Honest question about ice core sampling and its limitations:?

Question

Let's assume global warming is real...let's also assume it partially melts the ice caps, which is one of the main fears of AGW proponents...wouldn't this effect erase all ice core "data" during, and a lot of the "data" preceeding, such a warming period? Wouldn't the ice cores only show periods of time where the global temp would result in net ice growth...in effect not recording above average temperatures at all?

Think about it as pages in a book: The sheets of ice created during the winter months trap CO2. A period of extreme warmth causes the top layer to melt away, effectively removing those pages from the book forever (along with never adding pages for the years this melting occurs). The pages don't begin to accumulate data again until the temps fall enough to maintain a permanent layer through the warm months...long after the warming period has ended. Aren't we simply guessing the CO2 levels during past warming periods?

Answer 1

The theory is that antartic ice builds up by precipitation, then slowly flows into the ocean by glacial movement, so hot weather wouldn't melt the record away.  

A source of error for ice cores is that stuff frozen in the ice can leach out.  Proxy data is inherantly speculative as we can't calibrate proxies.

Only Al Gore would use data from one ice core and claim it provides an accurate record of past climate.

Answer 2

I'll turn off the "snarky" filter.  

If large layers of ice had melted then the age dating and time series of gas concentrations would be all messed up and it isn't.  There are a lot of markers and isotope ratios that the people who do this look at to make sure the data is self-consistent.  They don't just collect the bubbles and look at the CO2 concentrations.  They look at the annual layering, they look for synchronicity between compositions of layers at different locations, and they look for step changes in gas concentrations and isotope ratios outside of what might be expected based on natural variability to see if things like you are suggesting have occurred.  There simply isn't any evidence in the ice core records that there were large segments of time when the ice melted.  That the ice core data also agrees with totally independent records over smaller timescales from things like coral carbonate analysis leads people who know to be fairly well convinced the ice core data is reliable.  

The Antarctic and Greenland ice caps have been stable for hundreds of thousands of years.  Take that to the bank.

edit:  psssttttt TC:  

Check this:

http://www.ncdc.noaa.gov/paleo/globalwar...

It's always a bad idea to post plots from wingnut websites.  Old Nahale (operator of Biology Cabinet) is a bit of a crackpot.  Some of his other articles are hysterical.

Ok, so you're not going to read the NOAA website.  But you should because continued reliance on bad analysis from suspect sources is why you skeptics are losing the war.  The plot you linked to, and the associated analysis from the biocab website, is not a correct interpretation, the NCDC analysis is.  

This exchange is like your continued linking to the flawed mid-troposphere temperature records that ignore the correction for stratospheric cooling.  It only fools people who don't understand the whole system, and more and more those people don't count.  People who really do need to understand this keep up to date, and they understand that data get reanalyzed.  There are no major discrepancies in any of the temperature records that indicate a substantial problem with the idea that CO2 is forcing global temperatures.  You are only fooling the fools, and you would get quickly taken apart, and then subsequently ignored as being irrelevant to the debate, in a rigorous scientific discussion.  

The thumbs down I get I wear with pride.  It shows I'm getting to people.  That the skeptics like you disagree with what I am saying is a good thing.  

.gov, .edu, .ac uber alles!

Answer 3

This can be a tricky one, ice core measurements give no direct record of ocean temperatures.That means a very large piece of the puzzle is missing.Yes you are right as to the compacted snow/firn it's one of the biggest faults of ice core sampling.One of it's strong points is it can determine the chemical makeup of atmospheric precipitation.They do however try to compare ice core sampling  with other types of testing.It can be very accurate given perfect conditions in idea locations.Terrestrial sampling of any sort has limitations that is basically restricted to location.

Answer 4

A very interesting train of thought you have, since we can obtain ice cores that date back well over a 100,000 years, and the Holocene climate optimum saw global temperatures that were 2 degrees C. higher than present, and lasted from 7500 years ago until 4500 years ago. It would be logical to suggest that Greenland and Antarctica are relatively safe from melting, at least over the next 3000 years.

http://biocab.org/Holocene-Delta_T_and_D...

pssst: GCNP58:

Just look at the data, it all comes from the same place, the s****. straw man approach at debate is one of the reasons why you get so many thumbs down on your cheeky replies.

Give me a break with that stratospheric cooling c**p, the only cooling the stratosphere has done in the last thirty years is associated with volcanics. Was there a correction applied for the stratospheric warming associated with volcanic SO2 emmisions. No it is just another lame delta T appllied to a published dataset, to fudge it so it agrees with the AGW theory, and if it is so correct why is not the main source of tropsheric temperature data on the US government website. I cannot believe that you have bought that bill of goods on the stratosphere. I challenge you to show me any cooling the stratosphere has experienced over the last ten years.

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Answer 5

We won't find any answers for todays global warming questions in ice core samples. We only need to look at the recorded histroy of the industrial revelution to find the causes. Past warming periods have nothing to do with mankinds abuse of mother earth.

Answer 6

This is complicated, but in general terms:

we can tell the age of any segment of ice using various techniques, such as carbon dating.  So if there is a gap in age in the ice core, it indicates a sustained period of warming.

Answer 7

That's an interesting point.  Just goes to show that all the science in the world could be swayed by inaccuracies in the data.  I've always wondered why we put so much stock in science when after a while most of it is later proven wrong.

It wasn't too long ago that their was a scientific consensus that the earth was flat and the sun revolved around the earth.

All I know about the ice core samples is that they show periods of warming followed by increases in CO2.  Just the opposite of what Al Gore tries to tell us proves CO2 causes global warming.  Of course we now know that the movie that won an Academy Award and won Al Gore the Nobel Peace Prize was mostly fictitious.  How ironic.

So even if the data were pure it would disprove that global warming is caused by increases in CO2.  Isn't that what the global warming evangelists put all their faith in?

Answer 8

I like your philosophy.  Too bad that is not where the money is going to.