StudentOfClimatology

I think 2 different concepts are being argued over, especially the second point:

1.) O^18 / O^16 ratio is indicative of changes in global SST / change in global ice volume --> relate to global surface Temps, although not directly

2.) O^18 / O^16 ratio corresponds to temperature of snow when the snow fell, which isn't necessarily where the snow fell ..

Bingo, and both of these are true.

Ice cores are the very foundation of paleoclimate research today, so I'm surprised so many people don't understand how to interpret them. If anything, they're hemispheric SST proxies.

Did you intentionally take that sentence out of context? Sorry to be rude, but this has to be the 5th time I've gone over this. My specialized area of study is paleoclimate..this is 1st grade stuff.

That sentence is referring to dating of the estimated temperature..*when* the snow fell, not *where* the snow fell. The temperature of condensation determines the initial O^16/O^18 ratio as the precipitation process is just getting underway..the required temperature to keep O^2^18 bonded and bouyant during the evaporation process does not occur above 50-60N.

The ratio of concentrations of two isotopes of oxygen in the water molecules in ice serves as a proxy indicator of global temperatures. Oxygen has two commonly occurring natural isotopes, the usual 16O (which makes up more than 99% of naturally occurring oxygen on Earth) and the less abundant 18O. The two extra neutrons in 18O cause water molecules containing this isotope to be heavier than normal water molecules. These heavier water molecules cannot escape from ocean water to become water vapor in the atmosphere via evaporation as readily as lighter water molecules. This tendency for preferential evaporation of 18O varies, however, as a result of the ocean temperature.

The net result is that the ratio of 18O to 16O in ice samples provides clues about global ocean temperatures and the extent of the polar ice caps at a given time in Earth's history.

This is rich.

I'm sick of rehashing preschool science to you. Arguing that the O^18/^16 ratios are regionally representative is analogous to arguing that CO^2 is not well mixed, or that the dust concentration in the ice pack is regional.

http://www.econ.yale.edu/~nordhaus/homepage/documents/icecore_review.pdf

http://eo.ucar.edu/staff/rrussell/climate/paleoclimate/ice_core_proxy_records.html

The ratio of concentrations of two isotopes of oxygen in the water molecules in ice serves as a proxy indicator of global temperatures. Oxygen has two commonly occurring natural isotopes, the usual 16O (which makes up more than 99% of naturally occurring oxygen on Earth) and the less abundant 18O. The two extra neutrons in 18O cause water molecules containing this isotope to be heavier than normal water molecules. These heavier water molecules cannot escape from ocean water to become water vapor in the atmosphere via evaporation as readily as lighter water molecules. This tendency for preferential evaporation of 18O varies, however, as a result of the ocean temperature. Through a rather complex chain of events involving the global water cycle, this disparity between concentrations of oxygen-18 and oxygen-16 shows up in the snow that falls in polar regions, and thus in the ice formed from this snow. The net result is that the ratio of 18O to 16O in ice samples provides clues about global ocean temperatures and the extent of the polar ice caps at a given time in Earth's history.

No the temperatures are regional. Changes in isotope ratio during vapor transport are more important than changes at the source. The heavier isotopes are preferentially removed as water vapor is transported, lifted, cooled and percipitated. A local calibration is performed to relate isotope concentration to temperature on the ice sheet. Note that a part of the variation in the isotope record is due to changes in moisture transport to the ice sheet and not temperature.

They're not regional..the temperatures required to vaporize bonds w/ O^18 and maintain buoyancy (at the aforementioned ratio) are far above those found above 60N for most of the year. Nothing is regionally represented within the ice core data, whether it be dust concentration, or isotope formation/separation.

You can tell by reading the abstract that the paper is junk science which that journal has a habit of producing. The abstract equates ice core variability to global variability. There are several problems with that. First variation in the arctic is much larger than the tropics. Second variability in one region is not the same as global variability. . Regional variability can arise from variation in mean wind or ocean circulation. However circulation variability balances out over the globe. Large variation in global mean temperature requires a change in forcing or a major change in ocean circulation and there is no evidence for that in the holocene. Secondly the paper doesn't identify any natural cause for the global warming over the past 150 years. Natural variability can be warm or cool. To conclude that natural variability has been a major factor in warming a natural warming effect or combination of effects comparable in magnitude to the over 2.5 W/m2 of man-made GHG forcing would have to be identified.

I agree that the paper is fatally flawed, but too many people misunderstand what ice core proxies are actually measuring. The isotope ratios used to reconstruct temperature are governed by processes over the tropical, subtropical, and extratropical oceans, not over the Arctic. The heavier O^3 isotopes are mostly rained out by 50-60N, in fact.

The isotope ratios within ice cores are, for all intents and purposes, hemispheric SST proxies. The Arctic cores depict SSTs over the Northern Hemisphere, while the Antarctic cores depict SSTs over the Southern Hemisphere.

The article is rubbish research. It's published in Energy & Environment, the pal-reviewed denialist journal, and it's methodology is fatally flawed. The author used a cherry-picked portion of ice core records, performed a number of questionable statistical operations, and conflates his finding to represent the entire globe.

It doesn't matter what journal the paper was published in. All that matters is the content of the paper itself.

Anyway, I decided to purchase the paper and read it last night. There is a major flaw in the paper in my opinion, which is that the authors fail to tune for known/observed radiative forcings when assigning attribution to the 20th century warming. Their conclusion basically states that because the observed warming is within the natural standard deviation(s) of the Holocene, the observed 20th century warming is largely natural. In my opinion, this error undermines the entirety of the paper.

That said, their ice core analysis was good, as was their high resolution Holocene reconstruction (matches up well with GISP, GISP2, and GRIP).

This place has become almost unreadable lately.

No one takes you seriously because you're constantly inventing stuff and trying to pass it off as fact thereafter. It's irritating to read, honestly.

I'm happy to have a reasonable, science-based conversation with you, but you'll need to stop playing dress-up before I do so.

You are a irrational'ish poster, however troll post is obvious.

You're *literally* describing yourself to a tee here. Couldn't have scripted this one any better.

No, the PDO thing. We will never have a -PDO again. From now on land will be playing 'catch-up' with the ocean (thanks hiatus).

Point taken nflwxman. I am a skeptic on the other side of the spectrum.

When the PDO goes negative in a few years, will you never post here again?

ENSO is definitely based on sheer SSTA...they cannot be seperated. Strong ENSO events in the opposite PDO phase are not possible.

^Agreed TGW

TGW is trying to help you understand this..he doesn't agree with you regarding the PDO/ENSO because he actually knows what he's talking about.

Both ENSO and the PDO are detrended and the former is technically based on SST contrast, not temperatures. Even if we warm 100 degrees, it'll have no effect on these phenomenon. Get that into your head, please.

Are you this stupid? The PDO & ENSO are both based on SST contrast(s), not temperatures. If the oceans warmed 100 degrees everywhere, that wouldn't change the frequency of La Niñas or negative PDOs.

I can never tell if he is being sarcastic or serious. If the latter then he is a denier, but I think he tries to hide it. We will definitely need a super-nino to ever have a chance at another la nina, otherwise we will be stuck in neutral 'hell'.

The heat is not just on the surface, the 20C isotherm runs down to like 300 meters which is fookin' bat**** crazy.

No, it's actually normal for the 20C isotherm to reach 300-400m under an antecedent El Niño thermocline.

Literally everything you post here is pure horses**t.

Due to the Coriolis force, warm ocean currents are more prone to traveling north. The diminished overturning weakens the influence of the southward branch of the Labrador Current.

So the Earth is rotating faster now? Why would the coriolis force strengthen?

Plus, if more warm water is being transported northward, then more cold water must also be transported south..conservation of mass. This would represent a stronger AMOC, too.

I'm done responding to this crap.

That makes no sense. If the northern Gulf Stream is gaining latitude as you say, it can't be weaker..where's it getting the energy to penetrate further NE over the NATL?

Why do you make stuff up like this?

Choosing to ignore my posts won't change reality. Some of you are in for a rude awkening.

You pretty much answered your own hypothesis there ORH. Gulf Stream has moved north and it's trajectory has changed, hint hint AMOC shutdown.

If the Gulf Stream has moved north, that'd indicate a strengthening of the AMOC, not a weakening.

Do some research before posting next time.

How is the el nino related to the Atlantic SSTA field? Making stuff up like SOC now?

You're the one making stuff up, not me.

what's your degree program and at what school? i can't find any climatology programs near md

http://www.atmos.umd.edu

I have to say I'm rather skeptical myself at the conclusion in Marcott et al. that 1900-1909 was cooler than 95% of all Holocene decades. It's at odds with the limited instrumental records we have (BEST) showing a gradual warming trend from the mid 1700s into the early 20th century. It's also at odds with our understanding of the Little Ice Age, which is believed to have lasted from around 1300 C.E. to 1850 C.E. It's known to a great deal of certainty from temperature records, historic observations, glacial melt that the turn of the 20th century was warmer than the several hundred preceding years. So this claim would basically say the LIA is the only time since the dawn of the Holocene, where temperatures were lower than the early 20th century average. Color me skeptical.

I agree with you here. It's generally viewed that the 8200kyr event marked the coldest excursion within the Holocene, followed by the LIA and the DACP.

SoC, you seems to get in one major nasty debate a day with someone here. Often someone on the realist/alarmist side. Why?

It's definitely seemed that way recently, I admit. I'll try to tone it down. I'm just a bit frustrated because we had this exact debate ~ 6 months ago and I thought it had run its course. Denying that the HCO was the warmest period since the Eemian maximum is almost like denying AGW.

Not one of the dusty aged studies you shared is relevant to your claim that 80% of climate scientists reject Marcott et al 2013. Your claim was simply fiction, you know it and, more importantly, we all know it too.

But carry on with posting your nonsense - it only hurts your credibility and is immensely entertainingl

You'd honestly be laughed at by anyone with education in paleoclimate if you pulled crap in an academic setting. I mean, you were treating just aggregated proxy data as if it were analogous to yearly changes in the instrumental data..talk about hall-of-fame caliber nonsense.

Also, I added a *~* symbol before the number 80. I don't know what the exact number is but the point stands..the vast majority of work in the database suggests the HCO was significantly warmer than present, including Marcott et al 2013, as a matter of fact.

It's fun to watch you try to avoid accepting responsibility when you're caught, shall we say, 'embroidering' the facts. In this case you started off by claiming:

But when asked to share a link to four peer-reviewed studies that support your claim you failed to even link to one. Instead you went for the unsupported bluff:

You're full of it.

I linked you to 28 peer reviewed studies, all in unanimous agreement regarding the magnitude of the HCO relative to today's climate. I'm only aware of four studies in existence that argue otherwise.

If you don't want to read them, that's your choice. But I'm not going to do your research for you.

But of course you know as well as the rest of us that borehole and ice core proxies are regional, not global, so even if 1.5C number were true this was just a bit of misdirection.

Ice core proxies are not regional, they're hemispheric. The O^16/O^18 isotope ratios are determined primarily by temperatures at 300-1000mb over the sea surface between 10N/S and 60N/S latitude bands, where the heavier isotopes are circulated and subsequently rained out at higher latitudes due to the decease in macroscale buoyancy. The ratio between the variously isotopes is then calculated.

The ratio of concentrations of two isotopes of oxygen in the water molecules in ice serves as a proxy indicator of global temperatures. Oxygen has two commonly occurring natural isotopes, the usual 16O (which makes up more than 99% of naturally occurring oxygen on Earth) and the less abundant 18O. The two extra neutrons in 18O cause water molecules containing this isotope to be heavier than normal water molecules. These heavier water molecules cannot escape from ocean water to become water vapor in the atmosphere via evaporation as readily as lighter water molecules. This tendency for preferential evaporation of 18O varies, however, as a result of the ocean temperature. Through a rather complex chain of events involving the global water cycle, this disparity between concentrations of oxygen-18 and oxygen-16 shows up in the snow that falls in polar regions, and thus in the ice formed from this snow. The net result is that the ratio of 18O to 16O in ice samples provides clues about global ocean temperatures and the extent of the polar ice caps at a given time in Earth's history.

http://eo.ucar.edu/staff/rrussell/climate/paleoclimate/ice_core_proxy_records.html

But the more serious issue is that you try to misrepresent Marcott's work to prop up your disingenuous position. As SOC quoted, Marcott wrote: Our results indicate that global mean temperature for the decade 2000–2009 has not yet exceeded the warmest temperatures of the early Holocene.

But that's hardly definitive as to whether today's global temperature is equal or greater than that of the early Holocene.

After all, the Earth has continued to warm, and 2014 was the warmest year on record according to NASA.

So let's look a bit deeper into Marcott et al 2013. Below is Fig 3, and its caption, from the paper. The right hand vertical line is the mean for 2000 - 2009, and the anomaly is around 0.45 C from the 1961 - 1990 baseline. The lowest horizontal lozenge is the Holocene temperature spread (roughly -0.2 C - 0.51 C). Note that the Holocene max is only 0.06 C above the 2000 - 2009 mean, so if today's global temps have risen 0.06 C in recent years then we're tied with the HCO max, and if they've risen more than 0.06 C then we've exceeded the HCO.

Once again, you are not accounting for the resolution change between the paleoclimate reconstruction and the observational data. If you want to determine the HCO/modern day differential with any certainty, you need to tune the observational data to the proxy resolution, or statistically account for the smoothing process in the proxy data itself. Do you understand why this is?

Marcott explains this in the FAQ of the paper. If you'd actually have read it, you wouldn't be posting this nonsense..

That was fast, you should get out more.

Relax my friend.

Yeah, I'd actually just clicked on the cc-forum when you posted.

All the endless ranting about how we post garbage from the blogosphere...

No such ranting exists.

I'm just tired of rehashing what is largely settled science.

Here, I'll do your research for you. Gosh.

Tell me which papers you "can't find", and I'll link them for you. Call it a personal favor.

First, I'll quote Marcott et al directly, because you obviously did not read the paper. Even though their proxies are aggregated on a 200-300yr resolution and do not show the variability that most reconstructions present, they state:

Based on comparison of the instrumental record of global temperature change with the distribution of Holocene global average temperatures from our paleo-reconstruction, we find that the decade 2000-2009 has probably not exceeded the warmest temperatures of the early Holocene, but is warmer than ~75% of all temperatures during the Holocene

http://www.realclimate.org/index.php/archives/2013/03/response-by-marcott-et-al/comment-page-1

Again, this is basically settled science.