Historic Variations in Arctic sea ice. Part II: 1920-1950

by Tony Brown

Satellite observations that provide an hour by hour picture of every part of the Arctic make it easy to forget that large areas of it had not even been even explored 80 years ago – let alone its ice extent minutely observed.  This paper explores the controversy surrounding the period 1920-1950, which was a period of substantial warming in the Arctic.

 Historic variations in Arctic sea ice  is a series that attempts to determine the arctic warming events through the Holocene which commenced some 11000 years ago. Part 1 covered the warm period from approx. 1816 to 1860. This paper – Part 2 – examines the period of warming 1920-1940 with a decade long overlap. Part 3 will examine the evidence for other episodes of warming through the Holocene.

During the course of compiling this article numerous relevant papers and studies were referenced, personal research conducted at the Scott Polar Institute archives and library in Cambridge, the Met Office archives and library in Exeter, and communications made with such organisations as the University of Fairbanks in Alaska, NSIDC, and arctic climate scientists.

Introduction

To provide context for the decline of Arctic sea ice extent observed since 1979, we need to understand how sea ice has varied over the Holocene, and particularly over the past 1-2 centuries.  One period of particular interest is 1920-1940. This statement was made by the IPCC in AR4 of 2007:

‘Average Arctic temperatures increased at almost twice the global average rate in the past 100 years. Arctic temperatures have high decadal variability, and a warm period was also observed from 1925 to 1945’

The arctic ice melt extent noted by the IPCC, was supplemented in an interview by Dr Walt Meier of The National Snow and Ice Data Center in Boulder:

“Analysis of the temperatures does not support a cyclic explanation for the recent warming. The warming during the 1920s and 1930s was more regional in nature and focused on the Atlantic side of the Arctic (though there was warming in some other regions as well) and was most pronounced during winter. In contrast, the current warming as observed is amplified over almost the entire Arctic and is seen in all seasons. Another thing that is clear is that, the warming during the 1920s and 1930s was limited to the Arctic and lower latitude temperatures were not unusually warm.”

The period from around 1920 to 1940 has become controversial due to the substantial variance between the ‘official’ view of modest and geographically limited arctic (and global) warmth, and the view held by others that are unconvinced that current arctic (and global) warming is exceptional. The controversy was noted in Neven’s respected ‘Arctic sea ice’ blog where an excerpt from the Sunday Times was highlighted:

“Professor John Christy director of the Earth System Science Centre at the University of Alabama in Huntsville, said the Arctic had indeed warmed (in recent years), but there was also anecdotal and other evidence suggesting similar melts from 1938-43 and on other occasions.”

Neven’s reply: My question to Dr. Christy: Why do you lie?

The rationale behind this blunt response makes the short article-and the comments- worth reading.

How reliable are the sea ice observations during the first half of the 20^th century?

During the period 1920-1940, the Arctic Ocean was regarded as relatively unexplored territory.  A 1934 National Geographic article  discusses the Lindbergh’s flights over the Arctic:

 “National Geographic, Sept. 1934, pp. 261-304, “Flying Around the North Atlantic” by Anne Morrow Lindbergh. She and her husband crossed the icecap twice, followed the coastline, from Disko Bay area to Clavering Island, visited Dr.Lauge Koch’s research area, and literally ”redrew” the map of some areas of Greenland.”

The lack of data from Russia and other areas because its sheer remoteness made accurate data gathering problematic, large gaps in knowledge due to WW2 i.e no DMI maps (Danish Meteorological Institute) during this period, a hiatus in cooperation during the Cold war, uncertainty over final summer amounts as DMI did not usually record data after August, and estimates by climatological methods  means historic sea ice data is fragmented and incomplete. This is not helped by the different sea ice data bases often being at considerable variance with each other and changes in the way in which ice concentrations were calculated as described below:

“In 1968, The United States began reporting ice concentration in eights rather than tenths, then returned to tenths reporting in 1980. Canada retained the tenths format throughout the period. […….] SIC summary analyses in eights frequently overlay reconnaissance data which is plotted in tenths. Since SIC produced these charts for in-house, not public use, which of these formats is used is seldom noted on the charts….There is also a period when U.S. recon data receives a slightly different treatment from chart to chart…… With a good knowledge of codes and the history of code changes and a dash of intuition and care, it is possible to roam the data set without great fear of misinterpretation. Others entering without some preparation may find it hazardous.” [link]

Of course, professional arctic sea ice researchers are aware of these factors and adjust data accordingly but the preceding does raise the question as to whether X amount of ice in the satellite era (1979 onwards) is really the same as X amount in the period prior to that, derived through climatological or physical observations in often difficult conditions by such as whalers, which brings us to the thorny question of what the definition of ice extent actually is.

This concern led me to ask the following question of NSIDC:

“ …..how did pre satellite researchers estimating sea ice extent tell the difference between water, water floating on ice, and solid ice, and how can satellites differentiate between the three states? I was struck by Russian reports from the 1950’s at The Scott Polar institute in Cambridge when staff at the floating research stations commented about using Wellington boots in order to walk around the station, and how little dry ice islands eventually formed by the end of the summer surrounded by water on top of ice.”

I received the following reply from Julienne Stroeve (reproduced with permission):

“ … using passive microwave data it is very easy to tell the difference between ice and water as the dielectric constant differs quite a bit and this is reflected in large differences in the microwave emission. The main advantage of using passive microwave is that it can see the ice even if it’s cloudy or dark. There is a problem however in summer when melt ponds form on the ice since the sea ice algorithms then underestimate how much ice there really is (they think it’s open water). That’s one reason why we focus on extent rather than true ice area for the NSIDC sea ice news and analysis web site.

Visible and thermal imagery provides higher spatial resolution but is often hampered by clouds. Trying to do this work using earlier visible and thermal imagery requires the scientists to go through each image and manually filter out the clouds and determine where the ice is.

 The Arctic in those pre satellite days was simply too large to be effectively and continually monitored. Observers getting close enough to the ice edge to make physical observations might be deterred from proceeding further by apparently impenetrable ice although better, more open conditions, might lie beyond. Data from such as the Russian sector – where much warming occurred, was not always taken into account. (However, the reader should be aware that, as Larsen noted, ice did sporadically return whilst reports from 1939-45 are sparse for obvious reasons.)

In trying to determine the true extent of sea ice during the period we run the risk of comparing apples-physical observations, and oranges- satellite altimetry, and the different methods employed over the years creates uncertainties over whether each accurately picked up what is ice, what is water covered ice and what is open water. This makes it difficult to determine how modern ice extent compares to the past with any certainty.

This paper provides evidence that supports a conclusion that the official sea ice data bases covering 1920-1945/50 appear to very substantially overstate the ice area extent. Some of the thinning of the ice and reduction of glaciers noted today appears to have had their genesis in the period.

Section One The History of Sea Ice Data

There are many meetings and areas of research of particular significance to recent arctic ice science. The following are reasonably representative in noting key papers, players, and uncertainties that persist to this day.

This workshop in 1978 represents the knowledge of the time.

‘Workshop on Mapping and Archiving of Data On Snow Cover and Sea Ice Limits-Boulder, Colorado 2-3 November 1978)” (Published in May 1979) [link]

A conclusion from this Workshop is that:

“There is a wide need for ‘historical’ series of sea ice and snow cover charts. Operational series should be carefully revised, incorporating data from all sources … It is important that estimated and interpolated values be flagged in data sets derived from chart series. Final digitised products should be cross-checked and their consistency documented.”

The next meeting to highlight is from 1997:

Report on Study of the Arctic Change Workshop November 10-12, 1997 University of Washington Seattle, Washington

The most interesting item for our purposes is ‘Arctic warming during 1920-1940; A review of old Russian publications’ by Pisarev (A paper we return to later)

This was followed by:

Proceedings of the Workshop on SEA-ICE CHARTS OF THE ARCTIC (Seattle, WA, USA, 5-7 August 1998) Sponsored by the US National Ice Center July 1999 [link]

This extract is from the Executive Summary:

“The Workshop for Sea-ice Charts of the Arctic was convened…because of the perception that information contained in ice charts was under-utilised by the scientific community. Participants…distinguished ice charts of the historical era (1200 through 1930 A.D.) when information was primarily limited to ice extent, from ice charts of the modern era 1930 A.D. to present) when information about the ice pack interior is more generally available. Several reports illustrated the quantity and quality of the ice chart information, and suggested the data are adequate to support scientific investigations of the historical era (e.g., the Historical Ice Chart Archive Project) and from the modern era (e.g., Global Digital Sea-ice Data Bank).”

By 1995 the IPCC second assessment provided a focal point for climate science. References are made to them in the extended abstracts from the July 1999 workshop; this from “On The Use of Historical Sea-ice Charts in Assessments of Century-Scale Climate Variations” (page 1) by John E. Walsh, Konstantin Vinnikov and William L. Chapman [link]

“However, the sea-ice record presented by the IPCC extends back only to the early 1970s. Conclusions about sea-ice trends prior to the 1970s must be based on historical sea-ice charts. Thus the adequacy of these charts for meaningful detection of sea-ice trends is a key issue in the context of century-scale climate trend assessment, especially since the greenhouse scenarios of global climate models show substantial decreases of sea ice coverage over the next several decades. In this paper, we discuss the feasibility of using historical sea-ice charts to assess century-scale sea-ice trends in the context of the projections of a global climate model

And from “About Clarity and Resolution of Ice Charts” by Igor Appel on Page 28 of the extended abstracts;

“The main goal of the present meeting is to review and assess ice chart information to the scientific community.…. Research spans a wide range of temporal and spatial scales. Even consideration of climate change can be limited by small area. Therefore it is desirable to create ice charts with fine resolution. It is clear that resolution does not signify accuracy. There were a lot of discussions at the meeting about improving spatial resolution of ice charts; 10 km and finer resolution have been mentioned. But there are numerous examples demonstrating that ice charts created in different ice centers for the same area and day differ very significantly. Difference in location of ice edge can reach hundreds of kilometers.”

This apparent lack of consistency of sea ice charts makes this next document highly relevant as some issues mentioned in the first few workshops remain ongoing and the gathering and interpretation of historic sea ice data is incomplete.

The ‘Back to 1870’ project described here will re-examine existing material and input new data in a manner that enables modelling through a digitised gridded Pan Arctic data base. [link]

“The 30-year timeframe of gridded pan-Arctic sea ice data sets limits their utility in reanalysis and climate diagnostic applications. The one available pan-Arctic database extending back to the 1800s is the Hadley Centre’s HadISST, in which the gridded sea ice is essentially climatological prior to the 1950s, especially in the winter half of the year. Our project will synthesize various historical datasets that have recently become available for inclusion in a pan-Arctic sea ice dataset spanning 1870-2010.”

The International Ice Charting working group ‘Back to 1870’  project will be invaluable as there is a clear need to improve our understanding of past, present, and future ice extent.

Estimates of Arctic ice extent, density, volume etc.  has been carried out informally and formally for many years by whalers, explorers, the Hudson Bay co, indigenous peoples and many others. The Cambridge group notes the various data bases used to construct ice conditions prior to and during the period in question as follows:

• AARI gridded data, 1930-1970s [1990s]
• Danish Meteorological Institute yearbooks,(DMI)1870s-1960s
• ACSYS sea ice databank (North Atlantic ice edges, 1750-1966
• National Research Council of Canada (B. Hill), Newfoundland ice extent, 1810-2000+
• Alaskan ship reports (whaling and others) K. Wood and Bockstoce/Mahoney/Eicken, 1850-early 1900s
• HadISST-1 and coordination with new HadISST-2

Other influential reconstructions include those from Kelly, Chapman and Walsh, B Hill and S Jones (shown in the Cambridge 2011 document) and the Kinnard et al reconstruction.

The Danish Meteorological Institute (DMI)  yearbooks mentioned are online from 1893-1956 and from which this explanatory quote is taken: [link]

“The positions of direct observations are marked on each chart with red dots (Figure 1). Each chart shows the mapmakers’ inferred ice edge as well as the type of ice present, for example large ice fields or new ice, in certain locations. As a reference for today’s user, these descriptors have been converted into approximate percent-coverage values by V. Underhill and F. Fetterer at NSIDC, based on a combination of historical references

Coverage is considerably better over Greenland, Iceland, and Spitzbergen than for the rest of the Arctic, and direct observations over the Western Arctic are particularly sparse over the entire period of record. From 1946 to 1956, the ice edge in this region solely reflects annual climatology; the DMI probably did not have access to any data in this region because of the Cold War.“

This from the 1978 conference previously referenced:

“ Sea ice charts have been published (by DMI) from 1900 to 1956 for the Arctic seas, and from 1957 to 1964 for the Greenland waters (Fabricius 1961 DMI 1964) .The earlier data are from ship reports. Aerial reconnaissance has been used since 1959.”

“Please note that large portions of the pre-1953, and almost all of the pre-1900 data is either climatology (weather conditions averaged over a period of time) or interpolated data and the user is cautioned to use this data with care (see “Expert user guidance”, below). “ (Chapman)

Section 2   1920-1940:  A Period of warming in the Arctic

Section 2 examines the output of scientists during the last few decades who have examined the 1920-1940 warming.

This next item was presented at the Arctic change workshop in Seattle in 1997 as “Arctic Warming” During 1920-40: A Brief Review of Old Russian Publications by Sergey V. Pisarev and was briefly mentioned previously [link]. This rich source of information is briefly described in the index:

The idea of Arctic Warming during 1920–40 is supported in Russian publications by the following facts:
* retreating of glaciers, melting of sea islands, and retreat of permafrost
* decrease of sea ice amounts
* acceleration of ice drift
* change of cyclone paths
* increase of air temperature
* biological indications of Arctic warming
* ease of navigation
* increase in temperature and heat content of Atlantic Waters, entering Arctic Basin.

The two page extract linked above can be read in full.  The larger report it comes from is no longer available on the link cited [link].

A collaborative approach by two leading organisations suggested possible causes of the warming and queried the official ice estimates relating to the period:

The Early Twentieth-Century Warming in the Arctic—A Possible Mechanism by LENNART BENGTSSON, VLADIMIR A. SEMENOV, OLA M. JOHANNESSEN [link].  Excerpt:

The Arctic 1920–40 warming is one of the most puzzling climate anomalies of the twentieth century. Over some 15 yr the Arctic warmed by 1.78C and remained warm for more than a decade. This is a warming in the region comparable in magnitude to what is to be expected as a consequence of anthropogenic climate change in the next several decades. A gradual cooling commenced in the late 1940s bringing the temperature back to much lower values, although not as cold as before the warming started. …this warming was associated with and presumably initiated by a major increase in the westerly to southwesterly wind north of Norway leading to enhanced atmospheric and ocean heat transport from the comparatively warm North Atlantic Current through the passage between northern Norway and Spitsbergen into the Barents Sea….the increased winds were not related to the NAO, which in fact weakened during the 1920s and remained weak for the whole period of the warm Arctic anomaly. …the process behind the warming was most likely reduced sea ice cover, mainly in the Barents Sea. This is not an unexpected finding because of the climatic effect of sea ice in comparison with that of an open sea but is intriguing since previously available sea ice data (Chapman and Walsh 1993) did not indicate a reduced sea ice cover in the 1930s and 1940s. However, as we have shown here recent sea ice datasets [Johannessen et al. (2004) give a detailed presentation] actually showed a retreat in this period

The following extracts come from Johanssen et al 2004 [link]:

“The global gridded SAT data set (Jones et al., 1999) used most extensively for studies of climate variability has major gaps in the northern high latitudes, in particular over the ice-covered Arctic Ocean and some surrounding land areas.”

And:

“However, it remains open to debate whether the warming in recent decades is an enhanced greenhouse-warming signal or natural decadal and multidecadal variability (Polyakov and Johnson, 2000; Polyakov et al., 2002), e.g. as possibly expressed by the arctic warming observed in the 1920s and 1930s followed by cooling until the 1960s (e.g. Kelly et al., 1982). The uncertainties are exacerbated by a lack of homogeneous, century-scale instrumental data sets (see Moritz et al., 2002, whose fig. 2a includes no temperature data for the central Arctic) needed to resolve the inherent timescales of variability in the Arctic (Venegas and Mysak” Figure 1a shows the time evolution of the zonally averaged anomalies in annual mean SAT from 30–90◦N. Two characteristic warming events stand out, the first from the mid 1920s to about 1940 and the second starting about 1980 and still ongoing. Here, we show that the early twentieth-century warming was largely confined to north of 60◦N, whereas the latter warming encompasses the whole Earth (Jones et al., 1999) but is none the less significantly enhanced in the Arctic (Fig. 1a).”

“In the Atlantic–European sector (Greenland and Barents seas), the sea-ice extents from 1900 to the late 1950s are known only from spring and summer (April to August). …. An attempt has been made to obtain these missing mean annual data. Towards this end, the actual year-round data on the ice extent from 1959–1988 were used to derive an equation to calculate the annual average ice extent in the region….(enabling) the missing annual ice-extent means from 1900–1958 (to be) calculated. The main problem of any reconstruction is errors inevitable in the procedures of data series reconstruction. This problem can be resolved by comparing the actual and calculated annual ice extent averages…Thus, the methodological error of the reconstruction comprises only one third of the rms deviation of the actual series, indicating a sufficiently high reliability of the reconstruction method used.”

A report about North Western Russia entitled ‘Long-term climate trends of the Yamalo-Nenets AO, Russia’ from 2010 comments [link]

“All series show warm periods in the 1940s and 1990s, and a cold period in the 1960s. Salekard (the only station with observations at that time) was cold also around 1900.”

Page 40 summary and conclusions:

1. Increasing temperatures from 1900 to the mid-1940s (often referred to as the “early 20th century warming”).

2. Decreasing temperatures from the mid-1940s until about the mid-1960s.

3. A “recent warming” from the 1960s to 2003.

For Yamal this is shifted to the period 1965/70s-1990/95s.”

Note: This paper contains much useful meteorological information covering this significant area, including first and last day of snow cover, temperatures etc .

Reference was made earlier about the lack of Russian data possibly impacting on the historic charts. It was noted in this 2008 document ‘Observed sea ice extent in the Russian Arctic, 1933–2006’ by Mahoney, Barry, Smolyanitsky and Fetterer (two of whom are involved in the ‘Back to 1870 group.’) [link]

“We present a time series of sea ice extent in the Russian Arctic based on observational sea ice charts compiled by the Arctic and Antarctic Research Institute (AARI). These charts are perhaps the oldest operational sea ice data in existence and show that sea ice

extent in the Russian Arctic has generally decreased since the beginning of the chart series in 1933. This retreat has not been continuous, however.”

And:

“During the second International Polar Year in 1932, the Directorate of the Northern Sea Route was created in Russia to ‘‘develop the Northern Sea Route as a regularly operating transport system’’ [Barr, 1991, p. 27].  Shortly afterward, in 1933, the Arctic and Antarctic Research Institute (AARI) began to regularly produce sea ice charts of the Russian Arctic seas based on aerial, ship, and coastal reconnaissance. The AARI ice charts, as we will refer to them, therefore represent the longest operational ice chart record in existence” 

Generally speaking, from 1933 onwards there were four prime methods of ice observation, land, air, ship and official polar meteorological stations. Aviation, for much of the period examined, was in limited use especially in remoter areas which encompassed much of the region.

‘From the mid 1930s, aviation was used to collect ice information and from the mid 1940s became the main source of sea-ice information in the Siberian Arctic (JOHANNESSEN et al 2004)’

The Alaska edu link continues:

“The earliest chart in the AARI data set is from July 1933. Charts were produced every 10 or every 30 days, depending on time of year. Spatial coverage did not extend far into the central Arctic, and the charts were only produced during the summer months in the early part of the series.”

Other limitations are noted here:

“Because of a lack of sufficient data coverage we only consider the western (Russian) area of the Chukchi Sea. Similarly, the sea ice edge could not be consistently located in the westernmost sector of the Kara Sea, so this is excluded from our analysis.”

 “The eastern half of the Chukchi Sea was omitted because of insufficient data coverage. Similarly, the sea ice edge could not be consistently located in the westernmost sector of the Kara Sea. This area is excluded from the analysis”

“…. Period A, from the beginning of the record (1933) until the mid-1950s, was a period of declining summer sea ice extent over the whole Russian Arctic, though not consistently in every individual sea. Period A is not evident in the winter and spring months and is not as well defined during the autumn partly because of a lack of sea ice charts at this time of year at the beginning of the record. Period B extended from the mid-1950s to the mid-1980s and was a period of generally increasing or stable summer sea ice extent. For the Russian Arctic as a whole, this constituted a partial recovery of the sea ice lost during period A, though this is not the case in all seas. Periods A and B can also be seen in the MY ice record for the overall Russian Arctic (Figure 7), though as mentioned earlier, MY ice extent in the Barents and Kara seas peaked in the 1960s. Period C began in the mid-1980s and continued to the end of the record. It is characterized by a decrease in total and MY sea ice extent in all seas and seasons. In this regard, period C is markedly different from periods A and B.”

“The sources used to compile the HadISST data set are given by Rayner et al. [2003]. Up to 1978, HadISST used the Northern Hemisphere Walsh fields [Walsh and Chapman, 2001] as its main data source, which in turn relied upon ice charts from a number of different sources to locate the sea ice edge. However, prior to satellite observations, none of these charts provided coverage in the Russian Arctic further east than the Kara Sea [Kelly, 1979; Vinje,2001]. Where no sea ice edge data were available, a baseline climatology was used. Such instances are apparent in Figure 8 where the green data points are constant from year to year in the early part of the record.”

Item 4 of the paper ‘Discussion’ and item 5 ‘Conclusions’ on page 9 are worth reading in full.

Section three   A look back from the 1960’s and 70’s

The 1960’s and 70’s saw increased scientific attention to climatology with growing access to records and modern instruments, amid concerns we were headed towards another mini ice age. In this section we examine the 1920-1940 period from that mid-century perspective.

P59 of Volume 1 of Jean Groves book ‘The Little Ice Ages’ second edition, noted: ‘that the relationship between (Icelandic) glacier variations and climate change can be traced most closely since 1930 when glacier monitoring began and meteorological measurements were already long established. Very cold decades at the beginning of the twentieth century were followed by strong warming in the 1920’s and an unusually warm period from 1926 to 1946. Within ten years glaciers were in retreat and the whole period from 1930 to 1970 was one of predominant withdrawal. By 1962 all the monitored glaciers had retreated from their 1930 positions.”

It continues; ‘the tendency toward amelioration in the present century in the USSR, varying greatly in degree from the Ukraine to Siberia, was observed just before the last war and by Rubinstein in 1956 (with) mainly the winter months affected. The tendency is more pronounced in northern areas like the Barents sea, the shores of the Arctic ocean and the estuaries of the Ob and Yenisey rivers. Mitchells curves (showing temperature anomalies from 100 stations, one of the precursors to Giss) (demonstrate) there is indeed a world amelioration particularly in winter. It affects principally the Arctic and (secondly) the cold and temperate zones of the Northern Hemisphere including the US, Europe and Siberia. Thirdly it affects the tropics and finally in a much less perceptible way the temperate zones of the Southern Hemisphere. The only areas unaffected by the annual amelioration between 1900 and 1940 are North eastern Canada, a large part of south America, most of the SW quarter of Africa and certain regions of central Asia and Pakistan and of the Indian ocean SE Asia and Australia.’

Page 122 from this 1977 document returns us to arctic- rather than global- observations.

Hunt and Naske, 1977: A BASELINE STUDY OF HISTORIC ICE CONDITIONS IN THE BEAUFORT SEA, CHUKCHI SEA, AND BERING STRAIT [link]

It gives interesting insights into how data were collected by whalers, traders and govt. skippers and how each exercised their own degree of caution when approaching pack ice and the leads that may lie beyond. Whilst trips may be regular they were often following the same route so consequently observers may have had a limited perspective.

“Plotting their tracks is an exercise in frustration for anyone seeking a pattern in ice movements because patrol vessels steamed from point to point, doubling their track when necessary, avoiding the ice, of course, but otherwise disregarding it. One factor is common to all three types of Arctic cruises from which data has been drawn: the ice was viewed as a potential obstacle, an impediment to navigation. It was not a seasonal physical feature subjected to long ranged scientific curiosity. There were no standards by which its particular qualities might be described; comparisons were not drawn from season to season; information was never collected or exchanged. In fact, the ice observer was happiest when he had no reason to mention ice conditions.”

And

“ Since the Department of the Interior has operated ships annually since the 1920… the logs of several Bureau of Indian Affairs ships were eagerly sought… it was disappointing to learn that ice observations were not systematically recorded. The paucity of data cannot be attributed to negligence of reporting standards of an earlier age, as it shown by a second case. The logs of the Foss Tug Co. for recent years of barge voyages to the Arctic are sprucely kept and generously accessible, yet the printed form used by navigators has not provided for ice observations. This situation can be  understood, of course. Captains of both types of vessels were never indifferent to the ice, and they guided their ships in response to the closest scrutiny of the ice. Yet, except in the general sense, history was not made in documented form.”

Reading the extensive information and asides, the arctic ice researcher might surmise that any records -prior to the satellite era-should be discounted, as the inconsistency of ice data collection methods and unlikelihood of collecting data from leads that may lay beyond pack ice, confirms that comparing the past to the present mixes apples and oranges.

Page 12 of Hubert Lamb’s ‘Climate History and the Modern World’ (originally published 1982 using material collated during the previous decade) notes ‘…from around the beginning of the century up to 1940 a substantial climate change was in progress, average temperatures were rising,  most of all in the arctic where the sea ice was receding…the almost four and a half decades of near immunity to very cold winters ended abruptly with Europe’s notably severe war winters in 1940, 41 and 42 and another in 1947.’ 

Page 259  comments  ‘…warming was rapid from about 1920 to 1940 …it was during the second and third decades of the (20^th) century that the climatic warming became noticeable to everybody,  places near the arctic fringe such as Iceland, Spitsbergen and even Toronto experienced warming that was from twice to five times as great… the average total areas of the arctic sea ice seems to have declined by about between 10 and 20% ….when account is also taken of the changes in the atmospheric circulation and hence in the distribution of rainfall and its variability as well, it is hardly too much to say that the twentieth century climate regime from 1920 to 1960 changed the world.’ Page 261 ‘… the frequency of snow and ice decreased generally and the retreat of the glaciers from about 1925 became rapid.’

In the 1979 book ‘Earth’s Climate Past and Future’ M I Budyko of the State hydrological institute in Leningrad remarks ‘the greatest climatic change within the period of instrumental observations started at the end of the 19^th century. It was marked by a gradual rise in air temperatures at all latitudes in the northern hemisphere throughout the year. This warming was especially pronounced at high latitudes and during the cold seasons. The warming intensified in the 1910’s and reached its peak in the 1930’swhen the mean air temperature in the Northern Hemisphere was 0.6c higher that at the end of the 19^th century. In the 1940s the warming trend changed to a cooling trend which continued until recently. ‘..In the NH the air temperature rise was accompanied by a contraction of polar ice, a retreat of the permafrost boundary to higher latitudes, a northward shift of the forest and tundra boundary and other changes in natural conditions.’

Section four   Data from Contemporary sources-1920-1940

The comments from the IPCC , Walt Meier and blogs such as Neven, together with data from Walsh and Chapman, Kennard, Hadley and others, indicate  a modest intermittent often .localised arctic warming, through the 1920 to 40’s.  However, the data they base this on appears to be fragmented, and a different viewpoint can be construed from the work of other modern and mid twentieth century researchers referenced in the previous section. However the most telling glimpses into the past comes from those living during the period. Here we examine contemporary records for tangible evidence of arctic warming, discern the period it covers and put it into context with areas outside the arctic described as ‘not unusually warm.’

Continuing the theme of conditions in the Russian sector not being fully covered in official sea ice data- comments should be prefaced that due to World War Two, then the ‘Cold war,’ together with the remoteness of much of the area, international cooperation at the time, and for a period afterwards, was often limited as regards the Russian Arctic.

However, prior to this difficult period, and even during it, research still went on and much data was produced which, over the course of time, seems to have taken a back seat.

Arctic researcher Hans Ahlmann noted in 1952 that:

 “The extent of drift ice in Arctic waters has also diminished considerably in the last decades. According to information received in the U.S.S.R. in 1945, the area of drift ice in the Russian sector of the Arctic was reduced by no less than 1,000,000 square kilometers between 1924 and 1944.”

This reference by Ahlmann and others concerning the rapidly warming arctic can be picked up on the occasion of a lecture he gave in 1952 as the principal address at the meeting of the Seventeenth International Geographical Congress in Washington, D. C. [link]

It gives an intriguing glimpse of the science at the time, highlighting the warming that was of intense interest to many researchers.  Several relevant extracts are given below:

“The thickness of the ice forming annually in the North Polar Sea has diminished from an average of 365 centimeters at the time of Nansen’s Fram expedition of 1893-96 to 218 centimeters during the drift of the Russian icebreaker Sedov in 1937-40. The extent of drift ice in Arctic waters has also diminished considerably in the last decades.”

“ The shipping season in West Spitsbergen has lengthened from three months at the beginning of this century to about seven months at the beginning of the 1940s.”

“ The Northern Sea Route, the North-East Passage, could never have been put into regular usage if the ice conditions in recent years had been as difficult as they were during the first decades of this century.”

“The same influences that have affected the drift ice have affected the animal life of the North Polar Sea. Various kinds of fish, especially cod, have migrated northwards. Now for the first time cod is available to many Greenland Eskimos who previously had to rely on seal for food. In a (1947) speech…the Danish Prime Minister said:

“In the last generation changes that have had a decisive influence on all social life have occurred in Greenland. …These changes are primarily due to two circumstances. Firstly, the Greenland climate has changed, and with it Greenland’s natural and economic prospects…”

“…herring catches off the north coast of Iceland have greatly diminished in the last seven years, possibly because of changes in the sea currents connected with the present climatic fluctuation. Herring has become an open sea fishery; its 1952 season was extended to November instead of ending as usual in August.”

“…the International Council for the Exploration of the Sea adopt(ed) the following resolution at its meeting in Denmark in 1948: “Having considered a number of lectures on climatic fluctuations, the Council recommends that these important and far reaching problems ought to be more closely investigated, and that these investigations might be adequately supported by the Governments in the different countries”

Historic note: Dr. Ahlmann was Professor of Geography at the University of Stockholm, and from 1948 to 1951 served as President of the Commission on Snow and Ice of the International Association of Hydrology (I. U. G. G.). He forged particularly good links with Russian arctic scientists during a difficult period of international scientific cooperation (especially American), as noted here:

“…in 1934 Ahlmann was invited to lecture at the Arctic Research Institute on his Svalbard expeditions in 1931 and 1934. Ahlmann returned to the Soviet Union several more times, deepening his respect for Russian arctic research especially during visits in 1958 and 1960 as president of the International Union of Geographical Sciences.”  [link]

This next site gathers some thirty articles and science reports in chronological order concerning the warming that covered a wide area of the world in the period 1900 1949. [link]

Probably the best known and most widely quoted item is this from the Monthly Weather Review of Oct 1922. (Edited for space reasons.) [link] [link]

‘The Arctic seems to be warming up, states George Nicolas Ifft American consul at Bergen, Norway. “ …. fishermen, seal hunters, and explores who sail the seas about Spitsbergen and the eastern Arctic, all point to a radical change in climatic conditions, and hitherto unheard-of high temperatures……

In August, 1922, the Norwegian Department of Commerce sent an expedition to Spitsbergen and Bear Island under Dr. Adolf Hoel, lecturer on geology at the University of Christiania. The oceanographic observations (reported that) Ice conditions were exceptional. In fact, so little ice has never before been noted. The expedition all but established a record, sailing as far north as 81^o29′ in ice-free water. This is the farthest north ever reached with modern oceanographic apparatus…..

In connection with Dr. Hoel’s report…note the unusually warm summer in Arctic Norway and observations of Capt. Martin Ingebrigtsen, who sailed the eastern Arctic for 54 years past. He first noted warmer conditions in 1918, since that time it has steadily gotten warmer, to-day the Arctic of that region is not recognizable as the same region of 1868 to 1917.

Many old landmarks are so changed as to be unrecognisable. Where formerly great masses of ice were found, there are now often moraines, accumulations of earth and stones. At many points where glaciers formerly extended far into the sea they have entirely disappeared.

The change in temperature, says Captain Ingebrigtsen, has also brought about great change in the flora and fauna of the Arctic. This summer he sought for white fish in Spitsbergen waters (where) formerly great shoals were found. This year he saw none, although he visited all the old fishing grounds.

There were few seal in Spitzbergen waters , the catch being far under average. This did not surprise the captain. He pointed out that formerly the waters about Spitzbergen held an even summer temperature of about 3^o Celsius; this year recorded temperatures up to 15^o, and last winter the ocean did not freeze over even on the north coast of Spitsbergen.”

We can reinforce observations that determine the conditions around 1900 and 1940 with this Russian report from that latter year [link]:

“Is it getting warmer at the North Pole? Soundings and meteorological tests taken by the Soviet explorers who returned this week to Murmansk, Russia’s sole ice-free Arctic port, concluded that near Polar temperatures are on average six degrees(C) higher than registered by Nansen 40 years ago. Ice measurements were on average only 6½ feet against from 9¼ to 13 feet. The return of the Soviet icebreaker Sedoff (note variations in spelling) brought to a close a Polar expedition, involuntarily undertaken which led to important discoveries. For 2½ years she had drifted while trapped in Polar ice. Fifteen men volunteered to stay on board until relief came. In the drift to the north-west these men passed nearer to the North Pole than any other ship. Their highest latitude was 86 degrees 56min North. They discovered by soundings a near Polar sea pocket, 17,260 feet deep.”

Here we can identify the warming extending to around 1952 with again a useful reference to 1900 [link]:

“Dr. William S. Carlson, an Arctic expert, said to-night that the Polar icecaps were melting at an astonishing and unexplained rate and were threatening to swamp seaports by raising the ocean levels….it would take hundreds of years for the melting to have much effect, but the rate in the last half century had been exceedingly rapid.

The glaciers of Norway and Alaska are only half the size they were 50 years age. The temperature around Spitsbergen has so modified that the sailing time has lengthened from three to eight months of the year.”

Historical footnote:  William S. Carlson, for whom the University of Delaware’s International Polar Year public events are named, president of UD from 1946 to 1950, was an accomplished polar explorer and scientist.  [link]

 This 1939 report confirms the observed warming was considered widespread, and that the warming that caused this retreating ice could be dated to some 100 to 200 years prior to 1939. [link]

“One of the riddles which is puzzling geologists all over the world is the continuous retreat of the ice glaciers. Does this phenomenon indicate that the sun is getting hotter … or is it dependent upon comparatively unimportant changes in the earth’s atmosphere?

…these were discussed by Professor R. Speight, formerly professor of geology at Canterbury College, Christchurch, New Zealand in his presidential address to the …Science Congress to-day.

 The steady retreat of the glaciers in New Zealand …had been observed during the last 70 years. Photographs taken in 1896 and 1935 showed several glaciers had retreated distances varying from 100 yards to half a mile in 40 years.

The phenomenon, however, was world-wide. Equally impressive records were obtainable from Switzerland, Scandinavia, Iceland and the United States. In Alaska glaciers had been retreating from 100 to 200 years, the average rate of recession being about 50 feet a year. The Antarctic ice- sheet also showed signs of recent retreat.

Professor Speight said, ” (no) region of the world (shows) present signs of an advance. This is quite apart from the general retreat since the pleistocene age and may be merely a pacing phase. Its precise significance can only be determined by continued observation.”

This knowledge that some glaciers had been retreating for some hundreds of years had been expounded by Gordon Manley at various times. [link]

“The earth is getting warmer. The oceans are getting deeper. The glaciers are getting smaller. Even the fish are changing their way of life. All this and more is going on because of a vast, unaccountable, century-by-century change, in climate (according to)  Britain’s distinguished geographer, Professor Gordon Manley. Since about 1850 there have been hard and soft winters (he said) but the general tendency has been toward higher average temperatures. It means little at the North Pole, or in Central Europe or America. But there are certain “fringe areas,” on the meteorological edges between hot and cold weather, where the effects even now are spectacular.”

Historical footnote: Gordon Manley was a renowned English climatologist who assembled the (CET) series of monthly mean temperatures stretching back to 1659. He hypothesised that (some) glaciers had been in stasis or retreating since around 1750. [link]

The references concerning the long established retreat of the glaciers – and the specific reference to Alaska-  can be put into its context and given a useful time frame here: [link]

“Glacier Bay was first surveyed in detail in 1794 by a team from the H.M.S. Discovery, captained by George Vancouver. At the time the survey produced showed a mere indentation in the shoreline. That massive glacier was more than 4,000 feet thick in places, up to 20 miles wide, and extended more than 100 miles to the St. Elias mountain range. By 1879, however, naturalist John Muir discovered that the ice had retreated more than 30 miles forming an actual bay. By 1916, the Grand Pacific Glacier-  the main glacier credited with carving the bay – had melted back 60 miles to the head of what is now Tarr Inlet.”

Historical footnote:  George Vancouver was a renowned English officer of the British Royal Navy, best known for his 1791-95 expedition, which explored and charted North America’s northwestern Pacific Coast regions, including the coasts of contemporary Alaska. He gave his name to the city of Vancouver. [link]

John Muir was a renowned naturalist and “one of the patron saints of twentieth-century American environmental activity.”  He founded the Sierra club which to this day remains a leading environmental organisation. [link]

Practical on the ground observations are a useful adjunct to scientific papers, with here noted a comparison of warmer seasons from as far apart as Disko island (Baffin Bay off west coast of Greenland)  and Alaska, over as much as a 50 year comparison period. [link]

 ‘Similar (warming) changes have occurred throughout the Arctic in the natural vegetation… Thus, in 1937, when approaching Disko Island in Bob Bartlett’s schooner Morrisey, I noticed that the flat tops of mountains west of Godhavn that formerly showed no green vegetation above the 2000-foot level were distinctly green from several miles away. During the summer of 1926, which I spent in Alaska, I noticed that on Seward Peninsula the vegetation was fully one month farther advanced that in 1879 when the Swedish botanist Kjellman collected there.”

Historic footnote: Bob Bartlett was a familiar figure to our cinema going forefathers during the 1920’s and 30s, his adventures  eagerly awaited on British Pathe news reels as Captain on board the vessel Morrisey travelling a warming arctic.

This 1932 article demonstrates that, unlike the modern era, the warming affected both poles whilst highlighting the continued retreat of the glaciers generally and in Greenland and Alaska specifically: [link]

“Some great world change is taking place on the Antarctic Continent. Its glaciers are shrinking. L.A. Bernacchi, who visited the South Polar land 30 years ago, says that the Great Ice Barrier which fronts the continent with a wall of ice for 250 miles has receded at least 30 miles since it was first seen and surveyed. Sir James Ross…on the earliest Antarctic expedition of the nineteenth century, and those who followed him, left clear descriptions of this tremendous ice frontage and its position. It was a cliff 150ft. high and 1000ft. thick. But now it appears to be continuing its century-long process of shrinking; and that process may have been going on for centuries. It might imply, unless it is offset by some increase of ice in another less explored part of the Antarctic, that the climate of the South Pole is changing and becoming warmer. The shrinkage of the Alpine glaciers of Europe is a well-known and carefully measured fact. Professor Buchanan, of. Edinburgh, drew attention to it twenty years ago, and showed from old and accurate drawings of (many) that they were retreating rapidly. This led to the continuous measurement of the Swiss glaciers (and) examination of other glaciers of the Northern Hemisphere, Greenland, Alaska, and elsewhere. Prom these measurements many geologists concluded that the northern part of the globe was still recovering from the last of its Ice Ages, of which the more southerly of its glaciers in Europe were a relic. If all the glaciers of the Southern Hemisphere as well as those of the Northern are shrinking, the geologists would have a new problem to examine. It would be whether, instead of areas of cold and ice having shifted on the earth, the whole globe is growing warmer. Even if that could be shown the change might prove to be temporary.” [link]

By the time of this article in 1937 warming was an accepted fact and attempts were made to quantify its extent and attribute reasons for it. [link]

“The discovery by American seal fishers that …there has been a remarkable increase in the mean temperature of the Arctic, and that in some parts of the Polar basin no ice has been seen less than 9 degrees from the North Pole, agrees with the experience of many Arctic explorers in recent years. Just before the war a party of Russians exploring Nova Zemblya (Russia) discovered clear evidence of a branch of the Gulf Stream running north of that Arctic island, between it and Franz Josef Land (Far north of Russia), though all existing charts of that hot-water system place its most northerly extension well to the south of Nova Zemblya. (Recent) evidence has accumulated that the Gulf Stream has been diverted, and there is little doubt but that any increase of Arctic temperatures must be caused by warm ocean currents coming up from southerly latitudes.”

1939 heralded World War and the end of much international scientific cooperation for some years, making this next item something of a period piece, highlighting doubts that the warmth should be attributed to the Gulf Stream. One scientist believed that increased CO2 could be responsible for warming-an attribution to this gas that predates most estimates of any likely effect by 30 years, whilst others looked to the sun, so there are intriguing parallels to theories of our current age.

Historical footnote: GS Callendar had published his seminal article on CO2 in 1938.

From 1939 [link]:

1939. What is The World Coming To? Scientists have confirmed that Arctic regions around Spitzbergen are warming at the rate of approximately one degree in every two years. Since 1910, when observations first started there, the cumulative rise of winter temperature has amounted to nearly 16 degrees. Such a profound change has been at- tended by new and strange phenomena over the whole area surrounding the Polar basin…Polar ice fields are receding gradually northwards… soil which once remained solidly frozen throughout the year now undergoes a partial thaw during the Arctic summers. In the Barents Sea area where, during earlier observations, only small patches became free from ice, large spaces of open water now occur at frequent intervals. Ice-breakers and other vessels which regularly make journeys to the far North are now able to penetrate with comparative ease into regions which could not be reached twenty years ago. There has been a gradual drift northward of several kinds of fish into areas once completely ice covered. The milder conditions have not been confined to areas north of the Russian coast. From parts of Greenland comes evidence of a higher winter temperature, with considerably less snow, than in the early part of the twentieth century. ….Parts of the Polar regions not affected by the warm waters have grown decidedly warmer in the last 20 years, while temperatures have become higher in the far north-east of Siberia and well inland—remote from oceanic effects. In support of the belief that the Atlantic river of warmth cannot be wholly responsible for the widespread rise in temperature there are the trustworthy records by…. the Weather Bureau at Washington, which show that the rise in temperature at places as far apart as Canada and Africa. South America and Asia, Bombay and Santiago (Chile) has been well marked since the middle of last century. It is possible that the world as a whole is becoming warmer. One scientist…theorises that an increase in carbon dioxide (due to the huge amounts of coal being used) may be responsible…while astronomers look to the sun for an explanation. Quite apart from any fluctuations in the sun’s actual output of radiative energy, it is possible that the warmth received from the sun may vary from time to time due to the earth passing through regions of space in which meteoric dust is unevenly distributed.”

This next item from 1943 is a fascinating historic journal, all the more interesting because of its date and the location of many of the observations. It is inscribed;

“I also wish to express my indebtedness to Rear Admiral I. D. Papanin and to V. D. Novikov, who by their care and attention have aided in the completion and publication of this book. Moscow. May, 1943. N. N. Zubov, Naval Captain, Professor, Doctor of Geographical Sciences”

This link leads directly to ‘Arctic Ice’ by N.N.Zubov. [link]

“Thus, for example, a vessel which attempted to traverse the Northern Sea Route at any cost in August 1936 would have gotten the impression that the route was completely impassable due to ice. On the contrary, a through passage of the Northern Sea Route in the second half of September of that year did not present particular difficulties. “

(Authors note: this illustrates the potential problems in relying on DMI sea ice charts which terminate in August)

“We could cite numerous such examples , but the foregoing are sufficient to show that the navigational conditions, at least in seas such as the Greenland, Barents and Kara which have been more completely studied as to ice conditions, have become incomparably easier during the past 10 to 20 years than in previous years. Due to insufficiency of observations, the question of warming of the arctic in its whole broad connotation has been propounded only very recently, namely in connection with preparation for carrying out the Second International Polar Year, when I had to plan the sea expedition routes in advance. Certain phenomena connected with warming of the arctic had been noted earlier. For example, Knipovich was the first to turn his attention to the high temperatures of the Barents Sea in 1921. This warming was then confirmed in 1923 by our voyage on the Perseus to Franz Joseph Land without meeting ice.

Still more remarkable is the fact that the warming of the arctic is not confined to any particular region….the same signs of warming of the atmosphere and hydrosphere are found in the Bering Strait, in the Pacific Ocean as in the western sector of the Soviet Arctic.

 A warming of the Antarctic is evidently also going on simultaneously…On the background of general warming of the arctic we are observing warmer years and colder years, but there are not signs as yet that this warming is terminating…”

“Sumgin informed me that the southern boundary of permafrost in Siberia is everywhere receding northward. In 1837 this boundary, for example, ran somewhat south of the town of Mezen and was found at a depth of 2 m. In 1933 the Academy of Sciences Expedition found this boundary at the village of Semzha 40 km further north.

Historic footnote: The opening of a Northern sea route (also called the Northeast passage) has implications for understanding ice dynamics of the time, becoming an important supply route during World War 2 although until the period in question was not useable in any practical manner, as noted here:

“In 1932, a Soviet expedition led by Professor Otto Yulievich Schmidt was the first to sail all the way from Arkhangelsk to the Bering Strait in the same summer without wintering en route. After a couple more trial runs, in 1933 and 1934, the Northern Sea Route was officially defined and open and commercial exploitation began in 1935. The next year, part of the Baltic Fleet made the passage to the Pacific where armed conflict with Japan was looming [link]

The ‘Arctic Circle’ was an organisation based in Ottawa. Their annual ‘Arctic circular’ provides fascinating insights into the period. These short excerpts do not do justice to the publication which details many interesting facts about all facets of arctic life in the 1940’s.

This item from 1949 refers to page 3 of this document; [link]

“During the last three decades there has been a marked change in the climate of the Arctic which is being felt throughout the northern hemisphere where, especially, the mean temperature of the winters has increased considerably. In the North American sector this change is perhaps best understood and also most marked in Greenland, where long meteorological records exist from a number of points on the west coast, Thus at Jakobshavn, in latitude 69⁰ 13 North, the mean winter temperature for the years 1913-1922 was about 5 degrees F above the mean of 50 years and that of 1923-1932 almost 10.0 degrees F. above. In 1935-1936 the mean for the winter at Godhavn was 13.4⁰ higher than the normal at the end of last century, that of Godthaab 7.6⁰ and at Julianehaab 9.8^oF.  Increasing temperatures are not limited to the air; sea temperatures also have increased and while the amplitude is not so great, the result is even more profound and far reaching.”

This from page 4:

“The warming of the arctic seas has caused a diminishing of the arctic drift ice, which again has improved shipping conditions. In the 1907-1917 period Norwegian coal mines in Spitsbergen were able to load and export coal an average of 94 days each season, while 20 years later this period has been extended to 192 days. In 1878-80 Nordenskjold in the Vega was the first to navigate the North East Passage, but to do this he had to winter twice. In 1936 a convoy of fourteen Russian ships mode the trip in one season without encountering serious ice difficulties and during the last war this northern Sea route was used extensively by Soviet shipping. During 1942-45 even war ships, which are especially vulnerable to ice, were able to reach Thule without difficulty.

The seas around Greenland have also been remarkably open in later years. The east coast, which frequently remained completely blocked by pack-ice, in 1931-33 was almost free from ice. “

And this:

“In 1941-42 the low-powered, 80 ton R.C.M.P. schooner St. Roch made the North West Passage for the first time from the Pacific to the Atlantic and again in 1944 in the opposite direction in only 87 days.”

Historical footnote: Larsen, an experienced arctic seaman who commanded the vessel noted:
“The three seasons of the short Arctic Summers from 1940-42 had been extremely bad for navigation, the worst consecutive three I had experienced as far as ice and weather conditions were concerned, and in my remaining years in the Arctic I never saw their like.”

This allows us to observe that whilst Arctic conditions were often highly favourable for something like three decades, there were intermittent periods during the early years of World War 2 when the ice returned, but then abated again.

From page 5 of the ‘Arctic Circular’ comes this observation;

“The warming of the arctic seas has profoundly affected marine life. The Irminger Current, that branch of the Gulf Stream which washes the south western part of Greenland’s west coast, can now be traced as far north as Melville Bay. The increase in sea temperature of Greenland waters, varying from 5 to 8 degrees F., has brought the Atlantic Cod and the halibut, besides numerous other Atlantic fishes to Greenland, so that today the fishing banks off the west coast are among the richest in the world. At the same time many arctic marine animals, including the beluga or white whale, the arctic cod and the capelin, to mention only a few, have retreated north.”

 It also notes the harsh conditions in 1946 and 1947 and the exceptionally ice free conditions in 1948 on Page 17;

“Throughout the north mean temperatures were well above normal for the months of June and July except in the area of coastal and south-eastern Labrador (North East Canada). The highest temperatures recorded were in many cases 10 to 20 degrees (F) higher than the mean maximum computed over a considerable period of years. Arctic Bay (Canada) with a normal mean maximum of 51⁰ F in July, reported a maximum temperature of 68⁰ F and a mean temperature of 46°F as compared with the normal mean of 43°F. Nottingham Island with a mean maximum temperature of 49⁰ F for July and a mean of’ 42°F reported a mean of 49 degrees F and a maximum of 68⁰ F.” (Mention is also made of very icy conditions in 1941)

And this;

“In this connection it is interesting to note that the amount of water released by the melting of glaciers has already caused a measurable increase in the level of the Oceans.”

 

Page 47 records a somewhat ironic outcome to intended cold weather experiments by the Royal Navy in February 1949;

“In the course of this (six week) cruise, the Vengeance penetrated more than 450 miles north of the Arctic Circle. Thirty-three special observers were aboard to watch trials on new methods of keeping guns, radio and radar equipment free from ice, the effects of extreme cold on the ship’s company, and the efficiency of the latest type of survival suit. The weather throughout was abnormal for that time of year, and instead of northerly winds and extremely cold weather there were southerly winds, with higher temperatures, strong gales and snowstorms, which restricted flying operations. Owing to these unexpectedly warm conditions the trials were stopped on March 4, a week ahead of schedule.”

A number of additional contemporary reports has been placed at the end of this article as a small fraction of the material available, demonstrating the widespread warming in the arctic and further afield over many years.

Section Five   Comments and Conclusions

In trying to determine the true extent of sea ice melt during the period 1920-1940, we run the risk of comparing apples to oranges, since the different observing methods employed over the years makes it difficult to determine how modern ice extent compares to the past with any certainty.

However, the conclusion must be that drawn that warming was more widespread in the Arctic – not just the Atlantic side – than is currently noted in the official sea ice data bases covering 1920-1945/50 and that the official records appear to very substantially overstate the ice area extent during this period.

The 1920-1940’s arctic sea ice melt can therefore be seen as remarkable, albeit the caveats about apples and oranges need to be applied. Looking at the evidence available from each of the arctic oceans means the ice extent probably lies somewhere within that experienced during the first half of the 2000’s, but was probably not as low as 2007 and 2012.

It is anticipated that the ‘Back to 1870’ project will objectively look at the available information from all sources and put the period to 1870-and especially 1920-1940/50- into its proper context to today.

Supplementary information (dowload supplementaryinformation29jan2013amednded april2013) leads to a variety of additional studies of the period, some modern, but most dating from the 1920-1940 era

JC comment:  I would like to thank Tony Brown for posting his meticulously researched and fascinating essay at Climate Etc.

Moderation note:  This is a technical thread and a guest post.  Please keep your comments on topic and civil.