Arguments
Recent Comments
Prev 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 Next
Comments 30901 to 30950:
-
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.
-
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...
-
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.
-
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.
-
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.
-
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?
-
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.
-
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.
-
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?
-
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. . .
-
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.
-
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).
-
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.
-
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.
-
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.
-
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?
-
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?
-
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.
-
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.
-
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
-
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
-
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.
-
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.
-
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?
-
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.
-
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.
-
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.
-
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.
-
It's the sun
Dan Pangburn - "...further discussion is useless." I'm afraid I would have to agree.
-
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.
-
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. :-/
-
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.
-
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
-
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. :)
-
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.
-
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.
-
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.
-
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.
-
howardlee at 22:36 PM on 13 March 2015So what did-in the dinosaurs? A murder mystery…
Ranyl - basically yes! The late Cretaceous, before the eruptions, was quite cool, with some suggestion there was even ephemeral ice in Antarctica. But the climate was overall warmer than the 20th century and CO2 levels higher. Ocean currents were also different as Antarctica was still connected to South America and Australia. So there were important differences between then and now, but the fundamentals of rapid greenhouse gas emissions and pollution leading to abrupt climate change, acidification and environmental disaster are the same.
-
wili at 22:20 PM on 13 March 20152015 SkS Weekly News Roundup #11A
What should we make of the FOUR cyclones now swirling around the Western Pacivic and over Australia? Pam just hit cat 5 status.
Elsewhere: http://www.bbc.com/news/world-africa-31862881
"Angola floods kill at least 35 children and 27 adults".
-
Tom Curtis at 21:25 PM on 13 March 20152015 SkS Weekly News Roundup #11A
billthefrog @14, melting of sea ice does raise sea level. The reason is that the ice, being fresh, is less dense than the salt water on which it floats. As a result, it floats higher than it would if floating in fresh water. The difference in the amount of ice above water between the ice floating and salt water and equivalent ice floating on fresh water is excess volume that contributes to sea level rise. The total melting of all sea ice including floating ice shelves would raise sea level by about 4 cm. (Paper)
-
billthefrog at 20:17 PM on 13 March 20152015 SkS Weekly News Roundup #11A
@ scaddenp
As you well know, there is also the matter of isostacy to consider - especially at the local level. It is a standard (great white?) con trick to talk about there being a drop in measured MSL at such-and-such a place, and present this as a supposed counter argument to concerns over sea level rise.
In many areas that, until the geologically recent past, were covered by the Fenno-Scandian or Laurentide Ice Sheets, the crust is still physically rebounding following the loss of giga tonnes (terra tonnes?) of ice since the days of the last glacial maximum.
What I don't know* is whether or not isostacy has any overall meaningful impact on global sea level. Any ideas? (*That sentence should really have commenced... "Amongst the unimaginably vast number of things I don't know, is whether...)
@ curiouspa #
" ... Is the loss of Arctic sea ice a direct contibutor to sea level rise? ..."
I you look up "Archimede's Principle", especially the corollary regarding a body that is floating on a fluid, you should be easily able to work the answer out for yourself.
cheers bill f
-
ranyl at 20:16 PM on 13 March 2015So what did-in the dinosaurs? A murder mystery…
Thanks Howardleevery thorough,interesting to read and insightful.
And very scarey!
Aren't we putting something like 3xmega eruption ratesof CO2, not to mention, SO2, CFC's for ozone, and a wholehostofother very toxic stuff into the world ecosystem and all at a rate imagineably quickly and from a low CO2 start (meanign CO2 input has more warming potential)..
If we have any ancestors they really are going to wonder..
-
scaddenp at 13:33 PM on 13 March 20152015 SkS Weekly News Roundup #11A
"uncertain at this point why." which should be understood as multiple factors at play with uncertainty over which ones are the most important, as opposed to "havent a clue what's going on".
Actual sources of sealevel rise are land ice loss, thermal expansion and land water storage change. ( see here for article on this). I dont think it is totally accurate to say sea ice change makes no difference but it is miniscule compared to the others.
-
One Planet Only Forever at 11:31 AM on 13 March 20152015 SkS Weekly News Roundup #11A
Jim Hunt@6,
Thanks for the link to the extra information.
-
curiouspa at 11:30 AM on 13 March 20152015 SkS Weekly News Roundup #11A
scaddenp-thanks.
I looked over links provided. Consensus seems to be that overall Antarctic ice on land is decreasing based on loss of thickness. Sea ice is increasing a little, and uncertain at this point why.
One statement I saw "when land ice melts and flows into the oceans global sea levels rise on average; when sea ice melts sea levels do not change measurably"
Does that imply that expected sea level rise is mainly from land ice loss, such as Greenland ice loss in the Arctic? Is the loss of Arctic sea ice a direct contibutor to sea level rise, or only secondarily thru loss of albedo and resultant ocean warming?
-
Tom Curtis at 10:58 AM on 13 March 20152015 SkS Weekly News Roundup #11A
curiouspa @8, the gain in Antarctic sea ice is less than the loss in Antarctic land ice in terms of volume. The loss in Arctic land plus sea ice is greater than the loss in Antarctic land plus sea ice, a fact partly due to the fact that the Arctic has warmed more than the Antarctic (for well known reasons the explanation of which is partly explaineded by scaddenp @9). The Southern Ocean has been warming so that the Antarctic sea ice has grown even though the water on which it floats has been warming. That is due to the fact that:
1) increased rainfall due to the warming has resulted in fresher surface water, that freezes at a higher temperature; and
2) increased windspeed due to warming results in ice being pushed further north before it melts, with the open water created by the export of ice refreezing because it is further south.
Your intuition that "... if both poles were heated about the same amount, both would lose a similar amount of ice" is, therefore, incorrect (quite aside from the fact that the Arctic has been heated more).
-
howardlee at 10:47 AM on 13 March 2015So what did-in the dinosaurs? A murder mystery…
Villabollo - I don't know that the atmosphere in the Cretaceous was thicker (assuming you mean height of the atmosphere, rather than density) - perhaps someone else can chime in. The height of the troposphere - the layer with sufficient density to make a difference to the asteroid - is about 7-20km. An asteroid travelling at cosmic speeds of about 30,000mph (48,000kph) would travel through that in about 1.5 seconds. Even if the height of the troposphere was higher I doubt it would make much difference.
If you feel like an amusing exploration of this theme check out this "What if" post
-
howardlee at 10:21 AM on 13 March 2015So what did-in the dinosaurs? A murder mystery…
ubrew12 - great minds think alike, so they already looked into the idea that Chicxulub triggered the eruptions ("antipodeal focusing"), but no. Adrian Jones looked into that in his recent paper and concluded that earlier work was correct in establishing that India was in the wrong place at that point in its continental drift. The forces in rock opposite a Chicxulub impact are also apparently not quite enough to fracture rock. If they coincided with an area primed for an eruption anyway they might just set it off, but otherwise not.
-
Same Ordinary Fool at 09:29 AM on 13 March 2015So what did-in the dinosaurs? A murder mystery…
To me this is as momentous a geological mystery as the story of Continental Drift. Then there were many different arguments from various fields, though they all led to one conclusion, that was eventually observed - in the spreading sea floor under the Atlantic ocean. The dinosaur whodunit is more traditional, with multiple suspects.
It's inevitable that geological research will be done more with lab coats and a little less with boots on the ground. That's where the answers lie. But to this observer part of the appeal of geology was its simplicity, that resulted in part from the greater unknowns. Just following fossils and formations, looking for an informative outcrop. And what's on top is younger.
Prev 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 Next
