent publication by the same author using the same approach. It included data from another satellite in 2003. Here is the result:
The paper states that "The CO2 band at 720 cm-1 ... shows some interesting behavior, with strong negative brightness temperature difference features for 1997-1970 ... whereas, the 2003-1997 ... shows a zero signature." (Edited for clarity relative to my question--the essence of it is captured)
The "expanation" offered in the paper is essentially that there most be some compensating effect since it is known that CO2 concentrations increased between 1997 and 2003.
I'm willing, in my ignorance, to grant that that's true. However, I wonder, if the presence of a difference between 1970 and 1970 is seen as proof that CO2 isn't saturated, why is zero difference between 1997 and 2003 not powerful evidence that it is? It just seems to me that if the former evidence is enough to make one feel sure CO2 is absorbing more that the later evidence should convince the same person that CO2 is not absorbing more (between those dates).
Any insight would be appreciated!
Moderator Response:[RH] Fixed image width.
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dana1981 at 08:19 AM on 7 July 2013The Consensus Project Update and Dana on Al Jazeera Inside Story
Thanks sauerj. Al Jazeera's willingness to have thorough discussions of climate change without false balance is impressive and laudable. I just wish some more mainstream American cable news networks were willing to do the same. At most you'll get Chris Hayes devoting a few-minute-long segment on his MSNBC show to climate change with a good set of panelists every so often. Or you'll get Fox News putting Joe Bastardi on to see if he'll try and break his record for dumbest thing ever said about global warming.
I think Al Jazeera is launching an American station in the near future. I hope they're successful, and show the existing American networks how it's done. -
william5331 at 06:11 AM on 7 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
I think a number of the above commentators are right on the money. If I understand the situation correctly, the strength of the jet streams is a function of the speed of rotation of the two Hadley cells that create the jet stream in question. The polar jet stream is located where the Polar Hadley cell and the Ferrel cell meet. The Ferrel cell is an 'idler gear' between the Equatorial Hadley cell and the Polar Hadley cell, but the Polar Hadley cell, is a powered cell, powered by polar air made dense by radiating heat into space and lacking heat from the sun to counter this cooling. With a complete cover of snow and ice, the arctic absorbs very litte heat. Looking at the NSIDC website for October 2012, about half way down we see a report of rising air due to heat given off from open water and winds from the South West. In other words, a reversal of the Polar Hadley cell. As we have more open water for longer periods, this reversal should become more persistant and stronger. The jet stream which is becoming weaker and wobbling should disappear and we will have, essentially, a two cell system in the Northern Hemisphere. Weather patterns which are creeping northward, should lurch northward. The effect should initially be seen in Autumn and should spread further back into summer over the ensuing years. We will have, in essence, an offshore wind as the land cools off in the fall but a lot of heat is available in the open Arctic ocean. This offshore wind, though, will persist day and night rather than being a phenomenon that occurs only each evening as in temperate areas. The effect on agriculture should be pretty much as described in "A change in the Weather" mentioned above. What I find worrying is that if you take a bit of lisence in interpreting the preliminary results from El'gygytgyn, it seems that we already are in a new climate regime but the effects are not yet being felt. In other words, the climate is not yet in equilibrium with the present CO2 levels. We have set the system in motion towards a new equilbrium but now all sorts of feed back mechanisms will work their way through until we are in the new climate. If so, and as we head with gay abandon towards 500ppm, it should be exciting times.
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A Change in the Weather at 02:57 AM on 7 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
In 2005, I had an intuition about the link between the Arctic ice cap and the behavior of the jet stream. It became the predicate of my novel, A Change in the Weather. I continue to be stunned and amazed--and really, anguished--that my intuition appears to have been accurate.
The story is a thought experiment about the imminence and abruptness of this change, and how it might affect the economy and social organization of America as seen through the lens of a single family. The politics of it would certainly be off-topic here, but I think it's safe to say the first consequence would be the failure of agriculture, which will put tremendous strains on society not only in the US but across the globe.
Look at what happened in Michigan in March 2012. Nighttime temperatures set all-time record highs for the entire month because the jet sream had lifted its skirt so far north. The tropical air that wafted underneath coaxed the apple trees into an early blossom. When the jet stream dropped back to its habitual latitudes, the blossoms couldn't survive the cold. Michigan lost 90% of its apple crop.
I think when the ice cap finally inverts from white heat reflector to black heat absorber, even just for a few weeks in late summer, these erratic excursions will be greatly amplified and interfere with the rainfall patterns that agriculture has depended on for millennia. In my book, it happens in 2018. That's just five years from now. I've checked this with Dr. Francis, Dr. Masters, and Dr. Mark Serreze at the NSIDC, and Dr. Ken Dunton at UT-Austin. They think this timeframe is plausible.
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sauerj at 02:44 AM on 7 July 2013The Consensus Project Update and Dana on Al Jazeera Inside Story
Dana, Both sets of interviews are very good & informative (recommend all to watch). I am impressed by Al Jazeera's integrity to sound journalism (i.e. not pandering to the typical argumentative interview via including the 'denialist' in the mix). Everyone was professional yet gave a piece of their own personality to this "debate of our time" (in other words, it was neat to hear & see you, Dana, in person). As an older guy myself (& increasing realizing how fast life slips by), I sadly wonder, Dana, what it will feel like for you, when in 20-25 years from now, you will be the 'old' guy in the mix (remembering & memorializing the late climate heros before you), and yet still talking in hopeful terms about these same basic policy initiatives. I hope not, but yet ...
I thought the question on the rudimentary development of people's belief & its possible change (& the study sited, starting at 7:50 on 2nd interview) to be interesting. It implied that scientific announcements and weather upsets have little impact, but that political 'browbeating', and I would add, bolstered by repetitive ideological news broadcasts have, back to the study, the strongest impact on shaping & solidifying a person's 'bent', moving from a budding presumption to an entrenched imutable convention. Sadly, I would say this seems to match my unscientific observations, casting yet even more doubt that change via good & noble things, like logic & truth, will have a remotely easy time of it. ... But, I'm just another agent of noise speaking from my own entrenched and immutable position.
Thanks again for posting and for your continued hard work!
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citizenschallenge at 23:37 PM on 6 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
yup, also see:
Weather Extremes Tied to Jet Stream Changes
By: Seth Borenstein
Published: June 25, 2013http://www.wunderground.com/news/heat-wave-alaska-jet-stream-may-be-blame-20130625
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grindupBaker at 12:27 PM on 6 July 20132001-2010, A Decade of Climate Extremes
Our neighbour's Premier Alison Redford just said on CBC they were overdue for their bit of heavy rain because it was 120 years since they had one. It'll be interesting to hear what is said for the next one.
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Daniel Bailey at 11:34 AM on 6 July 2013There is no consensus
I've cobbled the following list together from a variety of sources and persons. Apologies, but it's been too long to remember whom they were for proper attribution:
The IPCC’s conclusion that most of the warming since 1950 is very likely due to human emissions of greenhouse gases and has been endorsed by this great cloud of witnesses:the National Academy of Sciences,
http://www.nap.edu/openbook.php?record_id=10139&page=1the National Aeronautics and Space Administration,
http://climate.nasa.gov/causes/the National Center for Atmospheric Research,
http://eo.ucar.edu/basics/cc_1.htmlthe National Oceanic and Atmospheric Administration,
http://www.ncdc.noaa.gov/oa/climate/globalwarming.htmlthe American Geophysical Union,
http://www.agu.org/sci_pol/positions/climate_change2008.shtmlthe American Institute of Physics,
http://www.aip.org/fyi/2004/042.html
http://www.aip.org/gov/policy12.htmlthe American Physical Society,
http://www.aps.org/policy/statements/07_1.cfmthe American Meteorological Society,
http://www.ametsoc.org/POLICY/climatechangeresearch_2003.html
http://www.ametsoc.org/policy/2007climatechange.html
http://www.ametsoc.org/policy/2012climatechange.htmlthe American Statistical Association,
http://www.amstat.org/news/climatechange.cfmthe American Association for the Advancement of Science,
http://www.aaas.org/news/press_room/climate_change/the Federation of American Scientists,
http://www.fas.org/press/statements/_docs/08grand_challenges.htmlthe American Quaternary Association,
http://www.inqua.org/documents/QP%2016-2.pdf
http://www.agu.org/fora/eos/pdfs/2006EO360008.pdfthe American Society of Agronomy,
https://www.soils.org/files/science-policy/asa-cssa-sssa-climate-change-policy-statement.pdfthe Crop Science Society of America,
https://www.soils.org/files/science-policy/asa-cssa-sssa-climate-change-policy-statement.pdfthe Soil Science Society of America,
https://www.soils.org/files/science-policy/asa-cssa-sssa-climate-change-policy-statement.pdfthe American Astronomical Society,
http://aas.org/governance/resolutions.php%23climate#climatethe American Chemical Society,
http://portal.acs.org/portal/fileFetch/C/WPCP_011538/pdf/WPCP_011538.pdfthe Geological Society of America,
http://www.geosociety.org/positions/position10.htmthe American Institute of Biological Sciences,
http://www.nationalacademies.org/includes/G8+5energy-climate09.pdfthe American Society for Microbiology,
http://www.asm.org/images/docfilename/0000006005/globalwarming%5B1%5D.pdfthe Society of American Foresters,
http://www.safnet.org/fp/documents/climate_change_expires12-8-2013.pdf
http://www.safnet.org/publications/jof/jof_cctf.pdfthe Australian Institute of Physics,
http://www.aip.org.au/scipolicy/Science%20Policy.pdfthe Australian Meteorological and Oceanographic Society,
http://www.amos.org.au/documents/item/26the Australian Bureau of Meteorology and the CSIRO,
http://www.csiro.au/files/files/pvfo.pdfthe Geological Society of Australia,
the Federation of Australian Scientific and Technological Societies,
http://www.fasts.org/images/policy-discussion/statement-climate-change.pdfthe Australian Coral Reef Society,
http://www.australiancoralreefsociety.org/c/document_library/get_file?uuid=5d093a51-a77e-4ae0-bd9f-67e459d57ac1&groupId=10136the Royal Meteorological Society,
http://www.rmets.org/news/detail.php?ID=332the British Antarctic Survey,
http://www.antarctica.ac.uk/bas_research/science/climate/position-statement.phpthe Geological Society of London,
http://www.geolsoc.org.uk/gsl/views/policy_statements/page7426.htmlthe Society of Biology (UK),
http://www.societyofbiology.org/policy/policy-issues/climate-changethe Canadian Foundation for Climate and Atmospheric Sciences,
the Canadian Meteorological and Oceanographic Society,
http://www.cmos.ca/climatechangepole.htmlthe Royal Society of New Zealand,
http://www.royalsociety.org.nz/organisation/panels/climate/climate-change-statement/the Polish Academy of Sciences,
the European Science Foundation,
the European Geosciences Union,
http://www.egu.eu/statements/position-statement-of-the-divisions-of-atmospheric-and-climate-sciences-7-july-2005.html
http://www.egu.eu/statements/egu-position-statement-on-ocean-acidification.htmlthe European Physical Society,
http://nuclear.epsdivisions.org/Reports/eps-position-paper-energy-for-the-futurethe European Federation of Geologists,
the Network of African Science Academies,
http://www.interacademies.net/File.aspx?id=4825the International Union for Quaternary Research,
http://www.inqua.org/documents/iscc.pdfthe International Union of Geodesy and Geophysics,
http://www.iugg.org/resolutions/perugia07.pdfthe Wildlife Society (International),
http://joomla.wildlife.org/documents/positionstatements/35-Global%20Climate%20Change%20and%20Wildlife.pdfand the World Meteorological Organization.
http://www.wmo.ch/pages/mediacentre/statann/documents/SG21_2006_E.pdfThere aren’t any national or international scientific societies disputing the conclusion that most of the warming since 1950 is very likely to be due to human emissions of greenhouse gases, though a few are non-committal.
The last organization to oppose this conclusion was the American Association of Petroleum Geologists (AAPG). They changed their position statement in 2007 to a non-committal position because they recognized that AAPG doesn’t have experience or credibility in the field of climate change and wisely said “… as a group we have no particular claim to knowledge of global atmospheric geophysics through either our education or our daily professional work.”
http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change#Non-committal_statements
http://dpa.aapg.org/gac/statements/climatechange.pdf
http://64.207.34.58/StaticContent/3/TPGs/2010_TPGMarApr.pdfThere are people maintaining lists of these orgainzations, but I'll have to try and dig up the links. Been about 3 years since I lasted looked at them...
The now-defunct LogicalScience.com website maintained a seemingly-complete listing, but it has gone into the great Internet Twilight zone. However, the most recent archive of the site can be found:
http://web.archive.org/web/20111130013640
Moderator Response:[RH] Fixed the few super long URL's that were breaking the page formatting.
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Alpinist at 08:55 AM on 6 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
Jeff Masters site has had several recent posts on this as well including this: http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2452 from just a couple days ago.
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Chris G at 05:44 AM on 6 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
Not an expert, but I could follow both arguments; I also found Dr. Francis' to be more compelling.
As I understand it: The jet stream(s) are not driving forces; they are a product of the large circulation patterns for polar, intertropical, and Hadley cellss; they exist where the circulation patterns meet. Physics predicts, and we have observed, that warming anamolies increase toward the poles. The waves in the jet stream are largely a result of the different speeds of the larger circulation patterns. When air (or any fluid) flows past other air, turbulence is created. For less deltas, the turbulence has larger, slower waves. I suppose an analogy could be that shorter frequency waves have higher energy than longer frequency waves; and in this case the energy in the wave is a product of the energy differences between the air masses in the different circulation patterns.
If someone has a better understanding, I'd be glad to hear it.
So, if this is by-and-large correct, then we would expect to see changes in the jet stream waves (amplitude, frequency, and location) with any lessoning of temperature gradient between equator and pole. The Arctic ice is particularly interesting if you think of it as an temperature buffer. There is a fair amount of energy delta between several million cubic meters of ice and the same mass of water, at the same temperature. So, I think that there would be a change in the jet stream pattern regardless of if the Arctic were land or sea, but I suspect that the difference is enhanced by the larger differences we are seeing being ice minimum and ice maximum.
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citizenschallenge at 01:11 AM on 6 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
Fascinating article, thanks for printing it.
And thanks chriskoz for voicing my thought:
"Note how (Trenbirth) says "there might be influence somewhere in Europe, for example, but not over entire NH". To which I may reply: well, the same jetstream flies over Canada US and in Europe, why do you think America is "immune" to it?
==============
And sorry for doing this, but it is only slightly off topic considering how science skeptics love pointing out the 1920/30s arctic warming (where they fail to mention the warming was rather localized, originating around Spitsbergen) trying to imply that there is nothing unusual about current events.
I've been reading: "The Arctic Warming 1919 to 1939" by: Arnd Bernaerts
http://www.arctic-heats-up.com/pdf/chapter_8.pdf
Which has introduced me to the notion that intense navel activity caused a great deal of ocean mixing, disrupting the thermohaline current, and leading to the freak warming event that started off Spitsbergen and spread outward from there:
" a long barrage between the Orkney Islands and Norway ... (USA and UK mines laid) 73.000 mines __about 5,000 exploded prematurely soon after laying __20,000 mines were disposed of while the work was in progress __from the remaining ca. 50,000 mines __more than 30,000 mines were already ‘gone’ in spring 1919, either drifted away, or exploded during winter storms; __rest 20,000 were swept in 1919." {ch.8 p.94}
In all something like 200,000 mines were laid in various North Atlantic locations.
~ ~ ~
As for ships and U-boats:
"The situation became dramatic when U-boats destroyed more ships than Britain could build in early 1917. In April 1917, the same total rate of the previous annual rate of 1916, ca. 850,000 tons, was destroyed by U-boats. In April 1917, Britain together with the Allies lost 10 vessels every day. During the year of 1917, U-boats alone sank 6,200,000 tons, which means more than 3000 ships, and, during the war months of 1918, another 2,500,000 ship tonnage. The total loss of the Allies ship tonnage during WWI is of about 12,000,000 tons, namely 5,200 vessels. The total loss of the Allies together with the Axis naval vessels (battle ships, cruisers, destroyers, sub-marines, and other naval ships) amounted to 650, respectively 1,200,000 tons." {ch.8 p.88}
~ ~ ~ ~ ~ ~ ~
It's one of those thoughts that at first blush is way out there, but then on reflection and considering the new found appreciation for the amount of deep ocean churning whales and other sea creatures produce as they dive to deep depths then return to surface (http://www.biogeosciences-discuss.net/9/8387/2012/bgd-9-8387-2012.html) - it doesn't seem so far fetched.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I'm curious how has the scientific community reacted to Bernaerts' hypothesis?
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DSL at 23:32 PM on 5 July 2013Nils-Axel Mörner is Wrong About Sea Level Rise
Klaus, perhaps after Morner has addressed his integrity here, he can go to Open Mind and address this.
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Boswarm at 22:42 PM on 5 July 2013Peak Water, Peak Oil…Now, Peak Soil?
Stephen Leahy,
I did not infer or imply you made this stuff up?
Read my comment again. It's the bits left out that got to me. Then you say:
"Iceland has not recovered, it remains Europe's largest desert despite the amazing efforts of the soil cons service. "
It has recovered and adapting to the new soil conditions, and as it warms, the position will improve. The statistics prove this. See the references in my previous coment especially www.bondi.is
"FYI It is a 1000 word article, not a transcript of 3 days of talks" - I know what you wrote, I have all the transcripts from the conference, yet so much was omitted in the true story of Iceland farming.
- Fertilizer usage reduced since 1981
- Barley 15,000 tonnes per year for zero in 1970
- Beef cattle increase to 2011
- Horse breeding doubled
- Pigs increase X 6
- Laying Hens plus 50,000 since 1970.
What these figures exhibit is a shift from dairy and sheep to other forms.
It's called adapting, not peak soil. Iceland is becoming one of the most unique farming communities in the world with now less than 6.5% of the population producing more agricultural and pastoral product than 77% of the population did in 1901. Change and adaption is what Iceland farmers are great at. If you visited the Westfjords you would have seen a great change from an old farming practices to the new.
Have a look at the constant change between agriculture and pastoral - it's called adaption.
Your article was a correct representation of the conference, but needed a lot of information regarding the true nature of the industry in Iceland to create balance.
I am sorry if I have upset you in my comments above and here. I have seen Iceland over many years, and it is improving greatly, except for the fact that the good farmers, agricultualists and pastoralists are aging and not been replaced. It should be retiltled - PEAK FARMER.
And if vrooomie had any manners like you have Stephen, he would have asked similar questions. We have to keep fighting to reduce the carbon pollution or we will all be at peak END.
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chriskoz at 21:23 PM on 5 July 20132001-2010, A Decade of Climate Extremes
Cornelius@7,
"dramatic music" is for large, poorly educated audience. Like most TV shows, they must add some "drama" to entice audience. Otherwise they would go out of business if they'd left with viewers like you & me only.
I think it is getting better: not so long ago they used to entice audience by falsely pretending the existence of "debate": i.e. showing Monckton, Bob Carter and even Tony Abbott arguing this science is "crap". No need to say that none of those characters (with the exception of Bob Carter) are even worth mentioning along the names of the scientists, let alone give then any air time. In case of Bob Carter, if giving him any time, it is mandatory to mention his personal bias due to regular payments from The Heartland Institute in appreciation for his scientific opinion. Otherwise his apearance is misleading for poorly educatred audience.
But not a hint of any "skepticism" in this program. Let's hope this change is for good, at least in Catalyst.
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chriskoz at 20:38 PM on 5 July 2013Two Expert — and Diverging — Views on Arctic’s Impact on Weather ‘Whiplash’
I don't think Kevin's & Jennifer's views are diverging by much. Kevin does not contradict the theory of meandering jetstream's signifficance on NH weather, he's just a bit skeptic (in a good sense) and is looking for more evidence. Note how he sais "there might be influence somewhere in Europe, for example, but not over entire NH". To which I may reply: well, the same jetstream flies over Canada US and in Europe, why do you think America is "immune" to it?
Personally, I give more edge to Jennifer's view because she's more knowledgeable expert in this particular topic. And some evidence confirming meandering jetstream's theory at work in America (e.g. tropical cyclone Sandy) do exist to back her.
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Cornelius Breadbasket at 18:03 PM on 5 July 20132001-2010, A Decade of Climate Extremes
mikeh1 @ 5
I'll share this one. I'd prefer it without the dramatic music - but it is a very well put together documentary. Thank you!
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johncl at 17:58 PM on 5 July 2013Climate change science: what’s in a name?
I do believe the next glacial period is estimated to be around 50000 years from now if the natural forcings (Milankovitch cycles) are the main driver. The question remains though whether the new state of the biosphere with a substantial higher CO2 concentration (so far 40% over what it should be) will even allow the planet to cool down enough for serious glaciation. Most likely it will cool down though as the tilt surely must have a substantial effect on the amount of energy absorbed (but I am really only guessing here). Our CO2 emissions will most likely not go down much in the coming decades and every year really reduces the chance for these natural forcings to overcome the artificial injection of insulation in the atmosphere. But they will still come "on top", including the weather patterns, so I wonder how the next major El Niño will affect us. No doubt another round of high scores.
About the terms, I still think AGW is the correct term as its our deliberate warming of the planet which is of essence here, climate change is just one effect of this. And as villabolo say here the effect it has on food production is probably the immediate one we will notice, partially also because there are so many of us on the planet now. Add a bit of energy crisis due to oil shortage and the "green revolution" goes *poof*, and we are back to being more relient on whatever energy the soil and the sun gives our crops. Some freak weather incidents on top (due to e.g. a messed up jetstream) will then add the little extra challenge. I say we live in interesting times...
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skymccain at 16:34 PM on 5 July 2013Climate change science: what’s in a name?
Thank you KR.
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Bert from Eltham at 12:31 PM on 5 July 2013Understanding the long-term carbon-cycle: weathering of rocks - a vitally important carbon-sink
Bear with me.
The mindless universe started with inflation.
Soon after cooling enough atoms of H, and He and a bit of Li formed.
Some of these atoms some time later gravitationally collapsed into stars.
These early stars were responsible for nucleosynthesis of heavier nuclei.
It was only supernovae that actually produced nuclei above Iron 56.
All this newly formed matter that was strewn everywhere then finally at some cool places formed new stars and planets.
The third stone from the Sun was geologically active with ordinary chemistry to make a near habitable planet. The above is very good article.
Early mono cellular life transformed the oceans and atmosphere and forever changed the simple chemistry that was in effect up till then and it took four billion years!
Finally multi cellular life evolved. Until we came along. We are all trashing our only home because of greed.
Worth a look.
http://www.youtube.com/watch?v=9nnwvoH-4XI
Bert
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mikeh1 at 09:18 AM on 5 July 20132001-2010, A Decade of Climate Extremes
Moderator - the following may be a better link to the Catalyst story. The mp4 works well on a tablet but not so well on a desktop.
http://www.abc.net.au/catalyst/stories/3796205.htm
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mikeh1 at 09:15 AM on 5 July 20132001-2010, A Decade of Climate Extremes
The following is a link to last night's excellent Australian ABC Catalyst science program on extreme weather.
http://mpegmedia.abc.net.au/tv/catalyst/catalyst_14_11_wildweather.mp4
It includes interviews with the following climate scientists.
Dr Erich Fischer, Institute for Atmospheric and Climate Science, ETH
Dr Karl Braganza, Australian Bureau of Meteorology
Dr Lisa Alexander, Climate Change Research Centre, UNSW
Dr Susan Wijffels, Marine and Atmospheric Research, CSIRO
Professor Jennifer Francis, Institute of Marine and Coastal Sciences, Rutgers University -
KR at 09:01 AM on 5 July 2013Climate change science: what’s in a name?
skymccain - "...why we have not entered the cooling part of this glacial/interglacial cycle yet."
We were starting the cooling portion of this cycle, with Holocene temperatures starting to decline, until the Industrial Revolution. Now, apparently, Milankovitch cycle cooling is off the table for many thousands of years.
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skymccain at 08:23 AM on 5 July 2013Climate change science: what’s in a name?
I especially like this post. The comments remind me that I would like to read more about why we have not entered the cooling part of this glacial/interglacial cycle yet. There has been so much written on why the warming. That's important, don't get me wrong, but it may also help to identify the factors that in the past triggered a cooling trend. I won't play completely ignorant as I have studied the Berger insolation data and have formed my own opinion. However, I am not a professional and have no standing so would like to hear professionals explain when we might look forward to the trip toward another ice age. What do you think?
Best wishes, Sky
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Dikran Marsupial at 06:30 AM on 5 July 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
KK Tung wrote " While Dikran may disagree with my summary, I think he has failed to come up with an example where our procedure fails to yield the right answer within the 95% confidence interval (CI) most of the time. "
This is simply incorrect. In the example here, the linear trend due to the anthropogenic component is estimated by the MLR procedure to be 0.0019 +/- 0.00039, the true value is 0.003, which is not in the 95% confidence interval. In this example, the MLR procedure underestimetes the anthropogenic component and the difference is statistically significant. Sadly there seems little point in continuing the discussion if this cannot be acknowledged and accepted, so I will leave it at that, so as not to distract from Prof. Tung's discussion with Dumb Scientist.
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Cornelius Breadbasket at 05:47 AM on 5 July 20132001-2010, A Decade of Climate Extremes
shoymore @ 3
You are right. On the BBC there is rarely a mention of CO2 or human influence - whether it is the changing of the jet-stream, the melting of the Arctic or extreme weather (a notable exception being the piece I linked to). I feel that this is because so many contrarians have made life difficult for good journalists like Richard Black (who was solidly under attack by 'climate sceptics' and has now left the BBC) that they are terrified of being victimised in a similar way. Apologies if this is off topic.
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shoyemore at 05:05 AM on 5 July 20132001-2010, A Decade of Climate Extremes
BBC did do a good news report last night on their national evening bulletin, with a reporter speaking about the extreme heat in Death Valley.
However, CO2 was not mentioned. The reporter also said "Global temperature rise has stalled, but it is the extremes that matter, and they will continue."
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John Hartz at 04:36 AM on 5 July 2013Climate change science: what’s in a name?
What's missing from the OP and the discussion thread to date is a basic understanding of how climate scientists define the Earth's "climate system."
Per the SkS Glosary and the IPCC, "climate system" is defined to be:
The climate system is the highly complex system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the land surface and the biosphere, and the interactions between them. The climate system evolves in time under the influence of its own internal dynamics and because of external forcings such as volcanic eruptions, solar variations and anthropogenic forcings such as the changing composition of the atmosphere and land use change.
Definition courtesy of IPCC AR4.
The above is a working definition that we all should adhere to.
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villabolo at 04:26 AM on 5 July 2013Climate change science: what’s in a name?
Johncl @7
"What I often feel is missing from the terms is the effect beside climate change. There is no doubt the chance of a major "biosphere change" - not not only climate. I believe many people dont consider a bit more wind in their hair now and then a problem".
Unfortunately the general public will consider the term "biosphere change" as too abstract and scientific sounding. Also, most people are inured to hearing words like environment and nature.
The only way to get their attention is to mention the destructive effect of global warming on crops and food prices. That is the only "nature" that most of the general public will be concerned about.
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grindupBaker at 03:03 AM on 5 July 2013Climate change science: what’s in a name?
I suggest not messing around with the basic phrase in the terminology because Anthropogenic Global Warming is complete enough and accurate enough. The issue is in explaining clearly what happens, has happened, will happen. Messing around with phrases at some point becomes treating other people like children (or, even worse, like consumers). Adopt supplemental detail phrases if necessary and provided they are clear, correct & concise. If you can make a case that significant potential energy or kinetic energy increase has occurred then maybe. I gave it a quick rough shot with sea level rise & more water in air (potential) and tried to find ocean current info (kinetic) but it's negligible. So why "energy" ? Pedantic nonsense.
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Smith at 02:52 AM on 5 July 2013Climate change science: what’s in a name?
I’m cautious about introducing novel terms, because it can be counter-productive, making things even more confusing despite good intentions.
In light of this remark, is the use of the term "Climate Change Science" a deliberate departure from the more traditional and common term "Climate Science"? If so, could you please illustrate the distinction?
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John Hartz at 02:27 AM on 5 July 20132001-2010, A Decade of Climate Extremes
Cornelius Breadbasket #1:
As should be the case with a report of this importance, MSM outlets throughout the world are publishing/posting articles about the findings contained in the WMO report, The Global Climate 2001-2010, A Decade of Climate Extremes.
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KK Tung at 02:21 AM on 5 July 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
On the “thermodynamics argument”: Dumb Scientist has repeatedly touted the thermodynamic argument as putting an upper limit on internal variability:
"Again, attribution is really a thermodynamics problem that needs to be calculated in terms of energy, not curve-fitting temperature timeseries. Your curve-fitting claim that ~40% of the surface warming over the last 50 years can be attributed to a single mode of internal variability contradicts Isaac Held and Huber and Knutti 2012 who used thermodynamics to conclude that all modes of internal variability couldn't be responsible for more than about 25% of this surface warming."
First, attribution is not necessarily a thermodynamics problem. The method adopted by IPCC AR4, the “optimal fingerprint detection and attribution method”. “is based on a regression of the observation onto model simulated patterns and relies on the spatio-temporal response patterns from different forcings being clearly distinct…..The global energy budget is not necessarily conserved and observed changes in the energy budget are not considered”. This quote came from Huber and Knutti, 2012.
Secondly, none of the published work could put such a tight upper bond on the contribution by internal variability. Huber and Knutti (2010) in Nature Geoscience, mainly used a zonal mean energy balance model of intermediate complexity, meaning a model without ocean dynamics. I believe this model has a diffusive ocean and therefore is not possible to have internal variability beyond a few months: “The energy balance model has no natural interannual variability but is able to reproduce the observed global trend of past temperature and ocean heat uptake”. The model’s ocean heat uptake is constrained using observation in the upper 700 meters: “Ocean heat uptake for 3000 m depth is also larger, but the model is only constrained using data to 700 m depth”. Given these uncertainties, which the authors acknowledged to be large, I would take the results to be a consistency test of models that have simulated the observed warming as almost entirely a response to forcing.
Towards the end of the paper, the authors compared the 50-year linear trends derived from unforced control runs in the CMIP3 models with the observed 50-year trends. These models do have internal ocean variability. ( DS, please note, this part is not based on a thermodynamic argument, but the result was what you referred to as from a thermodynamic argument.) The authors concluded “For global surface temperature it is extremely unlikely (<5% probability) that internal variability contributed more than 26+/-12% and 18+/-9% to the observed trends over the last 50 and 100 years, respectively”. So the “upper bound” is 38% for the last 50 years and 27% for the past 100 years, respectively. Given the uncertainty in the model’s oceans, I do not think these upper bounds rule out our ~40% and ~0% contribution of internal variability to the 50-year and 100-year trends, respectively.
On Isaac Held’s blog#16 that DS refers to as providing an upper bound of 25% for the contribution of internal variability to the surface warming for the past 50 years: We need to recognize that Held is using a very simple two-box ocean model to illustrate the process of energy balance that can be used to constrain the contribution from internal variability. The exact figure of 25% as the upper bound should not be taken too seriously, and it could easily be 40%, given the fact that there is at least a factor of two variation in climate sensitivity in the IPCC models and he picked one particular value of climate sensitivity from one of the GFDL models for illustrative purpose. There were many other simplifying assumptions so that an analytic result could be obtained. One of them is the assumption that ξ, the fraction of temperature change that is forced, remains constant in time as anthropogenic forcing increases. This would have required an increasing magnitude of internal variability. With this assumption, he was able to obtain the following formula:
Ocean heat uptake per unit forcing=Ocean heat uptake per unit forcing as if the entire temperature change were forced - (1-ξ)/ξ.
The last term is due to internal variability. It is negative, because ocean is supplying heat to the atmosphere to be radiated to space. Held estimated a typical value for the first term on the right-hand side to be ~0.3, from which he estimated that if ξ is smaller than 0.75 then the total ocean heat uptake would become negative. So the fraction of warming contributed by internal variability, (1-ξ), cannot be greater than 25% during a period when the ocean heat uptake is positive. This number can easily become ~40% if the forced response is slightly more efficient in storing heat in the ocean. Recent evidence of finding more and more of the forced warming in deeper and deeper ocean layers may suggest that the ocean is more efficient in storing heat than previously thought. Changing 0.3 to 0.5 would yield close to 40% for this upper bound.
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Klaus Flemløse at 02:09 AM on 5 July 2013Nils-Axel Mörner is Wrong About Sea Level Rise
Many thanks to Tom Curtis, Micheal Sweet and DSL for their remarks. I appreciate them.
I have for a long time followed Professor Nils-Axel Mörners attacks against climate scientists and believes that he has gone far over the line of dignity. Prompted by Tom Curtis analysis of Mörner pictures, I have written to Nils-Axel Mörner to get his version of the images and how they should be interpreted. In addition, I asked Mörner to publish all the pictures from his trip so that all indications of fraud and scams can be swept away. He deserves a fair trial. Only by getting his version is possible.Prof Nils-Axel Mörner has informed me, that he was not aware of the discussion about him on Skeptical Sciences. He is now.
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KK Tung at 02:06 AM on 5 July 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
Our exchanges on analysis procedures of a technical nature probably have left most of our readers confused. So let me summarize the major points under debate. Both Dumb Scientist (DS) and Dikran Marsupial have focused on the technical aspects of the Multiple Linear Regression analysis (MLR). This was one of the three data analysis methods that were used on the problem with the aim of deducing the secular trend after removing the oscillatory influence of Atlantic Multi-decadal Oscillation (AMO). Our PNAS paper used two methods, the MLR and the wavelet analysis, and obtained approximately the same result. Previously, Wu et al (2011, Climate Dynamics) used the method of Empirical Mode Decomposition (EMD) and obtained similar results. The EMD method was relatively new, and there were questions on whether other, more commonly used methods could yield the same result. Our PNAS paper was in part (though a small part) trying to reproduce their results using two other methods. The larger aim of our PNAS paper was to argue that the AMO is mostly natural.
Two technical aspects of the MLR have been debated here. Dikran chose to focus on our use of a linear regressor as a placeholder in an intermediate step of the MLR process. This issue was discussed in part 1 of my post, and shown that when the residual is added back as in the published papers (Foster and Rahmstorf (2011), Zhou and Tung (2013), Tung and Zhou (2013)), the sensitivity to the particular intermediate step is greatly reduced. While Dikran may disagree with my summary, I think he has failed to come up with an example where our procedure fails to yield the right answer within the 95% confidence interval (CI) most of the time. Please see my posts 171 and 172 for a summary.
Although I had originally thought that Dumb Scientist also focused on our use of linear regressor as the reason for his assertion that our argument was circular, he later clarified that his focus was on how the definition of the AMO index from the North Atlantic temperature affects the deduced anthropogenic trend. This is a more worthwhile challenge. My collaborator Dr. Zhou and I were interested to follow this debate to find out under what condition the MLR procedure would fail. After all, no empirical method is expected to work under all conditions. So we thank DS for his efforts.
His sequence of examples has evolved into the following: Consider a hypothetical example where we know what the true answer is, and make such an example as realistic as possible (with respect to the correlation between the global mean data and the N. Atlantic data, and the variances in each) so that if the MLR procedure fails in this hypothetical case it is likely to fail in the real case also. The observed temperature (HadCRUT4) warms at the rate of 0.17 C per decade after 1979. This was proposed previously by Foster and Rahmstorf (2011) as the “true anthropogenic trend”. Tung and Zhou (2013), on the other hand, argued that this observed rate of warming includes the rising half cycle of the AMO, which when removed, would yield an anthropogenic trend that is approximately half as large. So the question is, what if the true anthropogenic warming trend is actually 0.17 C per decade in a hypothetical example, will the MLR procedure erroneously say that it is smaller? While I have always maintained that such a theoretical possibility exists, it has been surprisingly difficult to actually come up with an example where MLR fails, and we collectively have gone through examples where the hypothesized anthropogenic warming goes from quadratic to a fifth order polynomial. The example that DS finally came up with consists of a 7th order polynomial for the anthropogenic trend (called human). It has the property that it is warming at 0.17 C per decade post 1979, but no warming before that. The latter fact is unrealistic but necessarily follows from the high order polynomial form assumed for this anthropogenic warming if one uses only analytic forms. There is in addition a 70-year oscillation, which is the AMO (called nature by DS). The global mean temperature is assumed to consist of human + nature + random noise. The N. Atlantic temperature that is used to define an AMO index also consists of these three components but in different proportions. The AMO Index is obtained by linearly detrending the N. Atlantic temperature. The idea is that because the anthopogenic trend is highly nonlinear, linearly detrending the N. Atlantic temperature yields an AMO contaminated by the nonlinear part of the anthropogenic trend. Therefore, if this “AMO” is removed by the MLR procedure, what remains is a more linear trend that is an underestimate of the true nonlinear anthropogenic trend. At least that is the aim of DS, as I understand it.
MLR can fail if the two components that we try to separate (in this case, the AMO and the nonlinear anthropogenic trend) have approximately the same scale, about 35 years, as is the case with DS’s latest example with the high order polynomial. Although the MLR method still can yield the right answer within the 95% CI most of the time (see my posts 178 and 179), it is nevertheless showing symptoms of non-robustness, e.g. sensitivity to the choice of regressors (smoothed vs non smoothed), which neither DS nor we understand at the moment, and we don't have the time to investigate it deeper. In the real case considered in our papers, such sensitivity does not exist and we got approximately the same answer. However, this example is not relevant, despite efforts by DS to make it realistic in other aspects, because we know, based on our current understanding of greenhouse warming, that there has been a warming since 1900. So the time scale for the anthropogenic warming is not 35 years but over 100 years.
The following example remedies this one deficiency in the example by DS that makes his case study less relevant. That is, we still use the hypothesis, as DS did, that the true post-1979 warming is entirely anthropogenic, and so the true human warming rate is 0.17 C per decade. Before that time there is a gentler warming, which is equal to the smoothed secular trend in the observed warming from 1850 to 1979. Everything else remains the same as in DS’s example. We perform 10,000 Monte-Carlo simulations using his method for the MLR. (We think 10,000 is sufficient; there is no need for 100,000 Monte-Carlo simulations.) The MLR procedure obtains the correct answer, defined as within the 95% CI of 0.17 C per decade for the post 1979 trend, most of the time. Specifically, we obtain the correct answer 80% of the time if we use the linear regressor in the intermediate step, 95% of the time correct if we use the QCO2 as the regressor in the intermediate step, and 91% of the time correct if we use human as the regressor, as DS did. Therefore, regardless of the intermediate steps, the MLR is able to successfully separate the components to obtain the “true” answer. The reason that this time the MLR is able to separate the two components is because the anthropogenic warming and the AMO have different time scales, as they should in the real case.
Some details of how we came up with the hypothetical anthropogenic warming follow. As did DS, we tried to be consistent with observation. We start with the HadCRUT4 surface temperature data. We fit it with a 6th order polynomial over the entire period of 1850-2011, instead of just over the period 1979-2011 as DS did. This produces the observed 0.17 C per decade of warming after 1979, the same as in DS. But in contrast, the warming here exists over the entire period, not just after 1979. The polynomial is smoothed by a cubic spline so that the trend is monotonic before 1979. This anthropogenic component will be called human. It is denoted by the red curve in Figure a. To create the AMO the-above-obtained human is subtracted from HadRUT4 data. The difference is smoothed with a 50-90 year wavelet band pass filter. This is the AMO (note: not the AMO Index). This is called nature (denoted by the purple curve in Figure b) and is the counterpart to DS’s 70-year sinusoid.
The global data consists of these two components plus a random noise of standard deviation of 0.1. The AMO Index is created using the N. Atlantic temperature, linearly detrended. For the N. Atlantic temperature, we assume it is composed of an anthropogenic warming given by 0.8*human (since the observed long-term trend in the N. Atlantic is smaller than that in the global mean) and the natural component is 1.4*nature (since the AMO in the N. Atlantic is known to be larger than that in the global mean). The correlation coefficient between the global data and the N. Atlantic data in this synthetic example is 0.74+/-0.06, very close to the observed correlation of 0.79. There is in addition a random noise in the N. Atlantic with standard deviation of 0.15. The synthetic global variance is 0.071+/-0.008 and the synthetic N. Atlantic variance is 0.066+/-0.011, very close to the real variances of 0.07 and 0.05, respectively.
In conclusion, it has been surprisingly difficult to come up with a synthetic data where the MLR method fails to yield the right answer most of the time. The latest example by DS comes closest, but has an unrealistic deficiency. In all the cases considered, none has failed both of our methods, the MLR and the wavelet method. These debates have served the purpose of strengthening our confidence in using these methods, and in the technical correctness of the results that we obtained in our PNAS paper using the two methods, although we should always be on guard for the possible failures of any method we use. It should be pointed out however that none of these technical discussions concerns the larger picture: whether the AMO is forced or natural.
I hope with this summary we can conclude the technical discussion on the MLR procedure, and can now move on to the other threads, such as the “thermodynamic argument”, which supposedly sets an upper limit on how large natural internal variability can be.
Moderator Response:[RH] Fixed image width.
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