Guest essay by Roger Graves
The subject of the extent of Arctic ice cover has been much in the news, with an apparently unending series of attempts to predict its future extent on the basis of a relatively few years’ worth of data. However, it is possible to make some general predictions, based on a much longer-term sequence of historical events. Obviously these will not be accurate predictions, since they are based on mere verifiable historical data, unlike, say, the highly accurate predictions of the IPCC based on computer models which no doubt will soon tell us of balmy tropical seas to be found in the Arctic in the near future. Nevertheless, they can still offer a general guide to what we are likely to see in the future.
First, a significant warming of the Arctic was noted in 1922. The U.S Monthly Weather Review of November 1922 contained a report from the US Consul in Bergen, Norway, saying “The Arctic seems to be warming up. Reports from fisherman, seal hunters and explorers who sail the seas about Spitzbergen and the eastern Arctic , all point to a radical change in climatic conditions, and hitherto unheard-of high temperatures in that part of the earth’s surface.”
The article goes on to say “Ice conditions were exceptional. In fact so little ice has never before been noted. … Many old landmarks are so changed as to be unrecognizable. … At many points where glaciers formerly extended far into the sea they have entirely disappeared.”
Second, the Arctic was navigable in the early 1940’s, although people might be forgiven for not noticing it at the time because World War II happened to be in progress then. The Royal Canadian Mounted Police schooner St Roch sailed across the Arctic ocean west to east during the period 1940-1942, and in 1944 made the east to west return trip. During the period 1944-1948 she again patrolled Arctic waters.
The St Roch was not a 30,000 ton purpose-built ice breaker, but was instead a 300 ton wooden schooner. Granted, she was a tough little boat designed for Arctic conditions, but she had no significant ice-breaking capability, so there must have been open water for her all the way.
We also know that when regular satellite coverage became available in 1979, Arctic ice had a much greater extent than it does today. According to NOAA’s data, ice coverage began noticeably decreasing in extent sometime in the mid 90’s. The chart shown below is fig 4.2 of this reference. Incidentally, the September data shown here is an excellent example of how not to apply linear regression. Yes, you can draw a straight line through any collection of quasi-random points and call it a least-squares linear regression. No, it does not magically make the data into a linear progression from larger to smaller, as they have attempted to show in this case. Although I don’t have access to the original data, I would say that the data seems to approximate to a section of a sine wave, which is what one would expect if Arctic ice cover followed a cyclic pattern.
Noticeable melting in 1922, and noticeable melting again in the mid 90’s suggests a warm/cold temperature cycle in the Arctic some 70 years in extent or thereabouts. Further, the St Roch data indicates that a warm peak of this cycle probably occurred sometime in the 1940’s.
For the sake of argument, let us assume a 70-year cycle with a warm peak in 1945. This would place the next cold trough 35 years later, in 1980 (which is not inconsistent with the NOAA data shown above) and the next warm peak at 2015, which is reasonably close to the recent summer ice minimum.
Counting backwards from 1945, a previous warm peak would have occurred in 1875, and a cold trough would have occurred one half cycle earlier, in 1840.
We also know that the ill-fated Franklin expedition to discover the North-West Passage set out in 1845, a few years after this cold trough, when ice coverage would have been at or near a maximum. As we also know, the expedition failed disastrously, which is what one would expect under such conditions.
I will be the first to admit that my arithmetic is only approximate. However, historical data would seem to support a cyclic ebb and flow of Arctic ice cover. Based on the suggested cycle period of 70 years, we can expect Arctic ice cover to increase from the present day until about the year 2050. Anyone about to invest large sums of money in North-West Passage shipping might well be advised to take note.