Recent Comments

Prev  2485  2486  2487  2488  2489  2490  2491  2492  2493  2494  2495  2496  2497  2498  2499  2500  Next

Comments 124601 to 124650:

124601. Charlie A at 10:05 AM on 8 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        I fail to see how the papers regarding clover grown in 700ppm CO2 relates to the UN assertion of 50% reduction in yield by 2020 in rain-fed agriculture in Africa. Chris Field, the current co-chair of IPCC WG2 fails to find any evidence to support those claims either. http://www.timesonline.co.uk/tol/news/environment/article7017907.ece
124602. Cliff Oates at 09:50 AM on 8 February 2010
        It's the sun
        The problem of correlating the earth's global temperatures with observed driving factors is complex at best. Our weather is dominated by the oceans. These comprise 70 percent of the globe surface and represent a tremendous heat sink which is circulating continuously. As such we would expect that observed temperatures would have an appreciable time lag behind the driving factors.I would expect the time lag to be more than two solar cycles. Any calculation of the earth’s thermal balance would have to include a deep understanding of the interaction of the solar radiation with the ocean areas. The past observations of long term global shifts (the medieval warming and the little ice age) would suggest that the sun’s variation has caused large temperature changes in the past. In examining sunspot average numbers with smoothing filters of 25 to 30 years shows a significant increase from 1920 to 1970. Could that be a cause of the global temperature increase? Sunspots not only affect the total radiant energy, but also the frequency distribution. Also since oceans comprise 70 percent of the globe surface, are land measurements a true indication of global temperatures? I believe that ascribing the global temperature increase to the effects of greenhouse gasses is a vastly simplified solution to a very complex problem.
        Response:

        You make some good points. Yes, there is a climate lag. An important point to realise is that the lag doesn't mean there's a gap between a forcing (eg - warming sun) and the climate response. Climate responds immediately to a forcing. The lag refers to the time it takes for the climate to reach equilibrium after an imposed forcing.
        
        For example, say the sun warms. As the sun warms, there is more energy coming into our planet than escaping back to space, so the planet starts accumulating heat and warms. Eventually the sun stops warming. At this point, there is still more energy coming in than radiating back to space so the planet continues to warm. As the planet warms, it radiates more energy out to space. Eventually the energy out increases to match the energy coming back in and the planet is in equilibrium again. The time it takes for the planet to reach equilibrium is the climate lag.
        
        Currently what is happening is the planet's energy imbalance is increasing. We are not approaching equilibrium which is what you would expect if we were responding to an earlier period of warming sun. Instead, something else is causing less energy to escape out to space. Satellites measuring the radiation escaping out to space find that the less energy is occuring at the wavelengths that carbon dioxide absorb energy. So at a time when CO2 levels are reaching the highest levels in over 15 million years, we're also observing less energy escaping to space at the very wavelengths that CO2 absorb infrared radiation.
        
        These topics have been covered in previous posts. There is a post that goes into more detail re climate lag. We peruse the many papers that examine the possibility that the sun is causing global warming. You make a good point about the importance of oceans - not only do they comprise most of the Earth's surface, they also absorb most of the infrared radiation that is trapped by greenhouse gases. Consequently, a better metric for global warming is the planet's total heat content which includes all the heat accumulating in the oceans.
        
        

124603. Marcus at 09:46 AM on 8 February 2010
        Could climate shifts be causing global warming?
        Here's the point, as I see it. 30 years of solar irradiance, volcanic activity & ocean circulation data all point to conditions which should have brought on a modest, long-term *cooling* of the planet, yet instead we experienced a period of the most rapid warming since temperature records were first taken. Also, from what little study I've done on these matters, most natural climate shifts usually take place over centuries (like the Medieval Warm Period & Little Ice Age, which both occurred over multi-century time frames), & yet here we are, today, with the largest magnitude & rate of change we've seen in all of human history. Yet still there are those who are desperate to blame *anything* but the burning of fossil fuels for this situation!
124604. Riccardo at 09:18 AM on 8 February 2010
        Lessons from the Monckton/Plimer debate
        acrim, it is untrue that "Frohlich and Lean used the proxy models to make umjustified alterations in the TSI data to agree with those models.". Or better, it is only partly true and for sure there are no "unjustified" alterations. But probably you do not bother to read how PMOD is constructed and you're repeating something read somewhere else, otherwise you could have been more specific on the use of the proxy model.
124605. acrim at 08:36 AM on 8 February 2010
        Lessons from the Monckton/Plimer debate
        @Jesús Rosino: The proxy evidence agrees with PMOD because Frohlich and Lean used the proxy models to make umjustified alterations in the TSI data to agree with those models. This simple fact is frequently glossed over in these discussions!
124606. acrim at 08:31 AM on 8 February 2010
        Lessons from the Monckton/Plimer debate
        @Jesús Rosino: The proxy evidence agrees with PMOD because Frohlich and Lean used the proxy models to make umjustified alterations in the TSI data to agree with those models. This simple fact is frequently glossed over in these discussions!
124607. Riccardo at 08:21 AM on 8 February 2010
        It's cooling
        Pat T, simplification is a quite risky game. Thinking of a monotonic warming when a monotonic forcing is applied is such a game. Look at the instrumental record and you'll see many periods of no warming and yet overall the temperature has increased. From 2002 to 2009 all the yearly averaged temperatures are within about 0.14 °C, i.e. +/- 0.07 °C. This is what the numbers say, undisputable. But this is only the begining of the story, not the end. Next step is understand what those numbers mean. To do this you have to look at how temperature behaves. You'll soon discover that there's an interannual varibility of about +/- 0.1 °C and that, in turn, in ten years you can not (statistically) assess a trend lower than about 0.2 °C/decade. Look at this graph (thanks to Tamino); temperature fluctuates between the lower and the upper bounds. You can (statistacally) say that temperature is still following the trend line until it goes out of the bounds. We are not there, not even close. This is as far as the numbers are concerned. Then comes the physics, explained by John in this post. Not the numbers nor the physics make us think it's cooling.
124608. CBDunkerson at 07:42 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadota, others have addressed most of your points as I would have, but there is one remaining I'd like to answer; "The point is, is that you can't infer that because internal variables are climate-sensitive, then 'imposed' forcings are." Please read my prior response again. This is not an inference. People are saying that climate sensitivity applies to both internal and external forcings because that is DEMONSTRABLY true. AIRS satellite data shows that over many years temperature shifts from many sources (El Nino, La Nina, volcanic dimming, GHG warming, et cetera) were consistently accompanied by shifts in atmospheric water vapor in line with climate models. The source of the warming is irrelevant to the climate sensitivity of the feedback effect. Ditto arctic sea ice albedo feedback. Ditto ocean CO2 absorption temperature feedback. Et cetera. In your own terminology, you are attempting to 'split' the 'effects of atmospheric heat from GHG forcing' from the 'effects of atmospheric heat from ocean heat transfer'... and that's just nonsense. Once the extra heat is in the atmosphere its effects are identical regardless of where it came from.
124609. Pat T at 07:22 AM on 8 February 2010
        It's cooling
        .....and GISS is Northern Hemisphere-biased. Either way, even the measures that put 2005 as the warmest put it at 0.01 deg C above 1998. I.e., about even. 1 year of natural variability offsetting 11 years of CO2 isn't "cherry picking one year." If it's "still warming" then the temperature should still be rising - rather than simply still warm relative to the recent past. The height analogy is a good one because the temperature has remained within a few tenths of a degree C below to, by some measures one hundredth of a degree above the 1998 mean. It's been flat. Perhaps it's been flat DESPITE natural forcings that ought to have pushed it down. So say that.
124610. Ned at 07:12 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadonta writes: "All of this does not mean it is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02." I'd like to second Doug Bostrom's surprise at your inclusion of this. Is the small absolute magnitude of the concentration of CO2 in the atmosphere somehow relevant? That factoid is a common staple of unscientific denialist propaganda ("CO2 is only a tiny fraction of the atmosphere, so how can it cause warming?"). It's a bit surprising and disappointing to see it popping up here. If you are seriously uncertain about whether a trace gas could be responsible for a large radiative forcing, please consider the case of halocarbons (e.g., CFCs) which have a substantial radiative forcing from concentrations that are measured in parts per trillion: http://www.esrl.noaa.gov/research/themes/forcing/
124611. Ned at 07:00 AM on 8 February 2010
        Could climate shifts be causing global warming?
        RSVP writes: "In figure 2, it looks like you could take the portion of the curve between 1910 and 1950, cut, paste and align to about 1970 and things would match up. So over a similar period, roughly the same temperature increase is seen, and yet we are talking about two periods in human history where in the second, the volume of CO2 far exceeds the first, ergo... " ... ergo, you have trouble reading graphs? Just kidding. 1910 to 1950 is a 40-year period, during which the dashed line goes up by about 0.20C and the quadratic line goes up by a bit less than that. 1970 to 2000 is a 30-year period, during which the dashed line goes up by about 0.25C and the quadratic line goes up by a bit less than that. (In fact, the dashed line stops before 2000, so the 0.25C rise is in less than 30 years). In other words, the recent warming was both greater and more rapid. I hope that helps. Enjoy the rest of the weekend...
124612. slincoln_wx at 06:29 AM on 8 February 2010
        Could climate shifts be causing global warming?
        "We know, from the past, that climate is sensitive to solar variation, orbital changes, oceanic circulation and continental configuration. It may be sensitive to various internal variables, which may also include climate shifts, as discussed in Swanson 2009. All of this does not mean it is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02. " You are right in saying that the reasons you listed dont necessarily mean that CO2 causes climate changes. But that's a strawman argument, as those arent the reasons that CO2 is known to cause climate changes in the first place.
124613. slincoln_wx at 06:27 AM on 8 February 2010
        Could climate shifts be causing global warming?
        Doesn't this article still beg the question - wouldn't there have to be something to cause the climate shift? So isn't it likely the other way around... is climate change causing climate shifts?
124614. Doug Bostrom at 05:50 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadonta at 05:03 AM on 8 February, 2010 "All of this does not mean [climate] is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02." Well, from that it looks as though you are rejecting what is known about thermal radiation physics, or at least how it applies to C02. If you hypothesize that thermal radiation physics are selectively wrong for the example of C02, you need to show how, don't you? Assuming you don't think our basic understanding of thermal radiation physics is incorrect and/or that our theoretical and empirical observations of what happens when C02 molecules are illuminated at various thermal wavelengths are incorrect, in order to dismiss C02's impact on climate you really need to explain how the climate could be insensitive to the outcome of C02's basic physical behaviors. Unless you're able to demonstrate how we have very fundamental misunderstandings about some very fundamental physics, you inevitably have to accept that net effect of C02 in the atmosphere is to retard the emission of thermal radiation from the top of the atmosphere at a staggeringly large power level. The numerical outcome of additional C02 in a single cm2 column of air reaching the top of the atmosphere may not seem impressive, but take the entire surface of the planet into consideration and it's a whole different ballgame. Knowing the behaviors of C02 with regard to thermal radiation, we can with a pleasingly high degree of confidence predict what will happen when the proportion of C02 in the atmosphere is changed. If C02 in the atmosphere is increased, it will more efficiently retard emission of thermal radiation at the top of the atmosphere. This is not controversial in the slightest. We have no indication that this top-of-atmosphere retardation of thermal emission by C02 is highly variable; unlike other effects having to so with ocean heat transport, solar variation, etc. it is a forcing that is constantly present. The amount of power involved here is beyond our intuitive numeracy to describe. Given sufficient time, there is really no conceivable way it will not affect the climate. If you say otherwise, you're not really credible unless you start at the beginning and show otherwise, in reasonable detail.
124615. padruig at 05:07 AM on 8 February 2010
        Could climate shifts be causing global warming?
        While Swanson et.al. is at the surface interesting, their hypothesis should be seen as a part of the modeling process and not a competing hypothesis to anthropogenic factors. Swanson wrote a guest article on RealClimate.org (Jul 2009) shortly after his GRL article publication in which he helps clarify the the contribution of his hypothesis to the greater area of study. "What do our results have to do with Global Warming, i.e., the century-scale response to greenhouse gas emissions? VERY LITTLE, contrary to claims that others have made on our behalf."
124616. RSVP at 05:06 AM on 8 February 2010
        Could climate shifts be causing global warming?
        In figure 2, it looks like you could take the portion of the curve between 1910 and 1950, cut, paste and align to about 1970 and things would match up. So over a similar period, roughly the same temperature increase is seen, and yet we are talking about two periods in human history where in the second, the volume of CO2 far exceeds the first, ergo...
124617. thingadonta at 05:03 AM on 8 February 2010
        Could climate shifts be causing global warming?
        re#5 The point is, is that you can't infer that because internal variables are climate-sensitive, then 'imposed' forcings are. This is a classic case of 'lumping'. 'Lumping' versus 'splitting' is a classic problem that plagues many disciplines , and I can see now it plagues climate science as well, and, as usual, the 'lumpers' don't even realise that they are making such (invalid) inferences, or probably even that they are 'lumpers'. (Most skeptics I would also suggest, tend to be 'splitters'). The discussion in Swanson 2009 that if internal variables are climate sensitive, then imposed forcings are climate sensitive, is an invalid inferance. John Cook sees no issue with this, so both he, and Swanson 2009, (and also probably the peers who reviewed the paper) are 'lumpers' as well (like most academics and public servants I have come across- ?a case of failure of peer review). To repeat: -automatically inferring that because internal climate variables may be climate sensitive, it means overall the climate is sensitive and/or all climate variables are sensitive, is an invalid inferance. Another example of invalid 'lumping' is eg: -inferring that because the climate has changed significantly in the past from other variables than c02(eg Medieval Warm Period), then climate must be also sensitive to C02-exactly the same case, as above, of invalid lumping. This is a completely invalid inferance. The climate can be sensitive to some internal and/or imposed variables, and not others. We know, from the past, that climate is sensitive to solar variation, orbital changes, oceanic circulation and continental configuration. It may be sensitive to various internal variables, which may also include climate shifts, as discussed in Swanson 2009. All of this does not mean it is sensitive to trace greenhouse gas changes (<0.1% by volume), such as c02.
124618. CBDunkerson at 02:26 AM on 8 February 2010
        Could climate shifts be causing global warming?
        Karl_from_Wylie, oceanic oscillations are neither newly discovered nor potentially more impactful on climate change than humans. If you read the article above carefully you will see that the issue at hand is whether they are responsible for the comparatively minor fluctuations observed around the ongoing long term human induced warming. Ranger, science has come a long way since the industrial revolution (let alone the middle ages). The fact that past generations could not determine the extent and cause of temperature changes in their time does not mean we cannot do so in ours. Measured variances in wavelengths of infrared radiation clearly show that the wavelengths associated with the CO2 greenhouse effect are responsible for recent warming. We're even making headway in figuring out the causes of those past climate shifts, but without direct observation (which would require a time machine) those are still in question. Also, CO2 from wildfires is insignificant compared to human industry... and the Sun plays an enormous (indeed the primary) role in determining the temperatures of the inner planets. However, the energy put out by the Sun isn't changing in any significant way. Indeed, it went down a minuscule amount while we experienced the steepest warming on record.
124619. Ranger at 01:55 AM on 8 February 2010
        Could climate shifts be causing global warming?
        What caused the warming when the Vikings settled England? What caused the Earth to cool again? What about co2 produced by uncontrolled wildfires for milliana? The earth will cool. The Sun has no effect on the Temps of the inner planets?
124620. CBDunkerson at 01:28 AM on 8 February 2010
        Could climate shifts be causing global warming?
        thingadonta, while some feedback effects may vary based on the type of forcing, most of the major factors would not. That is, regardless of whether the atmospheric temperature goes up due to CO2 accumulation, increased solar radiation, oceanic heat transfer, or a martian death beam slowly cooking the planet... we know that increased air temperatures will lead to increased atmospheric water vapor, and a significant positive temperature feedback effect from that. The ice albedo feedback is evidently more sensitive to shifts in northern insolation and water temperature, but even so if minor variations in ocean heat distribution were causing significant feedback in arctic sea ice coverage (supportive of high sensitivity for Tsonis and Swanson's results) then an overall increase in ocean heat would perforce show similarly high sensitivity. Ergo, the SOURCE of the forcing is often irrelevant to the imposed feedbacks and overall climate sensitivity. Heat is heat... where it came from doesn't change the effects it is going to have.
124621. Karl_from_Wylie at 01:19 AM on 8 February 2010
        Could climate shifts be causing global warming?
        A newly discovered cause of Climate change other than man and potentially more impactful? Wonder if there are other undiscovered causes of Climate change? And perhaps these causes could have more impact than man. Hmmm?
124622. thingadonta at 01:08 AM on 8 February 2010
        Could climate shifts be causing global warming?
        A quibble. "Another issue discussed in Swanson 2009 is that if climate is more sensitive to internal variability than currently thought, this would also mean climate is more sensitive to imposed forcings" I don't see how this statement is logically valid. Just because A is sensitive to variability, doesn't mean B is sensitive to variability. 'Variability', whether internal or imposed, must include, by definition, non-variability (ie a subset of variability). Or, in other words, climate can be less sensitive to imposed forcings, because logically, such an effect comes under the definition of 'variable'. It's much like the self-contradictory statement 'everything is possible', which is of course self-contradictory because it would also mean that the impossible is possible.
124623. Riccardo at 22:13 PM on 7 February 2010
        Could climate shifts be causing global warming?
        Good and timely post; i bet we'll need point people here a lot in the near future. Indeed, my impression is that this is one of the hardest point to grasp, (multi) decadal cyclical variability, or climate shifts. I noticed a lot of interest in the scientific community on this topic and Trenberth's words, so grossly misinterpreted, every so often come to my mind, it's a travesty that we can not yet account for this variability.
124624. CBDunkerson at 21:41 PM on 7 February 2010
        Could climate shifts be causing global warming?
        It seems likely that there is some truth to both the sulfate and oceanic heat balance theories. Each has a clear impact on temperatures, but we don't really have sufficient data to determine the magnitudes. We're talking about pre-1970s after all. There were no satellites to measure the sulfate aerosol levels in the atmosphere or the severity of a particular oceanic oscillation... instead we've got estimates. Ditto for the impacts of even earlier volcanic and solar activity. Take different estimates of these factors and you get different results on which has driven temperature shifts over the past century. The article notes that when the Arctic is included the current 'cool' phase is not very pronounced at all. If you look back it can be seen that this actually fits another pattern in the data. Assuming these climate shifts run for about 30 years we can see (as reflected in figure 1); to 1910: Steep cooling to 1940: Steep warming to 1970: Moderate cooling to 2000: Steep warming to 2010: Essentially flat The magnitude of the cooling phases is decreasing... which is consistent with a relatively fixed amplitude up and down oscillation overlaid with an accelerating warming trend. Basically, if Tsonis and Swanson's findings are correct then it looks as if we have reached a point where we no longer have alternating 'warming and cooling' climate shifts, but rather 'warming and flat'... and logically in the next iteration it would vary between 'warming and less warming'. This is why we sometimes hear suggestions that warming could be 'on hold' for another two decades... based on the assumption of this playing out as a 30 year 'flat' phase. Of course, even if Tsonis and Swanson are correct, positive feedbacks which have passed a certain threshold (e.g. Arctic sea ice) could shift the balance and result in resumed warming even during this 'cool' phase.
124625. David Horton at 20:23 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Ah, Charlie A. "By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%.". Mmmm, let's check out the logic of that statement shall we? I know you don't like to do the research yourself. OK "By 2020" - well that's ten years away. And since we know that agriculture in some countries (Australia is the one I am intimately equated with) is already under strain, and the forecast is for worsening conditions in the part of Australia (and therefore other similar countries, certainly in the southern hemisphere) that has the most agriculture, I suggest that 2020 as a date for big reductions in crops is not unreasonable. "Some countries" - see they are being very cautious here to avoid the "alarmist" stuff that the denierindustry loves to accuse them of. Just "some countries", not all, because circumstances will differ across Africa, "some countries". So what are you saying Charlie - you think NO African countries are going to have agriculture under threat in ten years? Hmmm, I have a house to mortgage if you want to bet your shirt on that. "Could be" - again, you see, cautious. I would say "will be" but then I've read a lot of literature and I'm living through the global warming of Australia on a farm. "Up to 50%" - enough caution already. But what do you think would be a fair figure Charlie - 10%, 20%, 30%, 40%? Well, I don't know, either, precisely, no one does, but those figures are all "up to 50%". You think none of them are right Charlie? "appears that there isn't any scientific backup for the rather dramatic conclusion" - you reckon Charlie? We've already seen that it isn't a "dramatic conclusion", in fact it's rather wimpy, really. But CSIRO and other agencies in Australia have undertaken studies here showing the real (and already developing) threats to agriculture in what was once one of the breadbaskets of the world. Threats so real that even our former prime minister, a notorious climate change denier, set in train 5 years ago an investigation to see whether Australian agriculture could be moved from the southern half of the continent, where it has flourished for 220 years, to the tropical north (it can't in any meaningful way). Southern Africa is in a similar geographical situation to Australia, and I'm betting science bodies there are making the same grim projections. My apologies for the lengthy response, I grow weary of this glib denialism ("So the 2020 date is probably messed up") that thinks nothing bad is going to happen, or indeed could happen, to this planet as a result of human activities. Try doing the literature search Charlie, it ain't that hard. Come back when you are ready to discuss things sensibly.
124626. Doug Bostrom at 18:02 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie A at 14:05 PM on 7 February, 2010 "I haven't done the literature search myself, but it appears that there isn't any scientific backup for the rather dramatic conclusion." Come now, you've shown you can do better that that! How "appears", if you've not looked the literature?
124627. angliss at 16:23 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        I don't know about the year being right, but the basic problem is quite real. Here's some papers about problems with food crops around the world The first one shows that the mean losses in protein content were 13.9%, 15.3%, 9.9%, and 9.8% for potatoes, barley, rice, and wheat respectively. That means that these four staple crops all got less nutritious as a result of higher CO2 concentrations (never mind drought) http://www3.interscience.wiley.com/journal/119416696/abstract The second paper shows that African staples cassava and sorghum didn’t technically become less nutritious and lose protein content, they did became poisonous as a result of higher CO2 and the crop yields plummeted – at less than double current CO2 concentrations, crop yield for cassava fell by 90%. http://www.biolsci.monash.edu.au/staff/gleadow/docs/gleadow-2009-cassava-online.pdf Another paper by the same group found that white clover, an important pasture food for domesticated animals, will become more poisonous at higher CO2 concentrations too. http://www.biolsci.monash.edu.au/staff/gleadow/docs/2009-clover-cg-co2.pdf And let's not forget that plants in general aren't going to grow as much as most current models expect, because there's not enough fixed nitrogen globally for plants to absorb even the percentage that GCMs are anticipating. Here's the original paper, followed by my blog about said paper http://www.agu.org/pubs/crossref/2009/2009GL041009.shtml http://www.scholarsandrogues.com/2010/02/02/climate-insufficient-nitrogen/ So the 2020 date is probably messed up. But the overall sentiment - that staple food crops will become scarce and/or less nutritious, leading to large parts of the world having food shortages - is right on.
124628. Charlie A at 14:05 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Carrot eater says " .... authors of WG2 ..... lazy". Not just the WG2. Here's the latest blooper, which appeared in the synthesis report, and has been quoted by the IPCC Chair and UN Secretary General Ban: http://www.timesonline.co.uk/tol/news/environment/article7017907.ece "By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%. Agricultural production, including access to food, in many African countries is projected to be severely compromised." I haven't done the literature search myself, but it appears that there isn't any scientific backup for the rather dramatic conclusion.
124629. carrot eater at 13:00 PM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Whoever the authors of WG2 were (the list doesn't have familiar names), some of them seem to have been rather lazy.
124630. Doug Bostrom at 12:48 PM on 7 February 2010
        There's no empirical evidence
        Ranger at 09:12 AM on 7 February, 2010 "So how can the nominal co2 emissions of industry cause the earth to warm when since fires have always been a part of the enviornment?" Because the rate at which we are extracting and liberating carbon stored over vast periods of time is as though thousands and thousands of years of wildfires are occurring concentrated in a space of a few decades. We're performing sort of a mini version of what happens with discontinuous natural burps of C02 in the past. The difference is, we're mindful, nature is not. More precisely, by looking for carbon isotope ratios in the C02 now in the atmosphere, we can actually identify which part is contributed by normal processes of the type you refer to versus which are being contributed by "sudden liberation" of the kind accompanied by fossil fuel combustion. The measured uptick in C02 turns out be from fossil fuels. One of the few things on which almost everyone is found in agreement!
124631. Charlie A at 11:54 AM on 7 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        The "physics" as you like to call it tells us that melting snow delivers the same amount of water to a river whether it melts on top of a glacier or on top of rock. The long term average outflow from a basin is simply the precipitation minus the evaporation/sublimation. Mass loss of glaciers adds fossil water, much like pumping or mining water from an underground aquifer. Ignoring the fossil water, the presence or absence of a glacier simply affects the timing of when the precipitation shows up as basin discharge. The critical period for most water users is the low flow period during winter. Winter river flow is mostly base flow, some from precipitation, and very little if any from snow and glacial melt. I figured that somebody must have done the more detailed calculations/modeling to see the effect of glacier disappearance. It turns out that there is a relatively comprehensive report that was funded by the UK Department for International Development, titled "An assessment of the impacts of deglaciation on the water resources of the Himalaya; by Gwynn Rees and David N. Collins, June 2004. aka "Sagarmatha report" http://www.nerc-wallingford.ac.uk/ih/www/research/SAGARMATHA/volume2.pdf They ran simulations of what might happen with global average increases in temperature of 3C/century, 6C/century, and 15C/century. Page 44 of the report (56 of pdf) reports: ==================================================== "Changes in decadal mean winter flows, observed at two selected sites, are similar to the mean flow behaviour. Winter flows of the Indus at Partab Bridge mostly peak between 5% and 10% higher than the baseline winter flow in the first decade and then reduce to around -13% of baseline by decade 10, according to both the +0.03 and +0.06 C/year incremental temperature scenarios (Figure 4.9). For the Modi Khola at Kusma (Figure 4.15), decadal mean winter flows increase gradually throughout the 100-year model run, to a maximum of over +10% versus the baseline winter flow by decade 10, according to the +0.06 C/year scenario. While the relative changes are less in winter, any variation in water availability during this traditionally dry period could have serious impacts for water users". ===============================================
124632. kepler at 11:36 AM on 7 February 2010
        How do we know CO2 is causing warming?
        ok, thanks for clarifying. i'm sorry for the confusion on the multiple articles and i apologize if my comments might be construed by others that you were 'making up' the graphs. that was not the purpose of my post. i was confused and wanted clarification. i know you didn't take it that way but just in case people come around and read this later, i wanted my intent clearly spelled out here. so if i understand you right, since 1997 was warmer and contained more water vapor, then that is why most of the IR showed increased emissions vs. 1970. if that is true, why? if the surface temperatures were warmer that just means that the black body radiation curve peak frequency shifts a little higher (and peak wavelength shift lower) but i would expect the magnitude or intensity to remain the same. and shifting that peak wavelength would mean moving further away from the 15um wavelength that CO2 absorbs. sorry if this is elementary stuff for you and if there is a site that explains this in more detail you can paste a link and i'll go do my homework.
124633. Ranger at 09:12 AM on 7 February 2010
        There's no empirical evidence
        I have a question. I live in West Texas where just a few generations ago fires used to burn up our whole world. Before the White Europeans stole the land from my ancestors the prairies were purified and cleansed of brush and trees by fires Native Peoples and lighting set. Millions of acers burned uncontrolled every time it turned off dry and especially after a wet year when we grew a lot of grass. Since hiways, roads, cultivated lands stop wildfires today not much of the prairies burn anymore. In fact the pasture land is not grass it is trees, cactus and brush. I still hear on the news of concern about co2 and other gasses wildfires emmitt into the sky. So how can the nominal co2 emissions of industry cause the earth to warm when since fires have always been a part of the enviornment? Ranger Texas
124634. kepler at 02:54 AM on 7 February 2010
        How do we know CO2 is causing warming?
        yes, it does appear that there are two papers by Harries relating to this same data set! thanks for clarifying. But my question i have goes for both. when you look at the raw data, the IR wavelengths that should be absorbed by CO2 (corresponding to the 700waves/cm) you'll see that 1997 had more emission of this IR frequency than 1970. when you look at the 'simulated' results then you see graphs like you display. why are the massaged, biased, simulated graphs of more value than the actual measurements? that is really my question - i'm sure there is a good reason but i'm not up to par with the authors here and had a hard time following the paper when they talked about adding in biases for SST and water vapor. agreed that temperatures and humidity for 1997 and 1970 (Apr-Jun) were probably very different but i don't see why we need to artificially bias the data to account for that. thanks in advance for your help!
        Response: These are good questions - when I first read the paper, I asked the author (John Harries) similar questions.The simulated graphs are not of more value than observed data - they are compared to observations to confirm the veracity of their simulations (successfully). Given that the simulated change in spectrum matches so closely with the observed data, this enables the authors to filter out temperature and humidity effects, thus displaying the exact effect due to trace-gases only.
        
        Note - the enhanced greenhouse effect is also confirmed by surface measurements of downward IR radiation. Independent confirmation from completely separate sets of observed data are always the ideal result.
124635. Riccardo at 01:40 AM on 7 February 2010
        Increasing CO2 has little to no effect
        matt sykes, #2 fig. 1 is a difference spectrum between 1976 and 1990. It shows only the changes during this period of time. If you want to compare the spectrum in fig. 3 (an emission spectrum), you need an absorption spectrum from space looking down. You can play with this using calculated spectra #3 there's much more energy in the visible than IR coming from the sun. It is this that warms the earth, not the IR. As far as CO2 absorption is concerned, it's not true that the IR around the 700 cm-1 band is much more than what the earth emits at the same wavelength. Integrating it over all the IR is wrong. Then the earth emits in the IR and this emission happens to peak around a CO2 absorption band; part of it is trapped producing warming. This is the very basics of the greenhouse effect. #4 The lifetime of the excited state is of the order of nano- to -micro- seconds depending on temperature and pressure. The extra energy can be released in two ways, by re-emission of a photon or by thermalization by collision (warming) of the surrounding air molecules; the re-emitted part will be absorbed again by other CO2 molecules and the process repeats itself until the pressure is so low that the photons have a high probability to escape to empty space. This is the way it works, again the basics of the greenhouse effect. If you increase CO2 concentration you slow down the process. You clearly still get cooling at night but not all of the energy absorbed during the day. It is not going to happen even if you do not increase CO2. A good example is the moon which, having no atmosphere, have enormous temperature gradients across the day/night line. I would more easily believe in your genuine interest had you not said "that logically there seem to be problems with the theory". Given that dozens of really smart people have worked on this for decades you'd better ask yourself "am i missing something?".
124636. ConcernedCitizen at 22:05 PM on 6 February 2010
        Increasing CO2 has little to no effect
        @Ricardo. Point #2. That doesnt answer my question. Graph 1 shows energy being absorbed by all the gasses mentioned. Graph 2 shows enery be emitted by only some of them. Thats my point. How is it selective so that only some of the gasses emmit energy back o the surface which is what the second graph implies? Point #3. Energy ballance. So an increase in CO2 will absorb, and re-emit to space more IR from the sun as well as absorb and re-emit to earth more IR from the earth. Since the sun produces more IR than the earth how does the extra CO2 cause warming and not cooling? Point #4. Excited state duration. If the duration is less than 12 hours then all the energy absorbed by CO2 during the day will be lost at night. How does this generate net warming over a period of days-years? I am not being argumentative, I am geneuinely interested in the science behind GH gasses, it is just that logically there seem to be problems with the theory. I am glad you mentioned excited state durtation by the way because I could not find any information on this online and to me it is a critical factor in heat storage.
124637. Doug Bostrom at 19:39 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        By the way, the little "gotcha" on the Kehrwald paper does not affect the actual significance of the work, which has to do with ice cores revealing a long term mass imbalance: "Ice cores drilled from glaciers around the world generally contain horizons with elevated levels of beta radioactivity including 36Cl and 3H associated with atmospheric thermonuclear bomb testing in the 1950s and 1960s. Ice cores collected in 2006 from Naimona’nyi Glacier in the Himalaya (Tibet) lack these distinctive marker horizons suggesting no net accumulation of mass (ice)since at least 1950. Naimona’nyi is the highest glacier (6050 masl) documented to be losing mass annually suggesting the possibility of similar mass loss on other high-elevation glaciers in low and mid-latitudes under a warmer Earth scenario. If climatic conditions dominating the mass balance of Naimona’nyi extend to other glaciers in the region, the implications for water resources could be serious as these glaciers feed the headwaters of the Indus, Ganges, and Brahmaputra Rivers that sustain one of the world’s most populous regions. As Charlie A so helpfully demonstrated by pointing out Thayyen and Gergan's paper, losing significant ice in the general region concerned will have significant hydrological impacts. So at the end of the day, the bloody WWF imbroglio once again affects nothing in actual physics, but this was sure an object lesson on how much irritation it must be causing in academic circles.
124638. Doug Bostrom at 19:17 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        thingadonta at 18:36 PM on 6 February, 2010 It all sounded so reasonable, sort of, until you got to this part: "I suspect, your comments about the CFC are also misguided. I suspect most of the rise /declne in ozone is probably natural, and unrelated to human activities. Academia is stuffed and stacked with people searching everywhere for human effects on natural systems- its the very reason for their academic existance, so they sometimes see human effects which are simply not there, and/ or natural (global warming). " A neat trick, sort of a deck of jokers. Any findings having to do with humans interacting with their environment with which you disagree, you can put down to lying academics, without a scintilla of actual evidence, data? How credible do you think that is?
124639. Doug Bostrom at 19:11 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie A at 17:14 PM on 6 February, 2010 "I said "The dry season corresponds to the winter, near zero melt season. The melt season occurs during the summer, which is also peak monsoon season." You say "For the Ganges, about 70% of flow is glacial meltwater during summer, for many other rivers serving the enormous concentration of population in the northern portion of India, between 50 and 60%. How about the other side, China? 23% of China's population receives most water from glacial melt during the dry season. * I'm glad to see that your references agree with me." They do? "In other words, glaciers don't do the sort of seasonal smoothing that is so important in some other areas of the world." Really, did you read Thayyee and Gergan? That's not what they say. "You will find the Barnett is confusing discharge from a glacial basin with glacial melt. In other words, he adds snowmelt to glacier melt." No, what you've failed to pick up is that much snow melt is derived from glaciers. Again, I think our lack of training here is a problem. Read Thayyee and Gergan, carefully. "Perhaps Kehrwald 2008 has an error ???? " Going straight back to the WWF, if you follow his cite. Ouch.
124640. lodolite at 19:04 PM on 6 February 2010
        Guest post in Guardian on microsite influences
        Thanks, I'll go do some reading. I have no science background at all so I find reading others comments often increases understanding of what I read. Other times I just get lost.
124641. Charlie A at 17:29 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        It is often difficult to determine whether a specific change is happening due to 1) the natural warming of coming out of an ice age 2) natural variability (google Hurst Phenomena for some interesting reading. Those hydrologists at work again) 3) global warming or climate change due to well mixed greenhouse gases such as CO2 and methane, 4) other anthropogenic causes. In the case of Himalayan Glaciers, it appears that CO2 is not the culprit. http://newscenter.lbl.gov/feature-stories/2010/02/03/black-carbon-himalayan-glaciers/ Full paper is at http://www.atmos-chem-phys-discuss.net/9/26593/2009/acpd-9-26593-2009.pdf for a change, it isn't behind a paywall.
124642. Charlie A at 17:14 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        I said "The dry season corresponds to the winter, near zero melt season. The melt season occurs during the summer, which is also peak monsoon season." You say "For the Ganges, about 70% of flow is glacial meltwater during summer, for many other rivers serving the enormous concentration of population in the northern portion of India, between 50 and 60%. How about the other side, China? 23% of China's population receives most water from glacial melt during the dry season. * I'm glad to see that your references agree with me. The peak melt coincides with the peak precipitation. When the monsoon is dumping lots of water on the region, the addition of a bit of glacial melt doesn't benefit the river users much, and might actually be counterproductive if it causes flooding. And the low flow periods are during the winter, when glacial melt is negligible. In other words, glaciers don't do the sort of seasonal smoothing that is so important in some other areas of the world. Rather than take Barnett 2005 as gospel, you should click on through to his references for the related statements ... his refs 40,41, and 43. All are papers where the lead author is Pratap Sing of the National Institute of Hydrology. You will find the Barnett is confusing discharge from a glacial basin with glacial melt. In other words, he adds snowmelt to glacier melt. Again, I suggest you look at figures 3 and 8 of http://www.the-cryosphere-discuss.net/3/443/2009/tcd-3-443-2009-print.pdf Note how during the dry season that glacial melt is an insignificant percentage of the flow. Or look at Table 1 which shows that glacier melt supplies approximately 9% of total annual flow of the Ganges. ----------------------------------------- Regarding the area of glaciers in TP, you can look at the joint report by United Nations Environment Programme (UNEP) and the World Glacier Monitoring Service (WGMS). See http://www.grid.unep.ch/glaciers/ and in particular section 6.9 Regional Glacier Changes, Central Asia. "Central Asia with an estimated total ice cover of 114 800 km2 has as its dominant mountain range 0the Himalaya, where most of the glaciers occur (33 050 km2). That is consistent with other estimates I've seen. And table 3.1 from http://www.grid.unep.ch/glaciers/pdfs/3.pdf shows global estimates of ALL glaciers excepting those in Greenland, Antartic and Artic as ranging from 510,000 sq km to 540,000 sq km. Now compare that estimate to Kehrwald 2008 which says that the measured area of Tibetan Plateau glaciers was 500,000 sq km in 1995. Perhaps Kehrwald 2008 has an error ????
124643. Doug Bostrom at 16:38 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie A at 13:13 PM on 6 February, 2010 And belatedly I see your distinction between snow melt and glacial melt, something I have somewhat personal experience with as here where I live we depend to some extent on snow melt. I find it astonishing that you dismiss the findings of researchers in this field with casual references to conflation and "alarmism". The Thayyee and Gergan paper is very interesting indeed. It looks at the IPCC roll up of the general contribution of glaciers to stream flow and points out that the Himalaya should be examined more closely in distinction from the IPCC's generalized conclusions. The paper hardly seems to dismiss the role of ice and snow as an important source of water for major river systems: "River Ganga is being replenishedby the melt water from around 4000 glaciers spread over India and Nepal and the River Indus is being fed by more than 3300 glaciers. Snow and glacier melt together 5 with monsoonal precipitation determines the headwater flow regimes of large parts of the Himalayas, including central and eastern Himalayan tributaries of River Ganga and Brahmaputra. Snow and glacier melt contribution is very significant in many of these Himalayan Rivers. On an average, annual snow and glacier melt contribution is estimated to be 60% in Satluj river at Bhakra dam (Singh and Jain, 2002), 49% in 10 Chenab river at Akhnoor (Singh et al., 1997) and 35% in Beas river at Pandoh (Ku-mar et al., 2007). " Now, if you read this paper carefully, you'll see that much of the snow the authors are speaking of is that which is lying on top of glaciers. So while it is technically true that the particular portion of the Himalayan catchment they are looking at is dominated by snow melt, if the glacier this snow melt sits on vanishes clearly the hydrological picture is going to change. This portion highlights that: Figure 6 explains the role of glaciers and precipitation in controlling the river flow variations in a Himalayan catchment. While discharge at Tela and Gujjar Hut stations were reduced by 58 and 50 percentage, respectively from 1998 to 2004, discharge from the glacier catchment showed comparatively steadied response. Analysis of specific runoff from each sub-catchment showed that the contributions from Tela catchment (41.8km) reduced from 25mm/day in 1998 to 9mm/day in 2004 (Table 1). Similarly, runoff contributions from the Gujjar Hut sub-catchment (20.3km 2) reduced from 18 mm/day to 4 mm/day during the same period, whereas runoff from the glacier catchment (15.7km2) varied between 29 to 15mm/day. Variations observed in the summer specific runoff from the non-glacierised part of the catchment covering 62 km 2 are obviously driven by the variations in the precipitation. The lowest specific runoff of the glacier catchment observed during the study period was 15mm/day, which is much higher than the lowest specific runoff of 9mm/day and 4mm/day of the non- glacierised Tela and Gujjar hut sub-catchments, respectively. This highlights the buffering role of the glaciers during the years of low summer flow in the glacier fed rivers of the “Himalayan catchment”. I'm wondering if all this confusion about glacial melt versus snow melt is because amateurs are scrutinizing papers without the training needed to properly deal with terminology. I couldn't say for sure; I'm an amateur.
124644. Doug Bostrom at 15:45 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie A at 13:13 PM on 6 February, 2010 "Section 6, para 17 has multiple errors ---" There is no such paragraph in the article. You actually were referring to section 6, paragraph 18. Anyway... "The dry season corresponds to the winter, near zero melt season. The melt season occurs during the summer, which is also peak monsoon season." Wrong, or at least your generalization is much worse than what you're accusing this paper of committing. For the Ganges, about 70% of flow is glacial meltwater during summer, for many other rivers serving the enormous concentration of population in the northern portion of India, between 50 and 60%. How about the other side, China? 23% of China's population receives most water from glacial melt during the dry season. * "The surface area of glaciers across the TP is projected ... (References are available upon request)." Based on the accuracy of your claim #1, it would indeed be helpful to see those references. * http://meteora.ucsd.edu/cap/pdffiles/barnett_warmsnow.pdf
124645. kepler at 14:53 PM on 6 February 2010
        How do we know CO2 is causing warming?
        the link cited in this article requires a membership but i found a pdf copy of the article here: ams.confex.com/ams/pdfpapers/24874.pdf i must say i'm at a loss how skepticalscience arrived at the graph here - it doesn't appear in the actual paper. and in fact (in fig. 1 of the paper) the delta brightness temperature increases for the 700 waves/centimeter point (where CO2 absorbs IR). i agree that CH4 has less in 1997 than 1970 but the majority of the spectrum analyzed showed an INCREASE in emission in 1997 as compared to 1970. in that figure 1 of the paper, they show lines of average measurements and then upper and lower error lines. it is true that the lower error line dips to 0 and slightly below for the 700/cm so maybe you just reported the lower error graph. and i will agree that this wavenumber was lower than the rest but they were still above zero which shows an increase in emission in 1997 vs 1970. the authors even state in the conclusion that we shouldn't infer atmospheric temperature changes from this snapshot. here is their quote: Although these strongly affect the OLR the atmospheric temperature and humidity response cannot be unequivocally determined owing to the snapshot nature of the observations.
        Response: The graph above comes from Figure 1c in Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997 (Harries 2001) (unfortunately the full paper cannot be found online - dang pay walls). This is a different paper to the one you link to (thanks for the link to the full paper, btw). The conclusion from Harries 2001 is 'Our results provide direct experimental evidence for a signi®cant increase in the Earth's greenhouse effect that is consistent with concerns over radiative forcing of climate.'
124646. Charlie A at 13:13 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Doug_bostrom at 04:23 AM on 6 February, 2010 "Perhaps you'd better read the article and discover where are the errors, then mention them here specifically? " I would prefer to engage the authors in discussion, but they have failed to respond to repeated inquiries. Even better, I would expect the authors to proactively correct errors in their article to keep others from further propagating the errors. Typical misstatements: Section 6, para 17 has multiple errors --- 1) "TP ice riled are a critical resource for 1/6 of the world's population becuase they provide dry season runoff" This is incorrect for most of the TP. The dry season corresponds to the winter, near zero melt season. The melt season occurs during the summer, which is also peak monsoon season. 2. "The surface area of glaciers across the TP is projected to decrease from 500,000 sq km measured in 1995 to 100,000 sq km in 2030." There are multiple estimates of total glacier area in the TP that range from around 100,000 sq km to 110,000 sq km. None are anywhere near 500,000 sq km. (References are available upon request). Considering that these are the two major conclusions of the paper, these two errors alone are significant enough to warrant a corrigendum or errata. A couple of other errors: 3. "Himalayan glaciers have been retreating more rapidly than glaciers elsewhere in the world". There is no scientific basis for this statement. ----------------------------------------- Both this paper and Barnett et al, 2005 conflate glacier melt and snowmelt. There are many areas in the world that have no glaciers, but do depend upon snowmelt to even out seasonal variations in streamflow. Some alarmists seem to confuse glacial melt and snowmelt. O On the other hand, hydrologists at the Indian Institute of Hydrology clearly distinguish between them. See for example, Figure 3 of "Role of glaciers in watershed hydrology: “Himalayan catchment” perspective" by R. J. Thayyen12 and J. T. Gergan. Or look at Figure 8 which has monthly variations in discharge and percentage contribution from the glacier catchment in the stream flow.
124647. Charlie A at 12:55 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Predictions are key to testing a hypothesis. Of course, if one puts forth a hypothesis of Anthropogenic global warming in such an unclear fashion that the actual hypothesis is unclear and any predictions (ooops, I mean projections) made are also unclear, then it is impossible to falsify the hypothesis. A untestable, unfalsifiable hypothesis is more akin to a faith. One may or may not believe in God, but God's existence is an untestable, unfalsifiable hypothesis. It is best to avoid such types of hypotheses in true science.
124648. Marcus at 12:01 PM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Doug_bostrom, this sudden switch from attacking the science of global warming to attacking the predicted impacts of global warming-as suggested by the IPCC-seems indicative of a rear-guard action by the so-called skeptics. Unless I'm wrong, rear-guard actions are only performed by the side which is *losing* the war-which suggests to me that, for all their bluster & bravado, the skeptics *know* they're losing the war over the science, so are desperately trying to nit-pick the predictions of the IPCC in some desperate bid to save some face.
124649. Doug Bostrom at 11:52 AM on 6 February 2010
        The role of stratospheric water vapor in global warming
        SNRatio at 09:02 AM on 6 February, 2010 Thanks! I've only been looking seriously at this whole topic (climate change) for a few months but have already been spiraling toward the ocean because it's -so- bulky, so loaded with thermal inertia yet ineluctably a big influence on us air breathers and our climate. The energy quantities in the ocean are just staggeringly large, compared to the atmosphere. Over on RC a favorite skeptic and I were comparing notes on the amount of additional energy flowing into the Arctic ocean due to the ice anomaly there. His figure was more realistic than mine, I think, a "mere" 40TW of additional juice pouring into the ocean on a typical summer day. I think the actual power level would be a bit larger than that if the the numbers were done rigorously, but all the same we found ourselves agreeing on how these numbers are so large they entirely exceed our intuitive grasp. And the ocean sucks up this energy without batting an eye, at least over the short term. Remarkable. I'm curious to know what'll happen over the long term in the Arctic; thermohaline circulation is obviously dependent on Arctic ocean temperature. Meanwhile, just like everything else in nature there's likely little or no "overengineering" in the way the present circulation works, it's more something that's converged on some sort of quasi-stable behavior. A little sneeze from the ocean can mean a lot up here.
124650. Doug Bostrom at 11:37 AM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Seems to be quite a fad, picking over the IPCC report, but all that seems to be coming off is a bit of gristle. No meat? Nothing about the physics?

Prev  2485  2486  2487  2488  2489  2490  2491  2492  2493  2494  2495  2496  2497  2498  2499  2500  Next