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Ice core scientists in East Greenland reach bedrock

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Re: Ice core scientists in East Greenland reach bedrock

#251

Post by macinjosh »

I have a hard time trusting climate data from before we had satellites or other forms of precise automated recording. If climate scientists are telling us they _know_ detailed information about global atmospheric temperatures, greenhouse gas concentrations, etc. over millions years because they cored some ice from a select set of places on earth, I just don't know how an average person is supposed to believe that. It appears to the layman to be data generation on par with an episode of CSI where the lab somehow 'enhances' low res photos to high res.

Where are the million year long experiments demonstrating how ice and its contents changes over such long time spans, that vast majority of which we were not even conscious for as a species? It is too many variable to fit into any sort of computing technology today, and the science is mostly based on statistics which everyone knows can be twisted easily.

Re: Ice core scientists in East Greenland reach bedrock

#252

Post by groby_b »

wheelerof4te wrote: post #183
adolph wrote: post #72

Earlier quoted context omitted.

120k years ago in context: * 170,000 years ago: humans are wearing clothing by this date. * 125,000 years ago: the peak of the Eemian interglacial period. * ~120,000 years ago: possibly the earliest evidence of use of symbols etched onto bone * 75,000 years ago: Toba Volcano supereruption that may have contributed to human populations being lowered to about 15,000 people https://en.wikipedia.org/wiki/Timeline_of_preh…

"75,000 years ago: Toba Volcano supereruption that may have contributed to human populations being lowered to about 15,000 people." The key question is: How much CO2 did that super-eruption emit into the atmosphere? In our hurry to attribute climate change to our meager impact on this planet, we tend to forget what horrors an eruption of this magnitude can cause. And who knows how many of them happened during the pas…

"And who knows how many of them happened during the past millennia.

Geologists. And the answer is "none" for the past 25 or so millenia, and "one" since Toba.

Also, unless you've had supervolcanoes go off in your bedroom and didn't tell anybody, the evidence for human impact is exceedingly clear.

Re: Ice core scientists in East Greenland reach bedrock

#253

Post by dtgriscom »

hcnews wrote: post #226
foota wrote: post #197

Earlier quoted context omitted.

Who knew, drilling is O(N^2)

It's not O(N^2) is it? It can be a continuous line of ice being pushed up. Depending on the weight bearing ability of the lift and digging capacity, you would figure out a fixed distance after which you would place the buckets to carry up the ice. Its an interesting interview question at the very least. (More complications arise as and how you get deeper into the ice).

You can't have a continuous line of ice coming up, unless you're digging for slush. Each intact X-meter core must be hauled up on its own, and then the drill has to go back down. The deeper you are, the longer it takes to haul up one core and send the drill back down. So, retrieving the cores is clearly O(N^2).

Drilling the core itself is O(N), but as you go deeper the core retrieval dominates. Not to mention everything getting more complex the deeper you go.

Re: Ice core scientists in East Greenland reach bedrock

#254

Post by dtgriscom »

lexicality wrote: post #89
johnnyApplePRNG wrote: post #71

That's a rate of about 4.3 centimeters per hour. Can anybody elaborate as to why this process takes so long?

it's a very high aspect ratio hole (267:1) so they have to peck-drill it and it takes a very long time to lift the drillbit to remove the swarf from the end

I'm going to see if I can work the term "swarf" into conversation tomorrow. (We all need goals.)

Re: Ice core scientists in East Greenland reach bedrock

#255

Post by quickthrower2 »

foota wrote: post #197
sleet_spotter wrote: post #127

Earlier quoted context omitted.

As the hole gets deeper, the amount of time to bring up core sections and send the drill back down become significant. That combined with the previously mentioned short field season. Drilling more than a few hundred meters becomes very difficult logistically as well, especially in such a remote setting.

Who knew, drilling is O(N^2)

Anyone who has hung a heavy picture/frame? :-)

(you need to pull the drill out periodically to let the dust out, and the distance of that pull increases with depth. But it is O(K1 * N^2 + K2 * N) where K1/K2 are pull-out and drilling-in (both seconds per mm), and for short holes most of the time will be drilling not removing dust.

Re: Ice core scientists in East Greenland reach bedrock

#256

Post by wheelerof4te »

groby_b wrote: post #252
wheelerof4te wrote: post #183

Earlier quoted context omitted.

"75,000 years ago: Toba Volcano supereruption that may have contributed to human populations being lowered to about 15,000 people." The key question is: How much CO2 did that super-eruption emit into the atmosphere? In our hurry to attribute climate change to our meager impact on this planet, we tend to forget what horrors an eruption of this magnitude can cause. And who knows how many of them happened during the pas…

"And who knows how many of them happened during the past millennia. Geologists. And the answer is "none" for the past 25 or so millenia, and "one" since Toba. Also, unless you've had supervolcanoes go off in your bedroom and didn't tell anybody, the evidence for human impact is exceedingly clear.

"Geologists."

Geologists might know, same as astronomers might know what Black Holes and Pulsars really are.

On the other hand, it is a geologist's call to search for answers and for truth. Saying that they truly know is the same as saying nothing.

Re: Ice core scientists in East Greenland reach bedrock

#257

Post by wheelerof4te »

FireBeyond wrote: post #229
wheelerof4te wrote: post #183

Earlier quoted context omitted.

"75,000 years ago: Toba Volcano supereruption that may have contributed to human populations being lowered to about 15,000 people." The key question is: How much CO2 did that super-eruption emit into the atmosphere? In our hurry to attribute climate change to our meager impact on this planet, we tend to forget what horrors an eruption of this magnitude can cause. And who knows how many of them happened during the pas…

I think people struggle with the magnitude. Mt St Helens, for example. Not the largest eruption. But a landslide of approximately 2.5km^3 (over 3 billion cubic yards). Okay, some say, so that is a lot of earth... and then you learn that the landslide was moving at speeds of up to 160mph. That's a LOT of energy.

It sure is. And we've yet to survive our modern-day supervulcano eruption.

Re: Ice core scientists in East Greenland reach bedrock

#258

Post by ummonk »

kfrzcode wrote: post #243
aeroman wrote: post #122

Earlier quoted context omitted.

As a "cloud person", I just want to add a few things to the description of how clouds affect the climate (and why high clouds have a wamring effect). All clouds are white, so they all reflect sunlight back into space (during the day), cooling the Earth. All clouds are (almost) black in the infra-red, meaning the amount of energy they emit in the infra-red is determined by their temperature. Colder clouds emit less en…

I will give you the benefit of doubt given it's Hacker News you likely are an expert, but this feels like one of those "sounds too intuitive to be that simple" type complex factors. Any literature on the topic from which I can improve my understand?

What part of it do you doubt? It’s obvious that clouds are white, and it’s obvious that they are cooler than the earth and even colder higher up (clouds form because the adiabatic expansion of rising air cools it down and causes water to condense, and the higher up you go the colder the atmosphere due to greater expansion - anybody who has hiked the mountains has experienced this).

The only assertion here that one has to take on faith is that clouds are approximate black bodies at infrared wavelengths (which isn’t surprising - most things tend to be), and the relative magnitude of the cooling vs warming effects. Oh and there is an unstated dependency that the Earth is also an approximate black body at infrared wavelengths.

Re: Ice core scientists in East Greenland reach bedrock

#259

Post by ChuckMcM »

samstave wrote: post #215
ChuckMcM wrote: post #41

This is a very important project. There is a joke in here about "why not wait 2 years for the ice to melt off if you wanted to look at the mud underneath?" But as the article states, "'This will change climate models because it redefines our basic understanding of how ice moves,' explains Dorthe Dahl-Jensen." Much, if not the majority, of climate science is the creation of models (differential equations mostly) that…

It would seem to me, that the best way to do long-scale climate models of a body ; knowing its composition in layers over time is really important to be able to calculate the flow of the layers of composition as particles. Think of the experiment of light as wave/particle... Glacial/geological scales operate as thus ; as physical masses of particles, but move in more wave-like manners - so you'll have material suspen…

Perhaps? Not sure I'm following the methodology you're suggesting. Most (perhaps all?) of the climate models I've read about or played with are based on energy balance. (energy in vs energy out)

Start with Solar insolation (energy in) then subtract all the ways that energy leaves the planet (reflection and radiatively from the atmosphere.) Then add that the planet is its own heat source (molten core and all that) and that energy contribution. Then add variable convection to the atmosphere based on latitude. The list goes on and on (which is kind of like harmonics in a Fourier series).

Then random things pop out like how reducing the weight of ice (by melting) increases volcanic activity kinds of things.

Re: Ice core scientists in East Greenland reach bedrock

#260

Post by S201 »

BurningFrog wrote: post #188
mytailorisrich wrote: post #98

Earlier quoted context omitted.

Iirc, the CO2 concentration now as been pumped up higher than it was then, which is in part what is worrying because temps might then potentially shoot even higher. Bottom line: we need large scale carbon capture quickly because even if we reach net zero CO2 will take millenia to drop back to the level it was pre-industrial revolution. Edit: I wouldn't focus on "pre-industrial levels" specifically, the point is that…

> Bottom line: we need large scale carbon capture quickly The short term solution/bandaid is pumping SO2 into the stratosphere while we figure out carbon capture.

Is there anything left to really "figure out" about carbon capture? The tech works, it's just too expensive. Given a sufficient amount of cheap enough energy it could be scaled up as far as I understand.

As a layperson, it's just one more reason I so wish we'd invest in nuclear. Nuclear powered DAC plants might be the only way to scale it fast enough. Sure, it would still be expensive, but that's much cheaper than not massively reducing CO2 in the atmosphere.

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