UKC

Really interesting that we can tell exactly what the climate was like in the past few thousand years from Greenland ice core samples, and how we can use this to predict future temperatures. Remarkable science and something I'd love to get involved in if I'd had my time again.

youtube.com/watch?v=L1mjG_F8ppw&

No idea how they would measure temperatures so precisely though. What sort of thermometer would they have used?

Good link for you here if you're interested, that isn't too technical: 

https://www.bas.ac.uk/data/our-data/publication/ice-cores-and-climate-chang...

Temps aren't measured directly in ice cores for this (and wouldn't represent historical air temperate anyway). In my type of glaciology (which is more contemporary process based) we use these kind of things:

https://www.campbellsci.eu/water-temperature

When I was at university (Royal Holloway) we used a particular sort of mass spectrometer (link 1) to analyse the elemental isotopes in foramenifera shells (link 2 is a photo of one). This machine would fire a laser at the foramenifera which would turn the shell into a gas which would then be put through a mass spectrometer. This in turn would analyse the diffent isotopes of a number of different elements. You might already know how this works but for those who don't I'll explain it as best I can. 

An element like will have a set number of protons. Oxygen has 8 for example. If you add the number of protons to the number of neutrons you get the atomic weight. Although the number of protons for an element is fixed the number of neutrons isn't. Oxygen most commonly has 8 neutrons but occasionally has a different number. 

One isotope of oxygen has 10 neutrons (called oxygen 18 - as 18 is it's atomic weight) . This effectively means a molecule of water made up of oxygen 18 will weigh more than one made of the more common oxygen 16. This in turn means that when water is evaporated from the oceans oxygen 18 is less likely to evaporate and more likely to stay behind. Therefore water in clouds and rain will have more oxygen 16 on than water found in the ocean (at the same lattitude). Therefore as snow falls in the polar regions a disproportionate amount of oxygen 16 gets trapped there as snow and ice. If one analyses the isotopes of the oxygen or hydrogen in the polar ice caps you can calculate the global temperature. 

Back to the foramenifera. Their shells are made of calcium but have a lot of impurities. As it so happens each element can be used to calculate different qualities of the water it was formed in (since that's where the material used to make the shell comes from). By analysing the isotopes in a foramenifera shell you can calcuatle the sea temperature, salinity, lattitude and other things I've since forgotten ( it was more than 10 years ago that I was taught this). Even cooler though is that the mass spectrometer I mentioned above can analyse each part of a foramenifera shell separatly which means you can see how the sea water changed throughout the life of the foramenifera. And if you take a core from the sea floor which contains dead foramenifera throughout you can get a wealth of information about past global climate. I think it's absolutely incredible. 

https://www.cranfield.ac.uk/facilities/laser-ablation#:~:text=to%20Copy%20L...(LA%2DICP,U%2C%20with%20minimum%20sample%20destruction.

https://www.nhm.ac.uk/content/dam/nhmwww/our-science/our-work/biodiversity/...

Thanks for that and very interesting. I guess as bodies of water warm, e.g. oceans, they are able to hold less dissolved CO2 and such.

Welcome. Yup, this - but as RBonney alludes too, there are also isotopic changes - in the case of seawater, it's carbon and nitrogen isotopes. This then ends up changing the isotopic ratio of evaporated water, which forms rain (snow) and subsequently ice sheets - and IIRC this is what is being measured. Been a long time since I have done any kind of learning of ice-core/paleoclimate stuff though, so I *might* be wrong.

So we’ve got WEF/Great Reset conspiracy guff on another thread, a bit of climate change denial here. I presume you’re going to give us a full house later with a good ol’ anti-vax thread?

Credit where credit’s due though, this is certainly a more subtle approach than your previous incarnations. 

the borehole temperature is a proxy for it tho..

Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past. (wiki)

OP: these thermometers measure to thousandths - https://www.instrumart.com/categories/791/precision-thermometers

Struggling to get my head round it, so which way round does it work?

Do naturally concurring global temperature fluctuations heat or cool the oceans allowing them to both absorb or release from solution CO2 from the atmosphere. In which case levels of CO2 in the atmosphere would to some extent follow changes in oceanic temperatures.

Or is it that excess levels of CO2 in the atmosphere, of which a very tiny percentage is man made heat the atmosphere to such an extent that they drive the oceans to warm, releasing more CO2 as they warm?

Ignoring the greening effect of CO2 which gives a huge life boost to plants and crops, and ignoring the ice core data that shows us that temperatures were several degrees higher for extended periods of time in recent history, and ignoring that when our detailed climate recordings started in the mid 1800's it happened to coincide with the lowest average global temperature for 1,000's of years, this would lead to a kind of viscous doom cycle with no end, and disastrous for the planet if you like?

Aaaand we get to the point.

Pity really, I thought this thread might have survived as an interesting little geology/chemistry lesson.

jk

Both. This is a positive feedback mechanism, and would indeed lead to a doom cycle (viscosity unknown, but it'd probably at least get quite muggy), if there were no other mechanisms feeding in. The environment is complex, and other factors will eventually result in a new equilibrium being reached (although possibly not one that we'll like, and the process of getting there could be especially nasty). For example, the more CO2 released from solution in the ocean, the less left - and the harder it gets to release more. It doesn't have "no end", but the end probably isn't a great place to be.

Oh - and while CO2 itself forms a small fraction of the Earth's current atmosphere, the fraction of that CO2 released by human activity is by no means "a very tiny percentage". But you probably already know that.

That was going to be my point

Or is it that excess levels of CO2 in the atmosphere, of which a very tiny percentage is man made 

We use infrared gas analysers to measure plant photosynthesis. The increase in background CO2 levels in my career are truly terrifying - and nearly all arise from human activity. We are the frogs in the metaphorical pan of heating water - except we know it's happening and are choosing to ignore it.

There it is. I'm not engaging any more beyond one comment: warmer water can dissolve less CO2 than colder water, but this is orders (note plural) of magnitude less than anthropogenic emitted CO2, or even the historic changes we observe in the atmosphere (which is directly sampled). Believe it or not, climate scientists aren't stupid and consider these things, using actual numbers - not just broad processes. 

I lied, I'll add something: if climate scientists are part of some great get rich conspiracy, I'd like some of the get rich part please. 

We have left this thread up as I think it was a really interesting read. The OP has been banned: they've created 100+ accounts in the past. I had a glimmer of hope that they were asking genuine questions this time and not simply posting conspiracy BS but hey ho.

Good shout....I agree it's a really interesting thread and I hope it continues in good faith...!

It's a great example of the forums that information from real experts can be diluted sufficiently for the rest of us to engage with and understand!

I applaud the high quality of moderation on UKC/H 👏👏

Me too which is why I replied - but will be back now! Thanks for the great work as always

this is a good read re CO2 vs temperature:

https://www.carbonbrief.org/explainer-how-the-rise-and-fall-of-co2-levels-i...

Good job Paul.

Where on earth do you find someone technically literate enough to make just the right faux naïve mistakes to confuse the layperson but also willing to do so in order to achieve, what, a worse world. Even if someone creating dozens of campaigning profiles on here isn't that literate mercenary, just a credulous fool down a rabbit hole, someone who should know better dug the hole then pushed the fool in.

jk

As a matter of interest - do you know it is one user creating all these accounts?  If so, why not just ban their IP address (rather than playing whack-a-mole with each new account)?

If you are struggling with this, there is an enormous literature of the use of isotopes as geothermometers, going back more than half a century, that might help you. Better than jumping to poorly informed conclusions.

I can't disclose how we're matching it to the same user. It's not the same IP address though.

This now sounds far too interesting.

Probably not. There are any number of mundane ways for a website owner to fingerprint a particular user, with varying degrees of certainty and specificity, particularly if you combine together different markers. But using most of them to actually block a user would be impractical, easy to get around and/or would come with a risk of inadvertently blocking others as well.

https://wikipedia.org/wiki/Device_fingerprint

If it's one person then they seem to have a fairly regular approach to posting - a recent registration (without profile), posting fairly innocuous comments on other unrelated threads and saving the giveaway stuff for the main thrust (climate/covid denial). Sometimes it's difficult (to me anyway) to tell them from an AI bot such is the general blandness of what they say.

I sensed it with the name of the poster, the topic title. They're getting better with the gradual ease in though. I'm getting closer to thinking it will soon be time for having forums with only "verified" posters. Yes, it's a shame for privacy but in the end, one can go use a different forum if one wants.

i haven't read his other threads, but this thread reads like someone wanting to understand- pretty harmless. i find the responses far more alarming..

If this is the 100th profile plus 'just writing to understand' then he or she is one mighty determined scholar!

I'll grant you it was a much better effort than some but the direction of travel was abundantly clear. If it's human generated campaigning I'm actually quite impressed, if it's not, I'm terrified.

jk

Thanks, even if the OP was denying the earth was flat or vaccine not warmed or whatever claptrap, I'm certainly interested and learning from the responses. Thanks all!

In reply to RBonney.

I'm still trying to understand how reliably the proportion of isotopes in ice cores can imply the global temps. I realise that as it gets hotter more water can evaporate, but how reliable is the rate of snow at a pole as a temp indicator? Wondering if different average temps can flip weather systems into very different behaviour patterns and hotter could lead to a flip to a different set of global weather systems where the poles became way dryer or way wetter than expected if we just scaling up what we see now. Sorry if this is a daft question, I'll go and sit at the back of the class

That's the shtick, though; "just asking questions". Trying to sew superficially plausible doubt. Classic information warfare tactic.

Paul's comment about hundreds of prior profiles is illuminating, and show just how dedicated this person/organisation/bot is.

Anyway, about that top ten apocalypse track...

Interesting your comments about dedication, with a person (or person directing bots), the topic of say: pro Russian [war] propoganda is an obvious one to be funded with time and money, or a US political position... But why so much effort on a topic like this? I mean WHY????? What's the motivation for dedicating that much effort, cuis bono, who stands to gain, it baffles me.

There appears to be plenty of funding for 'alternative climate science'. You have to ask who would benefit from a continued reliance on fossil fuels. I mean, it's not as if there is any money to be made from fossil fuels, is it...?

and this is why I hang around UKC despite the dwindling frequency of any actual climbing on my part. The depth of knowledge and expert input on here is exceptional and rarely fails to hand the ill informed their arses. Well done mods for leaving the thread up, sunlight being the best disinfectant and all that (decidedly unscientific) guff.

It's a long time since I was taught it so I'm really not sure. I think the isotopes in ice cores are a very good indication of global averages, or maybe just equitorial averages. I think the isotopes from the foramenifera are Indicators of local temperatures.

Unfortunately I can't add any more but I'm sure there's better information than I've provided on the internet. 

Sowing social media with bullshit and conspiracy theories represents a relatively small outlay for state actors opposing western liberal democracies, with a big pay back in weakening public faith in democratic governance and national institutions. To take just one example, vaccine up take is well down, childhood diseases that were on the point of extinction are on the rise and we'll all pay the price, one way or another.

Thanks, it took me an embarrassing long time for the penny to drop that the ratio not the quantity is the key, so the balance of water in atmosphere versus water in ocean is indicated, which is probably a pretty decent proxy for global temp!

It’s not about rate of snow, rather the isotopic composition of the snow which is then compressed to ice. The ice sheet itself actually has annual layers, kind of like tree rings - which can be counted back to get an age! There are also some sort of dating techniques (maybe using carbon, but honestly I’m not sure without looking it up) to put ages onto samples which are analysed for isotopes. Chronology can also be tied using distinct layers in the ice - such as the ash from volcanic eruptions, which is geochemically unique.

So to answer your Q: the technique is pretty robust to different snowfall rates, whether that be longer term shifts or synoptic cycles. 

Hopefully the mods won't start banning people for this