October 19, 2010

Lessons of the Loch Sunart Monster

Have you ever met a cryptozoologist? Cryptozoologists study and search for animals which are considered to be legendary or otherwise nonexistent by mainstream biologists. Bigfoot, the Abominable Snowman, the Loch Ness Monster are all favorite subjects of these “scientists.”

Cryptozoologists believe that the Loch Ness Monster may live in lochs (fiords or fjords) inland in the western half of Scotland. Loch Ness is one of many lochs in western Scotland, so the famed monster may be found in a variety of different locations. In the eyes of some global warming alarmists, there is a potential monster in Loch Sunart taking the form of a sediment core from the bottom that is capable of reconstructing the temperature history of the area over a long time period, and characterized by a head that it much higher than its middle or tail. It seems that The Loch Sunart Monster may have a very interesting story to tell.

A recent study in the prestigious Quaternary Science Reviews shows us that the Loch monsters inhabit an area with extraordinarily evidence of interest to the current global warming issue. The authors of the study of interest are from the University of St. Andrews (we certainly hope they play golf) and they appear to have considerable expertise in the Loch Sunart area and in converting sediment cores into usable climate information—the work is very impressive. Researchers Cage and Austin note that “Marginal marine environments such as fjords tend to act as natural sediment traps and typically have high sediment accumulation rates (~ 1 cm yr-1), providing the potential for high-resolution palaeoenvironmental studies on decadal to centennial timescales and presenting a unique opportunity to study land–ocean interactions.” With respect to Loch Sunart, they state “The westerly location of Loch Sunart on the European North Atlantic seaboard results in a strong regional relationship between North Atlantic driven weather systems and marine climate” (see Figure 1 for the location of Loch Sunart). Up until this important study, they claim “However, the sea lochs (fjords) of NW Scotland have largely been overlooked in the context of late Holocene investigations of climatic variability.”


Figure 1. Location of Loch Sunart (black rectangle) on the NW coast of Scotland with a schematic of surface ocean currents to the west of Scotland and Ireland (from Cage and Austin, 2010)

In July of 2004, the authors drilled a sediment core 22.5 m (nearly 75 feet) from the bottom of Loch Sunart. Cage and Austin spent many hours in the lab measuring everything from oxygen isotopes, carbon isotopes, magnetic susceptibility, radiocarbon dates, X-ray fluorescence, naturally-occurring radionuclides, and … you get the idea. The core from Loch Sunart therefore yielded a times series of these different variables from 900 AD to the near present, and given known relationships between the measurements and the temperature at the sea bottom, a relatively high-resolution reconstruction of temperatures is developed from the core—the Loch Sunart Monster!

Figure 2 shows the Lock Sunart Monster in all its glory. It is the reconstructed bottom water temperature anomalies from 900 to the near present, and at first glance, the head of the monster (the warming from 1940 to present) seems menacing and we are certain there are those who would declare that this feature was related to the buildup of greenhouse gases over this recent half century. Indeed, the authors state “The reconstructed temperatures from Loch Sunart show decadal and centennial-scale variability over the past 1000 years. The record appears to capture the recent, late twentieth century warming, with bottom water temperatures increasing by ~1.5 ºC from AD 1940 onwards. This change is similar in its timing to the average Northern Hemisphere temperature increase and to the observed magnitude of change (1–1.5 ºC) observed in Scottish coastal waters.”


Figure 2. The Loch Sunart Monster—the reconstructed bottom water temperature anomalies (black line) with uncertainties based on assumptions regarding saltiness of the water (gray region) (from Cage and Austin, 2010).

The authors note that “The Loch Sunart temperature reconstruction exhibits a gradual cooling trend that continues from AD 1608 to 1941, with the coldest temperature anomalies (~0.75ºC) of this period occurring between the early 1930s and 1940s.” So in the last 400 years, the sea bottom of Loch Sunart cooled, the coldest period over the past 400 years occurred 70 years ago, and then the water warmed up to levels that were typical during the beginning of the 400-year period. Note that the warm recent decade is not at all unusual looking over the entire record. In fact, Cage and Austin state “the record presented here captures the end of the ‘Medieval Climate Anomaly’ (MCA), a period of warm or wet climate usually taken to occur between AD 800 and 1300. The MCA is thought to have been at least as warm as present” and “The Loch Sunart reconstruction for the late MCA suggests temperatures from AD 916 to 1035 were similar to those recorded over the late twentieth century.” And if you missed it looking at the graph, Cage and Austin point out “perhaps the most distinctive feature of the Loch Sunart temperature record is the short-lived event between AD 1540 and1600, which is characterized by a very abrupt warming transition at AD 1540. This period had an average temperature anomaly of 1.1ºC above the long-term mean, which is higher than most of the 20th century and the late MCA.” So the Loch Sunart Monster’s tail and back are as prominent as its head.

The cryptozoologists are definitely in the realm of pseudo-science (not unlike a lot folks haunting the global warming issue!). Their search for the Loch Ness Monster brought our attention to findings from Loch Sunart, and once again we find the evidence showing that the modern warming is absolutely nothing special over the past 1,000 years. Cage and Austin conclude “we note from this study that changes in twentieth century marine climate cannot yet be resolved from a background of natural variability over the last millennium.” The core tells us that warming has occurred many times in the past, warming of the past 70 years is more related to unusually cold conditions 70 years ago, and there isn’t much happening recently that looks very out of the ordinary when compared to the 1,000 year record. Once revealed, the Loch Sunart Monster isn’t so scary after all.

Reference:

Cage, A.G. and, W.E.N. Austin. 2010. Marine climate variability during the last millennium: The Loch Sunart record, Scotland, UK. Quaternary Science Reviews, 29, 1633-1647.




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