While it took me a while to get the time together to write an article about the Marcott paper, that does not mean I have not been looking at it and discussing it from nearly the day it was released. There has been volumes of discussion within The Right Climate Stuff group that I have been involved with. The ones that lean towards CO2 as something to be concerned about were initially rather excited about this paper, but that has taken a course correction as it has become clear how poor the science is in the Marcott paper.
Many skeptics are calling this the newest hockey stick and there is certainly some accuracy to that, but what I initially found interesting was the Holocene cooling that he shows. In one respect his paper is different because it shows the cooling that has been taking place for thousands of years. That also makes the stick at the end more extreme, but it is something most will not show.
For those who missed the details of the Marcott paper I will provide a brief summary. The paper was published on March 8th in the ultimate of peer-reviewed journals, Science Magazine. The paper was loudly broadcast by the media as further proof of global warming. The paper basically says that the most modern period of the Holocene (the current interglacial which the Marcott paper states as 11,300 years) has been warmer than ~75% of the Holocene. The paper states that this is especially significant as the Holocene has shown steady cooling for the past few thousand years, but that has now completely reversed. The conclusion is that mankind has drastically altered the natural climate of the Earth.
The paper itself is a composite of 73 different temperature proxies. These proxies were used to reconstruct the Earth’s climate over the past 11,300 years. The 73 proxies were not uniformly distributed around the world. The following is a summary of the spatial distribution.
Tropics: 33 proxies
NH Polar: 12 proxies
NH Mid: 20 proxies
NH Tropics: 16 proxies
SH Polar: 4 proxies
SH Mid: 9 proxies
SH Tropics: 12 proxies
NH Total: 48 proxies
SH Total: 25 proxies
The NH is over represented by 3x in the polar region and 2x in the mid-latitudes. This of course can be dealt with easily enough, but the real resolution in the NH is better than the SH. None of this is directly critical to the paper, but it is something worth noting.
Far more troublesome to the conclusion of the paper is the dating of the proxies. Other sites have some excellent write-ups on the re-dating in the paper itself and I will touch on it, but my more immediate concern is how recent most of the proxies are based on the published data of the proxies.
Here is the breakdown of the last date in the proxies he used.
1950+ 9 proxies (1960, 1970, 1991, 3x 1995, 1998, 1999, 2000)
1900-1950: 16 proxies
1800-1899: 11 proxies
1600-1799: 7 proxies
1000-1599: 14 proxies
< 1000: 15 proxies
This leaves one proxy (GeoB 3313-1) with the last known data of ~1750 AD. There are 3 data points for temp after that, but no dates associated.
Since the modern period by almost everyone is considered to be post 1950, only 9 of the 73 proxies contain any data that can be relevant to the global warming issue. Right away that concerned me, but when I looked at the data for those 9 proxies something very interesting became apparent.
I will be referring to those 9 proxies as the Marcott 9. They are perhaps the most interesting proxies that he used and those proxies disprove the conclusion of his paper. In order of the most modern data, the Marcott 9 are:
Lake 850, most recent data is from 2000.
Flarken Lake, most recent data is from 1999.
Lake Nujulla, most recent data is from 1998.
Tsuolbmajavri Lake, most recent data is from 1995.
Homestead Scarp, most recent data is from 1995
Mount Honey, most recent data is from 1995
Composite MD01-2421…, most recent data is from 1991
Moose Lake, most recent data is from 1970
Agassiz & Renland, most recent data is from 1960
What is most interesting about all of these proxies is that none of them show the warming result the paper ended up with. Not a single one.
Without further ado, here are charts for the Marcott 9.
These nine proxies are the only ones of the 73 that Marcott used that have data past 1950. The only one that shows any kind of warming is the last one which is the Agassiz-Renland ice core and the warm point was not the most recent, but the proxy from 1940. The last point which is 1960 shows as cooler than the data from 1940. The ice core certainly does indicate that the warming in the 1930-1940 period was impressive, but few claim that mankind caused that warming.
There is far more to discuss about this paper. I have an idea where I am going to go with my research, but others may beat me to it which will alter the path I take. Based on what information is being found by others, primarily by Steve McIntyre over at Climate Audit is that Marcott re-dated data that didn’t fit into the hockey-stick result.
This agrees with what I have found as well. All of the Marcott 9 had altered dates associated with the last date with the Moose Lake data changing the least at 20 years. Flarken and Tsuolbmajarvi Lake were moved back into the 1800’s and the MD01 Composite removed the last 3 data points. The end-point strategy for this paper was full of shenanigans. Since it is only the end-point data that matters to the conclusion of the paper, well, let the Marcott 9 speak for themselves.