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Comments 30501 to 30550:
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Tom Curtis at 09:07 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
Joel_Huberman @12, the definition, with my emphasis is:
"Radiative forcing is the change in the net, downward minus upward, radiative flux (expressed in W m–2) at the tropopause or top of atmosphere due to a change in an external driver of climate change, such as, for example, a change in the concentration of carbon dioxide or the output of the Sun."
Feldman et al measure the change at the bottom of the atmosphere, which they call the "surface radiative forcing". "Surface radiative forcing" and "radiative forcing" are not the same thing. For what it is worth, the change in downward flux at the surface due to a change in CO2, and absent any feedbacks, is about four fifths of the change in radiative forcing (as calculated by the IPCC approximation).
As you note, "surface radiative forcing" also differs from radiative forcing in allowing considerable atmospheric adjustment increase in CO2. That adjustment includes an increase in temperature and, importantly, an increase in H2O content. H2O absorption bands have considerable overlap with the main CO2 absorption bands. That is largely inconsequential for radiative forcing, for CO2 only decreases in concentration very slowly with altitude, whereas H2O is virtually absent above 3 km (except where there are very strong updrafts). Consequently, at the tropopause, the effect of H2O absorption in those bands is very small. In contrast, at the surface much of the effect of CO2 would occure regardless because of the presence of H2O. Further, the increase in temperature will increase the downward flux from all radiative components of the atmosphere including CO2.
It turns out the "surface radiative forcing" Feldman et al calculate is approximately equal to the radiative forcing as calculated for the TOA using the IPCC's approximate formula. As the change in net TOA flux allowing adjustments is considerably less than that, there must be some other difference in the surface energy budget making up the difference. To the extent that Feldman et al's results are respresentative of the global average, that difference will be made up by increased convection or evapo-transpiration, or heat flow from another region (or some combination of the three).
That response is a lot longer than needed as, except for specifying the difference in location (which you probably understood but thought too obvious to need stating), your understanding was correct. I just took the opportunity to flesh out some more of my thoughts on the topic :)
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scaddenp at 07:20 AM on 25 March 2015So what did-in the dinosaurs? A murder mystery…
Any time you are talking paleo-anything then "settled science" isnt usually used. Multiple hypothesis are common because we lack the data to constrain them. That is very different to evaluation of climate theory, especially in terms of modern climate where data is so much better.
However, when talking about Milankovich, I take issue with "Milankovitch cycles which correlate with, and are proposed to be, causal to extreme abrupt Climate Change cycles" In terms of global temperature change (not temperate change at the poles), the rate of change is only around 0.15 degrees per century at most. Compare that to 20th century rate of change.
The younger dryas (and Bond/Heinrich events, not milankovich forced) have rates of change which appear to much higher if somewhat localized. Fortunately, it appears that these phenomena only occur as ice age ends.
If this discussion if going to continue on Pleistocene climates, then I suggest it be moved to this thread.
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Watchdog at 05:29 AM on 25 March 2015So what did-in the dinosaurs? A murder mystery…
CBDunderson wrote: "However, there are exceptions like the Older and Younger Dryas periods... when an explosion of nitrogen fixing plants led to rapid CO2 declines... and corresponding temperature drops."
That's a competing hypothesis - concurrent with at least a half-dozen others.
The jury is far from out on that being "settled science".
From Wiki-Younger Dryas - There are prevailing theories of its Cause including several hypotheses replete with evidences; including those connecting the Dryas stadials with both Bolide Impact and Volcanism.
•••
Effects of the Global Cooling period of the Younger Dryas affecting both the Northern and Southern Hemispheres.Replacement of forest in Scandinavia with glacial tundra (which is the habitat of the plant Dryas octopetala)
Glaciation or increased snow in mountain ranges around the world
Formation of solifluction layers and loess deposits in Northern Europe
More dust in the atmosphere, originating from deserts in Asia
Drought in the Levant, perhaps motivating the Natufian culture to develop agriculture
The Huelmo/Mascardi Cold Reversal in the Southern Hemisphere ended at the same time
Decline of the Clovis Culture and extinction of animal species in North America
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References to Hypothesized Causes, Extend and Effects of the Younger Dryas
en.wikipedia.org/wiki/Younger_Dryas -
jja at 05:07 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
the 0.6 value of TOA is derived from Hansen and Sato (2010) and corresponds with an average value whose mid-point correltes with 2007. Recent NODC ocean heat content analysis shows that the TOA today is significantly higher and at ~1.0 Watts per meter squared in 2013.
It is plausible that, with significant reductions in SE asian aerosol emissions, we are currently at 1.2 Watts per meter squared and facing a significant rate of increase in coming years.
see: https://forum.arctic-sea-ice.net/index.php/topic,1183.0.html -
Joel_Huberman at 04:49 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
Tom Curtis @10,11. Thanks for your excellent explanations. Clearly I had much to learn about how radiative forcings are calculated. May I ask you another question to test my new understanding?
Consider the first sentence of the IPCC definition of radiative forcing--"Radiative forcing is the change in the net, downward minus upward, radiative flux (expressed in W m–2) at the tropopause or top of atmosphere due to a change in an external driver of climate change, such as, for example, a change in the concentration of carbon dioxide or the output of the Sun." Based on the full definition and on your explanation, it now seems to me that the reason the measurements by Feldman et al. of changes in downward radiation due to changes in CO2 concentration do not correspond to radiative forcings is that these CO2-radiation changes may have induced other changes--changes in water vapor concentration or in cloud abundance, for example--which will also have effects on both upward and downward radiative fluxes at the TOA. Consequently, the net effect of a change in CO2 concentration will be composed of both a direct effect on CO2-radiation (downward and upward) plus indirect effects on other downward and upward heat transfer mechanisms. Feldman et al. measured a direct effect, but radiative forcing is the net effect. Is my current interpretation correct?
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Tom Curtis at 04:14 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
Pblackmar @9, temperature increase at the surface due to radiative forcing is not a simple function of changes in back radiation (ie, the changes measured in this paper). That is because radiation is not the only energy transfer between the surface and atmosphere. Consequently, increases in back radiation may be matched by increases or decreases in convection, and or evapotranspiration. Rather, both changes in temperature, back radiation, convection and evapo-transpiration will occur to reestablish the change of temperature with altitude in the troposphere which enables an energy balance at the tropopause. Consequently the approach you mention will not reliably forecast future temperature changes.
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Tom Curtis at 04:09 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
Joel_Huberman @8, not quite right.
The energy imbalance at the top of atmosphere is composed of the change in radiative forcing minus the change in outgoing longwave radiation (OLR) due to the increased surface temperature. The total radiative forcing relative to 1750 in 2011 was 2.2 W/m^2, as shown by the IPCC AR5:
It follows that the OLR to space has increased 1.6 W/m^2. (Note, the imbalance at the TOA equals the imbalance at the surface to a very close approximation. If it did not, the atmosphere would heat, or cool very rapidly. The difference between that shown for the surface and TOA in your figure is entirely due to different rounding conventions.)
The radiative forcing, itself is the change in the downward energy balance at the tropopause after the stratosphere has reached radiative equilibrium (full IPCC AR5 definition at bottom of post). For convenience, we normally just refer to the Top of Atmosphere (TOA) rather than at the tropopause. That is reasonable because both are close approximations of each other.
Finally, the measured change discussed in the OP is in the "thermal down surface" shown in your diagram, as you correctly state. In the band of CO2 absorption, that change will have been due to increased CO2 concentration, increased H2O concentration and increased temperature. They appear to have determined the CO2 only contribution by comparision with a radiative transfer model (which unlike GCMs, are fully deterministic, and are very accurate). That change is small relative to the change in radiative forcing at the TOA, a fact which is well known. In fact, it is so well known that from time to time a denier will graph the expected changes at the bottom of the atmosphere as "proof" that radiative forcing from CO2 is much less than that expected by the IPCC - a proof that they are totally dishonest or hopelessly ignorant on the subject they purport to teach to others.
IPCC AR5 definition of Radiative Forcing (from WG1, Annex III)
"Radiative forcing Radiative forcing is the change in the net, downward
minus upward, radiative flux (expressed in W m–2) at the tropopause
or top of atmosphere due to a change in an external driver of climate
change, such as, for example, a change in the concentration of carbon dioxide
or the output of the Sun. Sometimes internal drivers are still treated as
forcings even though they result from the alteration in climate, for example
aerosol or greenhouse gas changes in paleoclimates. The traditional radiative
forcing is computed with all tropospheric properties held fixed at their
unperturbed values, and after allowing for stratospheric temperatures, if
perturbed, to readjust to radiative-dynamical equilibrium. Radiative forcing
is called instantaneous if no change in stratospheric temperature is
accounted for. The radiative forcing once rapid adjustments are accounted
for is termed the effective radiative forcing. For the purposes of this report,
radiative forcing is further defined as the change relative to the year 1750
and, unless otherwise noted, refers to a global and annual average value.
Radiative forcing is not to be confused with cloud radiative forcing, which
describes an unrelated measure of the impact of clouds on the radiative
flux at the top of the atmosphere." -
Pblackmar at 04:04 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
Fig 2 appears to be linear. Can a 100 yr projection be made to reduce impacts of internal variability forcing and accurately estimate temp increase given a consistent increase in CO2? Thx
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Joel_Huberman at 03:05 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
Thanks for an excellent summary of an important new contribution.
I felt that one of the sentences in the article, "The extra heating reported here is not directly comparable with the effect known as radiative forcing, which is used to help project climate change," deserved further clarification. I think that this graph, taken from the IPCC AR5 WG1 final report (page 181) helps to explain the difference between the extra heating measured by Feldman et al. and the total radiative forcing used to project climate change:
Notice that the radiation "imbalance" (0.6 W/m2; lower left corner of the figure) is the very small difference between total incoming radiation and total outgoing radiation at the top of the atmosphere (TOA). This imbalance represents the "radiative forcing, which is used to help project climate change," and it is determined by interplay between many factors.
A large portion of the total heat radiation leaving the Earth's surface is returned to the Earth as "thermal, down surface" radiation (342 W/m2) by greenhouse gases and clouds (large orange downward arrow at lower right). Downward radiation from CO2 (as measured by Feldlman et al.) forms a significant component of that 342 W/m2, but downward radiation from water vapor and clouds is the major component according to my understanding. Downward radiation from CO2 is just one of the many factors affecting the final imbalance of 0.6 W/m2.
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CBDunkerson at 01:16 AM on 25 March 2015So what did-in the dinosaurs? A murder mystery…
Watchdog wrote: "I wanted to establish an agreement that CO2 does not cause abrupt Cooling."
That is often, but not always, true. Most natural processes (e.g. rock weathering) draw down the atmospheric CO2 level slowly over the course of thousands of years. However, there are exceptions like the Older and Younger Dryas periods... when an explosion of nitrogen fixing plants led to rapid CO2 declines... and corresponding temperature drops.
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Watchdog at 00:50 AM on 25 March 2015So what did-in the dinosaurs? A murder mystery…
I'm familiar with Milankovitch cycles which correlate with, and are proposed to be, causal to extreme abrupt Climate Change cycles. During most of its cycle, temperatures are significantly below our current average.
Global fridid temps occurring, e.g., within the K/T extinction period, were directly caused by Bolidal impact(s) and/or extensive Deccan Traps Volcanism of that time period.
I wanted to establish an agreement that CO2 does not cause abrupt Cooling.
I also look for agreement that extensive periods of Cooling, such as that of our Last Glaciation period which in turn lowered Ocean levels by 400', as well as those longer periods evidenced in Antarctic Ice Core Data, would self-evidently be deadly to _large areas_ of life-forms.
This Vostok data graph shows a correlation between Temperature and CO2.
Source of following graph, labeled:
"Vostok Ice Cores - Temperature and CO2" - is www.climatedata.info
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jja at 00:08 AM on 25 March 2015New measurements confirm extra heating from our carbon dioxide
Theo
you have an error of selection bias and improper time scales
The .2 value is a decadal average. You used a random start and end date instead of the annual average value and an 11 year time period.
Use the values from 2000 to 2010 and the points from the solid blue median line in the graphic. -
CBDunkerson at 23:27 PM on 24 March 2015So what did-in the dinosaurs? A murder mystery…
Watchdog, yes decreasing atmospheric CO2 levels cause cooling. If you look at atmospheric CO2 graphs they line up very well with the temperature and (inverted) ice volume graphs you showed.
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bozzza at 18:51 PM on 24 March 2015IPCC were wrong about Himalayan glaciers
@9, isn't the point that 'soot' can be scrubbed whereas CO2 cannot be scrubbed!??!
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Kevin C at 18:30 PM on 24 March 2015New measurements confirm extra heating from our carbon dioxide
Theo: I haven't looked into this, but the two obvious differences between this observation and a radiative forcing are that:
- Radiative forcing us a top of atmosphere flux difference, whereas this is at the surface.
- Radiative forcing is a global mean, where as these are local values.
But there may be other differences.
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bozzza at 18:19 PM on 24 March 2015It's not urgent
Dr David Mills was on youtube years ago saying it is now impossible not to go over 440ppm...! He also said it was being debated whether it was possible to go over it and then come back down under it but seeing as that was years ago I'm sure someone has information on where that specific debate is now.
(Dr David Mills was the candian guy who wanted to do Solar Thermal in Australia after having trained and invented processes in Australia but no dice so went to America and no dice, so, well... I suppose he gave in the end!)
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bozzza at 17:22 PM on 24 March 2015CO2 emissions do not correlate with CO2 concentration
Is this particular myth and its answer saying: "The Keeling curve has not yet reflected the economic activity rise of China yet?"
* No, I wasn't quite sure how to punctutate that!!
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bozzza at 17:15 PM on 24 March 2015An exponential increase in CO2 will result in a linear increase in temperature
... I believe the relevant term is 'partial pressures' having read through some of the pages of answers and comments given to other myths but I don't really understand what was being said.
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bozzza at 17:10 PM on 24 March 2015An exponential increase in CO2 will result in a linear increase in temperature
@ 6, this is most certainly interesting: can't wait for a reply to your post by one fitter than me to make one... but you know I'll be trying to work out a sensible response to it from now until then!
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Theo168 at 14:07 PM on 24 March 2015New measurements confirm extra heating from our carbon dioxide
It's about time basic radiative forcing was validated 'in the wild'
Question - why doesn't the paper not compare measurement with theory? My back of envelope calc predicted 0.29 W/m2 vs measured 0.2W/m2.
5.35*ln(389.85/369.52) = 0.29 W/m2
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So what did-in the dinosaurs? A murder mystery…
Watchdog - CO2 is a warming, not cooling, influence. Glacial and interglacial temperatures track with Milankovitch cycle forcings and positive feedbacks including CO2 (lagging the forcings by hundreds of years) and water vapor, plus longer term vegetation and ice albedo changes.
And now we're increasing CO2 on our own, with our increasing greenhouse gases acting as a direct warming forcing - with the predicted warming occurring as expected.
Where do you get 'cooling' from CO2? Reference(s), please.
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Watchdog at 10:58 AM on 24 March 2015So what did-in the dinosaurs? A murder mystery…
Daniel @ 65..
Did CO2 cause Earth's cyclical periods of catastrophic Global Cooling, and, the following Warming periods?
You said, "Regional trends". That is "indistinct".
Can you please define And quantify what you meant by "regional"?
During the last period of glaciation, Earth experienced major advances in global (Southern and Northern Hemispheres) glaciation as the result of the Global Cooling leading to a 400' decline in Oceans levels which in turn translates to a Volume of millions of cubic miles of ICE. I repeat that as a means of focussing upon the quantification of the total ICE; whose extent in both hemispheres is shown in a map posted below.
The area of of the ICE CAPS in Both Hemispheres during that recent time period of Global Cooling are not the total areas of both total and major disruptions of the Biota. Disruptions extended well beyond the actual edges of the massive glaciers.
Counter-Intuitively to some, Frigid Temps along with Massive Glaciation - results in a sharp decline of rainfall - even the extent of causing desertification; all of which in turn results in failure in vegetation and food supply. In other words: a catastrophic impact upon the biotic eco-system.
Global extent of ICE glaciation of 20kya
Above - Maximum Glaciation -— 20kya
•••The 3 graphs below drawn from Antarctic Ice Core Data support the above graph of Greenland Ice Core Temps. The first two graphs of Temperatures show cyclical periods of Global Cooling and Warming which correspond to the third graph of the fluctuatihng ICE Volumes over the past 450,000 years.
Again I ask: Is CO2 the Cause of Global Cooling?
_Moderator Response:[JH] Again, please document the sources of the graphics and data that you include in your posts.
[RH] Adjusted image width.
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chriskoz at 08:50 AM on 24 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Glenn@12,
Thanks. Your simple figures indicate why the release of all available FF (5000GtC) will result in climate change of scale comparable to LIP, what I was missing from the article.
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wili at 06:47 AM on 24 March 20152015 SkS Weekly Digest #12
A breaking story that SkS should probably get on top of:
http://forum.arctic-sea-ice.net/index.php/topic,1199.0.html
Moderator Response:[JH] Rest assurred, the all-volunteer SkS author team is "on top" of this new research finding.
PS - I have activated the links. Please learn how to do this using the edit tools provided.
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Daniel Bailey at 06:30 AM on 24 March 2015So what did-in the dinosaurs? A murder mystery…
The Greenland cited data is only indicative of regional trends over the period you indicate. You need to support your contentions with a global reconstruction.
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Watchdog at 06:22 AM on 24 March 2015So what did-in the dinosaurs? A murder mystery…
ranyl, My "1000 yr Global Cooling period during the last glaciation period",
is also supported by Greenland Ice Core Data.The following graph is based upon GreenLand Ice Core Data.
NOTE: Multiple significant cyclical Cooling & Warming Temperature periods from Today on back to 17kya, including extreme Cooling & Warming Climate Change from 10kya on back which occurred during the last glaciation.
My focus has obviously been upon obvious negative effects of extreme Global Cooling upon the Biota, of which one known cause is the Atmospheric Blockage of Solar Radiation due to e.g, Volcanic Emissions.
ranyl - Can CO2 - which is said to be the cause of Global Warming - also be the cause of Global Cooling? -
uncletimrob at 05:51 AM on 24 March 2015New measurements confirm extra heating from our carbon dioxide
Thank you. One of my interests is amateur radio and I've been working with a fellow ham on IR cloudbounce communication. This is a nice lok at IR from another perspective. A very interesting article.
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jja at 05:16 AM on 24 March 2015New measurements confirm extra heating from our carbon dioxide
Interestingly, this quote from the abstract:
This (CO2 component warming) is approximately ten per cent of the trend in downwelling longwave radiation5, 6, 7And that the overall increase in the rates of warming being experienced by the planet (also called the Top of Atmosphere energy inbalance, or TOA) is growing at a much more rapid rate. This is especially true when one considers that the emissions of Chinese aerosols during this same period increased by over 400%
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howardlee at 04:33 AM on 24 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
I found this statement in the introduction of the just-released textbook: "Volcanism and Global Environmental Change" edited by Schmidt, Fristad and Elkins-Tanton: "The composition of some past volcanically-released gases are frighteningly evocative of anthropogenic emissions..." (my emphasis).
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howardlee at 04:22 AM on 24 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
ginckgo @1Methanosarcina may possibly have played a role in the P-T extinction but I'm skeptical of the Rothman et al theory for the following reasons:
It is a one-off explanation, whereas LIPs have a criminal record – they are a serial killer with a consistent “MO”: greenhouse gas release, warming, rising sea levels, ocean acidification and anoxia.
Rothman et al use a 82-million-years-wide time window for the horizontal gene transfer that enabled the runaway methanogenesis. Even if we overlook the often elastic nature of molecular clocks, and that their clock is not calibrated to fossils, that’s a time window extending from the lower Permian to the lowest Jurassic. For the mutation to have happened exactly coincident with the Siberian Traps eruptions is just too fortuitous to be probable. The authors explain the coincidence by citing nickel fertilization by the Siberian Traps eruptions – but that would place the mutation, even more fortuitously, as having occurred between the Emeishan and Siberian LIPs, or else we should have had the Guadeloupian Mass Extinction.
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New measurements confirm extra heating from our carbon dioxide
Yep. The denialati were yelping about this paper last month (archived link). With the usual nonsense references to Salby, volcanos, "it's the sun", 2nd law of thermodynamics, etc...
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PhilippeChantreau at 01:47 AM on 24 March 2015New measurements confirm extra heating from our carbon dioxide
Now prepare for the onslaught of flat-earthing pseudo physics that some will undoubtedly launch following these results...
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wili at 00:56 AM on 24 March 20152015 SkS Weekly News Roundup #12B
And...Cruz is now running for president.
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DSL at 00:31 AM on 24 March 2015DMI show cooling Arctic
bozzza, a little more argument would be helpful.
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ranyl at 23:35 PM on 23 March 2015So what did-in the dinosaurs? A murder mystery…
Well Watchdog I refer to Howardlee article and references within for CO2 mechanisms and James Mason articles. (http://www.skepticalscience.com/pollution-part-2.html)
However not sure why you feel it necessary to point out CO2 is colourless, so is sarin!
And the publishers pointing out CO2 role are very aware of the effects of eruptions and bolides (although the previaling opinion now is that the global climate effects are more like 5-20years not the 1000 years as you suggest.
e.g. http://www.newscientist.com/article/dn23458-supervolcano-eruptions-may-not-be-so-deadly-after-all.html#.VRAVi2ezWdI
Therefore as I have no problems with accepting all the effects from a volcanic eruption of bollide impact cause major issues, just no mass extinctions, unless a CO2 impulse part of the picture.
Again what is about CO2 the makes you feel it is not involved as a pivotal player?
There must be something for all the scientific evidence and expert opinion is, that a large CO2 impulse can easily cause major prolonged global ecosystem disturbance that can reach the scale of a mass extinction, yet you don't, therefore just wondering how come that is?
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Glenn Tamblyn at 20:22 PM on 23 March 2015Antarctica is gaining ice
bozzza
That might have been a fair possibility a week ago. Now a late rise in extent would look less likely. That said, a record low maximum extent doesn't tell us what the minimum in September will look like. 2012 was the record minimum, but it certainly wasn't an unusually low maximum. It all depends on the weather up there over the next 6 months.
Regions to watch:
- The Kara and Laptev Seas. They seem to have been stubbonly refusing to thicken over this winter so might melt out quickly.
- The central Arctic Basin above the Barentz and Kara. Much of the ice there seems to be quite broken up - more easily moved around, splashed with water etc.
- The Beaufort Sea. Currently a lot of the older, thicker ice is there (and the Canadian Archepelago). If the weather applies a blow torch to that, while it may not contribute much to what happens to Extent and Area, it could have a big impact on what happens to Volume.
If you haven't discovered it already, Neven's Arctic Sea Ice Blog is a treasure house:
- The Arctic Sea Ice Graphics page give you links to loads of different resources, webcams, long term data sets etc. If a Polar Bear is going to get it's picture taken by a drifting ice buoy, somone at Neven's blog will probably spot it.
- His Forum has a lot of true Arctic Nerds (in the very best sense of the word) who can dissect data you may not have even heard of. One regular (Wipneus) produces his own area/extent calculations by combining the best of the raw data feeds from multiple satellites. A regular here at SkS, Jim Hunt, can wax lyrical about what the thermocouple tree below a buoy can tell us about the mixing of waters below the ice - when he isn't tearing David Rose at the Mail in England a 'new one'.
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uncletimrob at 20:12 PM on 23 March 20152015 SkS Weekly News Roundup #12B
re: Ted Cruz goes full Orwell. Well who voted him in? He's not a scientist but feels capable to mock those who are and deny science because he either is to thick to understand it, or frankly doesn't care because he has a political agenda ( keep voting for me ). "You get what you pay for" pollitically is "you get who you vote for". Until these morons are voted out we will continue to reap the benefits of their limited intellect or ability to reconcile ther beliefs with REAL science.
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bozzza at 16:35 PM on 23 March 2015DMI show cooling Arctic
I think figure 1 gives the deniers some ammunition to work with.
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bozzza at 15:57 PM on 23 March 2015We didn't have global warming during the Industrial Revolution
I like the graph: it has mutiple inflection points that may serve us all well as a time guide. For instance I might like to reflect on the Keeling Curve in comparison to it, for example--> it is my opinion that the rise of China hasn't been reflected in the Keeling Curve yet though I am willing to be corrected.
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Tom Curtis at 15:49 PM on 23 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
angela @22:
"I speak for the genral public..."
Really? Who appointed you to that position? And can we see the documentation showing that you have been appointed to "speak for the general public". Personally I only ever speak for myself. That is probably because I am flabberghasted at the arrogance shown by people who claim to speak for the "the general public" (or whoever else they want to drag in to give their questions unwarrented authority).
Moderator Response:[TD] I believe Angela is a bot, so I've deleted her/its comments. Angela is quite welcome to prove me wrong by posting a comment having more substance.
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bozzza at 15:42 PM on 23 March 2015Climatology versus Pseudoscience book tests whose predictions have been right
@10, regarding contributors that work for government departments these people go from working in the field and contributing data to the desk jobs of organising the reports and analysis and finally perhaps rise to the rank of giving them to ministers. It can take 30 years to get to these latter stages of which none are more important than the other.
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bozzza at 15:08 PM on 23 March 2015Antarctica is gaining ice
The year 2010-2011 for the Arctic, (from here) , shows a late peak... not to mention a very flat projection towards said late peak. The following year, 2011-2012, didn't seem to suffer in terms of ice extent!!
From this may I be permitted to guess that we perhaps haven't seen the maximum ice extent for 2014-2015 yet??
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denisaf at 13:02 PM on 23 March 20152015 SkS Weekly News Roundup #12B
A major point missing in the discussion of water usage is the existing commitmnet to use water in the operation of many aspects of infrastructre operation and maintenence. For example, thermal power stations use vast quntities of cooling water. Decisions about using water more effectively are constrained by these commitments.
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John Mason at 12:33 PM on 23 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Bill - sort of spot-on! Certain elements may through their similar properties substitute directly for Zr in zircon. U, Th and Hf are examples. However, lead is not one of these elements. Its non-radiogenic "primordial" isotope, Pb 204, does not occur in zircons. Any Pb that is present within a zircon crystal is therefore a product of radioactive decay - isotopes like Pb 207 and 208 - and that's why these tiny crystals are proving such excellent geochronometers.
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Glenn Tamblyn at 11:04 AM on 23 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
Chriskoz
In addition to JM's comment, we need to remember the roughly logarithmc nature of the CO2 forcing. John has described a rise from aeound 2000 ppm up to around 8000 ppm - 2 doublings. A comparble change for us is a rise from 280 to 1120 ppm. So we only need to cause a rise of 840 ppm to produce a comparable forcing to a roughly 5000-6000 ppm change back then - around 6 or 7 times different.
So the ratio you use of 27,000 to 1,000 should actually be looked at as more like 4-5,000 to 1,000. Obviously if we can restrict emissions to 1000 GTonnes then we will hopefully be OK. But emissions of several 1,000 GTonnes are certainly achievable if we don't achieve restrictions. So an impact that is at least a significant proportion of the impact of the end-Permian certainly seems plausible if we don't act.
Even an end-Permian-lite would still be disastrous for a human population for 10 billion or so people.Of course this relativity only applies to the radiative forcing aspect. The ratio of severity for ocean acidification will be diffferent.
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Watchdog at 04:38 AM on 23 March 2015So what did-in the dinosaurs? A murder mystery…
ranyl @53 - You asked me: "Watchdog, as howardlee's research is extensive and the evidence convinving, what is it about CO2 being the primary murder weapon that makes you feel that this possibility is in error?"
Great Question
All published science research connected with the K/T extinction have also been "extensive with convincing evidences". And as howardlee notes, "The case is probably not closed".
Currently, the answer to the overall question is akin to a jig-saw puzzle; all of whose pieces have neither been clearly identified as yet; nor, therefore, can presently be assembled into a finalized overall picture.
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Frontnotes concerning the deleterious effects of asteroidal impacts and volcanic particulate and aerosol emissions upon biotic life..
V. Rough Quantification of Chicxulub's Effects upon North America:
Chicxulub's energy is equivalent to 100,000,000 - 1MT HBombs
One 1MT HBomb creates a crater 0.2 miles in diameter and 0.04 miles deep.
It's energy converts to: shockblast, thermal, seismic waves and ejecta debris
Within a circle 3.4 miles in diameter c.98% of life is killed.
Serious damage extends out to a circle c. 10 miles in diameter.
Moderate damage occurs out to a circle c. 20 miles in diameter.
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Chicxulub's energy of c.10^8 1MT HBombs - created a crater variously estimated to be c. 100 miles in diameter and c. 12 miles in depth.
Its arrival angle is estimated to be 20° to 30° from the horizontal with a general directional heading toward the remainder of North America.
“These asymmetric signatures suggest a trajectory for the Chicxulub bolide from the southeast to the northwest at a 20°–30° angle from the horizontal. As a result, biotic extinctions may have been most severe and catastrophic in the Northern Hemisphere.” [url]http://geology.geoscienceworld.org/content/24/11/963.abstract[/url]
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Asteroidal Craters and Antipodal Locations:
In addition to Chicxulub (not necessarily connected with Deccan Traps), evidences exist for 2 or more major asteroidal impacts occurring c. 65MYA.
1. Antipodal location of the Deccan Traps is at the Eastern Pacific, whose seafloor evidences a major asteroidal impact.
2. A proposed crater location - 2.5 times the diameter of Chicxulub - lies East and South of Mumbai, India
[url]http://www.dinodatabase.com/dinothry.asp[/url]
[url]https://gsa.confex.com/gsa/2003AM/finalprogram/abstract_58126.htm[/img]
Comparative Volcanic Eruption Effects upon Global Temperature
On June 15, 1991, Mt. Pinatubo erupted, spewing Ash Dust, Smoke and 30 Million Tons of Sulphur Dioxide into the stratosphere. It's ash and aerosols plume was 250 miles wide, reaching an altitude of 34km.
The SO2 formed into sulphuric acid which depleted the Ozone Layer.
From 1991 to 1993, average global temps declined by 0.5°C.
In 1992 the USA experienced its coldest summer in 77 yrs.
A combination of ash particulates, smoke, and aerosol droplets of H2SO4 (see: noted historical “darkening of the skies” events) into the stratosphere lowers Solar Radiation arriving to Earth, thus, historical Lowering of Global Temperatures and ensuing widespread impact upon the biota.
Size Comparison of Historical Ejecta Events
Volume of Ejecta of 1991AD Pinatubo has been estimated at 2 cubic miles
Ejecta from 1883AD Krakatoa was Twice that of Pinatubo.
1815AD Tambora was 10 times larger than Krakatoa.
10,000BCE Toba Ejecta was 2,800 cubic km: 100X larger than Tambora, and coincided with the onset of the last glaciation period. .. Greenland Ice Core data evidences a 1000-year lowering of Temps in Toba's aftermath.
Chicxulub's Crater Volume is c. 28,000 km3 (c.10 times Toba's)
The volume of the basalt lava of Deccan Flats is c. 512,000 km3,
which is 500,000 times as large as that from Mt. St. Helen’s 1km3.
Add in possibilities of theorized additional large asteroidal impacts of 65MYA?
CONCLUSION
Historically and Evidentially, Massive Asteroidal and Massive Volcanic Events can not be deemed as mere “suspects". Taken fully and solely by themselves, the Effects of these Events which are dulely noted above - when taken alone by themselves - are of sufficient intensities to be causal to massive extinctions of life forms.
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ranyl — What is it about the colorless gas CO2 that leads you to think that CO2 is the prime suspect in the deaths of dinosaurs?Moderator Response:[JH] Yopu are now skating on the thin ice of excessive repitition which is prohibited by the SkS Comments Policy.
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Theorist at 04:20 AM on 23 March 2015So what did-in the dinosaurs? A murder mystery…
Tom Curtis @60
I agree with your last statement but just to clarify your last statement:
The study makes the point that 50% of the living microplankton disappeared AT THE ONSET of Phase 2 of the Deccan eruptions. Each Phase has four lava mega-flows. Within Phase 2 the magnitude of the four mega-flows increases substantially with time. Therefore, it is reasonable to assume that the Deccan Traps volcanism was not responsible for the extinction.
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michael sweet at 23:55 PM on 22 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Ryland,
I frequently ask posters here to provide evidence (preferably peer reviewed) to support their positions. Since Chris had no data, only his claim of personal authority, I asked for evidence of that.
If other posters want to be taken seriously they have to provide evidence to support their positions. That is the scientific method. Everyone is required to provide citations to support their position if asked (better posters like Tom provide evidence when they make the claim). All claims are evaluated based on the supporting evidence, not on the authority of the poster. I have an MS in chemistry. If I make a chemical based claim I am still required to provide citations if asked, even if the other poster has no chemical experience.
Kevin Cowtan is a reknowned world authority on temperature records who posts at this site. If questioned by skeptics who have no qualifications (which happens frequently), he provides citations to support his positions. I do not ask Dr. Cowtan for citations because I know his reputation and am comfortable that he can support his claims. Likewise mpelto is an occasional poster on this site who is a world authority on glaciers. If questioned by novices he provides citations to support his positions.
I am sorry, I meant Andrew Montford the well known denier.
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billthefrog at 23:37 PM on 22 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 2)
John,
I think I have a vague grasp of how zircon dating works, but it wouldn't surprise me if I've got the wrong end of the stick. Is this how it goes?...
When the zircon - nominally ZrSiO4 - is initially formed, other silicates, such as USi04 and ThSiO4, can be present in minute quantities. The decay paths of Uranium and Thorium will result in a variety of Lead isotopes ending up being present in a modern-day sample.
However, there is a bit I'm really shaky on, as I don't know the differing chemistry of the Actinoids and the Transition metals. I think any Lead originally present when the Zircon is formed does not get incorporated into the structure of the crystal lattice. Ergo, any Lead present in the modern sample is there as a daughter product formed post-crystallisation.
The relative abundances of the Lead isotopes, can therefore be used as a dating mechanism.
How much of that have I misunderstood?
cheers bill f
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ryland at 23:03 PM on 22 March 2015The cause of the greatest mass-extinctions of all? Pollution (Part 1)
Michael Sweet @18 Thank you for answering my question. With regard to your question "What evidence do you have that Chris really has a geology degree?" etc. The answer is none. But then, I don't have evidence of the background of many of those who comment here and equally those who comment here have no evidence of my background. Is it a pre-requisite to provide details? Not sure who Montfort is. Anyway, thanks again for your courtesy.
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