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Joel_Huberman at 23:57 PM on 15 March 20152015 SkS Weekly News Roundup #11B
Sailrick @ 2 & 3, Uncletimrob @ 4: My opinion, upon having skimmed through the paper by Stephens et al., is that the paper is an excellent example of the scientific process at work. The paper builds on current climate science and adds more precise measurements of albedo in the two hemispheres. The authors point out that the albedos of the two hemispheres are more closely matched than models easily predict--but that's not surprising, since models are just models and will always need finer tweaking. There's nothing in this paper that in any way invalidates any aspect of current climate science.
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Joel_Huberman at 23:42 PM on 15 March 20152015 SkS Weekly News Roundup #11B
Tom Curtis @ 5: Thanks for your very insightful view of energy efficiency. I'll promote that view in all my future efforts to educate. With regard to the Sun's resource size, I think we might as well label it infinite, because the Sun will outlast the planet Earth and will far outlast humans on Earth.
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Tom Curtis at 23:24 PM on 15 March 2015Human CO2 is a tiny % of CO2 emissions
DangerousDan @274, CO2 in beer and some softdrinks (ie, brewed Ginger Beer) comes from fermentation, and as such was originally drawn from the atmosphere by photosynthesis. Because they are originally drawn from the atmosphere, their return to the atmosphere merely completes the cycle. It does not increase atmospheric concentrations.
CO2 in carbonated drinks, however, may come from a variety of sources including fossil CO2, by cracking CO2 from the air by refrigeration, or from by products of other processes. The Coca Cola company, in particular, have stated that most of their CO2 used in drinks comes from by products of other processes, and hence do not constitute additional emissions to those other processes.
Finally, even if all the CO2 in soft drinks was additional emissions, it would constitute a tiny proportion of total emissions. Roy Spencer estimates total emissions from soft drinks as 1.46 million tonnes of CO2 per year. For comparison, the annual emission from fossil fuels 28.6 billion tonnes of CO2 per year. That is, soft drinks would contribute 0.005% of the problem if (contrary to fact) they used no recycled CO2.
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Tom Curtis at 22:20 PM on 15 March 20152015 SkS Weekly News Roundup #11B
uncletimrob @1, people who say that solar is less efficient than gass are very confused. All energy used on Earth except geothermal comes from the Sun. It may come directly as in solar. It may come indirectly as in wind power (where the winds get their energy from the Sun). For natural gas, the energy came from the Sun long ago. It was converted into chemical energy at about 10% efficiency by photosynthesis. However, most (greater than 99.9%) of the resulting chemical energy was wasted in respiration either by the plant or plant eaters. The miniscule amount of chemical that remained was buried and in a process that lost still more of the energy, converted to gas. The gas was then pumped out of the ground, and distributed (requiring more energy) until finally we get to burn it. Clearly, as an energy source, gas is far more inefficient than solar.
I imagine those who support fossil fuel use into the future will object to a full energy cycle calculation of energy efficiency. They will consider most of the energy efficiency as a spent cost, and therefore irrelevant. A bonus even, as when we burn fuels we are obtaining energy from yesterdays Sun, today.
However, even in those terms solar is far more efficient than any fossil fuel. The simple fact is that whether we use solar or fossil fuels, we are using a fuel with a finite resource base. If you want to calculate efficiency, the only efficiency that matters is the proportion of the finite resource base used to obtain that energy. And the fact is that the finite resource base for solar is so large that it is effectively free for the taking. Each kilowatt hour of solar generated at 10% efficiency of incoming solar radiation represents a far, far smaller proportion of the total resource base of solar power than each kilowatt hour of electricity generated from gas does of the total fossil fuel resource base.
Again, fossil fuel boosters won't be happy with that estimate of efficiency. The reason is that they want to impose an almost irrelevant accounting measure to make their preferred technology look good.
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DangerousDan at 19:31 PM on 15 March 2015Human CO2 is a tiny % of CO2 emissions
Co2 from Man made drinks. Is co2 from say beer. A natural co2 emission? or a human emision. Or does it change after it is consumed. Some co2 is absorbed and expelled by the lungs. The remainder is belched back out?
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uncletimrob at 18:30 PM on 15 March 20152015 SkS Weekly News Roundup #11B
@3 Sailrick
"And then there's Physics" blog has come interesting commentary on the albedo paper here:
https://andthentheresphysics.wordpress.com/2015/03/11/new-albedo-paper/
I'm no expert so will leave the argments to those who are, but the blog is worth a look.
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sailrick at 17:29 PM on 15 March 20152015 SkS Weekly News Roundup #11B
obviously the line from the comment is hyperbolic. the commentor thinking it's another proverbial nail in the coffin of AGW.
I read most of Judith's article about the paper, but am not knowledgeable enough to critique it.
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sailrick at 16:36 PM on 15 March 20152015 SkS Weekly News Roundup #11B
I came across this in a comment at an NPR article " a new paper appeared that found a colossal error in the climate models"
It refers to a post at Judith Curry's blog, about a new paper on albedo.
Graeme L. Stephens, Denis O’Brien, Peter J. Webster, Peter Pilewski, Seiji Kato, and Jui-lin Li are the authors
Link to manuscript: http://webster.eas.gatech.edu/Papers/albedo2015.pdf
And I was wondering if you are doing an article on it.
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uncletimrob at 15:48 PM on 15 March 20152015 SkS Weekly News Roundup #11B
@ Will natural gas dim solar’s shine? The technology of turning heat into electricity is mature and with a maximunm efficiency of around 60% for gas fired stations IIRC. In comparison PV technology is not so mature or so efficient and there will need to be further advances in storage technology before PV can really contribute a bigger slice of our energy needs. Personally I believe that here in OZ we are well placed for PV to have a bigger input than it currently has.
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SpaceCow at 12:53 PM on 15 March 2015They changed the name from 'global warming' to 'climate change'
=( NASA just came out and disproved your definition of Global Warming/Climate Change.
"Global warming: the increase in Earth’s average surface temperature due to rising levels of greenhouse gases.Climate change: a long-term change in the Earth’s climate, or of a region on Earth."
http://pmm.nasa.gov/education/articles/whats-name-global-warming-vs-climate-changeModerator Response:[TD] A) "Disproved" is inaccurate/wrong/odd.
B) Please read that page you linked to, then actually read this Skeptical Science post. Really, read them. Both. Carefully.
C) Feel free to comment again, correcting yourself.
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chriskoz at 12:36 PM on 15 March 2015Scientists link Arctic warming to intense summer heatwaves in the northern hemisphere
According to decade old teachings by Kerry Emanuel, the N Atlantic tropical cyclones supposed to increase in intensity. See e.g. Emanuel 2005 showing increase in hurricane power dissipation index (PDI) in all cyclone regions since 1970. Emanuel 2005 found strong correlation of PDI with regional sea surface temperature.
So, a clarification is needed what "decline in storminess" means here. Is it in both frequency and intensity? Certainly the storms in question cannot be cyclones/tropical storms because that would contradict Kerry's findings.
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Tom Curtis at 12:24 PM on 15 March 20152015 SkS Weekly News Roundup #11A
OPOF @25, sea ice area is also reported, and shows a similar dip to that in sea ice extent:
(Source)
It is, however, not at record low values indicating that the ice is more compact than in 2007.
To be quite honest, however, the minimum variation in extent and area does not occur until mid May. Until that point, any difference between different years can be washed out by occurrences in mid May - ie, they are almost irrelevant for predicting September minimums. So while it is interesting that sea ice extent is at record low values, and sea ice area is at near record low values for the time of year, that is still consistent with a September sea ice extent greater than last year, and probably will not result in a new September sea ice minimum.
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One Planet Only Forever at 12:02 PM on 15 March 20152015 SkS Weekly News Roundup #11A
Jim Hunt@6
The Arctic ice extent reported by NSIDC has held fairly steady for the past several days rather than continuing the stead decline that occured from Feb 25 to March 8. And the value for March 13 is a notable increase of the extent. However, it is still well below any of the previous years in the record. A temporary condition seems to have been producing the reduction of the 15% sea ice extent. Maybe an event was pushing areas of broken up ice into a tighter packing.
I appreciate that the 15% and 30% sea ice extents are important for navigation. So I understand why the systems are set up to provide that information on a daily basis. And I can see the logic and importance of monitoring the trend of changes in ice extent and trying to develop better ways to predict upcoming ice extents. However, I believe an evaluation of the total ice area, meaning that in areas that are not solid ice only the amount of ice area would be calculated as part of the total ice area would eliminate fluctuations of extents of broken up ice that could occur. Is the Cryosphere Today area calcualted that way? I only quickly reviewed the website and could not see any obvious indication of how he ice area in the chart was determined.
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bcglrofindel at 11:35 AM on 15 March 2015Measuring Earth's energy imbalance
@scaddenp, thanks I had started there actually and was only able to find stuff on Ceres from 2000 onwards.
@MA Rodger, thanks for that, pretty much exactly what I'd been looking for. The articles I had found so far already had me suspecting your observation about troubles combining the series for instrumentation/calibration reasons. Even just having the two separate trends as you provided though is just what I was trying to learn. I'm still reasing through, but is it generally true then that the satellite observed energy imbalance has been largely without a trend at the inter-annual/decade level? Sure doesn't appear to be trending much in in the ERBE set, and the Ceres post 2000 data is declared unlikely to have a trend by the IPCC. I find that result counter intuitive though as CO2 concentration over that same time has verg steadily been increasing...
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PluviAL at 07:23 AM on 15 March 2015So what did-in the dinosaurs? A murder mystery…
@ 18, 20, Thanks for the info. I just ordered "Waking the Giant" looks really interesting. I expect that this view will grow as we get more information about this feedback loops, and more interest on the subject. The idea seems to alwasy be played down. I remeber seeing an article on GIA in which the authors concluded that since the chemical changes in the rock only went so far, that the effect could not have gone furhter. That seems narrow minded. Heat, and mechanical distortioins might be expressed otherwise. Bill McGuire, also poopoos the idea that the feedback loops may go far from the source. My expectation is that it is way underestimated. Exited to read his book soon.
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wili at 03:52 AM on 15 March 2015Scientists link Arctic warming to intense summer heatwaves in the northern hemisphere
Thanks, dorlomin. That makes a lot of sense. That _was_ quite a train of storms that came through Great Britain and environs last year.
I wonder what a general decrease in winds portends for all that wind power we are putting in, though.
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dorlomin at 03:14 AM on 15 March 2015Scientists link Arctic warming to intense summer heatwaves in the northern hemisphere
@Wili. Windstorms are driven by differences in air pressure. Air pressure differences are caused by temperature differences. As the Arctic warms in summer the differnces between it and the "mid latitudes" will drop, this could lead to a drop in certain types of windstorm.
This is not about the autumn\winter windstorms that make the news, or increases in thunderstorms into the mid latitudes. Last year (winter 2013/14) we seen how a big kink in the boreal polar jet dragged lots of warm moist air from around the US "South Atlantic" states and spun monster storms into the UK and Europe.
A changing climate will mean some kinds of weather become less frequent including some storm types.
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Dean Morrison at 01:18 AM on 15 March 2015Global warming stopped in
1998,1995,2002,2007,2010, ????
Surely this article in need of another update, since all global temperature datasets now show 2014 as the hottest on record?
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funglestrumpet at 00:23 AM on 15 March 2015So what did-in the dinosaurs? A murder mystery…
@ billthefrog #19
Thanks! I never thought of that. It makes a lot of sense.
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It's the sun
PS - In all fairness, Pangburn hasn't been arguing on SkS for very long, and has yet to make a clear causal claim (something I've been trying to extract). But given his history on other sites and his own blog posts, I'm not sanguine about better results here.
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ranyl at 16:35 PM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
Thanks Howardlee, it is further;y concerning that for this Co2 induced warming assault on biodiversity that the earth has already lost 30-50% of its biodivesity and has extinction levels that geologoically noteable, before the warming infliuences are even really starting to bite.
For an analogy it seems we've given th eearth leuakeamia and now its caught a high fever producingknown to be deadly virus.
Whilst our dicision makers moan about 2C cuts and many of the so called solutions are laced with mining, toxic waste and have direct biodiversity harming impacts (e.g. PV panels).
Seems Volacnoes could possibly be woken up on land but put to sleep in the ocean.
WOnder if th erate of change in the oceans weight and uplift make any difference?
Wonder if the the rate melt makes any difference?
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jja at 15:31 PM on 14 March 2015Scientists link Arctic warming to intense summer heatwaves in the northern hemisphere
This work definatively shows the "new normal" patterns of standing wave high/low pressure regions and cut-off blocking regimes that have grown to dominate the mid-lattitude region with unprecidented temperature and precipitation extremes. Just wait until China has effective reduced its aerosol emissions. . .
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It's the sun
Dan Pangburn's argument appears to be one I've seen before - where a 'break-even' point is defined in some fashion (TSI, or a particular sunspot number as in an earlier Pangburn post here, etc.) - it's assumed that any energy above that breakpoint will integrate and accumulate positively, and any below that breakpoint will integrate negatively.
Utterly neglecting the other side of the equation, the outgoing LWR which scales with temperature and effective Earth emissivity, and that climate energy is driven by the difference between incoming and outgoing energies. There is no fixed break-even since temperatures change in response to forcing, the difference is between two moving values, and hence no fixed threshold.
In fact, since the sign of the speculative integration against a particular 'break-even' is solely and rather arbitrarily set by where that breakpoint is defined, different breakpoints can suggest either ridiculously large warming or cooling depending on how they relate to the time series as a whole. It's a hypothesis focused entirely on the climate energy input, wholly ignoring energy output - and therefore it's meaningless.
Pangburn has been pushing this hypothesis for several years, in the face of multiple replies pointing out these issues - it's unlikely he's going to change his mind now. But readers should be aware of the difference between a fixed integrative threshold, and an imbalance (the case in reality) between two moving values. And judge such simplistic hypotheses accordingly.
Moderator Response:[PS] Thank you for bringing up Dan's previous posting history. This shows excessive repetition and amount now to just sloganeering without supporting evidence.
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DSL at 12:52 PM on 14 March 20152015 SkS Weekly News Roundup #11A
February GIS L-OTI is out: 0.79C. That's the second warmest February (1998) on record and the 7th warmest month overall. The last 12 months are now the warmest (0.71C) on record, beating Feb 2014 - Jan 2015 (0.68C).
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Tom Curtis at 12:09 PM on 14 March 2015It's the sun
PS inline @1121, no, there is no point in putting up the time integral of CO2 forcing. The correct relationship is Heat Content (not temperature) to the time integral of (Incoming energy - outgoing energy). CO2 changes the time integral of outgoing energy by reducing OLR. Increasing temperature changes the time integral of outgoing energy by increasing OLR. Because Pangburn persistently ignores OLR, his formulation is nonsense. However, it is his formulation I wanted to test, hence the first graph.
Moderator Response:[PS] frankly not much point to time integral of TSI either but I thought that might help see the issue.
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ubrew12 at 11:34 AM on 14 March 2015Scientists link Arctic warming to intense summer heatwaves in the northern hemisphere
Just speculating: From the paper's abstract: "Weakening of the zonal wind is explained by a reduction in poleward temperature gradient". In Fluid Mechanics, turbulent eddies get their strength from the main fluid flow (here, the 'zonal wind'). If that wind weakens, the eddies themselves should weaken: the overall flow becomes less 'turbulent' and more 'laminar' (undisturbed). With less turbulent mixing, if you happen to be in a heatwave, there's less chance of a disturbance to relieve you. Like a river cascading down a sharp incline breaks into turbulence: its hard to find a spot where a floating leaf can remain stuck in place for awhile. But as the river approaches the sea, the incline becomes imperceptable. The river meanders in long ox-bows, left and right, and becomes much less turbulent. Now a leaf can drift to a still area and remain stuck there for days.
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Tom Curtis at 10:26 AM on 14 March 20152015 SkS Weekly News Roundup #11A
Riduna @22, I have no doubt that fresh water runoff from ice sheets contributes. Never-the-less, the theory as explained in the literature was (from memory) increased surface fresh water from precipitation.
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Tom Curtis at 10:23 AM on 14 March 2015It's the sun
As Dan Pangburn does not appear interested in following reason, I thought I would short cut the argument. His claim is that the integral of TSI explains the temperature history since 1880. Therefore, I took the record of TSI forcing used in Kevin C's simple response funtion climate model (default setting). I tested the regression of offsets of that forcing to 1960 to determine which best correlated with the GISS LOTI. As it happened, 0 offset was best. I then regressed the resulting integral of TSI against the GISS LOTI up to 1960, and projected the regression on to 2010:
For the record, the correlation over the full interval is 0.917 and the r squared is 0.841. I did not calculate the Root Mean Squared Error, but as you can see it is lousy. Sufficiently so as to falsify the model.
For comparison, here are the full forcings with a simple, two box response function as shown with default settings minus ENSO from Kevin's model:
R squared is given as 0.877. Better than the integral of TSI, but not stunningly so. The overall fit, however, smashes the Pangburn model. If you hold to the quaint notion that scientific results should be determined by empirical evidence, then there is no question as to which model is superior.
Dan Pangburn may not be happy with my regression. If not, however, it is incumbent on him to do better - and to tell us how he did it. Absent such an attempt, his counter theory is not science. It is merely a thought bubble. And until he does better, showing us the graph of the regression and explaining his methods, we are quite right to ignore that thought bubble.
Moderator Response:[PS] As you pointed out earlier, there is rather large gap in Dan's physical understanding. Are you going to put up the CO2 time integral as well?
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Riduna at 09:45 AM on 14 March 20152015 SkS Weekly News Roundup #11A
Tom @ 10 … “increased rainfall”. More likely fresh water run-off from increased ice sheet mass loss?
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mancan18 at 09:28 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
Excellent article Howardlee.
Always wondered about an asteroid impact being solely to blame for the extinction of the dinosaurs. This thesis seemed to become entangled with the nuclear winter arguments regarding the impact of a nuclear war. Hence the reason it became the accepted idea as to what caused the demise of the dinosaurs. I would have thought that if there had been significant climate cooling due to blocking out the sun from the aerosols ejected into the atmosphere from an asteroid impact, then there would have been a significant drop in the CO2 levels due to the reduced activity of plants before the vulcan outgassing of CO2 had its full impact. A large asteroid impact on the scale of Chixulub should have a similar climate impact as a single LIP, and it seems that you need a few LIPs occuring over a short geological period to actually trigger a mass extinction event.
Perhaps, now that it is possible to date geological evidence more accurately, then a more refined history of of the sun's orbital dynamics, maturity and radiation levels; atmospheric composition; continental drift; vulcanism; climate change; and extinction events can be done. This may help put some of these controversies to rest.
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billthefrog at 08:40 AM on 14 March 20152015 SkS Weekly News Roundup #11A
@ scaddenp #20
Yep, that's what my gut-feel says - it's just that I've never seen anything formal, and certainly don't expect to be right about anything just on gut-feel.
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billthefrog at 08:35 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
@PluviaL #14
Last year I went to a lecture given by Bill McGuire, the Emeritus Professor of Geophysical & Climate Hazards at University College London. His talk was entitled "Waking the Giant", and it examined the effects wrought by isostacy as a direct consequence of past climate change. (And I've got a signed copy.)
cheers bill f
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billthefrog at 08:24 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
@ funglestrumpet #16
I'm pretty sure that ubrew12's point was that a longitudinal shock wave emanating from Chicxalub could have had percussions (pun intended) at the hot spot responsible for the basaltic mega-eruptions at the Deccan Traps. I don't for one moment think that some form of planetary-scale exit-wound was being mooted.
I once did some sums in preparation for an astronomy presentation, and calculated that the kinetic energy of the impactor was roughly equivalent to the total solar energy hitting TOA for about one month. The term "made the planet ring like a bell" is one that I have seen applied to this little nudge.
@ Howard
One of my chums, sadly no longer with us, was a Fellow of the Geological Society of London, and he always had a soft spot for the Deccan Traps as the "culprit".
There is, of course, another "suspect" - namely the so-called Shiva Crater Impact Spot. Does this have any real support in the rock-bashing community? (Those with any familiarity with the Hindu pantheon will appreciate the name.)
cheers bill f
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howardlee at 07:07 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
Pluvial @ 14:
On climate afffecting volcanism yes there is, but in a tiny way. The first is a feedback in which melting ice reduces pressure on magma chambers in glaciated parts of the world, encouraging them to erupt. Example: Iceland today. The other is in rising sea levels supressing mid-ocean-ridge volcanism (and the converse). This is a mild, slow, long-term negative feeback completely dwarfed by human emissions. Minus the cosmic periods, your complex medium waves idea is very similar to this feedback.
Asteroid storms - I have seen a suggestion of long term periodicities in asteroid impacts but would have to dig further to find that paper. As is clear in the article, there is no evidence that they have much effect on the inner workings of the Earth or even its long-term climate, which is surprising.
Cosmic periods - there was a suggestion a while back that there was a periodicity in the cosmic ray flux into the atmosphere based on the motion of our solar system through the arms of the Milky Way galaxy, but that has been refuted by more accurate mapping of the arms and our place within them.
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howardlee at 06:39 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
Villabolo @15: All I have found is this paper researching the atmospheric "erosion" by the Chicxulub impactor. It states that "no more than about 7% of the vaporized bolide plus atmospheric mass will escape the gravitation of the Earth," in other words there will be a net gain, not loss, of mass. As they say in the title - surprising!
Massive atmosphere loss happened at the time of the formation of our moon, mainly by a thermal process called "Jeans escape." That drove off our first atmosphere and replaced it with rock vapor, until volatiles expelled by cooling magma replaced it. But Earth retained a substantial atmosphere through the Late Heavy Bombardment,when the planet was pelted with large asteroids. This paper suggests there was probably a net gain of atmosphere through that time, in agreement with the paper above.
We had a number of very large impacts since then (Manicouagan, Acraman, Popigai, Sudbury, Vredefort, and Chicxulub) with no reports of anything suggesting significant atmosphere loss.
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funglestrumpet at 06:30 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
@ ubrew12
Why would a body, such as an asteroid, exit at the antipodes of its impact point?
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MA Rodger at 06:12 AM on 14 March 2015Measuring Earth's energy imbalance
bcglorfindel @52.
I think you'll find the problem with creating a global data series using both ERBE & CERES mainly boils down to calibration issues. There is one graph that I can recall that does stitch the two together, fig 2e in Allan et al (2014). The green trace WFOV uses ERBE data.
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villabolo at 05:37 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
howardlee @ #10:
Yes I know. What I was wondering was whether a substantial part of the atmosphere would have been ejected into space making our current atmosphere thinner than before. I didn't find a comment on the effects on the atmosphere in the link you cited.
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scaddenp at 05:30 AM on 14 March 20152015 SkS Weekly News Roundup #11A
Bill - on time scales of one to two hundred years, isostacy doesnt figure much in the calculation.
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PluviAL at 04:56 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
One of the funnest, most informative, article I have read here; moving first graphic;).
Such a broad perspective brings up two questions 1) Is there a periodicity to asteroid "storms"? It'd be kind of like we have shooting star storms, but for different causes. 2) Does climate affect volcanism and seismicity?
The argument here is that volcanism affects climate, but the other seems just as likely to me through GIA, it just conjecture on my part, but the science seems to be moving in that direction.
Thus we could have feedback mechanisms between, cosmic periods, volcanism, climate change, back to volcanism, then climate change again. I call this idea, complex medium waves (CMW), because the period may be affected by chemical changes in the lithosphere, thus magma chemistry and flow characteristics. This may take tens of thousands of years, so it may fit well in this argument.
It is just conjecture on my part because I have no education, and little study along those lines, but I am very curious to know more. This story is very helpful, especially with the rich sources. Nice work.
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It's the sun
Dan Pangburn - "...further discussion is useless." I'm afraid I would have to agree.
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Dan Pangburn at 03:53 AM on 14 March 2015It's the sun
KR - To see the effect that TSI has on temperature requires the time-integral of TSI. Without even that trivial science skill, further discussion is useless.
Moderator Response:[PS] By all means feel free to link to or post what you mean by a "time integral of TSI". Be sure to do the same for the CO2 forcing.
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wili at 03:15 AM on 14 March 2015Scientists link Arctic warming to intense summer heatwaves in the northern hemisphere
"A decline in summer storminess is consistent with model projections of the impacts of a warming Arctic"
Could someone explain why this would be the case?
It seems counterintuitive to me, but then I am often surprised by how my idiot intuition leads me astray when making assumptions about how climate works. :-/
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wili at 03:07 AM on 14 March 20152015 SkS Weekly News Roundup #11A
curiouspa, besides following JH's advise, consider that seasons still exist. Then think somemore. In particular, consider what happens to the saltiness of the surface water around Antartcica after a bunch of that landbased ice sheet melts during the summer, and what are the likely, predictable consequences of that for ice extent during the next winter.
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billthefrog at 02:33 AM on 14 March 20152015 SkS Weekly News Roundup #11A
@ Tom Curtis #15
Hi Tom,
Yep, I realise there is a slight density difference between sea water and fresh water, with sea water being in the order of 2.5% - 3% more dense.
One needs to look closely at the figure of ~4 cms additional SLR that Prof Peter Noerdlinger is talking about. This, however, is not based solely on a total melt out of sea ice (i.e. ice that has formed at sea).
Instead, he has also included the contribution from ice shelves (ie ice that has formed on land and has subsequently flowed out onto the sea surface).
From figures available on Cryosphere Today, the annual average area of global sea ice (NH + SH) is 19 million sq kms. If one takes an average thickness at a reasonably generous 2 metres, and somehow smears this over the approx 360 million sq kms of ocean surface, that would give us an ice coating of just over 10.5 cms.
As the density of ice is around 92% of fresh water, this would in turn equate to a fresh water "film" of some 9.71 cms in depth floating on top of the denser sea water below. Comparing densities of fresh and salt water, the same mass of salt water would have been about 9.47 cms deep.
Obviously, the difference between these is only in the order of 2.5mm, and that's why I ignored this second (third?) order effect in my earlier response to curiouspa.
Ice shelves are a different matter all together, and I am somewhat surprised by the fact that they have been lumped together in this fashion. Massive chunks of ice coming down from the Jacobshavn Isbrae, from Petermann, Pine Island or Thwaites, or, more spectacularly from things like the Larssen B Shelf most assuredly do contribute to overall SLR.
cheers bill f
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CollinMaessen at 02:25 AM on 14 March 2015New Series: Science Communicators – Why We Love Communicating Science
Thanks everyone for the suggestions, I've added them to my notes. :)
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It's the sun
Dan Pangburn - If CO2 isn't the point of discussion (or rather, the relative influences of anthropogenic GHGs and the myth that 'it's the sun' responsible for all recent climate changes), then why did you bring it up? Particularly when your claim is so unsupported?
In the meantime, since we are concerned with changes in temperature, graphing those against changes in TSI is entirely appropriate to investigate correlations.
Regarding the oceans, both Rob and I have agreed that GHGs have little effect on how the oceans absorb SW radiation - but you seem to be missing the physics where GHG changes greatly affect how the oceans lose that energy, causing a forcing imbalance and therefore warming the oceans.
Climate temperatures are a balance between incoming energy gain and outgoing loss scaled by the Stephan-Boltzmann relationship, and changes in a balance can come from a finger on either side of the scales.
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macoles at 00:37 AM on 14 March 2015So what did-in the dinosaurs? A murder mystery…
Thanks howardlee, can't wait to tell my science loving 11 year old daughter about this great example of scientific process in action.
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Dan Pangburn at 00:35 AM on 14 March 2015It's the sun
Rob - I agree and restate: Atmospheric CO2 increasing from 3 parts in 10,000 to 4 parts in 10,000 can not significantly change the rate that the oceans absorb sunlight.
KR - The effect of CO2 is not the point of discussion here.
Temperature change, in degrees K, multiplied by the effect thermal capacitance (thermal inertia?), in Joule sec/m/m/K results in units Joule sec/m/m.
Forcing is in Joule/m/m.
My only point here is that it is misleading to compare these on the same graph. The correct comparison is between the temperature change and the time-integral of the net (you can call it total) forcing.
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CBDunkerson at 00:08 AM on 14 March 20152015 SkS Weekly News Roundup #11A
In terms of global ice changes I think looking at the rough percentages helps;
- Antarctic land ice: 90%, decreasing
- Greenland land ice: 9%, decreasing
- All other ice: 1%, decreasing
So yes, it is possible to find examples where ice is increasing (e.g. Antarctic sea ice & individual glaciers), but those are a subset of 1% of the planet's total ice... and even that 1% is overall in decline.
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