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sun tzu at 18:21 PM on 2 September 2010It's the sun
Thanks for the reply, actually the above question stemmed from reading a book by Sir Patrick Moore called 'Astronomy' where he briefly covered solar activity and the effects on the thermosphere (I am currently starting to study Astronomy and astrophysics as a past time and found it to be a great starting point!). The reason I considered the atmospheric effect is we have been undergoing a mild period of cooling over the last couple of years whilst the upper atmospheric altitude is apparently reduced. It occured to me that another effect of this is, if the atmosphere has a smaller diameter then is it logical that the planets solar foot print is also smaller meaning more solar energy just keeps on going through space rather than getting absorbed by atmospheric gasses?.. Another area I dont think I have seen mentioned on here is the question of why are the planet Mars Ice caps also receeding? is this in some way linked to our own warming or is it simply a matter of Mars orbit in realtion to the sun? has anyone been able to reference Martian Polar recession with our own warming cycles in relation to its proximity to the sun?... Im not 100% in favour of 'The sun did it' as there are many many other areas that affect global climate, Deforestation of the rain forests, Methane, CO2 Emissions, Atmospheric particulates, Atomic Testing infact a whole load of variables.. however, it does occur to me that perhaps CO2 is more an effect than a cause? eg CO2 release due to polar ice decay, Deforestation etc... I would hate to describe myself as a 'tree hugger' but from what I can tell perhaps everyone in both camps might be right here increased carbon gasses and solar activity may both have a role to play in global warming, amongst many many other variables!... another thought as well is the icecaps are receeding then doesnt that put alot more cold water at the bottom of the oceans too? and im guessing that might in someway cause for carbon release? Anyhow, looks like i have a few years worth of reading, experimenting and computer modelling to go lol... All I can say is Im half between 'Tax on Co2' being a government attempt to charge more for less resources (charge more for fuel and electricity whilst not having to invest in infrastructure for the ever growing global population,peak oil etc, after all Climategate has done the scientific community no favours at all either way) and a very serious genuine problem that needs to be addressed urgently yet is being cashed in on by unscupulous politicians and glory seeking scare mongerers!..anyhow, thanks for the excellent reply and will get thinking, researching and trying to test some ideas out! -
JMurphy at 17:45 PM on 2 September 2010How we know an ice age isn't just around the corner
It would also appear that the so-called skeptics' belief that last Winter in some parts of the Northern Hemisphere (AKA 'the world' in so-called skeptical speak) was a sign of things to come (i.e. the coming Ice Age), was a little premature : Northern Hemisphere winter snow anomalies: ENSO, NAO and the winter of 2009/10 Winter 2009/10 had anomalously large snowfall in the central parts of the United States and in northwestern Europe. Connections between seasonal snow anomalies and the large scale atmospheric circulation are explored. An El Niño state is associated with positive snowfall anomalies in the southern and central United States and along the eastern seaboard and negative anomalies to the north. A negative NAO causes positive snow anomalies across eastern North America and in northern Europe. It is argued that increased snowfall in the southern U.S. is contributed to by a southward displaced storm track but further north, in the eastern U.S. and northern Europe, positive snow anomalies arise from the cold temperature anomalies of a negative NAO. These relations are used with observed values of NINO3 and the NAO to conclude that the negative NAO and El Niño event were responsible for the northern hemisphere snow anomalies of winter 2009/10. -
scaddenp at 17:36 PM on 2 September 2010Climate change: Water vapor makes for a wet argument
TOP - the point about water vapour is that it is a feedback not a forcing. You dont have a physical process that increase or decrease water vapour content independent of temperature. ANY forcing that increases or decrease surface temperature will be amplified by the feedback of water vapour. With solar and aerosols stable or decreasing, its GHG that is the dominant post-1975 forcing. This isnt hand-waving - its backed by solid measurement of the extra radiation heating the surface matching the theoretical calculation of GHG effect resulting from the observed increases. -
scaddenp at 17:27 PM on 2 September 2010How we know an ice age isn't just around the corner
GC - give me some science to support the "temperatures will drift lower over next decade or so". What will be your position if they dont? And also, the 100 year rate of change is still near order of magnitude higher than rate of change from Milankovich cycle. -
Marcus at 17:05 PM on 2 September 2010Climate change: Water vapor makes for a wet argument
Yes I did miss the emoticon. I read some of your other posts, in other threads, & realized that (a) denialist you are not & (b) you usually provide some excellent analysis. Consider my comment retracted :)! -
HumanityRules at 16:22 PM on 2 September 2010Sea level rise: the broader picture
59.Dappledwater You seem to have mixed up the sources of your quotes but I get your point about regional variation. Figure 7 from Merrifield does suggest that the lack of good data in the southern and tropical oceans prior to 1950 comprises all comparisons of early and late 20th century SLR. It looks like the experts like to compare apples and oranges as well. -
HumanityRules at 16:16 PM on 2 September 2010Sea level rise: the broader picture
I've found 4 papers looking at closing the sea-level budget around 2003-2007. The latest is from this year. Basin patterns of global sea level changes for 2004–2007 You-Soon Chang, Anthony J. Rosati, Gabriel A. Vecchi Journal of Marine Systems 80 (2010) 115–124 Chang, like the others, calculate the steric and mass components using ARGO and GRACE and compare it to the total change calculated from altimetry. They handily summarize the 4 published attempts to close the sea-level budget in a table. Chang et al (2010) STERIC −0.11±0.22 MASS 0.70±0.34 TOT 2.67±0.52 Willis et al. (2008) STERIC −0.5±0.5 MASS 0.8±0.8 TOT 3.6±0.8 Leuliette and Miller (2009) STERIC 0.8±0.8 MASS 0.8±0.5 TOT 2.4±1.1(2.7±1.5) Cazenave et al. (2009) STERIC 0.37±0.1 MASS 1.9±0.1 TOT 2.5±0.4 Chang and Willis fail to close the budget and interestingly fail with pretty much the same numbers. Leuliette and Cazenave manage to close the budget but by very different means. Leuliette through an equal contribution from steric and mass. Cazenave primarily (80%) through mass. If we look at all the available estimates there appears to be no real concensus on this issue. -
Tom Dayton at 14:24 PM on 2 September 2010Water vapor is the most powerful greenhouse gas
daisym, I believe that some types of clouds are understood to have a net cooling effect, and some a net warming effect. The difficulty, I believe, is in figuring out the relative contributions of those types of clouds in any given scenario. Realclimate has a post addressing clouds' role in albedo changes. It has another post on the role of aerosols in triggering cloud formation. And it has another post on the purported role of galactic cosmic rays in triggering clouds. -
gallopingcamel at 14:02 PM on 2 September 2010How we know an ice age isn't just around the corner
ScaredAmoeba (#12), Your comments make sense although I believe you are judging "Denialists" too harshly. Ned (#13), It may sound odd but I do care about what will be happen long after my demise. I plant trees and work to reduce river pollution in the hope that my children (and yours) will benefit. GFW (#16), You seem to buy David Archer's idea that rising CO2 concentrations will have a more powerful effect than Milankovitch cycles. I hope you are right. How do you explain the glacial periods that occurred when CO2 concentrations were ten times higher than today? scaddenp (#17). I agree that the rate of change is important. However, you cannot assume that the rapid warming that occurred from the 1975 to 1998 will be the norm. Global temperatures have drifted lower over the last decade and are likely to fall for at least another 10 years.Response: "How do you explain the glacial periods that occurred when CO2 concentrations were ten times higher than today?"
The sun was cooler back when CO2 was higher.
"Global temperatures have drifted lower over the last decade"
Global temperatures have not drifted lower over the last decade - the planet is still accumulating heat and the hottest 12 months on record are June 2009 to May 2010.
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Daniel Bailey at 13:52 PM on 2 September 2010Climate change: Water vapor makes for a wet argument
Re: Marcus Denialist? Moi??? Been accused of many things in my life (never convicted) but never a denialist. Dude, you must've missed the smiley emoticon...see Poe's Law. The Yooper -
Joe Blog at 13:34 PM on 2 September 2010How we know an ice age isn't just around the corner
Bern No, these rapid changes where counter hemispherical(as you say, as good as can be ascertained from the paleo reconstructions) And im not just talking about the younger dryas event.. the rise out of glaciation was punctuated with rapid shifts, several degrees a decade. This whole "most rapid warming" is referring to extremely recent geological record... the last 1-2kybp. The early Holocene was not a stable climate. -
TOP at 13:04 PM on 2 September 2010Climate change: Water vapor makes for a wet argument
One of the Easy Teasy Lemon Squeezy sources says: It is currently not clear how much of the correlation between air traffic and cirrus cloudiness is actually due to a causal relationship. Hence the determination of the radiative forcing of contrail cirrus is fraught with large uncertainties; studies to resolve the differences and to constrain the error margins are certainly needed. All studies suggest that air traffic actually induces additional cirrus clouds, which seems plausible. However it is extremely difficult to demonstrate and prove such a correlation because the variation of cirrus cloudiness due to natural influences is much larger than the possible aviation effect. Hence, to look for the latter is like looking for a signal hidden in strong noise. This particular article is primarily concerned with parameters for models. Another one attributes a 1.2C increase in Tmax and a .3C increase in Tmin in areas with high contrail concentrations. This study used the paucity of civilian air traffic during 9/11 - 9/14/2001 to obtain temperature sensitivity to contrails. One of the factors that had to be corrected for was that the CONUS was essentially cloud free during that period. -
Marcus at 12:54 PM on 2 September 2010Climate change: Water vapor makes for a wet argument
No Joe Blog, the estimates I gave are based on the reports of J. T. Kiehl & Kevin E. Trenberth in "Earth’s Annual Global Mean Energy Budget"-from the "Bulletin of the American Meteorological Society 78 (2): 197–208." The point remains the same though, which is that on a ppmv basis CO2 is a significantly more powerful GHG than Water vapor, by at least 3:1. @ Daniel Bailey #6. Seriously, this kind of childish post might be acceptable for your fellow Denialists, but it really does nothing at all to advance anyone's understanding when you put up posts that are devoid of any intelligent analysis (like the fact that Ice & Snow don't *cause* Ice Ages, but are a symptom of Ice Ages caused by significantly reduced insolation.) -
TOP at 11:55 AM on 2 September 2010Climate change: Water vapor makes for a wet argument
This is a straw argument. Both water vapor and CO2 absorb IR radiation. Water vapor is a broad spectrum absorber with a large gap in absorption at IR wavelengths that effect the temperature regulation of the planet's atmosphere. CO2 is a notch absorber that overlaps and somewhat extends into the lower end (higher wavelength end) of the gap in water vapor's absorption. As the temperature of the atmosphere increases so the wavelength of the IR carrying heat by radiation shortens and moves away from the wavelength that CO2 absorbs and into the center of the gap in the water vapor absorption band allowing more IR energy to escape. The higher the temperature of the atmosphere, the less the effect of CO2. Of course it will be pretty toasty when that day comes. Anybody that has looked at the absorption of CO2 and methane overlaid on that of H2O would know this. Secondly H2O has another nice property. When it absorbs IR it causes the air in which it exists to rise with it. When the lapse rate causes the water vapor to condense the heat is released to continue traveling up while the air below is cooled. CO2 doesn't have this nice phase change under normal atmospheric conditions. But it goes along for the ride anyway. Water vapor is the most powerful greenhouse gas. That statement doesn't imply anything about the importance of CO2. CO2 is also a greenhouse gas. Speaking about CO2 out of the context of it's relation to the water vapor can be and is misleading. -
Bern at 11:53 AM on 2 September 2010How we know an ice age isn't just around the corner
Joe Blog - as I understand it that high-rate temperature change was strictly a localised phenomenon - one of the candidates for cause is the release of meltwater from behind the ice sheet over North America, interrupting the flow of warm water to Europe. While this would have caused a dramatic drop in temperatures in Europe, it probably would have led to even *warmer* temperatures further south - after all, if that equatorial heat isn't ending up at northern Europe, it's gotta go somewhere! I imagine a good global reconstruction for that time period would show this effect quite well, while also showing that the global average temperature continued to change at a relatively slow rate. -
Daniel Bailey at 11:37 AM on 2 September 2010Climate change: Water vapor makes for a wet argument
Yes, Virginia, water vapor IS a GHG, regardless of altitude. Except for the white lumpy kind that collects & causes ice ages. :) The Yooper -
Joe Blog at 11:35 AM on 2 September 2010Climate change: Water vapor makes for a wet argument
Marcus, i believe the figures you are using are derived by subtracting the persistent gases effect in isolation from the total 33k effect... but then water vapor should still be around the 65% mark... but in reality is more inline with about 80% i believe on "average". But if you stripped all the water vapor out of the atmosphere the temp doesn't drop by 26.4k, but more by around the 65%-70% mark (21.45k-23.1k) There is a good thread on it at real climate. And yes mattj, i too have been learning about the non linear response o water vapor over at science o doom. A not so simple Q with water vapor... even taken in isolation(ignoring possible albedo effects) -
Daniel Bailey at 11:30 AM on 2 September 2010Climate change: Water vapor makes for a wet argument
Re: MattJVapour trails or contrails, by affecting the Earth's radiation balance, act as a radiative forcing. Studies have found that vapour trails or contrails trap outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) at a greater rate than they reflect incoming solar radiation (negative radiative forcing). Therefore, the overall net effect of contrails is positive, i.e. a warming. However, the effect varies daily and annually, and overall the magnitude of the forcing is not well known: globally (for 1992 air traffic conditions), values range from 3.5 mW/m² to 17 mW/m². Other studies have determined that night flights are mostly responsible for the warming effect: while accounting for only 25% of daily air traffic, they contribute 60 to 80% of contrail radiative forcing. Similarly, winter flights account for only 22% of annual air traffic, but contribute half of the annual mean radiative forcing.
Easy Teasy Lemon Squeezy Source Higher humidity at lower elevations means that the water vapor in the exhaust is released below the saturation point of the air, thus no condensation/crystalization of the vapor & no contrail. The Yooper -
daisym at 11:19 AM on 2 September 2010Water vapor is the most powerful greenhouse gas
#94: Interesting! Now imagine that a decrease in water vapor in the atmosphere would cause fewer clouds to form. As a result, the Sun can warm the surface more than when clouds got in the way, which puts more water vapor back into the atmosphere to form clouds. Imagine a planet with no cloud cover. What would the surface temp be? If the answer is "hot", then clouds could rightly be said to have a cooling effect. If not, then the opposite would be the case. Which is it? Clouds have often been said to be where the biggest disagreement remains. Is the net effect of clouds to a positive or a negative feedback? I'm not aware that this has been settled. -
Marcus at 11:18 AM on 2 September 2010Climate change: Water vapor makes for a wet argument
Here's the thing, though. Water vapor accounts for just over 50% of the total Greenhouse effect-on average (it obviously varies according to temporal & geographic factors). Wheras CO2 accounts for just under 20% on-average. Yet water vapor accounts for between 1% to 3% of the atmosphere, whilst CO2 accounts for less than 0.1% of the atmosphere. This suggests that, on a ppmv basis, CO2 is clearly a more potent greenhouse gas than water vapor. -
MattJ at 11:07 AM on 2 September 2010Climate change: Water vapor makes for a wet argument
One consideration neglected by skeptic and non-skeptic alike is: water vapor is a GHG at some altitudes, but not all. Or so I learned years ago. The example given was that water vapor emissions from high altitude airliners was a problem, but water vapor at lower altitudes is not. Or has this result been overturned since then? -
cruzn246 at 11:03 AM on 2 September 2010Climate change: Water vapor makes for a wet argument
So where is all this heat?Moderator Response: Go to the home page. At the top right, click on the big image that says "Global Warming Is Still Happening." In the resulting page, click the "Intermediate" tab. -
adelady at 10:53 AM on 2 September 2010Weather vs Climate: Watch the waves, miss the turning of the tides
Iciattaglia, we all know that. Noone thinks that the earth itself is in danger of expiring. The climate change that concerns us is this climate and its stability. This climate phase has allowed humans to thrive and flourish because it suits the temperature range we can live in comfortably and it suits the kind of plants that sustain life. Our kind of abundant life, not the kind of life that just survives in ice or fire or sitting atop an undersea volcano. Your argument is about geology and time frames of many millions of years. We're concerned about biology and timeframes of centuries or millennia. -
scaddenp at 09:34 AM on 2 September 2010Urban Heat Islands: serious problem or holiday destination for skeptics?
I should also point out the UHI is affected by wind speed. I can think of well-sited stations where the prevailing wind off the sea means that no how big the urban center beside it is, there is no chance for heated air from the city to affect the bulb. BP's assumption for correlating UHI to change in urban size are too naive to be valuable. -
scaddenp at 09:27 AM on 2 September 2010It's Urban Heat Island effect
Hadfield - you might like to look at Are Temperature Trends affected by Economic Activity? for a starting point if you want reference to the 2004 effort. For the 2008 version, then an analysis was published here -
Joe Blog at 09:14 AM on 2 September 2010How we know an ice age isn't just around the corner
I think there is a bit o a misconception here in regards to rate o climate change.... coming outta the last glaciation, the rate o change was at times SEVERAL orders o magnitude above the current trends.... this is where the tipping point hypothesis have come from! http://www.chmi.cz/HK/OK/clivar-cz/PRA_posters/clivar_poster_pages2.pdf http://www.gisp2.sr.unh.edu/DATA/fancy.html http://math.ucr.edu/home/baez/temperature/ -
James Frank at 09:01 AM on 2 September 2010It's Urban Heat Island effect
Hadfield does have a point. The summary paper linked to has arguments against several of the explanations presented here. Have there been any responses to their paper that address these concerns? -
Daniel Bailey at 08:57 AM on 2 September 2010It's the sun
sun tzu @ 580 No harm in being a layman in anything. All of us were at one time. Remember the atmosphere is layered, like an onion. Forces that act on one layer may, or may not, act upon an adjacent one. Increasing CO2 exerts its main influence in the upper troposphere, the lowest layer, causing it to warm. Lack of energy being transmitted upward from the troposphere to the stratosphere means the stratosphere cools (which is measured by satellites). When layers cool, they can compress, thinning somewhat. Recent UV output from the sun has been declining, causing the thermosphere, one of the outer layers of the Earth's atmosphere, to compress downward, to a record low thickness. The net effect of this compression is less atmospheric drag on our communication & research satellites in low Earth orbit (which extends their service lifetime - bonus!). Note that changing energy levels of the various layers of the atmosphere or their thicknesses has no effect on the mass of the column of air above any point on the Earth (which is what determines the local air pressure). Atmospheric physics is a complex area of study. Even experts in it get confused sometimes (or tripped by the D-K Effect). For an introductory starting point, try start here first, then go here, then go here to figure out where to go next. Wiki, surprisingly, is a good source as well. Once you know what to type in, anyway (Catch-22: you have to know enough to search for what to learn about next, but how do you search if you're a complete beginner?). Hope this helps, The Yooper -
sun tzu at 08:32 AM on 2 September 2010It's the sun
http://science.nasa.gov/science-news/science-at-nasa/2000/ast30may_1m/ Apologies for spamming the forums! heres one source that discusses the low earth orbit/atmospheric friction/ solar activity -
sun tzu at 08:26 AM on 2 September 2010It's the sun
Eg. atmospheric density affecting solar absorbtion rates -
sun tzu at 08:20 AM on 2 September 2010It's the sun
What I am trying to articulate (badly) is the overall constitution of atmospheric gas density and thermal retention - is there a correlation there? -
sun tzu at 08:17 AM on 2 September 2010It's the sun
I have been reading many of the posts here and must admit I am a layman in terms of climatology, however, has anyone looked into comparing the density of atmospheric gasses/atmosphere/atmospheric ceiling over time?. As I understand it, Low earth orbit debris has been increasing due to a lower atmospheric ceiling, and if it is due to a lower ceiling/upper atmosphere density has the atmosphere increased in pressure or been absorbed somwhere else? (co2 into the ocean possibly? methane reacting with UV?). Now if the aforementioned where true, would it not be a similar scenario to how a refrigerator functions in that the denser gas acts as an insulator retaining the heat then as it is decompressed/expands it cools by realising the heat energy (like an aerosol can)?.. as i have previously stated I am a complete novice and apologise for not being able to submit any sources, this comment is intended more as food for thought than anything else and will most likely barking up the wrong tree altogether! -
Daniel Bailey at 08:09 AM on 2 September 2010Carbon dioxide equivalents
Re: TOPIt is an important distinction because CH4 is a much more powerful GHG. CO2 residency can be reduced by planting new trees. CH4 can't. Big point.
I understand your first point. Please keep in mind that:1. While on a molecule-for-molecule basis methane is about eighty times stronger greenhouse gas than carbon dioxide due to it's much smaller concentration in the atmosphere, the greenhouse effect attributed to methane is 4-9% of the whole, whereas that attributed to CO2 is 9-26%. Thus, the Radiative Forcing (W/m2) of methane is 0.48 while that of CO2 is 1.46. And keep in mind that the concentrations of methane (1745 ppb) are a tiny fraction of that of of CO2 (390 ppm). Yes, the methane will provide a modest increase in RF during its 12-year residence time before it degrades into CO2. But the warming coming from that CO2 concentration will (like the Energizer Bunny) keep on going, and going, and going... And thus rendering the need to sequester the methane moot (because it presto/chango converts to CO2). 2. AFA planting trees. Sure. Yup, in the tropics, it makes sense. But in temperate and more northerly climes, reforestation actually causes the new forests to become part of the warming problem. Because the new tree canopies are darker, they effectively change the albedo of the newly forested area, causing more heat to be retained near the ground. See here and here for a nice discussion.
And atmospheric aerosol pollution hasn't stopped per se so much as it has leveled off. CO2 concentrations have been doing their Icarus thing. Hence the emergence of the CO2 warming signal from the cooling effects of aerosols. Aerosols are still reducing the warming effect of CO2, not stopping it. Hence, we are buying the current generation time, at the expense of all future living generations. Unrestrained BAU will make this place a living H-E-Double-Hockey-Stick for our grandchildren's generation. Which will continue for centuries.States like Wisconsin that once were huge forests and now have a lot of worn out farm land are another target for trees.
Really? Have you BEEN to Wisconsin lately? Dude, I drive all across Wisconsin and Northern Michigan, daily. Every viable plot of land with soil decent enough for growing is under cultivation. The rest is either houses, swamps or stands of crapwood, like popple or jackpine. All the good soils were "expatriated" to Illinois, Indiana & Ohio by some white lumpy rainish-stuff millenia ago... The remnants of the once mighty forests that stood here (the stumps of which measure up to 8 feet across) are still visible in places. Those giants took many centuries to reach maturity in these poor soils. Reforestation going on now focuses on the fastest-growing pines, which are soft and unsuitable for building purposes (they use them to make paper, toilet paper and particle boards of various sizes & thicknesses). The CO2 drawdown potential of softwoods vs hardwoods is pretty low. The 6 foot-thick oak in my backyard somehow escaped (probably because all of the old hardwoods here are natural bonsai's and don't grow that high compared to their more southern relatives) the loggers of the 1800's (some of them my ancestors) and is estimated to be about 450-500 years old. Lotta board feet, but not useful for Carbon Capture & Sequestration purposes. ---------------------------------------------------------------------------------------------------------------------- Re: RSVPI am not sure China shares any more guilt here than those who consume their products...(which could be almost anyone).
Excellent point. In an intertwined, global, consumeristic society, all are guilty. You guys got me all fired up. I hates that. The Yooper -
nigelj at 07:49 AM on 2 September 2010How we know an ice age isn't just around the corner
A scientist called Ruddiman has a book speculating we started altering the climate with early farming thousands of years ago. It appears humanity has been heading off an ice age thats going too far too fast as in #17. An unconscious deliberate experiment or just chance? -
scaddenp at 07:26 AM on 2 September 2010How we know an ice age isn't just around the corner
GC - once again - RATE of change is what is more important. Maybe warmer would be better in long term but only if we get there slowly. I would like some explanation from you of why you think rate doesnt matter. -
michael sweet at 05:55 AM on 2 September 2010Sea level rise: the broader picture
HR at 56 YOU are comparing the 5.4 mm local rise to global 3.3 rise and saying it is similar to global changes from 1.8 to 3.3 mm/yr, not Ned. You are comparing apples and oranges and using a single standard. As I said, we EXPECT local changes to be more varied than global averages. Therefor 5.4 at a local site is comparable to 3.3 as a global average. We EXPECT global averages to be stable. Thus the global figure changing from 1.8 to 3.3 is significantly different. Even though these two data sets are similar in magnitude the meaning of the changes is different. Because of noise and other factors, single site data has more variability than global data does. You cannot use the same standard to compare two global averages that you use to compare a local point to the global average. It is often confusing to people who do not work with data all the time when there are issues like this. Even people who work with numbers all the time make mistakes. That is why we rely on experts to interpret the data. The experts have figured out how the data can be compared. Dougs post is a reasonable summary of expert opinion. -
tobyjoyce at 05:24 AM on 2 September 2010Arctic sea ice... take 2
Peter Hogarth, What an impressive video!!! It is like watching a dying beast gasping for breath, and flailing around to hang on to some life. Very emotional and unscientific, of course. -
GFW at 05:22 AM on 2 September 2010How we know an ice age isn't just around the corner
For those who fear a return of the Laurentide ice sheet, why is it not obvious that the correct response would be something like this flowchart a) Be carbon neutral for thousands of years b) If ice sheets start growing, burn some carbon - maybe 5 to 10 ppm increase in CO2 c) Continue to monitor ice sheets, return to (b) In other words, with our capability to dig up fossil fuels and burn them, we can *easily* dominate the Milankovitch cycles. The danger is going too far the other way, which we are near to doing. Recall that the "normal" interglacial CO2 concentration is 280-300 ppm. We can hold off any natural cooling by keeping CO2 at some slightly higher level, probably 320-350 ppm. Note that the rate of burning fuel to hold that range of CO2 concentration would be very low, so conventional fossil fuel reserves would last darn near forever (and we could mine methane hydrates after that - probably a few million year's worth, after that, the sun is warmer ...) Our mad dash to higher CO2 levels (currently 390 +2/y) might be great for Jurassic flora and fauna (if we had any) but is likely to be a significant extinction event for current species. -
RSVP at 04:46 AM on 2 September 2010Carbon dioxide equivalents
And yes it is hopeless, except that God only left so much fossil fuel on this Earth (probably for this very reason). -
RSVP at 04:44 AM on 2 September 2010Carbon dioxide equivalents
michael sweet asks... "How does this relate to DEMOCRACY for those of us who are not paranoid?" Not paranoid as much as considering how technically capable your average politician may be. -
RSVP at 04:39 AM on 2 September 2010Carbon dioxide equivalents
JMurphy said... "Anyway, although China is now the largest emitter of CO2..." I am not sure China shares any more guilt here than those who consume their products...(which could be almost anyone). -
Timothy Chase at 04:35 AM on 2 September 2010Arctic sea ice... take 2
From the main essay:As you might imagine, thick ice takes a lot more heat to melt, so the fact that it is disappearing so fast is of great concern.
I just wanted to check... I presume the big reason for this would be that it is denser -- more compact as the air has been squeezed out of it. Another reason would be that through previous summer seasons the saltwater has been drained out of it -- as saltwater has a lower freezing temperature -- leaving rotten ice -- which with cycles of being compacted and drained each summer after perhaps two or three years will be pure enough that you can drink the melt water -- implying a higher freezing point. -
The surprising result when you compare bad weather stations to good stations
Omnologos, you are making rather extraordinary claims. As discussed on the current page, in more detail on the intermediate version, checked against other readings to examine the UHI effect, and finally examined in detail for surface temperature reconstruction errors, there is no evidence of microsite or UHI contamination causing the observed warming trends - they are not spurious. You seem to believe otherwise, stating that perhaps "...the upwards trend can't be ascribed to an actual "warming"", or that "...maybe there is no trend.". Then show it. There's a large body of peer reviewed work demonstrating that there is a warming trend as shown in the surface temperature records; if you want to claim otherwise then I suggest you demonstrate it. Vague insinuations about data quality don't disprove warming, especially given the repeated analyses that validate the data. "Extraordinary claims require extraordinary evidence" - Carl Sagan. You've yet to provide any evidence whatsoever... -
JMurphy at 03:34 AM on 2 September 2010Carbon dioxide equivalents
TOP, have you put in a quote for planting trees in the Sahara, or do you have some figures we can all see which would show how viable a proposition it is ? I also notice that Wisconsin is presently 46% forested and is also important agriculturally, especially in the dairy industry. How much of that do you think they should give up so that they could plant more trees ? And if you reckon that "CO2 would drastically increase from today's numbers" if the "world emitted GHG per capita like China", you obviously agree that it would be far, far worse if the world emitted at US rates, I suppose ? Actually, it's a shame that the world DOESN'T emit at China's rate. -
Ned at 02:59 AM on 2 September 2010Urban Heat Islands: serious problem or holiday destination for skeptics?
Thanks, Philippe and muoncounter. The method used here (modeling a UHI bias based on log2 population change) doesn't seem super-convincing to me. But since BP proposed it, I thought I'd work out the quantitative implications, using a more realistic framework than the assumption that population increases uniformly everywhere. muoncounter, I agree on the "saturation" thing. But I think the bigger problem is in extrapolating the model in the opposite direction. Do we really expect a large UHI effect associated with the four doublings from 1 to 16 persons per km2? Sixteen persons per km2 is still a very sparse population. Bottom line, though ... even if you accept BP's model, you only get 3% of the global temperature increase coming from UHI. -
omnologos at 02:36 AM on 2 September 2010The surprising result when you compare bad weather stations to good stations
Some here seem to have a problem with Menne et al themselves (a case of being more royal than the king, perhaps). May I quote again: "The reason why station exposure does not play an obvious role in temperature trends probably warrants further investigation" If the answer were e.g. "it's the precision", perhaps Menne et al would have mentioned that without suggesting any "further investigation". As just written by @Dappledwater, the "obvious" result has been contradicted by the "surprising" one. That can only mean there is more food for our scientific curiosity. If on the other hand we are just obsessed with countering other people's arguments on the basis of them being deniers or skeptics or anything else, well, there goes the curiosity, and there goes the science. BTW, @Tom Dalton: you have completely misinterpreted my remarks. Please don't waste any more time with...shall I say it...reductio ad absurdum. Of course even if there were no warming trend, it's just US stuff we are analyzing, etc etc. -
TOP at 02:34 AM on 2 September 2010Carbon dioxide equivalents
Yooper Which then has a residence time on the century timescale. Actually surprised and disappointed you nit on this one. It is an important distinction because CH4 is a much more powerful GHG. CO2 residency can be reduced by planting new trees. CH4 can't. Big point. Your points about the thinning of the haze about corresponds to the drive to reduce pollution. I remember driving in rush hour traffic where you could gag on the fumes. And there was the acidification of lakes in the East. That has all stopped in your time frame and now we have another problem, but one with a simple solution. Plant trees. JMurphy I could see where a Londoner would have trouble with trees in London proper. But then London isn't the only treeless place on the planet. Look at the Sahara. Big tree farm possible there. Anyplace you have water and sunlight you can grow trees. No need for doom and gloom about places to plant trees. I have a motto, "Make hockey sticks from trees, make trees from hockey sticks." If you look at the Western US you will see a lot of logged out areas. There is another prime candidate. States like Wisconsin that once were huge forests and now have a lot of worn out farm land are another target for trees. In addition to China burning a lot of coal (you can see the plume of CO out over the Pacific by satellite) they are contributing to the deforestation of the Amazon in order to grow soybeans and other foodstuffs. Huge farms have been created in what was once rain forest. Since China is a growing economy and things are constantly changing there, it should be the prime target to implement improvements. But while they may have the technology, they aren't using it. Per capita doesn't work with China or anywhere else. A small town in China is 4 million people. If the entire world was emitting GHG per capita like China, CO2 would drastically increase from today's numbers. Bad suggestion. Adding India to the loop would be even worse. China has no choice but to look to renewable energy. At the current rate of coal mining they will be out of coal in 50 years. They take a long view. -
muoncounter at 02:29 AM on 2 September 2010Urban Heat Islands: serious problem or holiday destination for skeptics?
#20: "calculated the number of doublings of population density for every grid cell" Ned, Nice work. But I wonder: Wouldn't the UHI become, in essence, saturated? Once an area became sufficiently 'urban', would each statistical doubling of its population actually add twice as much 'urban heat'? So wouldn't the calculated effect based solely on the number of doublings overstate the UHI? -
CBDunkerson at 02:13 AM on 2 September 2010Antarctica is too cold to lose ice
barney2022, the volume of Antarctic ice is decreasing. Obviously that is the 'most important' issue overall, but the article above explaining WHY the ice volume is now in decline is certainly also relevant... despite involving processes which have existed for a very long time. Also, you say "cooling that is taking place in this region of the world"... actually, Antarctica has warmed considerably in the past few decades. -
Ned at 02:13 AM on 2 September 2010Antarctica is too cold to lose ice
To answer Barney's question, no. Antarctica is experiencing a net loss of land ice. There is also a slight increase in Antarctic sea ice, but that's a different subject (and it's not caused by "cooling" in any case, since the southern ocean is actually warming). See Is Antarctica losing or gaining ice?
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