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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 104901 to 104950:

  1. Climate change from 40 million years ago shows climate sensitivity to CO2
    TIS - the paper is about a transient event at 40my. The plate reconstruction in the paper infers drake strait had not opened and I am not aware (but could be uninformed) of evidence for persistent ice sheet in the antarctica at that time. I dont see really what you points have to do with this paper. However, you claim that development of ice sheets in antarctica would reduce CO2 and cool the ocean (presumably you mean ocean cooling reduces CO2??). I wonder what you think the mechanism for this is? Ice sheets definitely increase albedo but if you think changes to GHGs are an insignificant element in determining climate, then I am interested to you how the ice sheet development cools the global oceans. Can you make the arithmetic add up? Warming oceans can cause higher CO2 levels (amplifying warming - that is what "sensitivity" is about) but you do know that the elevated CO2 levels at present are from fossil fuel and not from out the ocean?
  2. Skeptical Science moving into solutions
    I'm inclined to agree with BillWalker - SS as it is now is a very valuable reference site, in part because it is apolitical. Solutions get complicated - even the question of their " scientific validity". Maybe a related site would be a good idea.
  3. Solving Global Warming - Not Easy, But Not Too Hard
    Some of the numbers are out of date. For example on wind, total world installed capacity at the end of 2009 was 158 GW, of which almost 40 GW was added in that year. That's a factor of 12, not 50, to get to 2000 GW. And by now it should be down to a factor of about 10, not 12. See here for this data: http://www.renewableenergyworld.com/rea/news/article/2010/02/global-wind-installations-boom-up-31-in-2009 I think a better source than Pacala and Socolow are the various McKinsey studies that also consider the economics, rather than just technical feasibility: http://ww1.mckinsey.com/clientservice/sustainability/service.asp in particular their GHG abatement cost curves: http://ww1.mckinsey.com/clientservice/sustainability/Costcurves.asp and this 2009 report on "Pathways to a low carbon economy": http://ww1.mckinsey.com/clientservice/sustainability/pathways_low_carbon_economy.asp The interesting thing is that the first chunk of carbon abatement actions actually *pay for themselves*: they are worth investing in independent of any government incentives or support.
  4. Solving Global Warming - Not Easy, But Not Too Hard
    [A little PS: Maybe a sister site for solutions would be a good thing - this is going to be a big topic!]
  5. Solving Global Warming - Not Easy, But Not Too Hard
    I would be suspicious of any wedge attributed to biofuels...especially ethanol. There are a number of drawbacks associated with biofuels, not the least of which is the problem of using our agricultural space to feed cars instead of people! The EROI (Energy Return On Investment) is not too exciting, either. Check out this very informative video by David Fridley of Lawrence Berkeley Labs and San Francisco Oil Awareness:"The Myths of Biofuels" There is a thought-provoking comment in the very last seconds of the video, when the use of horses is under discussion. Fridley says "...ultimately they [horses] will be extremely necessary." Kind of makes you wonder where we're going, doesn't it?
  6. forensicscience at 07:03 AM on 9 November 2010
    Solving Global Warming - Not Easy, But Not Too Hard
    Natural gas will never sacale to replace coal - coal has to be replaced by nuclear and/or renewables such as wind and/or solar baseload (CSP) as wel as PV. Just replacing coal alone will be the first and easiest target technologically, however politially and economically its going to be a major fight for coal has deep pockets and lobbying is their forte with decades worth of experience in arguing for its future. Replacing oil and the automobile industry is not as easy as getting everyones next car to do 60+ MPG but although many cars achieve that now and more will as oil gets more expensive its going to take politics to get everyone off of em and when it comes ot flying you can forget any presently available replacement regardless. Electric cars are a better prospect that hydrogen but aeroplanes are up for grabs with a new liquid fuel, bio or hydrogen. Replacing gas is another matter completely and herein lies the issues with fossil fuels:solid, liquid and gas can be readily used, transmitted and transported - what else as yet can be except enery carriers such as electricity itself, thats what coal is used or after all, electricity generation so its achieveable technologivally but politicially its a nighmare hence CCS being offered as an olive branch but its too expensive we are told.
  7. Keep those PJs on: a La Niña cannot erase decades of warming
    John Bruno #29: Perhaps clarifications like this could be include as 'inline postcripts'; [Note: User XYZ points out in 'this linked comment' that the claim of ABC may be based on this assumption/interpretation... which is problematic because of 123, and see the comments for more info]. That way the original post isn't rewritten and the comments can still be tracked back to the text, but any major issues raised in the comments are covered so people don't have to read the entire comment stream to find out whether they should raise it themselves. Obviously this would only apply to somewhat involved concepts... spelling errors and the like can always just be corrected in the text.
  8. Solving Global Warming - Not Easy, But Not Too Hard
    "Substituting natural gas for coal" I think you mean Substituting coal with natural gas?? The carbon footprint of gas fired power stations is around 500 gCO2/kwh, Coal is about 1000 gCO2/kwh. So you cut some emissions by half. For how long?? In any case it is a short term solution. Here in the UK we are just about out of gas, none left. We are squeezing the last dregs out of the North Sea.
  9. Keep those PJs on: a La Niña cannot erase decades of warming
    This whole issue gives one pause to think of what might transpire when the next 1998-style El Nino rears it's ugly head.
  10. Solving Global Warming - Not Easy, But Not Too Hard
    "One wedge would be created if twice today’s quantity of coal-based electricity in 2054 were produced at 60% instead of 40% efficiency." How is that proposed (technically)? Assuming you did it overnight (obviously not practical), you gain a 20% advantage. Population growth and cheaper electricity results in more consumerism, the 20% is eaten up by the demand and the building of more power stations. Result, you produce the same amount of emissions as you did before the efficiency improvements, CO2 emissions continue to rise. What you really need is more expensive energy and improved emissions reductions!
  11. The value of coherence in science
    Chris @50, "I would prefer to see myself as a member of one tribe only - the human race." I agree.
  12. Climate change from 40 million years ago shows climate sensitivity to CO2
    Norman wrote: "Even if Mars had more CO2 than it has currently (which is an assumption...no experimental evidence to support it)" Well... there is the evidence of possible past surface water. :] Look, you said that the only way that Mars could have had liquid water in the past was if the Sun had been hotter then. I have shown that this is incorrect... there are other things which impact the temperature of planets. DID Mars have a thicker atmosphere and liquid water in the past? That is the prevailing theory, but not something I'm advancing as established fact. I was correcting your 'Sun only' assumption... not stating any conclusion of my own. "Carbon Dioxide does not have an unlimited ability to absorb IR and redirect it. It absorbs a percentage of the IR spectrum (mostly at 15 micron range)." See the presentations the moderator and Tom Dayton linked to. Or consider the planet Venus. Further from the Sun, but more than 100 C hotter than Mercury. Pretty much tosses out the 'solar only' and 'limited CO2 warming' claims in one neat package. "In the past the Earth is cited as having a CO2 level of around 6000 PPM." Which would be about 'five doublings' from the pre-industrial revolution CO2 level. So 5 C warming from the increased CO2 and maybe 10 C to 30 C from feedbacks if we were to assume that climate sensitivity then was similar to now (which we shouldn't). Earliest evidence of liquid water on Earth was back when the Sun's output was about 70% of current. Lining those and various other factors (e.g. orbital differences) up gets more than a little involved, but the graph Tom cited seems like a good rough guide. Also worth mentioning that there is some indication that the Earth MAY have frozen over, or nearly so, in the past. Lookup 'Snowball Earth' for details.
  13. Climate change from 40 million years ago shows climate sensitivity to CO2
    Norman, there is graph titled "Atmospheric CO2 concentrations required to compensate for reduced solar luminosity in the past,..." in a slide presentation by Daniel Kirk-Davidoff titled "Paleoclimatology: An Introduction." It is Slide 4, Figure 2. You might find the rest of the slides instructive, too.
  14. Skeptical Science moving into solutions
    The idea is not that Skeptical Science will advocate any particular policy solution. Rather the site will examine the scientific validity of various solutions and skeptic arguments against them.
  15. Skeptical Science moving into solutions
    I might suggest starting off by limiting solutions discussions to proven technologies. Space based solar, thorium breeder reactors, and clean coal technology are all billed as 'wonderful things which can solve all of our problems'... but none of them has demonstrated that capability yet. There are technical hurdles which we are assured can be easily overcome, but there is no real world data history to examine. Of course, such an approach would knock geo-engineering out of discussion before we even begin... but we could always try to tackle the 'speculative future solutions' later. Anyone who has spend much time here has seen that it is difficult to get people to accept basic laws of physics when they've got a political agenda to the contrary. Moving on to competing technologies with variable results in different parts of the world is going to magnify that problem at least an order of magnitude. Adding in 'emerging technologies' basically reduces it to a pure public relations scrimmage. The best bet there may be to examine each future concept in detail with consideration of the benefits, drawbacks, and obstacles to be overcome.
  16. Climate change from 40 million years ago shows climate sensitivity to CO2
    RSVP: So you have nothing to fear in that sense, but what one does see is a lot of resistance to inquiry, or what might be considered offensive questioning. Assuming for the sake of argument that one really does see "resistance to inquiry," this may have something to do with the fact that the "skeptical" side relies so heavily on endlessly recycled misconceptions and conspiracy theories (as five minutes on virtually any SkS thread will demonstrate). Perhaps that explains some of the "resistance," along with the fact that extraordinary claims -- like the claim that our understanding of the threat AGW poses is significantly in error -- require extraordinary evidence that "skeptics" never seem to get around to providing. That said, I'd argue that the entire idea of this "resistance to inquiry" is basically false. Apart from SkS, consider the EPA Endangerment Findings, which patiently address nearly every "skeptical" argument in existence, from the plausible to the laughable. "Resistance" to the ignorance and misinformation on display in threads like this one is exactly what we should expect and want to see from scientists. The fact that all these demands for more (and more, and more) "inquiry" tend to come from people who display childlike credulity toward repeatedly debunked anti-AGW arguments makes it even harder to take them seriously. Real inquiry into this subject is happening where it really matters: among experts in the relevant fields.
  17. Climate change from 40 million years ago shows climate sensitivity to CO2
    Norman, Mars does have 70x more CO2 in the atmosphere than Earth does. This is because that atmosphere is 95.3% CO2, but the atmospheric pressure is 0.007 times that of the Earth's. However, CO2 is not the only greenhouse gas. Earth's atmosphere ranges from 0-7% water vapor, while Mars only has 0.03%. The Martian atmosphere also contains no methane. Conditions on Mars: Atmosphere (content, density, sky appearance) NASA - Mars NASA - Earth's Atmosphere Water vapor is the most powerful greenhouse gas (currently argument #25)
    Water vapour is the most dominant greenhouse gas. Water vapour is also the dominant positive feedback in our climate system and amplifies any warming caused by changes in atmospheric CO2. This positive feedback is why climate is so sensitive to CO2 warming.
  18. Skeptical Science moving into solutions
    While I agree with you in spirit, I worry about the effect of this change. As it stands now, this site is an amazing resource and helps in convincing skeptics that climate change is real. But as soon as you delve into solutions, it becomes political, and conservatives will then dismiss the site as having a liberal bias. While we certainly need to talk about solutions, I fear doing so here will greatly weaken the ability to use this site to convince political ideologues.
  19. What should we do about climate change?
    Peter Lang, your response to me gives Australian estimates to imply Texas is subsidized. That is obviously false. You do not mention the use of Nuclear reactors in Afganistan, Haiti and Zimbabwe. You have not answered my questions, you have avoided them. Provide a link if you have one. Since you have chosen not to answer these questions, it is clear that you feel Texas does not subsidize their wind and nuclear is unsafe in the third world. You have dominated this thread with claims supported only by nuclear industry data. I was neutral about nuclear when I started reading this thread. If your argument is the best nuclear can do, I am now convinced that nuclear is not worth much effort. I am still paying for the unapproved nuclear reactor that will not be on line for at least 10 years. Wind is paid for by the installer in advance and is not billed until it produces electricity. Who is being subsidized by this deal? If nuclear is only economic when they bill 10 years in advance it will never work. Nuclear engineers have been making wild claims for the past 40 years. You seem to be adding to that pile. Provide economic and waste treatment data for the running thorium reactor that you claim is so efficient, not just hopeful designs that have yet to be built.
  20. Ice-Free Arctic
    Camburn.... There is a huge difference between an ice breaker getting through the Northwest Passage and a 12.5 meter sailboat. The difference is that now we are seeing the NW Passage clear of ice.
  21. Skeptical Science moving into solutions
    You may want to consider modifications in the posting policy. A recent thread on skeptical science came to be dominated by a very few individuals with strong feelings about the topic. It seemed to me that people with other valid views left the thread rather than argue with the dominant people. If you limited the number of posts per day (or per thread) that would allow more people to get in a voice without sanctioning anyone. There were also issues on that thread about what sources were reliable.
  22. Eric (skeptic) at 00:26 AM on 9 November 2010
    Skeptical Science moving into solutions
    Not peer-reviewed science, but as usual Acres USA has several good articles on ecological crop production (I started subscribing a few months ago). On page 26-32 the author talks about the flaws with large scale monoculture and he describes an alternative. One of his main arguments is that native, perennial crops require a lot less energy than annual crops (energy needed for planting, herbicides/pesticides, etc) An old article by the same author: www.nfs.unl.edu/documents/SpecialtyForest/Shepard.pdf My main nitpick is that these articles are not very quantitative and rely on other qualitative benefits like quality of life (a legitimate argument, but not quantitative).
  23. Skeptical Science moving into solutions
    Would it be better to have a sister site?
  24. Skeptical Science moving into solutions
    It depends how it is done. There is of course the danger that you alienate the people that support what you are doing. Solutions are a more political and policy issue, which means it is fraught with potential problems.
  25. Skeptical Science moving into solutions
    I like this idea but part of me is thinking you almost need a whole different sister-site for it (Sceptical Solutions?) The problem is, as Alexandre says, the peer-reviewed literature is much more sparse. But more than that - and this is something the 'sceptics' use to their advantage - relying too much on peer-reviewed science in this area skews debate towards the easily measurable. For example how can we measure the response of ecosystems, or even of civilisations, to changes in climate that have never been observed in the past? We end up relying on a few studies that take an empirical approach even if these studies aren't representative of the reality we face.
  26. Keep those PJs on: a La Niña cannot erase decades of warming
    Alexandre at 23:29: I suspect even then and beyond, every La Nina and every local cool spell will induce the Pavlovian "it's cooling!" response.
  27. Keep those PJs on: a La Niña cannot erase decades of warming
    Gosh, will these guys draw the "it's cooling" argument at every La Nina? Even in the middle of a record-braking 2010? In 2050, with the trend firmly upwards until then, there will be guys saying "it stopped warming in 2048".
  28. Skeptical Science moving into solutions
    Great move. It's about time to talk about what to do. Yes, it will be more difficult to stay within peer reviewed literature. Much of it is political, ideological or just new technology that does not reach a level of a published paper. Yes, this will demand new moderating skills... Starting point must always be politeness.
  29. Climate change from 40 million years ago shows climate sensitivity to CO2
    #58 CBDunkerson, Not dimissing the model. But do you realize how many assumptions you have to make to support your claim? You do understand that the logic to arrive at a conclusion can be valid but the conclusion is still wrong because the initial assumption is not correct. Even if Mars had more CO2 than it has currently (which is an assumption...no experimental evidence to support it) Carbon Dioxide does not have an unlimited ability to absorb IR and redirect it. It absorbs a percentage of the IR spectrum (mostly at 15 micron range). CO2 at Earth's concentration is already far past the linear part of the logrithmic curve. In the past the Earth is cited as having a CO2 level of around 6000 PPM. Can you calculate how faint our Sun would have to be to keep the temp in the range that is cited? Then take that faint Sun radiation and direct it at Mars to see if Mars could have sustained liquid water at this time. One Historic episode where the majority of scientists were wrong was when locals took them meteorites (somewhere in the 1800's). The scientists used perfect logic and there understanding of Gravity. The locals claimed the rocks came from the sky...the scientists refuted this claim with the reasoning that they could not have come from the sky because they could not get up there (gravity and all), they reasoned the rocks were struck by lightning and that is what the locals saw and why the rocks were warm. Even if the logic was perfectly valid, the assumption supporting it was incorrect.
    Moderator Response: Regarding "Carbon Dioxide does not have an unlimited ability...," see the Argument "CO2 effect is saturated." If you want to discuss that topic further, please do so over there. (Everyone else please respond to Norman on that thread, not here.)
  30. Keep those PJs on: a La Niña cannot erase decades of warming
    I do not triumph the cooler, wetter weather as proof that no global warming is happening, but accept that it as part of a natural cycle. Yes, it's part of a natural cycle that is superimposed on top of a long-term anthropogenic warming trend. Consider the most recent La Nina episode (2008) -- it was the second strongest since the 1970s. One would normally think of La Nina years as "cold", and indeed 2008 was the coldest year of the past decade ... but it was still warmer than any year before 1997-1998. That is precisely the pattern that you would expect to see with a natural cycle (ENSO) superimposed on a long term rising trend. The troughs of the cycle are now higher than the peaks were previously.
  31. Keep those PJs on: a La Niña cannot erase decades of warming
    MarkR at 18:54 PM "So in a way it's correct, I think your post should clarify the difference. In annual terms it's far smaller, but from an El Nino peak the difference can be 0.6 ° C." Fair enough. I am willing to, although doesn't the comments section sufficiently clarify that? I am starting to view the comments section on SS and on many other sites including skeptic sites as a form of post publication review, like PLoS One does formally and the scientific community does informally. Another example is adelady's point that El Nino and La Nina are not causes of warming/cooling per se, they are defined as warming/cooling as driven by a natural cycle, i.e., they don't cause the phenomena, they are the phenomena, and the proximate causal mechanism is trade winds, etc. Back to broader question: should such (valid) points from any perspective be incorporated into the formal post? Or would that be redundant? (it would also make the comments section confusing, since they would no longer be relevant to the post)
  32. Keep those PJs on: a La Niña cannot erase decades of warming
    The Inconvenient Sceptic wrote : "We all know that next year will see a drop in global temperatures, but that is meaningless by itself. Many Skeptics will rejoice and the AGW crowd will talk about 2010 being the warmest year ever." Before we "all" can agree on next year, what do you mean by "drop in global temperature" ? Compared to this year ? Last year ? The average, of some form ? Please explain. As for the "Skeptics", they rejoice at any poorly-understood figure, whether it be temperature, ice extent, ocean heat, etc., so no change there. As usual, it will be best to ignore them. Who can tell whether 2010 will be the warmest year ? If it is, at least it will stop the so-called skeptics from using one of their zombie arguments - "global warming stopped in 1998" - although, I suppose, they will then move on to "global warming stopped in 2010"...
  33. Keep those PJs on: a La Niña cannot erase decades of warming
    John. ENSO and AMO are not _causes_ of heating and cooling, just as seasonal cycles and nightfall / sunrise aren't. They are cycles, they are just longer as well as less regular than seasonal or overnight or tidal cycles. It's what happens within those cycles that matters.
  34. Ice-Free Arctic
    You got there before I did, bratisla, but it is also worth noting that the St. Roch's previous attempt took over 2 years to complete. Conditions were obviously not as ice-free as they have been in at least the last 10 years, as can be seen from the number of successful attempts by all sort of sailing vessels, usually without any form of ice-breaking facilities. Wikipedia has lots of details and further information.
  35. Skeptical Science moving into solutions
    Funny you should raise this now. I've been thinking that we should have a lot more input from the biological science side. And when you're talking about "It's too hard" there must be some biological science backing up the argument I once heard from a gardening magazine about gardening saving the world by carbon sequestration. It's be nice to get away from power generation and public transport solutions every now and again. No till, mulching, and other techniques accumulating rather than releasing carbon from growing food (or forests for that matter) must have had some serious research. Clearly retaining soil and deepening it is a good thing in its own right. There must be some reasonalby good quality stuff on this from agriculture and horticulture, maybe even permaculture - do they have a respectable scientific journal?
  36. Climate change from 40 million years ago shows climate sensitivity to CO2
    Norman #52: "Mars currently has more CO2 in its atmopshere than Earth does" Yes, but as you note, Mars is further from the Sun. Ergo, it would need alot more CO2 in its atmosphere to have liquid water. Citations of 'fun facts for kids' sites aside, there is more to the temperature on Mars (and any other planet) than distance from the Sun. That is a major factor, but not the only determinant. Again, every examination of the theory that Mars once had liquid water I have seen includes the pre-requisite that Mars once had a thicker atmosphere. You cite Wikipedia for the next bit... take a look at what they have to say about "Atmosphere of Mars". "Instead, astrophysicists come to understand how stars evolve by observing numerous stars at the various points in their life, and by simulating stellar structure with computer models." You seem to have ignored everything before the word "and". The part about "observing numerous stars at various points in their life"? That's exactly what I was referring to. We have observed that stars later in their life cycle are hotter. No model required. Yes, there are ALSO models of the nuclear fusion processes in stars which indicate that they should get hotter over time... but that's just our understanding of nuclear physics confirming what we have observed directly. Your cavalier dismissal of all things modeled doesn't make the observed reality of stellar warming suddenly go away. Rather, it suggests that our understanding of the physics involved in stars may be wrong... but we somehow got the right answer (warming as they age) anyway.
  37. Keep those PJs on: a La Niña cannot erase decades of warming
    John (#26): (As you probably know), more precipitation is not quite a disproof of AGW, rather the opposite as a warming atmosphere can hold more moisture.
  38. The Inconvenient Skeptic at 21:00 PM on 8 November 2010
    Keep those PJs on: a La Niña cannot erase decades of warming
    The ENSO and the AMO both cause warming or cooling depending on the phase that is active. That is part of why there is natural variation in temperature. Things are never exactly the same twice. We all know that next year will see a drop in global temperatures, but that is meaningless by itself. Many Skeptics will rejoice and the AGW crowd will talk about 2010 being the warmest year ever. The real effect of the ocean cycles is to confuse the data and allow either side to take advantage of the current phase. That is not helpful to anyone. The real focus of both sides should be to ignore the understood variations and determine what the climate is doing. Triumphing understood anomalies because the results are what is desired ends up discrediting the significant results. Already my location in the US is far ahead of normal precipitation for this time of year. 25% of the monthly rainfall happened yesterday. That is a La Nina effect for my location. I do not triumph the cooler, wetter weather as proof that no global warming is happening, but accept that it as part of a natural cycle. John Kehr The Inconvenient Skeptic
  39. Keep those PJs on: a La Niña cannot erase decades of warming
    It is interesting to note that the UAH channel 4 and 5 temperatures are now back at all time record levels, despite the strong La Nina. UAH SST's are also going straight up at the moment. As mentioned above, when the next big El Nino hits, and the solar cycle has gained some momentum, it will get warm. Quickly.
  40. Ice-Free Arctic
    (first post here, so first and foremost many thanks for this very interesting and insightful site). I was a bit intrigued by the claim that a ship managed to get through the NW passage in 1944, since it means that it could have been a far safer way for the US and Canada to bring equipment to URSS. So I dug a bit, and I found an (interesting) article from the Calgary university about this exploit : http://www.ucalgary.ca/arcticexpedition/larsenexpeditions It states that the St Roch was an Arctic ship with extra-hard and heavy hull, and in 1944 it was fitted with larger engines to break more easily ice. An icebreaker, to be short. We cannot therefore deduce from this trip that NW passage was ice free in 1944.
  41. Climate change from 40 million years ago shows climate sensitivity to CO2
    Phila #56 "...modern climatology will be overthrown, and its adherents revealed as frauds and fools," This kind of thing doesnt happen. At worst they will say something like, "around the turn of the century, the prevalent theory was..., but since then it has been clearly demonstrated that...". So you have nothing to fear in that sense, but what one does see is a lot of resistance to inquiry, or what might be considered offensive questioning.
  42. CO2 has a short residence time
    DB, thanks for those graphs. They seem to confirm something that I've been meaning to ask about. Specifically, we know that right now the oceans are absorbing about half the CO2 human industry releases each year. It would seem logical that if we stopped releasing all that CO2 the oceans would then start to absorb some of the excess we have built up... which would lead to an initial rapid decline in atmospheric CO2 level and then a long slow decline once equilibrium between the atmosphere and oceans was reached. This matches what is shown in the chart. Thus, while it would take tens of thousands of years to get back down to the historical level of ~280 ppm from where we are now there is still a lot to be gained from limiting emissions as quickly as possible... because that could allow us to drop back down to 350 ppm or lower within a few decades. The biggest problem is really our continuous CO2 emissions... our annual output is overwhelming what the natural sinks can 'sequester' (short term) each year and building up in the atmosphere. If we reduced emissions by about half there'd be no further atmospheric accumulation, and if we reduced emissions further than 50% atmospheric levels would start to drop.
  43. Keep those PJs on: a La Niña cannot erase decades of warming
    The 0.6 °C claim comes from looking at shorter term temperatures; maybe daily or weekly. So in a way it's correct, I think your post should clarify the difference. In annual terms it's far smaller, but from an El Nino peak the difference can be 0.6 ° C.
  44. Climate change from 40 million years ago shows climate sensitivity to CO2
    Norman: A model can imply a generalization of patterns and perform fairly well, it cannot determine a specific case. I am sure astronomers will see various exceptions to predictions and rules. They may indeed. Still, the fact remains that anyone who chooses to bet on exceptions rather than scientific "predictions and rules" is likely to lose. The smart money tends to be against it, just as it's against the idea that modern climatology will be overthrown, and its adherents revealed as frauds and fools, by a bunch of carping amateurs who can't be bothered to do basic homework on the topics they claim to understand better than the experts.
  45. Climate change from 40 million years ago shows climate sensitivity to CO2
    Norman, one of the causes for the drastic reduction in CO2 of the Martian atmosphere probably was the stripping of the atmosphere by the solar wind, in the absence of protective Martian magnetic fields.
  46. Keep those PJs on: a La Niña cannot erase decades of warming
    Another significant point lost of the so-called "skeptics" here (I really do wish they'd stop saying they're "skeptics", because they're NOT) is that this decade was also dominated by the deepest solar minimum in over 100 years-yet in spite of this fact, global temperatures for 2000-2009 was still about +0.2 degrees warmer than for the whole of 1990-1999. Yet, if the "skeptics" are to be believed, then apparently we shouldn't be concerned about this.
  47. Climate change from 40 million years ago shows climate sensitivity to CO2
    Norman, why do you assume that a thicker ancient Martian atmosphere had the same amount of CO2 as today's Martian atmosphere? Instead, the current CO2 is what's left over after much of the original CO2 degraded in various ways, and crucially different from the case of the Earth, was not replaced by volcanic activity (due to lack of plate tectonics recycling crust). The ability of Mars to have had liquid water depends on several factors, most of which differed from now. The coolness of the Sun in ancient times would have been balanced by other factors.
  48. Keep those PJs on: a La Niña cannot erase decades of warming
    John Bruno at 13:03 PM, what is being overlooked is that the most recent El-Nino was identified as an El-Nino Modoki. An El-Nino Modoki is very different to the normal El-Nino as explained in this:- Impacts of recent El Nin˜o Modoki on dry/wet conditions in the Pacific rim during boreal summer Abstract Present work uses 1979–2005 monthly observational data to study the impacts of El Nin˜o Modoki on dry/wet conditions in the Pacific rim during boreal summer. The El Nin˜o Modoki phenomenon is characterized by the anomalously warm central equatorial Pacific flanked by anomalously cool regions in both west and east. Such zonal SST gradients result in anomalous two-cell Walker Circulation over the tropical Pacific, with a wet region in the central Pacific. There are two mid-tropospheric wave trains passing over the extratropical and subtropical North Pacific. They contain a positive phase of a Pacific-Japan pattern in the northwestern Pacific, and a positive phase of a summertime Pacific-North American pattern in the northeastern Pacific/North America region. The western North Pacific summer monsoon is enhanced, while the East Asian summer monsoon is weakened. In the South Pacific, there is a basin-wide low in the mid-latitude with enhanced Australian high and the eastern South Pacific subtropical high. Such an atmospheric circulation pattern favors a dry rim surrounding the wet central tropical Pacific. The El Nin˜o Modoki and its climate impacts are very different from those of El Nin˜o. Possible geographical regions for dry/wet conditions influenced by El Nin˜o Modoki and El Nin˜o are compared. The two phenomena also have very different temporal features. El Nin˜o Modoki has a large decadal background while El Nin˜o is predominated by interannual variability. Mixing-up the two different phenomena may increase the difficulty in understanding their mechanisms, climate impacts, and uncertainty in their predictions.
  49. Climate change from 40 million years ago shows climate sensitivity to CO2
    Re: HumanityRules (13) Missed your question earlier, sorry. The referenced quote "similar, perhaps, to a future anthropogenic greenhouse maximum" of about 4,000 PPM CO2 is a bit odd. It is caveated, however. My interpretation is that the 4,000 PPM CO2 level referenced as a future anthropogenic maximum is if mankind continues its Business As Usual without change (if we "burn it all"), and if the oceans lose ability to sequester CO2 as they have been doing, and if we trigger a methane hydrate/clathrate release as is thought to have occurred during the PETM, than a 4,000 PPM CO2 level is about the maximum achievable. A lot of uncertainly there. But I would not consider it alarmism, but only a reference to an upper limit, caveated appropriately for the intended audience of the magazine. But without seeing the quote in its context, that's as far as I will go. Hope that's clear, The Yooper
  50. Keep those PJs on: a La Niña cannot erase decades of warming
    Re: John Bruno (19) I think adelady's point with her music analogy was the common misconception that everything will continue as usual in a warming world with no ill consequences, just warmer. I.e., no synergistic or systemic issues worsening things, no tipping points, no population collapses, etc. And at some point you run out of keys... But what do I know, I'm basically tone deaf. :) PS: Thanks for the excellent post! The Yooper

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