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Comments 33501 to 33550:

33501. michael sweet at 00:45 AM on 27 October 2014
       Renewables can't provide baseload power
       

       Tristan,

       Weather forcasts of wind are usually very accurate the day before on an hourly basis so generation by wind is not really variable hourly, it is forecast.  Peaking plants (usually gas in the USA) adjust for small changes so no wind is wasted.  If wind goes down a little the peaking plant generates more, if wind goes up the peaking plant generates more.  This is the same as for current coal and nuclear plants.  With coal the generation is fixed.  As demand rises during the day, peaking plants come online.  With wind the currently existing peaking plants also cover changes in generation.  Coal and nuclear also require spinning backup in case the whole power plant goes out.  Wind generally does not need this backup, although it needs backup if the transmission line goes out.

33502. Tristan at 00:02 AM on 27 October 2014
       Renewables can't provide baseload power
       

       Found some good info here: http://masg.org.au/wp-content/uploads/2008/06/Wind-Energy-In-NSW-Myths-and-Facts.pdf

       In Australia:

       "These short-term variations in demand and supply are balanced every five minutes within the spot market. "

       which leads to

       "Under all but extraordinary circumstances, every unit of wind
       power sent into the electricity grid will reduce greenhouse gas
       emissions to meet any given level of market demand"

33503. Tristan at 23:41 PM on 26 October 2014
       Renewables can't provide baseload power
       

       scaddenp.

       Picking on wind because I'm interested in the details of how intermittent power generators have been integrated into the grid. If the wind picks up and there is more generation than expected, coal plants don't automatically shut off in response. The excess wind power is stored with some loss or wasted (that's not a feature of wind alone).

33504. michael sweet at 20:23 PM on 26 October 2014
       Renewables can't provide baseload power
       

        Tristan,

       I believe that 1 kWh of wind power replaces more than 2 kWh of coal energy.  When they burn the coal they are only about 40% efficient in converting heat to electricity.  60% of the energy is wasted.  They only count the energy that is useful in their generating statistics.  They do not count the energy that they wasted from the coal. The wasted energy is realeased into the environment as heat pollutiion.   On the other hand, 100% of the energy the wind generator makes is useful.  (A small amount of energy in both cases is lost in transmission).

       Some coal palnts in Germany are shutting down due to competition from renewables.  It is hard to tell if for one kWh of wind the energy source would have been coal, gas or oil, but it would have certainly been fossil fuel.  This post discusses that when Nuclear was shut down (in England) it was replaced with coal.  It stands to reason that when they have more wind forcast they throttle back the coal.

33505. michael sweet at 19:47 PM on 26 October 2014
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       Rett,

       The data in figure 2 is a 12 month average, not the maximun.  The Antarctic sea ice maximun (this year) was just over20 million km2.  Sea ice was only that high for about one week.  Sea ice has dropped to about 18 million km2.  The yearly average is lower than the maximum is.  The graph is also from last year so it does not include the most recent data.

       The yearly average is more informative than the maximum because it tells us about what is happeing the entire year.  A graph of all the data can be found here (the graph is area not extent so the maximun this year is 17 million km2.  The graph of the Antarctic is about half way down the page.)

33506. scaddenp at 19:39 PM on 26 October 2014
       Renewables can't provide baseload power
       

       Well I dont know why pick on wind in particular, but I would say, yes, every kWh of power from non-carbon source is kWh of coal power saved. I dont think you could ever precisely say that x wind turbines have been built to replace y coal plants. Perhaps you could explain more of the context of your question?

33507. Tristan at 17:04 PM on 26 October 2014
       Renewables can't provide baseload power
       

       Doesn't that assume that each kWh of wind power results in -1 kWh of coal power?

33508. Rett Smit at 16:54 PM on 26 October 2014
       Arctic sea ice loss is matched by Antarctic sea ice gain
       

       Is the scale on the Antarctic Sea Ice Extent graph in Figure 2 correct? I thought that Antarctic sea ice was up around the 20 million sq km mark. Thanks.

33509. grindupBaker at 15:26 PM on 26 October 2014
       What's the role of the deep ocean in global warming? Climate contrarians get this wrong
       

       Smith@2 & Andy Skuce@5 NOAA has 4,267 metres average ocean depth and Woods Hole Oceonographic has 3,682 metres. I don't know why the huge range (Woods Hole inclusion / NOAA exclusion of some shallow seas maybe ?). If "average ocean depth" is based on its volume and the area covered at the surface including continental shelves then if it's 4,267 metres then above 700 m and above 2,000 m cannot possibly in any practical way be more than 16.4% and 46.9% respectively (they can be less). If it's 3,682 metres then above 700 m and above 2,000 m cannot possibly in any practical way be more than 19.0% and 54.3% respectively. I infer that the "20%" and possibly the "50%" appear to be approximations not within 1% of actual.

33510. scaddenp at 15:11 PM on 26 October 2014
       Renewables can't provide baseload power
       

       Should be straightforward. Use total wind generation hours from say IEA, and use conversion of 0.542Kg CO2 per kWh.

33511. Tom Curtis at 15:08 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny @19, it is easy for you to say.  You do not, however, do it.  Nor do you show examples from the copious literature on the determinants of CO2 concentration and rates of draw down that support your claim.  I have no inclination to treat the mere assertion of "random internet guy" as evidence, and you evidently have nothing better to offer.

33512. Tom Curtis at 15:05 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny @18, thankyou, but I prefer this version, from which:

       "Supplementary Fig. 4a depicts ΔDIC_org as a function of atmospheric pCO2, with the present day value (ΔDIC_org at 380 μatm) set to 1. Extrapolating the observed trend to pre-industrial CO₂ levels (pCO₂ = 280 μatm) yields a value of ~0.95; that is, for a given amount of inorganic nutrients, biological carbon consumption under pre-industrial conditions was about 95% of today's level. On the basis of this relationship, an increase in atmospheric CO2 from 280 μatm to 380 μatm (present day) corresponds to an excess carbon sequestration of 22 Pg (range 14-29 Pg) for the past 150 yr (Supplementary Fig. 4b). Without this negative feedback mechanism, atmospheric CO₂ would be approximately 11 μatm higher than its present value. By the end of this century, this process would sequester an additional 94 Pg C to the deep ocean, bringing total excess carbon sequestration to 116 Pg C (range 76-154 Pg C). This reduces the increase in atmospheric CO₂ by a total of 58 μatm at 2100."

       That is, by 2100, CO2 concentrations will rise to 700 ppmv rather than to 760 ppmv, with a total change of radiative forcing of 0.44 W/m^2, or a 0.2 C difference in temperature based on the transient climate response.

       Returning to your original claim, we see that the actual study on which you purport to rely does not back it up.  The study finds it very convievable that we will achieve and maintain high CO2 concentrations.  They have found an effect that may reduce the increase in CO2 concentration by a small amount (and hasten its decline over millenial time scales).

       I say "may" because their plots were essentially predator free, and the presence of planckton eaters may significantly reduce the effect.  Further, the algal blooms are significantly limited by the availability of nutrients so the generalization of the results to non-isolate plots and to non arctic waters must be considered tenuous.  Further, you assume also that there are no other effects currently not-known or poorly quantified that will balance out in the other direction.

33513. Tristan at 14:39 PM on 26 October 2014
       Renewables can't provide baseload power
       

       Are there any published estimates of how much cO2eq has been averted by wind turbines globally (or just in the EU or US)

33514. Tom Curtis at 14:21 PM on 26 October 2014
       What's the role of the deep ocean in global warming? Climate contrarians get this wrong
       

       grindupBaker @9, I am not sure I understand your point.  The slow down in warming in GMST has resulted in a trend about half of the expected, and hence an increase in temperature over the purported 15 years of the slowdown of 0.15 C.  By your estimates, that represents 1.8 Zettajoules.  That represents 1.2% of the approximately 150 Zettajoule rise in ocean heat content over the same time.  Note that there was also a 150 Zettajoule rise in ocean heat content in the 15 years prior to that when GMST rose as expected.  The point then, is that the difference in the rate if rise in GMST between the two periods is:

       1) A result of additional warming of the oceans; but that

       2) That additional warming is so small a component of the total warming as to be negligible.

       In short, they are saying the additional heat is going into the ocean, not that all of the increase in OHC is due to surface heat going into the ocean instead.

       Further, and with respect to the cold water, if the cold water at the surface cools the surface temperatures, then it must do so (at least in part) by being warmed by the surface.  More directly, the colder the surface water, the harder it is for heat to escape from that water given a warm atmosphere and hence more of the incoming heat is retained in the ocean.  Consequently, I do not see how your description differs from that which you are criticizing.

33515. Donny at 14:17 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       www.sciencedaily.com/releases/2007/11/071117121016.htm

       Tom.... this should help you understand the science that I am talking about. 

       Moderator Response:

       [PS] Much more useful thank you.

33516. Tom Curtis at 14:05 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny, I don't believe I insulted you.  I said you don't understand the relevant science, which clearly you do not.  I concluded from that that when you make assertions about what we do, or do not know about the science you are not basing those claims on an understanding of the science.

       Now, I would be delighted to be proven wrong on either point.  Clearly we cannot do it with regard to the vacuum comment which you now claim was figurative (apparently never having heard of the phrase "all else being equal").  So, you claim the CO2 content in the atmosphere is modelled by a predator/prey relationship.  The obvious questions then are:

       1)  Which (set of) equation(s) to model the predator/prey relationship do you use?

       2)  Over what period have you modelled the CO2 content of the atmosphere using the equations specified in response to (1)? 

       (3)  What emperical evidence did you use to test the validity of those equations in modelling the CO2 concentration of the atmosphere?

       Absent answers to the above, you alternative theory of CO2 concentration is not scientific.  It is neither modelled (ie, you don't have an actual theory, just a phrase which can be trotted out to pretend its a theory) nor tested.  Ergo, absent answers to the above, my conclusion that your claims about the uncertainty of the science of global warming are not based on understanding the science are in fact borne out.

33517. grindupBaker at 13:50 PM on 26 October 2014
       What's the role of the deep ocean in global warming? Climate contrarians get this wrong
       

       I disagree with the analytical logic of the statement in the posting "...with heat that might otherwise add to the atmosphere seemingly entering the ocean on a regular basis...". In this disagreement I'm assuming that the statement relates to GMST fluctutations being due to the oceans absorbing heat (else my disagreement might be void). It is not that heat enters the oceans which could reduce an increase in GMST, it is that colder deeper water must rise to the surface if warmer surface waters are being pushed downwards. It is this colder deeper water reaching the surface waters that restrains an increase in GMST to less than that naively expected from solar or atmosperic changes just as it is warmer water rising to the surface (such as, obviously, El Nino) that boosts an increase in GMST to more than that naively expected from solar or atmosperic changes. It is not that "heat that might otherwise add to the atmosphere" gets added instead to the oceans. Rather It is that the temperature of the oceans varies between -0.2 degrees and +5 degrees (apart from a trivial ~3% in the tropics and sub-tropics sitting on top in a tiny pool) but GMST is +14.6 degrees. To make this important point (this isn't semantics) another way,  it requires only 12 zettajoules to raise GMST by 1 full degree including land to a depth of 6m and ocean to a depth of 1m (which I'm arbitrarily considering the "surface") so it is not sensible to state or imply that 150 zettajoules of heat added to oceans the last 10 years (for example) was "instead of" GMST going up an additional 0.3 degrees or some such over that 10 years. It's quite simply additional cold water from that vast reservoir of coldness getting to the surface. Obviously, a corollary to that is that the additional cold water from depth getting to the surface will cause it to warm by SWR, increasing OHC.

33518. Donny at 13:44 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Rob.... I respect the way you discuss these issues. ... even though I know you disagree with my views on how things are likely to play out.

33519. Donny at 13:41 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Tom.... were you bullied as a child?   Grow up and stop insulting someone you don't know. I forgot Tom knows everything about every scientific field.   

       Tom.... when I used the term vacuum. ... I was implying that there were no other variables. .... not if it was done in an actual vacuum.  I'm sorry you were the only person to not understand that. 

       With regard to your deforestation rant.... thanks for allowing for co2 to be considered plant food as I am sure that is settled science.  Oceans my friend cover twice as much space as land and have huge potential to buffer available co2. 

       Moderator Response:

       [PS]Everyone, please abide by comments policy. Inflammatory remarks do not move a debate forward. Donny, people are trying fill gaps in your understanding. You could do everyone a favour by familiarizing yourself with the basic science - start with either a textbook or the IPCC report.

33520. Tom Curtis at 13:08 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny, @7:

       "The only thing that is settled is... that in a vacuum increasing CO2 will increase the temperature."

       Also @10:

       "I think it will become increasingly hard to maintain elevated co2 levels because of poorly understood biological mechanisms. When mice are plentiful owls flourish until the mouse population declines. I think the same thing will happen with co2. CO2 is a food of sorts."

       So, from these two examples we establish that Donny does not know the science he disputes.  Specifically, CO2 in an atmosphere warms the surface.  Adding the equivalent mass of CO2 to that in the Earth's atmosphere to the Moon in gaseous form would increase the Moon's surface temperature neglibibly.  Remember, ΔT = ΔA_Eff * Γ, where ΔT is the change in temperature, ΔA_Eff is the change in the effective altitude of radiation to space, and Γ is the lapse rate.  No atmosphere means no lapse rate.

       Further, change of CO2 concentration over time is not modellable as a predator/prey relationship.  Further, even allowing the facts that CO2 is plant food, and increased CO2 therefore results in increased growth of plants, deforestation has contributed <10% of total CO2 emissions and therefore a food model for eliminating CO2 requires forestation to the extent of >10 times the total deforestation from the industrial period to now (for which theres is simply not the habitat space); and further, plants certainly are food for insects and other animals so that a growth in plant biomass will result in a growth insect and herbivore biomass which will limit the capacity of simple biomass growth to remove emissions.  (From the last point we see that Donny does not even understand the science he mistakenly appeals to in order to believe that there is no problem.)

       If he does not understand the science, he is in no position to assess whether the evidence todate settles it with reasonable certainty.  His claim that it is not settled is, therefore, a faith claim.  He is required to believe it by his ideology, not by the evidence.  

33521. Rob Honeycutt at 13:07 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Not saying we understand everything. I'm saying we have 150 years of research on all the fundamental elements of this issue. We actually understand a great deal. It's highly unlikely that something is going to pop up to substantially alter our fundamental understand of man-made global warming.

       Understanding of ocean currents are not likely to change any fundamental conclusions. 

       Definitely the more we know, the more we understand what we can know. But I would have to reject that makes us clueless. Understanding more does not means what we've already come to know is of less value. The big issues are well understood. That is settled science. The nuances are what are fascinating to learn.

       For instance, at the turn of the 20th century Arrhenius made the earliest calculations for climate sensitivity. Those estimates have been shown over time to be fairly good. We are highly unlikely to suddenly discover sensitivity is below 1.5C or higher than 5C. 

       Improving our understanding of central climate sensitivity estimates from, say, 2.8C to 2.9C doesn't mean Arrhenius' estimates were clueless. It was his work that put us on the path to our current understanding.

33522. Donny at 12:50 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Whether it's hundreds or thousands of approaches they all have the same problem of lack of enough time in the game.   They are all rookies.  

       You make it sound like we understand everything but we just haven't sorted out the details. ... in reality we don't understand much.   We think the ocean currents are a major player. ... but are basically clueless when it comes to understanding them.  And that's just the tip of the iceberg.   Sometimes the more you learn the more you realize how clueless you really are. 

       Moderator Response:

       [PS] This is empty rhetoric. Not knowing 100% is not the same as knowing nothing. Unless you have something other rhetoric to offer, with data/papers to back your claims, then I would suggest this discussion is over. Either discuss the science or find some other blog for your entertainment.

33523. Rob Honeycutt at 12:33 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny...  But you do understand, I hope, that the science on climate change approaches the theory from hundreds of different directions, and nearly all those approaches are in general agreement. Even if there is one new aspect that is interesting that pops up, it's unlikely to overturn the broader understanding of the science. It's merely going to reveal to us why things are the way we understand them to be.

33524. Donny at 12:28 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Rob... I think it will become increasingly hard to maintain elevated co2 levels because of poorly understood biological mechanisms.   When mice are plentiful owls flourish until the mouse population declines.  I think the same thing will happen with co2.  CO2 is a food of sorts. 

33525. Donny at 12:11 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Rob.... I understand what you are saying. ... but can't you see that there are biological mechanisms that very well could be "unchecking" our emissions as we speak.  And when I hear about the serious issues that warming is likely to cause. ... they don't seem overly scary.  These serious issues are also extremely weakly linked to warming.

33526. Rob Honeycutt at 12:03 PM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny...  So, are you saying you think there is potentially something out there that would completely alter our understanding regarding the human causation of global warming?

33527. Donny at 11:49 AM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Rob.... that would be true if everything else was a constant.... if nothing else changed.... it is pretty hard to isolate variables in nature. ... especially when studying the climate as so many systems are involved.  Geological systems,  biological systems, solar systems. The only thing that is settled is... that in a vacuum increasing CO2 will increase the temperature.   We however don't live in a vacuum.

33528. Rob Honeycutt at 11:25 AM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny...  When people say "settled science" they're referring to the fundamental principles. We understand that humans are warming the earth through emissions of greenhouse gases and that those emissions, unchecked, will likely cause serious issues in the future. That is settled science. 

       Science, though, is always pushing to better understand every aspect of the field of research.

33529. Donny at 11:10 AM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       I am not sure if you want to call the point rhetorical or not. ... but if you don't understand that the climate may not react the way we predict it will in response to increased CO2 because of factors like this that we are just discovering. .... then I don't know how else to discribe it to you.   Let me ask you ...if you think there are other key players in climate change that are still unknown or undiscovered?   Or was this the final piece of the puzzle? 

33530. Donny at 10:58 AM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Tom.  The point is.... the science is not yet settled or complete for that matter . .... hence newly discovered key climate change player.   

33531. Rob Honeycutt at 10:40 AM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny...  Think of it this way. You're assembling a puzzle. You have a large number of the pieces in place and they fit together well. You have a strong understanding of the overall image but not all the pieces are in place. You've been trying to fill in a certain area and then you come upon a key piece that explains one area of the image.

       The image didn't change, you just understand it much better.

33532. Tom Curtis at 10:11 AM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       Donny @1, can you explain exactly which physical law relevant to global warming has been refuted or ammended by this discovery in biology?  (Or are you just making an empty rhetorical point?)

33533. Donny at 09:25 AM on 26 October 2014
       2014 SkS Weekly News Roundup #43B
       

       How can a key player in climate change be recently discovered?   I thought the science was settled?   Except for all the aspects that aren't settled I guess.  Maybe it's a case of you don't know what you don't know. 

       Moderator Response:

       [PS] Please drop the rhetoric.

33534. Tom Curtis at 09:05 AM on 26 October 2014
       Models are unreliable
       

       Tom Dayton @778, your explanation is a good one except for the claim that "Using as your baseline an average of several consecutive years ... intersects the datasets and trend curves at the midpoint of that timespan".  That will only occur if the various datasets only differ in slope.  As the datasets also differ in the shape of the curves (due to differences in annual variation) they will not all intersect in the same year using a multi-year baseline, and different curves will likely intersect multiple times across the baseline period (and probably outside it as well).  The average difference across the baseline period (specifically the Root Mean Squared Difference) will be minimized.

       In reponse to BojanD, I would like to draw attention to two comments I made (in particular) in the discussion of the AR5 Fig 1.4.  First:

       "Use of a single year baseline means offsets can vary by 0.25 C over just a few years (CMIP3 comparison), while with the five year mean it can vary by 0.15 C (CMIP5 comparison). That is, choice of baselining interval with short baselines can make a difference equal to or greater than the projected decadal warming in the relative positions of observations to model ensemble. When you are only comparing trends or envelope over a decade or two, that is a large difference. It means the conclusion as to whether a model is falsified or not comes down largely to your choice of baseline, ie, a matter of convention."

        Note the range of potential offsets here were calculated specifically for the model temperature comparison.  For some data sets, with low annual variability choice of a single year baseline makes no practical difference.

       Second:

       "...On the contrary, a 1990 baseline makes the observations look warm. The emphasis on that point is so that my allies pick up on the fact. Intuitively, we would expect a 1990 baseline to cause the observations to look cool, for 1990 is a local high point in the observations. However, that is not the case, for though the observations are warm, the ensemble mean is warmer still relative to adjacent years. Thus, if anything, a 1990 baseline is favourable to a defence of the validity of models.

       But it is still wrong.

       It is wrong, basically, because you have to analyze the data as you motivated me to do to know whether it is favourable, unfavourable or neutral with regard to any position. The only way to avoid that necessity is to use a long (thirty year) baseline so that the baseline is robust with respect to time period used. Ideally, we should use the long baseline that minimizes the Root Mean Squared Error (RMSE) between the observation and the ensemble mean. By doing so, we ensure that any discrepancy between observations and ensemble are real, ie, are not artifacts of an ill chosen baseline."

       I will note the comments in the thread on IPCC AR5 Fig 1.4 are well worth reading in general (particularly those from SkS authors and regulars) for those who want to understand the issues relating to baselining better.

33535. Tom Dayton at 04:35 AM on 26 October 2014
       Models are unreliable
       

       BojanD:  An example of incorrect baselining by using the single year 1990 was an IPCC AR5 report preliminary draft's plot of model projections versus observations.  That error was pointed out by Tamino and  explained by Dana here on SkepticalScience.

       That particular error has a problem in addition to what I explained in my previous comment:  Each model curve is a different run of a model, with different parameters; think of each curve as being from an alternate Earth.  The mean curve of those curves inherently averages out the noise and so is representative of the population of all those curves--the Average Earth.  But there is only one observed dataset--only one of the many alternate Earths.  We can't create an average across all the alternate Earths' observed temperatures, because we've got only one Earth.  We have a really sparse sample of the population of alternate Earths' observed temperatures, that we are comparing to a much larger sample of the population of alternate Earths' modeled temperatures.

       We can't get more alternate Earths' observed temperatures.  But at least we can get a better estimate of the population of observed temperature at that year (1990) by averaging across the 30 years centered on 1990, and using that average as our baseline.

33536. Tom Dayton at 04:16 AM on 26 October 2014
       Another global warming contrarian paper found to be unrealistic and inaccurate
       

       BojanD, I replied to you on the Models Are Unreliable thread.

33537. Tom Dayton at 04:14 AM on 26 October 2014
       Models are unreliable
       

       BojanD asked on another thread:  "Since some of you know a thing or two about models, I would like to ask you a question that I just can't find an answer to. I'm looking for some credible explanation why 1990 is a baseline year to align model projections with measurements. Since misaligning them is one of the favorite contrarian tactics, I would like to have technical description why it is wrong. Thanks you!"

       (Somebody more knowledgeable than me--and there are lots of you--please correct any errors in my below explanation to BojanD.)

       BojanD, choosing any baseline does not change the slopes of the trend curves.  That's the first thing to note in a discussion of a fake skeptic's manipulation of baselines.  Up is still up.  Scary is still scary.

       Choosing a baseline affects only the position of the curve on the y (temperature) axis.  That is irrelevant if you are looking at only one curve.  It is relevant only if you are comparing trend curves, and even then only if those curves are not identical.  Real temperature data's trend curves never are identical, of course.  Computing all the data using the same, single, baseline year in effect moves all the data up and down the y axis to make all those datasets and therefore trend curves intersect at that baseline year.  Using as your baseline an average of several consecutive years does the same thing, but intersects the datasets and trend curves at the midpoint of that timespan.

       Choosing a baseline period has the effect of choosing the time period in which the curves intersect.  That has the effect of choosing which portions of the curves intersect.

       The differences among the trend curves are minimized at the midpoint of the baseline period.  The differences manifest most before and after that baseline period.

        

       Imagine trend curves Observed and Model both have positive slopes, but Observed's slope is shallower than Model's.  If you move the curves up and down the y axis (temperature) so they intersect at the far left of the x axis (years), then Observed will diverge below Model toward the right of the plot; Observed will be cooler than Model the closer to Now that you get.  If instead you make them intersect at the far right end of the x axis, Observed will diverge above Model toward the left of the plot; Observed will be warmer than Model in the past, but approach and then match Model at Now.

       How do you choose a fair timepoint at which the curves intersect?  That depends on the exact question you want to ask.  But almost regardless of the exact question you want to ask, it is inappropriate to choose any single year as the baseline period, because that year almost certainly will not be representative of the underlying, "true," population temperature even at that one-year moment in time.  If your single chosen year lies above or below the true population temperature at that year, then you will be making the trend curves' intersection unrepresentative of the population data.  You can't use even just a few years, because the true population temperature is obscured by short-term noise.  You really should baseline on the temperature averaged across 30 years or so.  That's why the definition of "climate" is based on 30 years.

       HotWhopper showed how Roy Spencer used a short and cherry-picked baseline period to produce his infamous plot of models over-projecting temperature in recent years, here and then with a different flavor here.

33538. Dikran Marsupial at 04:06 AM on 26 October 2014
       Another global warming contrarian paper found to be unrealistic and inaccurate
       

       BojanD it would help if you gave an example where a baseline of 1990 was used.

       A single year baseline is sometimes used for visualisation of warming rates, but it isn't something you would do to compare model output with observations, instead you would use a baseline period of say thirty years.  Different baseline periods are used for largely historical reasons, however if the results depend heavily on the exact baseline you have chosen, then the baseline period is likely to be too short (30 years ought to be about right).

33539. michael sweet at 03:31 AM on 26 October 2014
       Models are unreliable
       

       Tom,

       I agree "that there are some aspects of model performance which, if cherry picked, indicate they underestimate expected warming. Equally there are some other aspects of model performance which, if cherry picked, indicate they overestimate expected warming. "

       My comment was intended to illustrate the cherrypicking you mention for Shadow Dragon.  Perhaps Shadow Dragon will come back and clarify what they are interested in.  Hopefully their interest will be as even handed as your assessment is.

33540. BojanD at 01:05 AM on 26 October 2014
       Another global warming contrarian paper found to be unrealistic and inaccurate
       

       Since some of you know a thing or two about models, I would like to ask you a question that I just can't find an answer to. I'm looking for some credible explanation why 1990 is a baseline year to align model projections with measurements. Since misaligning them is one of the favorite contrarian tactics, I would like to have technical description why it is wrong. Thanks you!

33541. Miller, Bernd at 00:43 AM on 26 October 2014
       From Pole to Pole - a climate-themed tour through a zoo
       

       Glückwunsch! Ein gut ausgearbeiter Beitrag, der viele Fragen beantwortet. Weiter so.

       Moderator Response:

       [BW] Thanks for the comment! Here is the translation for non-German speakers: "Congratulation! A well-rounded article answering a lot of questions. Keep it up."

33542. wili at 22:56 PM on 25 October 2014
       2014 SkS Weekly News Roundup #43A
       

       Got it. I agree.

       I guess I had just read 'ISIS' as a kind of short hand for the whole mess that lead up to this particularly nasty recent turn of events.

33543. Tom Curtis at 22:32 PM on 25 October 2014
       2014 SkS Weekly News Roundup #43A
       

       wili @6, I am not denying the link from civil war in Syria, although there were a number of other exacerbating factors involved.  What I am denying is a link between the drought and the development of ISIS as a faction in that civil war, or its apparent success.  Drought will strain the civil capacity of a society, and if that society is already strained, may tip it over into civil disorder (including civil war).  It will not determine the form of the civil disorder, or how the different factions identify themselves or act, or how popular or successful they are.  Further, once a society has descended into a multifaction civil war with atrocities being committed by several (if not all) factions, the civil capacity of the society is prety much defunct in any event.  Drought can't tip the society into civil disorder because it is already well beyond that border.

33544. wili at 21:56 PM on 25 October 2014
       2014 SkS Weekly News Roundup #43A
       

       TC, it is of course devilishly hard to prove causation, but if you look at surface temperature and drought maps, Syria stands out as particularly hard hit, iirc. Of course, there are long standing oppressions and grievances in the area. But extreme heat and drought beyond historic norms would seem to be reasonable exacerbating factors at the least for why these long-term problems have been boiling over in the last few years there.

33545. Tom Curtis at 21:51 PM on 25 October 2014
       2014 SkS Weekly News Roundup #43A
       

       From Peru @3, I would not look to global warming for a proximate cause of the rise of ISIS.  There is sufficient explanation of that in the pre-existing chaotic political state in Syria and Iraq along with the partially sectarian nature of the conflict and a strong, extreme fundamentalist religious strand in Islam at the moment.  Once you have a vicious civil war in a country, famine is redundant as a cause of instability.

       Further, even if a study was done as to the impacts of global warming on the rise of ISIS, apart from the impacts in starting the initial civil war, there would be too many confounding factors to determine any influence.

       Having said that, there are still a number of middle east nations that have borderline stability currently, where a famine could in fact tip the balance.  Renewed famine in those nations would reasonably raise concerns about their ability to maintain the stability they have already.  

33546. Tom Curtis at 21:40 PM on 25 October 2014
       Models are unreliable
       

       michael sweet @775:

       "Many people thing that the models do not accurately include many positive feedbacks like arctic carbon or sea bed methane. This means they systematicly underestimate the expected warming and things are worse than we think."

       No!  That means that there are some aspects of model performance which, if cherry picked, indicate they underestimate expected warming.  Equally there are some other aspects of model performance which, if cherry picked, indicate they overestimate expected warming.  In practise they tend to balance out, with the best evidence suggesting they currently overestimate warming by 15%.  That evidence remains consistent with their actually underestimating warming (given uncertainties); but not (on a frequentist test) with their overestimateing warming by more than 100% (ie, we can be very confident of at least half of model ensemble mean predicted warming going forward).

       I will note that the models are underpredicting (by and large) slow feedbacks more than fast feedbacks.  On that basis I suspect the current 15% overestimate of warming figure is misleading in the long term, and that the actual future warming beyond several decades will be closer to the model mean or above it rather than below that 15%.

33547. wili at 21:19 PM on 25 October 2014
       2014 SkS Weekly News Roundup #43A
       

       FP, I don't know of any such studies. But one thing to watch going forward is Russian wheat production. Their ban on exports of wheat (after a bad winter harvest and then a devastating drought in '10) greatly exacerbated (at least) the already brutal conditions MENA countries, especially Egypt, which particularly dependent on Russian wheat. Conditions are already looking worse than back then for the prospects of the coming year's winter wheat.

33548. michael sweet at 20:49 PM on 25 October 2014
       Models are unreliable
       

       Shadow Dragon,

       It is good that you brought this up.  Many people thing that the models do not accurately include many positive feedbacks like arctic carbon or sea bed methane.  This means they systematicly underestimate the expected warming and things are worse than we think.

       One only has to look at sea level rise, one of the worst long term problems of AGW.  Sea level rise runs at the very top of the model results.   It is clear that future sea level rise is much more likely to run over the IPCCC projections than under them.

       Thank you for pointing out that the models are often too conservative.

33549. chriskoz at 20:07 PM on 25 October 2014
       From Pole to Pole - a climate-themed tour through a zoo
       

       I'm amazed by the wealth of interesting information about climate change impacts on selected fauna species not only herein but also in the links.

       I haven't seen such interesting and easy digestion of this subject anywhere yet, and that's the outstanding aspect of it. Thanks
       Baerbel.

       I havn't known for example that walrus is a species as much affected by the diminishing ice cover as flagship polar bears. Maybe media need to pay more attention to species such as walrus. Polar bears became such cliche, that many people deny their problem. But more evidence involving different species would convince more people that we have loss of biodiversity problem.

       I've learned about some species that were exotic to me, like Egyptian geese. Interesting to compare these geese with an American species that I know very well: Canadian geese. Here's an account from a hunter on the east coast. It apears Canadian geese also benefits from climate change, while people who depend on their migrations (like hunters/farmers) are distressed by the changes.

33550. Wol at 16:51 PM on 25 October 2014
       Scientists to Explain 'Climate at Your Doorstep' at New Online Hub
       

       A good idea, but one that could easily backfire.

       The denial industry is adept at picking the tiniest holes in an argument and exploiting it mercillesly, then moving seamlessly on to another hole.

       The arguments are so technical that simplified explanations are always going to have these holes to be picked on. I can see the denialists gaining support from this.

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