Icecore Data from Greenland - Dye3
The GISP (Greenland Ice Sheet Program) initiative collected 20 cores from the Greenland ice sheet.
the Dye 3 ice core
(located at lat. 65.19N, Long. 43.82W)
is the deepest at 2037 meters.
Though many analyses appear to have been done,
only two files are available
I was hoping for CO2 data, but, alas, only delta 18O (a temperature proxy)
Here are some plots of this data.
No data is collected for the firn - the top 82.11 meters.
When depth is used for the x-axis, the newest data is on the left;
when age is used, it is on the right.
- At a depth of about 1,540 meters, the delta 18O data changes significantly.
I have not found this discussed in the literature. However, it appears that fewer measurements
per meter were taken below this point.
Therefore, I am assuming that the filtering algorithm changed.
In other words, the data above this transition is more representative of reality,
and data below this level is more filtered.
- The full core covers about 20,000 years, but the dataset with associated dates
covers only about 4,000 years.
Constitutive properties of ice at Dye 3, Greenland
This zoom of the most recent few centuries shows without a doubt that the Little Ice Age (LIA)
(around 1650 AD) is not recorded. It is ice cores like these that
support the theory that the LIA was regional and not global.
However, you should also note that, because the data record ends in 1872 AD,
this data can not be used to determine if the current temperatures are higher than at any time
in the recent past.
δ18O is a well known temperature proxy.
However, it is also possible to actually measure the temperature of the
inside of the borehole. Combining the δ18O data from above
with borehole temperatures from the
Niels Bohr Institute Centre for Ice and Climate
produces the following.
Notice - there is no correlation at all between the two data sets.
Oh, and the Medieval Warm period (around 900 AD) and the LIA are very obvious.
What this data does indicate is that at the end of the last ice age, there was very little
ice on Greenland. Specifically, when it was much colder than today,
there was much less ice. It wasn't until after the global temperature started to rise
that significant ice accumulation began.
Let's be clear
Warmer weather causes more ice
Thus, the Al Gore doom and gloom of warmer weather causing the Greenland ice cap to melt
is totally disproved by simply looking at the data.
Well, it is not quite that simple
There are other possible scenarios, but the point is that there is a lot more ice now
than there was 4,000 years ago ..
and no one has presented any evidence of falling sea levels.
- It is possible that there was a lot more ice on Greenland during the last ice age
- Most of the ice melted when the Earth warmed
- Then, around 4,000 years ago, the Earth had cooled enough
that the ice started to come back
Do you see the point?
If 4,000 years of ice accumulation does not cause sea levels to fall,
then the Global Warming claim that the Greenland ice cap is melting can not
be used to predict a 26 foot sea level rise.
Well, this is only one core .. let's see what the others say.
Ref: Wikipedia provides some good background.