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Comments 122801 to 122850:

122801. Doug Bostrom at 18:02 PM on 8 March 2010
        Does record snowfall disprove global warming?
        Jeff Freymueller at 17:45 PM on 8 March 2010 I find it helpful to think of glaciers as reservoirs and their possible disappearance as a simple, easily understood extension of that analogy. Try telling an engineer responsible for maintaining year round flow through a water utility that you're going to remove several of his impoundments and he should not worry because the total precipitation available to his utility will be unchanged or even increased and he'll call you crazy, with good reason.
122802. Jeff Freymueller at 17:45 PM on 8 March 2010
        Does record snowfall disprove global warming?
        #34, chriscanaris, "I assume Tibet would be very much the kind of territory dependent on glacial melt for irrigation." Yes, very much so. I recently read a profile in Science that suggested the same was true of the mountainous areas of Nepal. As for Ecuador, it may be true at higher elevation, but not in the lowlands. But it is drier farther south in the Andes, and meltwater from glaciers is quite important in parts of Peru and Bolivia.
122803. Doug Bostrom at 16:56 PM on 8 March 2010
        New observations find underwater Arctic Shelf is perforated and venting methane
        Cowboy at 16:52 PM on 8 March, 2010 On a romp, posting years-old information, cowboy. That article you cited is of course from 2003; the rise in methane long since resumed. Your point?
122804. Doug Bostrom at 16:53 PM on 8 March 2010
        It hasn't warmed since 1998
        Cowboy at 16:42 PM on 8 March, 2010 21 years ago that was the latest news. Almost quaint, but for some reason it's finding a lot of currency in the past few weeks. Here's some more of that same article, helping to provide full context: "Dr. Kirby Hanson, the meteorologist who led the study, said in a telephone interview that the findings concerning the United States do not necessarily ''cast doubt'' on previous findings of a worldwide trend toward warmer temperatures, nor do they have a bearing one way or another on the theory that a buildup of pollutants is acting like a greenhouse and causing global warming. He said that the United States occupies only a small percentage of Earth's surface and that the new findings may be the result of regional variations. ... Dr. Hanson of NOAA said today that the new study does not in any way contradict the findings reported by the NASA scientists and others. He said that his study, in which he was joined by George A. Maul and Thomas A. Karl, also of NOAA, looked at only the 48 contiguous states. Dr. Hanson said that global warming caused by the greenhouse effect might have been countered by some cooling phenomenon that has not yet been identified and that the readings in his study recorded the net effect. ''We have to be careful about interpreting things like this,'' he said. One aspect of the study that Dr. Hanson said was interesting was the finding that the urbanization of the United States has apparently not had a statistically significant effect on average temperature readings. A number of scientists have theorized that the replacement of forests and pastures by asphalt streets and concrete buildings, which retain heat, is an important cause of rising temperatures. Dr. Hansen of NASA said today that he had ''no quarrel'' with the findings in the new study. He noted that the United States covered only 1.5 percent of Earth. ''If you have only one degree warming on a global average, how much do you get at random'' when taking measurements in such a relatively small area, he asked rhetorically. ''We are just arguing now about whether the global warming effect is large enough to see,'' he added. ''It is not suprising we are not seeing it in a region that covers only 1.5 percent of the globe.''
122805. Cowboy at 16:52 PM on 8 March 2010
        New observations find underwater Arctic Shelf is perforated and venting methane
        2003: (emphasis added) "The National Oceanic and Atmospheric Administration (NOAA) reports that atmospheric concentrations of methane, a potent greenhouse gas, have begun to level out AFTER TWO CENTURIES OF INCREASES. In a November 17 press release, NOAA reports that scientists are still trying to determine what this means." http://www.gcrio.org/OnLnDoc/pdf/methane031117.pdf
122806. Cowboy at 16:42 PM on 8 March 2010
        It hasn't warmed since 1998
        

        "Did global warming stop in 1998?" Did global warming START in 1998? U.S. Data Since 1895 Fail To Show Warming Trend LINK WASHINGTON, Jan. 25— After examining climate data extending back nearly 100 years, a team of Government scientists has concluded that there has been no significant change in average temperatures or rainfall in the United States over that entire period. While the nation's weather in individual years or even for periods of years has been hotter or cooler and drier or wetter than in other periods, the new study shows that over the last century there has been no trend in one direction or another. The study, made by scientists for the National Oceanic and Atmospheric Administration was published in the current issue of Geophysical Research Letters. It is based on temperature and precipitation readings taken at weather stations around the country from 1895 to 1987. ...

122807. Michael T. at 16:32 PM on 8 March 2010
        Does record snowfall disprove global warming?
        gallopingcamel at 15:48 PM on 8 March, 2010 There was no record cold in December or January in the U.S. Just take a look at these reports: http://www.ncdc.noaa.gov/sotc/?report=national&year=2010&month=1&submitted=Get+Report Notice there a no record cold states in Dec. or Jan. Record lows and record highs are a different story because that is just variability in the weather fluctuations. The long-term trend is for record highs to outpace lows as demonstrated by Meehl (2009). The cold weather in Eurasia and in the U.S was due to an extreme negative phase of the Arctic Oscillation. When this happens the surface pressure in the Arctic is relatively high and that allows the jet stream to weaken, and cause outbreaks of arctic air to move into middle latitudes. And the Arctic air being replaced by mid latitude air so the arctic is extremely warm. http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index.html This similar neg. AO pattern also happend last summer in the midwest U.S. which caused it to be a cool summer. The snowstorms on the east coast are consistent with El Nino bringing more precip up the coast clashing with arctic air which I described with the negative AO. These big precipitation events are consistent with global warming, but you can't say any weather extreme was caused by AGW. The southeast U.S., including Florida, was predicted to have a colder than usual winter this year by NOAA back in October: http://www.noaanews.noaa.gov/stories2009/20091015_winteroutlook.html
122808. Doug Bostrom at 16:30 PM on 8 March 2010
        Senator Inhofe's attempt to distract us from the scientific realities of global warming
        gallopingcamel at 02:03 AM on 7 March, 2010 "Next he posits that man made emissions are causing the rise in CO2. Probably OK but I have some quibbles. Let it go." Whoa, pardner! Hold the phone! That's reflective of a misunderstanding on your part which will leave you bereft of complete comprehension of this topic and unable to construct a useful mental model in your head, one delicious taco shy of a combination plate so to speak. Among other techniques isotope ratios especially tell us beyond a reasonable doubt that the rise in C02 we're seeing is anthropogenic. If you have a quibble with this you'll need to take it up with archaeologists and a number of other disciplines depending on radiocarbon dating methods; the calibrations here are an offshoot of radiocarbon dating refinements having nothing directly to do with climate change. As to lag/lead, that's been treated elsewhere in abundance, as Tom has pointed out. I just wanted to jump in and help you over the isotope matter before you wasted more of your time and effort by missing that fact.
122809. Doug Bostrom at 16:07 PM on 8 March 2010
        Senator Inhofe's attempt to distract us from the scientific realities of global warming
        gallopingcamel at 14:00 PM on 8 March 2010 If Lindzen is in disagreement not only with Trenberth but also a majority of other scientists qualified to discriminate between his work and Trenberth's, it's possible and reasonable to conclude Trenberth's analysis is the better of the two, less possible and less reasonable to form the opposite conclusion. That situation indeed being the case, it seems there is after all little controversy to discuss with regard to Lindzen versus Trenberth.
122810. 4 billion at 15:53 PM on 8 March 2010
        New observations find underwater Arctic Shelf is perforated and venting methane
        In 2007 Shakhova et al wrote, "Until recently, due to slightly negative annual temperatures within the water column and the lid-type coverage of shelf sediments by sub-sea permafrost, old organic carbon buried on the Siberian Arctic shelf was considered completely isolated from the modern carbon cycle." So it seems fair to say the observed venting is a new phenomenon. Shakova et al 2010, wrote, "The release to the atmosphere of only one percent of the methane assumed to be stored in shallow hydrate deposits might alter the current atmospheric burden of methane up to 3 to 4 times" The East Siberian Arctic Shelf covers a similar area to the Siberian traps which has been linked to a large increase in GHG's in the past. As the potential volume of GHG's from the ESAS is so large, perhaps similar to levels released by the Siberian traps, isn't it reasonable to suggest that the effects of ongoing and near complete venting of ESAS Methane will be similar to the effects of the Siberian traps event?
122811. gallopingcamel at 15:48 PM on 8 March 2010
        Does record snowfall disprove global warming?
        It pains me to meekly agree with almost everything in this post. The recent record cold in so many places in the USA and Europe proves absolutely nothing about climate trends. Given the current SSTs (highest since 1998) it would not surprise if this winter's snow records will be followed by a very warm summer in many places.
122812. Tom Dayton at 15:19 PM on 8 March 2010
        CO2 lags temperature
        captain_heroic44: The reverse of what is described in this post's paragraph "As the Southern Ocean warms, the solubility of CO2 in water falls (Martin 2005). This causes the oceans to give up more CO2, emitting it into the atmosphere." Cooler oceans can hold more CO2, so the oceans suck it out of the atmosphere.
122813. mazibuko at 15:16 PM on 8 March 2010
        CO2 effect is saturated
        Hi Riccardo, Thanks for the answer and links. I have trouble enough keeping on top of the literature in my own field, so it is very useful to come to a place like this and have someone with a good knowledge of the particular issue provide/point me to a summary. I saw a good clip on Richard Dawkin's TV today about how to spot baloney, which is perhaps apropos to this matter. One common form of baloney occurs when someone claims that his/her theory shoots down an existing and better understood theory, based on falsifying only one particular aspect of the better understood theory. The new theory, however, can't explain all the other phenomena that are explained by the better understood theory. Thus, the notion that all the multiple lines of evidence for a human forcing on climate can be falsified because all those silly (and agenda-driven!) scientists overlooked CO2 saturation seems to qualify as baloney. Thanks again, M
122814. chris1204 at 15:02 PM on 8 March 2010
        Does record snowfall disprove global warming?
        neilrieck: Good point about thermohaline circulation. Jeff: An intriguing post about the earth's oblateness. In relation to both your posts, I assume Tibet would be very much the kind of territory dependent on glacial melt for irrigation. Ecuador would be similar I suspect. Your 1997/1998 experience of torrential rain in Tibet during the great ENSO together with your student's experiences in Ecuador that year is anecdotal evidence of potentially complex hydrological responses to warming in these regions.
122815. neilrieck at 14:38 PM on 8 March 2010
        Does record snowfall disprove global warming?
        I do not know if the snow fall event in England this January was directly linked to climate warming or not, but it is logical. A number of months back I saw a description of the thermohaline circulation (which transports equatorial heat to North-West Europe) and learned that this current is (in part)driven by temperature differences between the equator and poles. As the poles get warmer, the current will deliver less warmth to Europe. Remembering that Moscow and Glasgow are both at the same latitude (55 degrees N), the people in Scotland could end up receiving harder Moscow-like winters.
122816. Jeff Freymueller at 14:28 PM on 8 March 2010
        Does record snowfall disprove global warming?
        This may be off-topic, but it is inspired by Figure 2 in the post. Here's another question that I have been wondering about after seeing Figure 2. There is a big spike in 1998 (maybe 1997-1999) in water vapor over the ocean. 1997-1998 was a whopping El Nino year, and there was some pretty amazing rainfall in some places that year. I experience some of that in Tibet that August, where we were trying to work (but not having much success) because it was the worst flooding in many years due to the heavy rainfall. One of my students was in Ecuador in early 1998, and they were also getting the worst floods in years. The same time period also shows up as an anomalous when you look at the earth's oblateness (deviation from being a sphere). See this paper for example: http://www.sciencemag.org/cgi/content/full/298/5600/1975 What's interesting about this is that the change in oblateness has the look of an event, a short-term change opposite to the usual trend as opposed to a change in trend, which has made the explanation advanced in the paper somewhat controversial. Since that time, as far as I know, oblateness has continued to decrease following the post-glacial rebound trend. I'm posting this question here because I wonder how many other global-averaged quantities had unusual values that year (global temperature was another)? Just fishing for ideas here and looking for replies about climate-related quantities because I can find the solid-earth ones easily enough myself. Here's the abstract of the Dickey et al paper: Earth's dynamic oblateness (J2) has been decreasing due to postglacial rebound (PGR). However, J2 began to increase in 1997, indicating a pronounced global-scale mass redistribution within Earth's system. We have determined that the observed increases in J2 are caused primarily by a recent surge in subpolar glacial melting and by mass shifts in the Southern, Pacific, and Indian oceans. When these effects are removed, the residual trend in J2 (-2.9 x 10-11 year-1) becomes consistent with previous estimates of PGR from satellite and eclipse data. The climatic significance of these rapid shifts in glacial and oceanic mass, however, remains to be investigated.
122817. Jeff Freymueller at 14:09 PM on 8 March 2010
        Does record snowfall disprove global warming?
        #30 chirscanaris, in many parts of high mountain Asia, agriculture is dependent on glacier melt because of the timing of the rain. The snowpack melts too quickly in spring, and they need the extended runoff from spring melting of glaciers. They can't afford to wait until the monsoon rains come to plant because the growing season would be too short. The specifics are no doubt place-dependent, but they might need the timing of rain to change in addition to the amount of precip. For your sea level question, I think the mass of water vapor that can stay in the atmosphere is small enough that it's a fairly small affect. As for the Sahara and Gobi, that's a good question and I would like to know the answer as well. If precipitation patterns change, some places will come out better off and some will end up worse off (either getting drier, or getting too soggy). I don't know if the winners and losers of that can be predicted with any confidence (the WG2 report of the IPCC is probably the place to look).
122818. gallopingcamel at 14:00 PM on 8 March 2010
        Senator Inhofe's attempt to distract us from the scientific realities of global warming
        Tom Dayton, my point is that the AGW predictions of global temperature trends do not fit the facts. The recent cooling trend baffles the Hockey Team. Simply a case of reality trumping theory. Speculations on why the AGW predictions are wrong are indeed distractions, but interesting none the less. Lindzen and Trenberth are experts in climate science, yet they disagree; neither of can claim sufficient expertise to know which of them is closest to the truth.
122819. oracle2world at 13:59 PM on 8 March 2010
        There is no consensus
        Dear Riccardo My point was that science is not "consensus". Science is Occam's Razor. The least long-winded explanation of a dataset is the current model. Folks in the scientific world who are chicken to speak out, is not "consensus". Stomach ulcers were thought to be caused by emotional distress, the consensus belief. Based on a plausible theory, with no one bothering to be skeptical about it. In 1982 a physician Barry Marshall proposed that a previously unidentified bacterium Helicobacter pylori was the cause. It fit the data better, which led to new treatment, that made some drug companies VERY unhappy. Folks back then thought Marshall was completely off his rocker to challenge "the consensus". Exactly like AGW skeptics today are thought to be unhinged. Actually the only question in the whole of AGW, is whether anthropogenic CO2 emissions account for temperature data better than the random variances inherent in climate. Right now, they don't.
122820. oracle2world at 13:37 PM on 8 March 2010
        Human CO2 is a tiny % of CO2 emissions
        That carbon cycle from the IPCC AR4 graphic? Looks a bit different from another one from our friends at the UN: http://unfccc.int/essential_background/feeling_the_heat/items/3158.php In short, how did 6 gigatonnes a few years ago now become 26 gigatonnes of human CO2 releases?
        Response: The UN graphic uses units of carbon. I use units of carbon dioxide. The difference is fairly simple - 1 gigatonne of carbon equals 3.66 gigatonnes of carbon dioxide. I explain the conversion process in more detail at Comparing CO2 emissions to CO2 levels.
122821. oracle2world at 13:27 PM on 8 March 2010
        Was Greenland really green in the past?
        So let me get this straight. A warmer Greenland was a "local phenomenon", but twelve trees in a Siberian forest suffice to represent centuries of global temperature?
122822. oracle2world at 13:07 PM on 8 March 2010
        There is no consensus
        Here is an endorsement from the AMA. Glad to know this counts as important, even if off the beaten track of the AMA's expertise. In other words, professional society endorsements are about as useful as a professional ball player's endorsement of a particular brand of chewing gum. American Medical Association In 2008, the American Medical Association issued a policy statement on global climate change declaring that they: Support the findings of the latest Intergovernmental Panel on Climate Change report, which states that the Earth is undergoing adverse global climate change and that these changes will negatively affect public health. --http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change
122823. chris1204 at 13:06 PM on 8 March 2010
        Does record snowfall disprove global warming?
        johnd: I think predictions of a coming ice age based on one very cold and snowy winter may be a touch premature. However,if the snow cover proves unusually enduring, you may be onto something because albedo and like mechanisms begin to come into play. jimalakirti: the reference to the earlier postings on Himalayan Glaciers is very much to the point. The survival of these glaciers is very much monsoon dependent. Irrespective of glacier survival, increased water vapour and increased precipitation should predict less dire consequences for population living in areas dependent of Himalayan water run off. Or do they? Satellite data indicating rising sea levels notwithstanding, if increased temperature leads to increased atmospheric water, does most of the increased water vapour stay in the atmosphere thus providing a negative feedback on sea level rise? Or does the water simply cycle faster with no mitigating impact on sea levels? Assuming some rise in precipitation, would increased rainfall provide welcome change to the world's driest areas ranging from the Sahara to the Gobi? Three potentially very different implications flowing from the one phenomenon, the relationship between temperature, water vapour, and precipitation.
122824. oracle2world at 12:53 PM on 8 March 2010
        Hurricanes aren't linked to global warming
        Glad the consensus has determined hurricane frequency should be retired to the ash heap of arguments. So how did this one slip through the consensus? ---- Global warming is causing more frequent hurricanes in the North Atlantic and Gulf of Mexico, according to a study from the National Center for Atmospheric Research. The increased frequency of tropical cyclones ``is largely a response'' to a 1 degree Celsius rise in sea water temperatures since 1905 that was caused by greenhouse gases, the study found. Since 1995, the North Atlantic has experienced an average of 15 tropical storms a year, of which eight became strong enough to be called hurricanes. That compares with 10 tropical storms and five hurricanes per year from 1930 to 1994, the report says. ``There is an 80 percent chance that the majority of the current increases have been impacted by global warming,'' said Greg Holland, director of the research center in Boulder, Colorado, and co-author of the study. ``The bad news is that we've gone up in numbers overall, and in the proportion of major hurricanes as well.'' -- http://www.climateark.org/shared/reader/welcome.aspx?linkid=81144
122825. oracle2world at 12:31 PM on 8 March 2010
        Does record snowfall disprove global warming?
        "... 2009 was the second hottest year on record." The key phrase here is "on record". Now when you state "the record" doesn't go back very far, and isn't comprehensive to start with, THEN you can go into your snowfall arguments. What you can take away from snowageddon, is that people don't like cold weather or heavy snow. Which is why global warming is a political non-starter. Given a choice folks like warm weather and will do what it takes to adapt.
122826. yocta at 12:21 PM on 8 March 2010
        Does record snowfall disprove global warming?
        johnd # 19 You mention the predictions made in the 1970s. I don't know if John Cook has a pagehere but this site has a good history of what actually was predicted in the 1970s. It doesn't appear to be the clear cut cooling as one might get the impression of. http://laymans-guide.com/new-ice-age/
        Response: I do have a page on the subject: Ice age predicted in the 70s. The page you linked to, A New Ice Age, is an outstanding summary of the whole 'ice age in the 1970s' situation. I've added it to the list of links about the 1970s ice age predictions.
122827. garythompson at 12:17 PM on 8 March 2010
        Does record snowfall disprove global warming?
        #18 - Riccardo - Can you send that link again, it appears to be in error (can't click on it). thanks!
122828. carrot eater at 11:29 AM on 8 March 2010
        Does record snowfall disprove global warming?
        Similarly to some others, I don't see any particular need to discuss 'snowmageddon' in a climate context. Weather will always happen, and will surprise now and then. Now, if we start seeing 'snowmageddon' every year for the next 10 years, then we might take a closer if there is any climate context.
122829. Ani at 10:39 AM on 8 March 2010
        Does record snowfall disprove global warming?
        hello, happens so the AO broke and the arctic dumped, it happens every few years. thats weather. since i assume differential heating is the cause for most weather i would look at the temp changes near the arctic. this is purely a guess but its something a meteorologist can look at since weather is forecasting the noise and climate science is doing away with the noise. eventually we will get some overlap the two sciences will complement each other.
122830. EOttawa at 10:30 AM on 8 March 2010
        Does record snowfall disprove global warming?
        libertarianromanticideal, The article from the Independent that I was responding to focused primarily on Britain. Several paragraphs in that article (from 2000) did indeed cite anecdotal evidence of less wintery conditions, including snowfalls.
122831. captain_heroic44 at 10:19 AM on 8 March 2010
        CO2 lags temperature
        Why does CO2 drop off when temperature goes back down?
122832. GFW at 10:05 AM on 8 March 2010
        Does record snowfall disprove global warming?
        Sordnay, I don't know about globally (I'm sure someone has done it) but for the continental US, Tamino at OpenMind showed quite conclusively that the annual snow cover is decreasing, but that that decrease is entirely attributable to earlier spring melting and "higher" (up mountains) melting through spring and summer. Winter snow cover isn't changing to any statistically significant degree.
122833. GFW at 10:01 AM on 8 March 2010
        Does record snowfall disprove global warming?
        This (northern hemisphere) winter had some unusual weather patterns. It was warmer than average overall, but colder than average over the major population centers known as Europe and the eastern US. So the warmth was mostly over the oceans. It's pretty easy to see what had to happen - the warm air over the Atlantic would get loaded up with moisture, and then, following whatever regional circulation was present, would get swept over colder land and air masses - voila, surprising amounts of snow in the UK and the eastern US.
122834. shargash at 09:54 AM on 8 March 2010
        Does record snowfall disprove global warming?
        ptbrown31, it isn't just the air temperature; the water temperature plays a big role too. You are right to emphasize that snowstorms are weather events, not climate. But it is also true that storms will tend to be more intense, the warmer the atmosphere and the warmer the oceans.
122835. johnd at 09:49 AM on 8 March 2010
        Does record snowfall disprove global warming?
        Is there any chance of posting a chart comparing the historic % atmospheric water vapour against CO2 levels from the last ice age to present? If the water vapour content of the atmosphere is a direct function of temperature, and CO2 is the primary forcing agent of temperature, such a chart should illustrate how well the CO2/water vapour relationship has been maintained as the planet has warmed.
122836. Sordnay at 09:43 AM on 8 March 2010
        Does record snowfall disprove global warming?
        John #10 The case with -15 to -5 is clear, and I do agree. You also say "Until it becomes so warm that snow is not possible" so it seems obvious to me that where temperature where (at preindustrial times) just close to minimum in order to snow, now after the experienced warming, that it should be harder to see snow, then the more warming the less area covered, right? Is that what it's happening? There is a statistical correlation between global warming anomaly and snow cover anomaly? If there is not, should anyone make any statement at all?
122837. ptbrown31 at 09:41 AM on 8 March 2010
        Does record snowfall disprove global warming?
        The point you make in this post, while it is true in general, does not apply to the so called "snowmageddon" events. Both of those major east coast snow storms were associated with COLDER than average temperatures in those regions. Because of this you can not imply that they were caused by warmer air and hence more water vapor. I think a better way to address snowstorms and global warming is to emphasize that weather is not climate. The 2000's decade set 2X more record high temperatures than record low temperatures (in the United States) but that does not mean that record low temperatures are no longer seen - that is simply weather. http://www.ucar.edu/news/releases/2009/maxmin.jsp In general, great website. Keep up the good work!
        Response: Thanks for the comment. I wasn't trying to make the point that "global warming caused snowmageddon" but that "record snowfall does not contradict global warming". Perhaps I could have communicated that more clearly. When I was writing the post, I had a whole bit about weather vs climate with the weighted dice metaphor but cut it for brevity's sake. Maybe I should have left it in but fortunately I can always include it in the Record snowfall disproves global warming skeptic argument.
122838. johnd at 09:40 AM on 8 March 2010
        Does record snowfall disprove global warming?
        These recent events are merely indicators that the natural climate cycle is about to, or has, entered another cooling cycle which will last several decades. Just as the predictions back in the 70's of a coming ice age were made by projecting from the then ending downward cooling cycle, the more recent doom and gloom global warming scenarios were being made by projecting from a soon to end upward warming cycle. More realistic projections can be made from the trend established by a number of these multi-decadal natural cycles rather than data obtained from the ridiculously short part cycle time frames that have been used merely because new technology has only allowed more accurate data to be collected over such a short period. I often wonder what would have been the case if the current technology for data collection had been available immediately post WW2 and used to make long term predictions. Perhaps it would have given the global cooling predictions the same credibility as the current global warming predictions have. There is no doubt that there is a long term warming trend, but at times the natural cycles may enhance it, and other times overwhelm it, and perhaps we are presently in the transition of moving from a period of the former to the latter.
        Response: The best type of climate projection comes from a physical understanding of what's happening in our climate. The 1970s is a good example. Some looked at the cooling trend and projected continued cooling into the future. However, others looked at the rising carbon dioxide in the atmosphere and aware of the greenhouse effect it causes, predicted that temperatures would start to warm. For this reason, the majority of papers in the 1970s that looked at future climate predicted warming due to rising CO2 levels.
122839. Riccardo at 09:28 AM on 8 March 2010
        Does record snowfall disprove global warming?
        garythompson, the 18 W/m^2 is where we are now, i.e. the sum of short and long wavelength effects. What matters for the future is how this number might change with warming. On the cloud feedback there's still a lot to learn, but generally it is considered to be positive.
122840. Peter Hogarth at 09:14 AM on 8 March 2010
        Does record snowfall disprove global warming?
        16.RSVP at 07:03 AM on 8 March, 2010 I'm sure there will be an albedo effect, but it's going to be relatively small in Winter. May be oversimplifying, but extra snow cover in places that normally don't see much is not exactly long lived once the clouds get out of the way and a relatively small extra percentage of the Earths surface is affected. If it got deep enough (or cold enough) to stay until summer in NH, then we'd have an issue, eg Greenland throws back a lot of incoming sunlight in early summer. I'll have a look for papers on this though.
122841. garythompson at 08:53 AM on 8 March 2010
        Does record snowfall disprove global warming?
        good article here john, thanks. in my opinion this just shows how compicated weather is and how little we know (or at least I know). in my opinion, and in the opinion of others who have posted here, this increased evaporation which will lead to increased precipitation (and clouds). Correct me if i'm wrong but won't that be a negative feedback (not only from the sun reflection from the clouds but also the snow albedo)? in reading the peer reviewed papers, there seems to be great uncertainty in the models with how to handle clouds. in Ramanathan's paper (http://www-ramanathan.ucsd.edu/RamAmbio.pdf), he outlines very well that a good estimate based on ERBE observations show clouds have a net cooling of around 18 W/m^2 which dwarfs the positive feedback from CO2 which is 2.5 W/m^2 but we don't know how clouds will respond to increased SST. But if the increase in SST causes more evaporation and more clouds wouldn't this cancel out any CO2 effect?
        Response: If clouds were imposing a cooling forcing of 18 W/m², the Earth would be experiencing a dramatic, negative energy imbalance and global temperatures would be plummeting precipitiously. That is not what is happening - the planet has a positive energy imbalance of around 0.8 W/m².
        
        However, the change in cloud cover has had a cooling effect - it's estimated the radiative forcing from 1850 to 2000 was a cooling of -0.7 W/m². I couldn't tell you off the top of my head how much of that is estimated from increased water vapor - my understanding is the main contributor to increased cloud cover is increased aerosols in the atmosphere which enhances cloud formation.
        
        Since 2000, several different satellite datasets show very little trend in cloud cover  (Loeb 2007a):
        
        
        
        There's a more detailed discussion on albedo at The albedo effect and global warming.
122842. joseph449008 at 08:14 AM on 8 March 2010
        Does record snowfall disprove global warming?
        

        The earlier article talks about positive feedback due to methane, but here nothing about negative feedback due to higher albedo produced by snow cover.

        No one said all-year-round global snow cover will increase with global warming. It's clear that during glacial periods, there was more ice globally. It's also clear that during very warm historical periods (e.g. the Eocene-Paleocene Thermal Maximum), there was little ice, and hence the Earth's albedo was lower. It's a positive feedback overall.
122843. Andy Skuce at 07:20 AM on 8 March 2010
        New observations find underwater Arctic Shelf is perforated and venting methane
        CBDunkerson wrote: "the reason that surface concentrations (and thus atmospheric release) of methane are highest in shallower waters is BECAUSE they are shallow... there is less water for the methane to disperse through. {snip] As to geological processes producing methane... look at the ocean floor map. What could possibly produce that much methane that consistently over that large an area? We're not seeing isolated spots of methane release, but rather an entire region producing methane. That clearly points to release from the permafrost due to warming." CBD: The maps of methane concentrations are actually not that consistent over the area, whether measured near the sea bed, in surface waters or in the atmosphere. The maps show elongated N-S stripes*, whereas the main trend of the bathymetry is roughly at right angles to this. However, I do think that melting permafrost is the most likely and, perhaps, the only explanation for the observed methane; I would just like to better understand the influence, if any, of the deep geology. I note that the authors report using a chromatograph to analyse the gas but they don't mention observing any ethane or other alkanes. They do say that they intend to do some isotopic work in future. *The N-S trends in their maps actually look a little suspicious to me and I wonder to what extent they have been influenced by the orientation of some of the sampling stations along N-S transects (Fig 1A) and the authors' use of a Kriging gridding process. The coastline on Fig 1A is different to those shown on 1B,C and D, particularly for the islands, but this is just drafting error. None of this is likely material to their main point but I wouldn't be surprised to see it picked up and blown out of proportion by a certain mining engineer.
122844. RSVP at 07:03 AM on 8 March 2010
        Does record snowfall disprove global warming?
        The earlier article talks about positive feedback due to methane, but here nothing about negative feedback due to higher albedo produced by snow cover.
        Response: This is a good question. While there has been an increase in extreme snowstorm events in some colder regions, this doesn't mean snow cover is showing a long-term increase. In fact, the long-term trend for Northern Hemisphere is a decreasing trend (see Tamino's Cherry Snow for a detailed analysis of snow cover trends). In fact, one paper does examine the question of feedback from changing snow cover: Assessing Snow Albedo Feedback in Simulated Climate Change (Qu 2004). So if there is any feedback from changing snow cover, it's a positive feedback.
122845. shargash at 06:52 AM on 8 March 2010
        Does record snowfall disprove global warming?
        Come on, guys. This isn't that hard to understand. If there's more moisture in the air, there's going to be more precipitation. If it is cold enough to snow, that precipitation will be in the form of snow. There hasn't been enough warming to banish winter yet. It may snow less often, but when it snows, it will snow more (on average). That's just the laws of physics. Learn them.
122846. John Mason at 06:28 AM on 8 March 2010
        Does record snowfall disprove global warming?
        Nickle, # 6: This is entirely likely to occur. The most basic laws of physics expect it to: 1) warmer SSTs = more evaporation 2) warmer air (even if it's -5 instead of -15) carries more moisture Add in a nor-easter, where the air is warmed as it circulates across the Gulf Stream then piles back into the Eastern Seaboard and meets cool arctic Northerlies, and Hey Presto! One big dumping of snow! Until it becomes so warm that snow is not possible, expect bigger & bigger dumpings! Cheers - John
122847. libertarianromanticideal at 06:01 AM on 8 March 2010
        Does record snowfall disprove global warming?
        Hi EOttawa you say: "Dr. Viner was not that far off. The article you referenced (from 2000), quotes Dr. Viner as saying that heavy snow will return occasionally and that "Snow will probably cause chaos in 20 years time"." Are you saying that heavy snow fall did disappear for awhile and now just returned? Rutgers University Global Snow Lab numbers (http://climate.rutgers.edu/snowcover/files/moncov.nhland.txt) doesn't support that. The Snow lab numbers (1967-2010) show that the just completed decade (2001-2010) had the snowiest Northern Hemisphere winters on record. The just completed winter was also the second snowiest on record, exceeded only by 1978. Average winter snow extent during the past decade was greater than 45,500,000 km2, beating out the 1960s by about 70,000 km2, and beating out the 1990s by nearly 1,000,000 km2. - Cheers, Christopher Skyi http://libertarianromanticideal.com/
122848. jimalakirti at 05:59 AM on 8 March 2010
        Does record snowfall disprove global warming?
        I recommend the earlier post on this site about glaciers. Some glaciers in the Himalaya region are growing because above about 15,000 feet or so all precipitation is in the form of snow, and the monsoons are being redirected to parts of the mountains so that they will get a lot more precipitation. What happens to the glaciers from which the monsoon is being removed? Well they will shrink. Some may even disappear within 20 years or so. By the way, that posting has about 80 or so of the most absurd trash one can imagine. Don't go there if you aren't prepared to have your head buzz and your ears ring.
122849. Riccardo at 05:53 AM on 8 March 2010
        CO2 effect is saturated
        mazibuko, the problems with those guys is that their reasoning looks straightforward and anyone can understand it. The mistake he makes becomes apparent only if you know the physics. So common people tend to trust those bogus falsifications. The problem with that "falsification" is not just related to the single band he considers, he arbitrarly put a limit to the amount of radiation CO2 can absorb. This is not true both experimentally (as shown in this post) and theoretically even for the 15 micron band alone; and it would not matter anyway.
122850. mazibuko at 05:19 AM on 8 March 2010
        CO2 effect is saturated
        What do you make of this claim? http://jimpeden.blogspot.com/2009/11/norm-kalmanovich-on-global-warming-hoax.html I haven't read it thoroughly, but it seems like they are missing the fact that CO2 is absorbed at several different wavelengths. The post devolves into the usual questioning of motives, but I was curious to hear thoughts on the main claim about the 14.77 micron band being used up. Thanks, M

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