AGW Part #5 – Limitations of Ice Core Data or The Smoking Gun

Ice core data as discussed in AGW Part #4, is the result of trapped gasses in microbubbles in ice. The ice is cut using a long tubular saw/drill and removed in long segments. The theory of ice cores is that once the snow pack becomes dense enough, the trapped air cannot travel through the ice core. Diffusion effects are clearly present however. Therefore, if you introduce a high concentration of gas at one point in the core, over time it will spread out. This tends to “filter” sudden spikes in temperature as recorded by gas concentrations over time. Below is an excellent illustration from an excellent site on ice core data here.

You can clearly see the end of the ice age in this graph but what is interesting is, on the right side the temperature looks like a scribble up and down rapidly over and over. Please note that the magnitude of the up and down scribble is almost 3 degrees C quite regularly. All of the global warming hype is about 0.6 degrees C Wow!.

Look to the left side of the graph and you can see that all of the up and down has stopped. This means that the variation in gas concentration has diffused to a more constant level. Do not discount this data just interpret that it cannot detect high frequency changes. My eye tells me that the left side is filtered to about 1000 years average. I used the website above to magnify the right side below.

It appears from this view that the high frequency “scribbles” are about 200 years in width with +/- 1.5 degree variations quite regularly.

Ok for those who have not spent days in dark labs studying linear datasets and filtering algorithms, the meaning of this data is that in recent ice cores less than 5000 years old the temperatures estimates are averaged from about 200 years. Our recent very short term measured temperature rise won’t even show on the graph because it will be rounded off by natural “filtering” of the ice core sample.

If 2000 years ago the temperature spiked up 6 degrees C for 20 years and returned to a perfect average, the ice core data would show a rounded hump with an approximate increase of 6*20/200 or 0.6 degrees C. You can clearly see extended rounded humps in the data of 3 degrees C in height. With no other data, these could in fact be the result of huge 20C temperature rises and falls for short 20 year periods of time (I hope not!).

What we know with absolute certainty though is that the actual temperatures experienced must have varied above and below the “filtered” ice core data quite considerably. Also, around 8000 years ago there is a huge sharp upward spike. If this is a rounded (smoothed by nature) version of the data can you imagine what the true peak temperature was. It could have been over 10C above average for 50 years.

I am so surpised by this spike I included it below.

The spike I am talking about is right after the ‘t’ in present above. The width is the same as the basic width of all of the other variations in the graph. This means it is at the maximum resolution of the dataset. I am going to look for this in other core samples, it looks to me like it could be a huge event. The magnitude of it is clearly much much greater than what we are seeing now from actual temperature measurment.

The above graph is zoomed out to 60K years. The data on the left looks smooth compared to the data on the right. The temperature at the far left seems to have much less variation than that at the right. Again I see a gigantic spike at between 50 and 52k years. Because of the filtering effect which reduces the peak height I think this is much bigger than the 8K year event… Amazing isn’t it! I wonder if it in reality crossed the 0 degree line on this graph.

Ok, this is the full dataset of the ice sample. I can clearly see 4 periodic ice ages and peaks from five recoveries. Note again that the right side has a much higher frequency than the left. This means that the diffusion of the gas microbubbles in the far left side of this graph only allows detection of variations of about 10,000 years of duration. From the graph just before this one 50K years looked smoothed out compared to recent data but on this curve the dataset looks quite noisy (a lot of up and down)

Ok, what can we conclude about this data -

1 – Clearly temperature varies on average in nature by at least 8 degrees C for a minimum of 200 year increments (the highest resolution of ice data). It certainly varies to maximums and minimums significantly beyond that point.

2 – Ice data absolutely cannot be used as a record of short term events less than 100 years.

3- Most of the time the Earth is much colder than today. — This is very bad news down the road!  I need to clarify this entry.  By the graph most of the time Earth is much colder than the last 10000 years.

4 – A temperature change of 1 degree C upward is very small in the scheme of things and if we can create a 1 degree rise it will be quite nice during the nearby (next) ice age.

5 – We still have not achieved the peak temperature recorded after each of the last 4 ice ages. Historically, without input from man, the earth should be warming.

Ok, I will stop here. I feel good about this post though, it should make us skeptical of the IPCC conclusons by itself but there is still more work to do.

I have got to find out more about that 8K year spike.