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Al Rodger
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Sam, As a check on your calculations, you may find this CDIAC webpage useful. It is updated with 2015 GHG concentrations & the various GHGs listed total to 527ppm CO2(eq). I should repeat that CO2(eq) values are a poor substitute for more detailed modelling of the consequences of our GHG emissions.
Toggle Commented Nov 20, 2016 on PIOMAS November 2016 at Arctic Sea Ice
Sam, The mechanisms being described as "slow feedbacks" by Hansen et al (2013) are the result of changes in albedo & GHGs, both resulting from melting of the chryosphere & vagitation change. As the name says, they are slow and they are feedbacks and will precipitate their own fast feedbacks (when/if they were to occur). Hansen et al (2013) cites papers suggesting the present level of global temperatures give a 30%-50% increase on warming due to slow feedbacks. This increases to 100% if warming moves to an ice-free world as per 35 million years ago. I interpret the message being given as saying that we are prodding a beast that can be very dangerous and that we do not entirely understand. Our continued CO2 emissions are an extreme folly. Were this not Neven's Arcic blog, I would spend a little more time considering the content of this comment but I feel we are now addressing quite broad subject-matter that is not cryospherical in nature.
Toggle Commented Nov 20, 2016 on PIOMAS November 2016 at Arctic Sea Ice
Wayne Kernochan, Just sticking with the CO2 growth.... Of course, time will tell what levels of CO2 growth will drop to soon enough. However, a view that CO2 growth will remain a 3.5ppm.pa until March 2017 is a long way from my own assement. Do note that the 0.93ppm/yr figure given by NOAA MLO data for 1999 is the CO2 growth over the year (Ave.CO2 Nov99-Feb00 minus Ave.CO2 Nove98-Feb99) and so strongly impacted by the La Nina conditions that had appeared immediately afrer the 1997/98 El Nino. (This time round, the La Nina is not anything like as strong, but a short and weak La Nina that will be replaced by neutral conditions by early next year.) The weekly data provided by NOAA shows annual CO2 growth remained above 2ppm.pa until week 20 of 1999. I do recomment using the weekly data to those assessing CO2 growth.
Toggle Commented Nov 20, 2016 on PIOMAS November 2016 at Arctic Sea Ice
Wayne Kernochan, Concerning your second comment. I am surprised by what you say. I too follow MLO CO2. The one exemplar we have for a strong El Nino affecting CO2 levels is the 1997/98 event. The weekly data if smoothed by say averaging over a 5-week period show clearly that the increase in CO2 levels over the 1997/98 El Nino peaked in early October 1998 and dropped down from that peak level over the following nine months or so. The decline is not smooth but bumpy. This 2015/26 El Nino saw CO2 rises peak in June, earlier than in 1998. The peak was a higher level (roughly +0.3ppm). We perhaps should expect a slighly larger margin with emissions being in excess of 2Gt(C)pa higher than in 1998 & an atmospheric fraction of 0.4. The rise in annual CO2 levels is now reducing bumpily, down from June's 4.0ppm.pa to 3.3ppm.pa in October. Give it time. Let the bumps come and go. By mid-2017 we will see a more representative rate of increase. And concerning your third comment, the concept CO2(eq) is really designed to allow decision-making within climate change mitigation, allowing the effort to reduce one GHG to be gauged against the effort to reduce another. Do not use CO2(eq) to calculate resulting global temperature rises, certainly not in the manner you (& Sam) describe. The pre-industrial levels of non-CO2 GHGs would be solely used to calculate the forcing these non-CO2 GHGs add, forcings which allow a straighforward calculation of the resulting warming. CO2(eq) is the CO2 level that would cause such a forcing. The pre-industrial CO2(eq) is simply not part of the calculation.
Toggle Commented Nov 20, 2016 on PIOMAS November 2016 at Arctic Sea Ice
Jeff Lemieux, I think you would describe Margaret Davidson as a technical/scientific civil servant rather than a scientist and her un-referenced statement is not well made. I'm sure that if there were some "OMG" field data out of West Antarctica, even preliminary data, it would not remain secret in the manner described. So I would suggest that Davidson is referring to something in plain sight. Perhaps she refewrs to Hanson et al (2016). That paper is based on a certain level of evidence but is more a discussion document rather than a focused piece of science. It does point to "West Antarctica and Wilkes Basin in East Antarctica (having) potential to cause rapid sea level rise" which sort of fits the bill although the paper does not provide the "roughly 3 meters by 2050-2060".
Toggle Commented Apr 15, 2016 on Greenland under early pressure too at Arctic Sea Ice
A final cautionary tale on the PIOMAS postings. In the past I (& others) have encountered at the NASA sites what I shall call "sticky caching." That is, you link to a web page and it shows you what it looked like last time you linked to it - updates since then do not register. I now hit 'refresh' when I'm expecting NASA updates & they haven't appeared (although I think the problem is passed at NASA). The relevance to PIOMAS is that I have just encountered "sticky caching" on the official PIOMAS page and that monthly page - the March update that I knew should have been there only appeared when I hit 'refresh'.
Toggle Commented Apr 5, 2016 on Winter analysis addendum at Arctic Sea Ice
Apologies, one and all. Neven saying it looked like the value for March 1st jogged my poor fuddled brain, and memories returned of an extraneous value appearing last month on that monthly page at the same time as February was posted. I commented at the time. It is that same number. Sorry for the false alarm.
Toggle Commented Apr 4, 2016 on Winter analysis addendum at Arctic Sea Ice
I know no more of the provenance of the monthly volume page I link to above. I only happened upon it a few months back. The numbers have in the past matched the daily data pointed to by the official PIOMAS page. Whether the monthly posting starts life as the final total or starts life as a provisional value, I know not? That the posted value isn't so far from any expected value wouldn't help in answering that. GWPF? Gentlemen Who Prefer Fantasy!! The quote from NSIDC's Ted Scambos that the 'gentlemen' leave off their version of the blog is “The Arctic is in crisis. Year by year, it’s slipping into a new state, and it’s hard to see how that won’t have an effect on weather throughout the Northern Hemisphere” Homewood, their blogger, calls this "no longer a case of science" which is probably correct. Once the science is settled, the scientific findings can be freely adopted beyond science. That Homewood chooses to use anomaly time-series to cloak the "'slippage' into that new state" simply demonstrates he is an untrustworthy source of information. So he and the 'gentlemen' are probably well made for each other.
Toggle Commented Apr 4, 2016 on Winter analysis addendum at Arctic Sea Ice
The PIOMAS monthly volume page is showing March's volume at 20.621k - 770 cu km below the previous lowest (2011). With that, it did occur to me that with the unprecedented Arctic temperatures for the first part of 2016, the PIOMAS model will be pushing into new territory. Interesting times for model-based data.
Toggle Commented Apr 4, 2016 on Winter analysis addendum at Arctic Sea Ice
Bill Fothergill, 170 Zj to melt 5.09 x 10^17Kg ice? I find the bottom paragraph on the PIOMAS page is a good memory jogger if I ever forget the ~3,000 Gt(ice)/Zj. (They actually say 16,400 cu km requires "about" 5 Zj.) Working that through, it works out on the nail at 5.1 x 10^17 kg ice. You have to say, it's a mighty fine web page, that PIOMAS one is!!
Toggle Commented Mar 29, 2016 on 2015/2016 Winter analysis at Arctic Sea Ice
Colorado Bob, Northern snow cover is the Cinderella of the Arctic AGW. We are already experiencing spring & summer anomalies that were projected by the IPCC to happen decades into the future. This dramatic snow loss sits alongside a smaller increase in the (far far more variable) snow cover over the autumn & winter. Mind, we are this year seeing large negative winter anomalies although these are not unprecedented (even in recent years). With the large temperature anomalies presently over NH land, these negative winter anomalies may (and this could all disappear under a change in the weather in coming weeks) stick around into April (but no signs of them going so far) and that may give the spring snow cover a run at a stonkingly-big new record. My snow graphs are numbers on Vc and Vd on this site. (I'm conscious that I'm plotting decadal values with annual values on Vd which is a bit wrong given the winter wobbles. I'm thinking of adding my annual graph to rectify that.) (I should perhaps also add given comment up-thread that in my view NH snow cover and global temperature both are no more scary than they were last year, or the year before.)
Toggle Commented Mar 15, 2016 on PIOMAS March 2016 at Arctic Sea Ice
Looking at the PIOMAS year-on-year graph, the 20,621k sq km figure posted on the monthly data page is almost certainly the last-day-of-February figure (which scales to 20,613k) posted by mistake. Jim, thanks for that. Pressing SEND worked. I do wonder if my problem was that when I first encountered that page it wasn't up & running properly. This was a long time ago now, but having tried repeatedly submitting my e-mail, name, shoe size, etc & pressing SEND I never once got a link come up. So I haven't bothered pressing SEND since, not until just now.
Toggle Commented Mar 9, 2016 on PIOMAS February 2016 at Arctic Sea Ice
I've not been monitoring it so I don't know how long PIOMAS has been showing February's value - possibly not long. What I find mystifying is the monthly data has been updated to March. And more, it is giving a March figure 800k below the March record set in 2011. (As I lost the link to the daily data which doesn't appear for me on the PIOMAS site, I can't see what has happened there.)
Toggle Commented Mar 9, 2016 on PIOMAS February 2016 at Arctic Sea Ice
With 2016 a pip away from the 2006 global SIA record, we are later in the year than the minimums of 2006 & 2011. Perhaps more telling, the Arctic SIA sits at the lowest level for time of year and there will need to be +800,000sq km added to SIA to prevent 2016 snatching 2011's lowest Arctic winter SIA record.
Tor Bejnar, You whetted my appetite so I went looking. I soon was finding talk (eg "How the Isthmus of Panama Put Ice in the Arctic" by Haug & Keigwin) that the Panama gap had closed as a significant feature on the climate by 4.2 million years ago but it required something else to kick the Arctic into proper icy conditions a million years later. The orbital obliquity which is one of the theories mentioned as a trigger(or the lack of orbital obliquity stopping the trigger 4.6-3.1My) is plotted in this earlier Haug & Tiedemann & paper.
Toggle Commented Apr 13, 2015 on The Ns are calling the maximum at Arctic Sea Ice
Tor Bejnar, Timing-wise, the appearance of the Panama Isthmus in terms of shutting off ocean currents can be different to the isolation of Pacific from Atlantic eco-systems. In terms of climate, Drakes Passage between Antarctica & S. America wasn't simply open or shut. And it too may have played a part in mid-ploicene climate change. It had been open for some millions of years but was still widening in the mid-pliocene, having suffered a bit of a squeeze in the early Miocene (c25-15my), according to Lagabrielle et al (2009). For ocean currents, it seems size matters.
Toggle Commented Apr 12, 2015 on The Ns are calling the maximum at Arctic Sea Ice
Bill Fothergill, Paul Whitehouse, David Whitehouse? Thank you for correcting my mistake. Names is not my strong point. Chris Reynolds, Regarding wobbles, I think we look in different places. I have been conscious that the annual cycle and trends in that annual cycle can create wobbles with some forms of analysis. So the daily anomaly trace shows wobbles because the summer melt is recently far bigger than the average over the anomaly base period. One approach is to consider different times of the year in isolation, as you have done. Another is to average over a full 12 months, as I have done. One use of rolling 12-month averages was to divide the record into four, carry out a linear regression and subtract the trend (so any change in long-term slope is addresses), then quantify the wobbles by calculating the standard deviation. The results were (from memory, units?) 1.2, 1.5, 0.9, 1.8. Another use of rolling 12-month averages was to calculate the SD for short periods (24-month) as a way of addressing changes in long-term trend. The graphical result is posted here. Again it shows recent times more wobbly but not that greatly so. If you iron out the wobbles to give, say, a set of decadal values (actually 8-year values, ave SD, M sq km) they are 1980-88 0.093, 1989-96 0.119, 1997-2004 0.076, 2005-13 0.140.
Toggle Commented Apr 8, 2015 on PIOMAS April 2015 at Arctic Sea Ice
Chris Reynolds, Yes. You are right to say significant wobbles are present before 2006. Post 2006 they are bigger but a quick comparison of the various parts of the NSIDC SIE data does show the post-2006 wobbles aren't so much bigger. As for the GWPF, you ask whether GWPF are stupid or mendacious. In the past I analysed of some of their work and I can assure you that it is not either/or - they are both (or their denial is so intrenched that they are driven to lying. I think that may be why GWPF stands for Gentlemen Who Prefer Fantasy.) The 'author' of the piece in question here, Paul Whitehouse, is a very low calibre actor in their pantomime although he is one of their alleged 'Academic Advisory Council'. (I say 'alleged' as I doubt they are any of these things.) Whitehouse attempts to brand the decline in Arctic sea ice as not anthropogenic and either not of any consequence or not happening, standard denialist ploys. The decline began "even before human effects were strong" and "decline between 1979 and about the mid-1990s is not that significant" And all this is probably still brought to you courtesy of the UK tax payer who support through tax relief the work of this supposed "educaional charity". (GWPF have retrenched from being entirely a charity but the lying and disinformation is published by a wholly-charity-owned organisation., This still bringing the UK Charities Commission and all other UK charitues into serious disrepute.) Perhaps I should have said somewhere- "Don't get me started"
Toggle Commented Apr 7, 2015 on PIOMAS April 2015 at Arctic Sea Ice
Chris Reynolds, I don't think it is so difficult to argue that the average annual Arctic SIE has not been slipping every downwards since 2006. The annual average (two clicks down here) has actually grown more wobbles in that period as the individual big summer melts appear and disappear from the annual average. Yet, to start using such a measure to argue for a stable Arctic would be a bit of a hostage to fortune. If summers did turn seriously less icy, this may not feed much onto the annual average, and the agent spreading such a message that "All is well with Arctic ice - look at the annual average!" could easily find himself well-&-truly stuck on the I'm-a-total-idiot step.
Toggle Commented Apr 6, 2015 on PIOMAS April 2015 at Arctic Sea Ice
Hey! The PIOMAS traces for 2015, 2014 & 2009 resemble railway tracks with the points being switched in mid-February:-) The 2014-2015 comparison of thicknesses across the Arctic, isn't the important factor that the thin bits will more easily melt out and increase feedbacks? Sticking all your ice in one place may protect the ice, but it will result in a warmer Arctic summer.
Toggle Commented Apr 5, 2015 on PIOMAS April 2015 at Arctic Sea Ice
So why did 2015 have a February icier than March, the first since the 1990s, when the trend has been for the maximum to be later and later? It's more like a big bite was taken out of the maximum (leaving February less bitten than March) rather than the maximum being early per se. Looking at the UH plots on the regional graphs page shows the Pacific gave the low ice levels for the season but the big bite was mainly the Barentz which peaked at the start of Feb before dropping 400k from then to mid-March before regaining half of the drop so as to provide a late March sub-maximum. The Bering had a smaller shorter bite but the big influence was the Barentz. So what was going in in the Barentz? A random wobble? Or something new for the future?
Toggle Commented Mar 30, 2015 on The Ns are calling the maximum at Arctic Sea Ice
WIth the Barentz still showing +30k a day, if that continues with a bit of coincidental stalling/upticking elsewhere, there could yet be a final icy flourish.
Toggle Commented Mar 28, 2015 on The Ns are calling the maximum at Arctic Sea Ice
DavidR. Interestingly, you are right about 2010. Yet when I stuck my ten pen'orth in back on March 15th, the path of the rise to the 2010 maximum from that date was not enough to exceed this year's February maximum in 2015. What has happened is that 2010 dropped between March 15th & 25th increasing the eventual late rise of that year while 2015 has risen between March 15th & 25th, reducing the required rise to top the February maximum. Yet the significance of this year's maximum means nothing of itself. It is as part of a trend that it is significant. And indeed contrarians do love pointing out errors made by those they oppose. What is perhaps exceeding strange is that while such denialist folk do their best to stoke up minor muddles to look like major scientific blunders, they are wholly oblivious to their own record of continual egregious error.
Toggle Commented Mar 26, 2015 on The Ns are calling the maximum at Arctic Sea Ice
Anybody seriously making comment and calling a maximum SIE for the year - I don't think their call really should be accused of being "speculation". Now, I think there is a big difference between somebody like the Ns calling the maximum for the year and somebody like me. When I called it a couple of weeks back I gave my reasoning and for folks like us making such a call, that reasoning will usually have one central dominating reason. How prescient or foolhardy the call can be judged by others, and that holds whatever the outcome. Next year, for instance, my reasoning could be shown to be foolish even though I was right this year. The analysis of the Ns will be a lot more complex, probably having to satisfy a series of seperate analyses before the decision to call is made.
Toggle Commented Mar 26, 2015 on The Ns are calling the maximum at Arctic Sea Ice
g man. (1) DMI use O&SISAF data. (2) O&SISAF do not document on-line why they include lake ice but their code includes it and their graphics of "sea ice" show the Great Lakes and Lagoda with winter ice concentrations. It also shows a far coarser coverage at ocean shorelines. (3) Smaller lakes are not shown to be included, probably because the mapping resolution is too coarse.
Toggle Commented Mar 24, 2015 on Early record, late record at Arctic Sea Ice