Guest Post by Steven Goddard
The Catlin Arctic Survey has generated quite a bit of discussion, more because of the difficulties they have faced than because of the scientific merit of their expedition. Their home page is covered with testimonials about the importance of measuring “ice decline” and raising “climate change awareness.”
Normally a scientific experiment will start out with a neutral approach, where the conclusions are derived from the data, rather than arriving at conclusions prior to attempting to collect data. The appearance of presumption presented on their web site that they are measuring “ice decline,” could easily be interpreted to be putting the cart before the horse.
It is also difficult to understand how they could be measuring “ice decline” from a single set of data points taken at minus 40C, measured over an eight week period.
Are they going to come back next year and measure again? Not likely, and even if they did the ice would not be in the same place next year – as it is blown around by the wind. There is little question that the ice will continue to thicken over the next few weeks, as it normally does not start to melt near the pole until late June or early July. Fortunately we do have an objective and consistently reliable data source to work with, from that same region.
The US Army keeps a set of buoys on the ice which continuously monitor ice thickness, temperature and location year round. These buoys maintain themselves with a minimum of trauma, twittering, publicity, rescue expeditions and frostbite – and are normally able to provide more than one year of data.
The Google Earth map below shows the attempted Catlin route in green markers, and the Army buoys in yellow. The buoys are marked with approximate thickness of the ice, which I estimated based on the water depth where the temperature rapidly drops below the freezing point of seawater (minus 2C.)
As an example, I estimated the thickness at buoy 2007J as 3.5 metres, based on the graph below. Above -350 cm, the water temperature drops off quickly below -2C, which means that it is frozen.
All five buoys show water temperatures indicating ice thickness in the range of 3-4 metres. Catlin is attempting to take another 10,000 or so measurements on the shifting, moving ice they are trying to travel across. While that data may be useful in understanding the local behaviour of the ice, it likely will provide little information about long-term ice trends, unless the same measurements are taken on a consistent basis over many years. You can also see in the 2007J graph above that the ice has thickened at least half a metre since March, 2008.
In most fields of science, that is considered an increase rather than a “decline.”
From the Army web site:
Data policy: We encourage the use of all data on this web site. Please reference any data use as:
Perovich, D.K., J.A. Richter-Menge, B. Elder, K. Claffey, and C. Polashenski, Observing and understanding climate change: Monitoring the mass balance, motion, and thickness of Arctic sea ice, http://www.crrel.usace.army.mil/sid/IMB/