by Tony Brown
Is our popular understanding of the ‘Little Ice Age’ (LIA) correct, as being a predominantly cold era lasting 500 years, leavened by a few brief warm spells?
The canonical description of the Little Ice Age is reflected in this quote [link]:
‘The Little Ice Age is a period between about 1300 and 1870 during which Europe and North America were subjected to much colder winters than during the 20th century. The period can be divided in two phases, the first beginning around 1300 and continuing until the late 1400s. There was a slightly warmer period in the 1500s, after which the climate deteriorated substantially. The period between 1600 and 1800 marks the height of the Little Ice Age.’
The nature of the LIA has been a matter of some contention. The beginning, end and overall severity of this period has been hotly contended by scholars such as Groves, Fagan, Lamb etc., though its extent is thought to roughly coincide with the period 1300-1850 as stated in the title of Professor Brian Fagan’s excellent book ‘The Little Ice Age-How Climate made History 1300-1850’.
Even more hotly disputed is its geographic spread –regional, hemispheric or global.
Some five years ago I started a project I termed the ‘Little Ice Age Thermometers’ to investigate the likely extent and depth of the LIA worldwide, but with a prime focus on the UK, through Central England Temperature, (CET) to 1659, compiled by Manley and now maintained by the Met Office, we have instrumental and numerous other written and physical records reaching through much of the LIA.
The purpose of this paper is to determine the extent and severity of the climate in the area broadly defined as Central England, for the individual years during the period commencing 1538 and portray it graphically in a number of ways. In order to maintain an interesting and largely non-technical narrative, the historic context, graphics and comments are in section 1, whilst conclusions and observations are in section 2. Finally, the more technical background to determining the temperature profile of each year is mentioned in Section 3, together with a variety of important caveats, additional observations, references and links that are integral to this article.
The temperature data and related articles arising from the Little Ice Age Thermometers project collected to date are here [link].
In 2011 I carried out a reconstruction that extended CET from 1659 to 1538 thereby incorporating another part of the epoch, in particular that cold part of the latter half of the 16th century made famous in Breughel’s paintings [link]. The calculations and numerous references relating to this article are here [link].
Here is the graph from ‘The Long Slow Thaw’ starting in 1538 which was updated to 2014 to show the recent uptick-this was said to be the warmest year in the record.
Figure 1-CET from 1538 to 2014
Additional CET data are shown in section 3.4 and 3.7.
Currently the author is extending CET through the 13th and 14th centuries in order to determine the apparent descent into the LIA during that time frame and eventually hopes to have a complete CET from 1086 to 1659, albeit from a slightly broader area and with decreasing levels of accuracy as we delve back in time. The earliest part of this timescale is especially prone to legends, superstitions and reliance on religious interpretations.
In carrying out the reconstruction from 1538 it should be noted that, as the normal temperature range within the British Isles is relatively narrow, anything ‘exceptional’ can often be unearthed from the numerous archives or academic material. At best, we can believe in the general direction of travel of the local instrumental record – but not on their accuracy to tenths of a degree. As Hubert Lamb noted regarding historical reconstructions, ‘we can understand the tendency but not the precision’ so looking at the direction of travel of temperatures is more profitable than expecting precision in the reconstruction to fractions of a degree.
With that overall context and as noted earlier, the purpose of this paper is to determine the extent and severity of each of the years in Central England from 1538 to the present day and then make observations on the findings. Looking at the overall temperature profile for a complete year, rather than merely examining exceptional winters, adds another perspective to our understanding of the period, so it is that criteria-the mean CET for each year- that have been used in order to try to define our understanding of the climate of Central England for the period. Individually severe winters are mentioned in 3.4 and 3.7.
To provide meaningful categorisation of temperature groupings, the point at which a year or a decade can be described as a genuinely cold LIA type occurrence needs to be defined, and in turn to assign other temperature profiles to the remaining years. This is detailed in section 3.1 and 3.3.
Briefly, the selected criteria are:
- up to and including 8.92C is a ‘Little Ice Age type’ cold year (LIA year) shown by a blue dot.
- from 8.93 to 9.019 is moderate; green dots
- from 9.20 to 9.78 is warm; orange dots
- above 9.79 is very warm; red dot
When the entire record to 1538 is examined in two different formats using
the data derived from these criteria, it looks as follows:
Figure 2 and Figure 3-Annual temperature profiles of extended CET
The parameters used to highlight years of varying degrees of warmth produces some surprises. The first is the sheer variability than can be observed in Figures 2 and 3, with the intermittent nature of genuinely cold years being juxtaposed in close proximity to years with a very different temperature profile. Other observations are discussed in Section 2, but any extended periods when the cold clearly predominated are rather limited, with 1670 to 1700 being the most notable. The early 1560’s to around 1625 also has a high proportion of cold years interrupted by warmer ones.
Are the data valid as being reasonably representative of CET and the wider UK climate over the years? Allowing for exaggeration and short memories by chroniclers, some 15 accounts of the changing climate and other references (see sections 3.5 and 3.10) seem to reinforce what our eyes are telling us. Professor Brian Fagan, writing in his book ‘The Little Ice Age,’ succinctly summarises the reality of the vagaries of the climate that can be observed:
“The little ice age of 1300 to about 1850 is part of a much longer sequence of short term changes from colder to warmer and back again which began millennia earlier. The harsh cold of the LIA winters live on in artistic masterpieces….(such as) Peter Breughel the elders ‘hunters in the snow’ (see Figure 9) painted during the first great winter of the LIA but there was much more to the LIA than freezing cold and it was framed by two distinctly warmer periods. A modern day European transported to the heights of the LIA would not find the climate very different even if winters were sometimes colder than today and summers very warm on occasion too. There was never a monolithic deep freeze rather a climatic see saw that swung constantly back and forwards in volatile and sometimes disastrous shifts. There were arctic winters, blazing summers, serious droughts, torrential rain years, often bountiful harvests and long periods of mild winters and warm summers. Cycles of excessive cold and unusual rainfall could last a decade a few years or just a single season. The pendulum of climate change rarely paused for more than a generation.”
So what is happening? Here are the four seasons from the Met Office data;
Figure 4-CET seasonal showing decadal change
Cold winters in general -which can exhibit the greatest annual temperature range of any season-are becoming increasingly absent, as noted by the Dean of Brasenose College, Oxford-compiler of a major book on historic climate- in 1898:
“By 1708 the middle aged would say, where are our old winters?”
Other seasons have also warmed to a greater or lesser extent.
Eyeballing the graph in Figure 1, a rapidly warming trend from around 1700 can be observed. It rose from the nadir of the coldest LIA period around 1690 and came to a crashing halt with the winter of 1740 which heralded the coldest year in the series. This caused Phil Jones of CRU to write an article on the period in 2006 confirming:
‘The study, therefore, highlights how estimates of natural climatic variability in this region based on more recent data may not fully encompass the possible known range.’
(See section 3.5 for full reference)
The considerable natural variability that Dr Jones observed in 2006 can be clearly seen in all the charts and was graphically described by Professor Fagan above. Whilst it is easy to note the short term changes as the weather oscillates between very warm and very cold years, the longer term effect is not so easy to discern. People – especially farmers in this essentially agricultural age that typified much of the earlier record – are very much affected by harsh winters or hot summers. But what sort of overall climate did they experience through their lifetime? To enable longer term trends to be viewed that could help smooth out the short term ‘noise’ caused by the considerable annual and decadal variations, a different format is required. Accordingly a formula was devised by the author to note the real world impact of the changing climate on a person aged 70 years old. This reflected the cumulative temperatures experienced during a three score and ten lifespan, and which would account for any longer term climatic cycles that may exist.
The mean average of each year and each decade was calculated that assumed a succession of British ‘Everyman’ was born at the start of each decade in the record and who died on the last year of the decade 70 years later. The average temperature experienced during each 70 year lifetime is seen here.
Figure 5-British Everyman of age 70
The low point can be clearly seen with someone born around 1660, who then experienced the worst few decades of the LIA. With some slight deviations a steady upwards trend can then be observed throughout the rest of the record. British Everyman has lived in an increasingly warming world for some 350 years. The criteria used are shown in section 3.4
There is one final set of graphics to be shown, two of which were shown previously as Figures 2 and 3. To these have been added for comparative purposes, data for sunspots and data for volcanic eruptions. Both of these are said to affect weather and to cool the climate. The very low sunspot counts occurred during the Sporer minimum, 1450 to 1550; Maunder Minimum , 1645 to 1715; Dalton Minimum, 1790 to 1820. The volcanos shown are those top 12 that had the greatest emissions according to an index called the VEI.
Figures 6, 7, 8 and 9
Further observations and comments regarding the four sets of data referenced above-including those on volcanos and sunspots, are made below in Section 2.
Section 2 Observations and comments
Some 70 % of the period from 1538 to the modern day could be classified as the LIA. Its intermittent nature perhaps better appreciated in scientific circles than in the popular imagination.
Whilst the various charts, such as Figures 6 and 7, together with Met office and other data referenced, demonstrate many individual cold years and more surprisingly perhaps, many warm ones as well, what can’t be discerned is one long uninterrupted block of blue representing very cold years extending from the beginning of the record and expiring sometime in the middle of the 19th century, thus matching the ‘official’ definitions of the LIA.
So clearly the period wasn’t one monolithic cold era. Indeed, this occurrence of warm and very warm years amongst the cold and moderate ones clearly confuses our popular understanding of this period. (See 3.9 for the scientific definition) Whilst the era might be characterised as generally cold with many moderate to very warm spells, it might also almost be characterised as generally warm with many moderate to very cold years.
Another notable feature is the sheer variability than can be observed in Figures 6 and 7, with the intermittent nature of genuinely cold years being juxtaposed in close proximity to years with a very different temperature profile. Any lengthy periods when the cold clearly predominated are rather limited.
A sporadic reduction of LIA type years from its low point in the 1690s can be discerned, but they still recur with some regularity for much of the record, even to the present day.
There is obvious warming in the reconstructed early part of the record, but as yet no analysis of available research material has yet been carried out to determine if this trend continues.
There is also obvious warming in recent years. Whilst the 30 year period from the early 1980s to today shows continued variation in the temperature profile, it is too short to determine if it may be indicative of a more permanent very warm trend that will be unique in the record.
The most consistently warm period appears to be the early 1920s to mid-1950s when for over 30 years no overall cold years were recorded (although there were some cold winters) this mildness is reflected in the Farmers quotes of the era referenced in Section 3.5.
Undoubtedly the period from the early 1920s to today in particular have shown a noticeable lessening in the frequency of cold years, although they have not disappeared entirely.
The British experience, as far as the available records go, seems to indicate that the LIA could be said to have finished as late as the early 1920s as far as cold years-if not very cold winters- are concerned. This seems a little far- fetched until literature such as this is examined from Bradley and Jones 1993 entitled ‘Little ice age summer temperature variations their nature and relevance to recent global warming trends’ whereby the authors state: ‘unusually warm conditions have prevailed since the 1920s probably related to a relative absence of major explosive volcanic eruptions and higher levels of greenhouse gases.’
In 2006 Jones confirmed that the very warm 1730s decade (see Section 3.5) indicated natural variability greater than at first realised.
The effect of sunspots on the climate is contentious. Looking at the data in Figure 8, it appears that the impact of the second half of the Sporer minimum on temperatures is difficult to discern. The Maunder minimum however appears to largely coincide with colder years, whilst the Dalton minimum is more mixed. However, there had been many cold years prior to the onset of these sunspot minimums and cold years returned after they had finished, so the relationship appears unproven and may be coincidental, where there is some correlation.
Moving on to the volcano data shown in Figure 9 – where impacts are as contentious as that of sunspots – it is said the massive 1258 eruption and a group of others a few decades later (outside the time scale of this article) helped to precipitate the LIA. Whilst there may appear to be some cause and effect with some of the volcanos listed, it is again by no means clear cut, as cold years often occurred prior to eruptions and returned when any effect of the sun screening emissions must have been washed out of the atmosphere. This is Hubert Lamb’s take on the matter, in the context of an appraisal of his work on the subject;
‘This painstaking work, using scientific reports from the well-documented eruption of Krakatoa in 1883, and also from Iceland, the Mediterranean, Alaska, Greenland, Kamchatka, and elsewhere, led to his thesis which developed an assessment of the world’s volcanic eruptions since 1500. His paper, ‘Volcanic dust in the atmosphere… A chronology and assessment of its meteorological significance’, was published by the Royal Society in 1970. And with its publication, the Lamb Dust Veil Index entered the scientific literature.
“My investigations had shown that beyond reasonable doubt that great volcanic eruptions do affect the weather and climate for several years afterwards, while suspended materials – not only the fine dust, but minute droplets and even gases – thrown up into the atmosphere by the blast are still present.”
The study showed that it was the greatest explosions in the low latitudes between about 30°N and 30°S that most regularly yield products that spread around the world, and that the most regular effect of such eruptions was a weakening of the strength of the global circulation. Whereas an eruption in the middle and high latitudes tended to strengthen the circulation in that hemisphere.”
This web site [link] describes the Smithsonian institute volcanism programme which provides details of eruptions throughout the world over thousands of years.
These larger eruptions as an explanation for the variable climate-at least in Britain- appear inconclusive, although undoubtedly those large volcanos with especially great amounts of sun veiling emissions can have a temporary effect on weather. The Laki eruption of 1783 (not listed) for example, is accompanied by a record in the Exeter Cathedral library (seen by the author) which describes the giving of alms to the poor due to the severity of the season.
It is perhaps the British Everyman (Figure 5) that is most intriguing. Despite heat-waves and extreme cold winters, hot years and cool ones, the British Everyman found the yearly effects of the weather over an entire life span of 70 years were translated into climatic swings and roundabouts, with few lifetimes overall being lived out in the cold spectrum. What is also intriguing is that whilst the low spot was that of someone born around 1660, over the next 350 years the trend has been inexorably upwards, which can be confirmed by also eyeballing the more conventional depiction of temperatures in Figure 1.
The data relate to complete calendar years rather than winters. Undoubtedly the severity and frequency of the very cold winters that allowed the famous ‘Thames frost fairs’ are getting less, which would impact on the overall average temperature, possibly helping to cause the long term temperature rise. See 3.7 for further references on severe winters. But this raises several questions, amongst them being; are less severe winters the main reason for the long term warming trend? What caused the severe winters and the severe Lia type years in the first place and what has caused them to diminish? Why was there so much warmth in between the cold years, in short why has climate been so variable?
Conclusions
By eventually comparing the era post 1538 to pre 1538 values back to around 1086, it should be possible to determine how ‘typical’ the climate over the last 500 years or so has been. It can also be determined whether we are now entering a new era typified by a climate substantially different to the past and one not merely reverting to some sort of ‘norm’ that many believe occurred during the MWP, Roman and Minoan period, when there were said to be centuries of mostly warm and settled weather. The present does not look so very different to other points of the period surveyed in this paper, with several notable periods of warmth and widespread heat-waves and droughts comparable to the modern era.
This leads us back to the theme of this paper which questions whether the LIA, as it is popularly-if not scientifically- characterised, is misunderstood and misnamed? The answer must be Yes. A prolonged era of rapidly changing temperatures with some notable periods of cold interspersed with some notably warm periods-neither of them especially extended- suggests the term LIA is a misnomer. (See 3.9 to see how the term was originally used in a scientific context). The climate variability from hot too cold with every variation in between throughout the record is noticeable, as is the rapidity with which these different climate states occur. As Brian Fagan noted:
‘The pendulum of climate change rarely paused for more than a Generation.’
The climate appears to be achieving some stability over the last century after the observable violent perturbations that punctuates the record. In trying to determine likely future behaviour we need to look to the past, and our mistaken popular notion of a monotonically cold period lasting 500 years does not help our understanding.
Bearing in mind the scientific definition of ‘The Little Ice Age (see 3.9) as having lasted some 4000 years, perhaps we need to determine if this period has as yet definitively ended and that can only be done with hindsight.
Section 3 Background information
This section contains technical information, explanations on the compilation of temperature profiles, historic temperature data, links, caveats and other information integral to the development of this article.
Although there is a great deal of instrumental, observational, academic and other records, trying to determine the relative cold or warmth of any CET year in the context of conferring on it the status of a genuinely cold ‘LIA type’ year that fulfils our understanding of this term, requires somewhat arbitrary calculations, so the criteria used to determine the various temperature profiles used in this article have been determined as follows;
The nadir of the LIA, according to CET and many academic studies, was the decade commencing 1690. Every year in it ranged from ‘very cold’ to ‘cold’ in terms of the temperatures we ‘usually’ expect in Britain, which normally has a temperate maritime climate. So this can be reasonably described as a LIA decade overall, with a decadal average of 8.107C.
The various years that comprised this decade -ranging from 8.92 to 7.25C- would all reasonably qualify as LIA years. There have been individually colder years in the record (lowest year was 6.84C in 1740) so these would also obviously fit the criteria as well. Now, even in Britain, anything above 8.92C would not be automatically thought of as a warm year, so the author has divided the data further as explained in 3.2
3.2 Criteria used for temperature groupings
The author anecdotally remembers half a dozen exceptionally cold winters and years, a number of years that were moderate and many that in British terms were overall warm or very warm, with the latter two groupings increasing over the last few decades. These were good for the garden and farming in general and sitting through an uncomfortably cool year recently, that played havoc with my garden, illustrated the differences in our perception of what may be comfortable and what isn’t.
So personal anecdotal experience can be joined to the actual Met office temperature record and other data, such as falls of snow, dates of birds nesting, dates of flowering of spring bulbs, onset of Autumn and harvest dates etc. In this context the chosen parameters can be seen as overall a reasonable representation of the changing climate through my lifetime, which criteria can then be usefully applied as a benchmark to the entire historic record to determine how the old compare to the modern.
The format enables us to highlight years that are ‘similar’ to each other by the use of colour coding and to make a distinction between the different climate states that lie within temperature parameters broad enough to overcome the problems of not knowing historic temperatures to fractions of a degree.
Definitions:
- up to and including 8.92C are an LIA year. (Blue dots)
- from 8.93 to 9.019 is ‘moderate’; green dots
- above 9.20 is ‘warm’; orange dots
- above 9.79 is ‘very warm’; red dots
3.3 It will be appreciated that mixing in all the seasons means that a cold winter might be negated by warmer than normal other seasons and might consequently be relegated to a status other than being a LIA year. In short, LIA type winters do not always translate to LIA type years.
However, looking at the overall temperature for a complete year rather than merely exceptional winters adds another perspective to our understanding of the period, so it is that criteria-the mean CET for each year- that have been used in order to try to define our understanding of the climate of Central England for the period.
3.4 LIA ‘Everyman’ criteria.
The monthly mean CET data from 1659 are here [link].
The estimated CET prior to this date (estimated CET temperatures calculated according to the formula used by Van Engelen, Buisman. And Unsen of the Royal Netherlands Meteorological Institute [link]):
- 1538 10.30C 1539 10.30C 1540 10.50C (would have been even hotter if it were not for the cold winter)
- 1541 10.20C 1542 9.70C 1543 9.50C 1544 9.50C 1545 9.20C 1546 10.00C 1547 9.90C 1548 9.50C
- 1549 9.50c 1550 9.50c 1551 9.40c 1552 9.51c 1553 9.50c 1554 9.00c 1555 9.40c 1556 9.60c
- 1557 9.40c 1558 9.70c 1559 9.40c 1560 9.30c 1561 9.00c 1562 8.80c 1563 9.30c 1564 8.00c
- 1565 8.30c 1566 9.20c 1567 8.80c 1568 8.80c 1569 8.70c 1570 8.60c 1571 8.80c 1572 8.50c
- 1573 9.50c 1574 9.40c 1575 8.90 1576 9.10c 1577 9.10c 1578 8.90c 1579 8.90c 1580 9.00c
- 1581 9.10c 1582 9.10c 1583 9.40c 1584 9.10c 1585 9.40c 1586 8.90c 1587 9.00c 1588 9.10c
- 1589 9.00c 1590 8.90c 1591 8.90c 1592 8.80c 1593 9.10c 1594 8.20c 1595 8.90c 1596 9.10c
- 1597 9.10c 1598 9.30c 1599 9.30c 1600 8.90c 1601 9.00c 1602 9.20c 1603 9.20c 1604 8.80c
- 1605 8.90c 1606 8.90c 1607 9.60c year was very warm until December. 1608 7.80c 1609 8.00c
- 1610 9.30c 1611 9.10c 1612 9.10c 1613 9.10c 1614 8.70c 1615 8.70c 1616 10.20c 1617 10.20c
- 1618 9.10c 1619 9.10c 1620 8.40c 1621 7.90c 1622 8.20c 1623 8.90c 1624 9.80c 1625 9.50c
- 1626 10.10c 1627 9.10c 1628 9.90c 1629 9.10c 1630 9.10c 1631 10.10c 1632 10.00c 1633 8.90c
- 1634 9.90c 1635 10.20c 1636 10.40c 1637 10.20c 1638 10.30c 1639 8.80c 1640 9.10c 1641 9.30c
- 1642 8.90c 1643 9.20c 1644 8.80c 1645 10.20c 1646 9.80c 1647 9.10c 1648 9.50c 1649 9.40c
- 1650 9.10c 1651 10.10c 1652 10.20c 1653 10.30c 1654 10.30c 1655 9.10c 1656 8.90c 1657 8.60c
- 1658 8.50c Note Instrumental record starts. Following for comparison purposes only 1659 8.83c
- 1660 9.08c 1661 9.75c 1662 9.50c 1663 8.58c 1664 9.33c 1665 8.25c 1666 9.83c
This is derived from my previous post Long Slow Thaw, with accompanying data and references [link].
Decadal averages to date and the average from 2010-2014 inclusive were used to calculate those born in the 1950 and 1960 decade.
3.5 Confirmation of cold and warm periods in date order
References cited below can be found [here].
Growing warmth is confirmed by Professor Dr C. Pfister the noted historian and geographer who identified Heat waves in 1525 and 1616 (authors note; roughly comparable to Europe 2003/2010)
In a paper ‘The year-long unprecedented European heat and drought of 1540 – a worst case’ in the journal Climatic Change an international group of 32 scientists shows that in 1540 Western Europe suffered a heat wave and ‘Megadrought’ that were broadly similar to the modern European heat waves of 2003 [link]
The compilation book ‘Climate since AD 1500’ edited by Phil Jones and incorporating work by a number of scientists, notes the warm periods around 1550 and 1630 and the cold intervals that separated them;
In this account from 1610 John Taylor, talking of the hills around him in Deeside Scotland, remarked that “the oldest men alive never saw but snow on the top of divers of these hills both in summer as in winter.” (From ‘The Little Ice Age’ by Brian Fagan)
A brief breakdown in the cold trend in Britain was observed in the diary entry of Samuel Pepys for January 1660/61-the year the Royal Society was established- when he wrote:
“It is strange what weather we have had all this winter; no cold at all; but the ways are dusty, and the flyes fly up and down, and the rose-bushes are full of leaves, such a time of the year as was never known in this world before here.”
That summers could still be hot was felt during 1666 when the UK had an extremely hot dry summer (brought on by a blocking high pressure system over Scandinavia). The hot dry North easterlies helped spread the devastating Great fire of London in 1666. The following winter, however was so cold that the great oak trees of the English Midlands split. (Humidity has a great part to play in temperatures)
The growing warmth of the early part of the 18th Century was noted here by Hubert Lamb on page 12 and 13 of his study ‘Climate present past and future’ [link]
“The remarkable turn of the climate of Europe towards greater warmth from soon after the beginning of the eighteenth century and affecting all seasons of the year in the 1730’s seems to have produced little comment at the time, though by then the temperatures were being observed with thermometers and entered into regularly maintained observation books in a number of places.”
The annals of Dumfermline Scotland from 1733/4, recorded that wheat was first grown in the district in 1733. Lamb wryly observes that was not correct, as enough wheat had been grown further north in the early 1500’s to sustain an export trade (before the 1560’s downturn).
This from a 2005 paper by Jones and Briffa [link] about the very warm period noted in old records and especially CET;
” The year 1740 is all the more remarkable given the anomalous warmth of the 1730s. This decade was the warmest in three of the long temperature series (CET, De Bilt and Uppsala) until the 1990’s occurred. The mildness of the decade is confirmed by the early ice break-up dates for Lake Malaren and Tallinn Harbour. The rapid warming in the CET record from the 1690s to the 1730s and then the extreme cold year of 1740 are examples of the magnitude of natural changes which can potentially be recorded in long series. Consideration of variability in these records from the early 19th century, therefore, may underestimate the range that is possible.”
That there was a gradual warming** of winter temperatures-the severity of which had substantially reduced the overall mean annual temperature during much of the earlier historic record- was noted by Reginald Jeffery in his book ‘Was it Wet or was it fine,’ written in 1898.
“By 1708 the middle aged would say where are our old winters?”
In their summary in Chapter 33 of their book ‘Climatic variations over the last 500 years’ P D Jones and R S Bradley in talking of regional evidence for Europe note; ‘from the evidence presented –in the book- the climate since 1500 has varied between extremely warm and extremely cool decades.
’…from warm temperatures during some decades of the early 16th century conditions began to gradually cool during the second half of the century. ‘Only a few short cool episodes lasting sometimes up to 30 years appear to have been synchronous on the Hemispheric and global scale. These are the decades of the 1590-1610’, the 1690-1710’s, the 1800-1810’s and the 1880’s to 1900. Synchronous warm periods are less evident although the 1650’s, 1730’s, 1820’s, the 1930’s and 1940’s appear to be the most important.
A farmer from Buchan in North East Scotland, one of the snowiest parts of lowland Britain, wrote in the agricultural section of the local newspaper during the exceptionally mild winter of 1933/34.
“1934 has opened true to the modern tradition of open, snowless winters. The long ago winters are no precedent for our modern samples. During the last decade, during several Januarys the lark has heralded spring up in the lift from the middle to the end of the month. Not full-fledged songs but preliminary bars in an effort to adapt to our climatic change.”
It then goes on to say:
“It is unwise to assume that the modern winters have displaced the old indefinitely” and also “Our modern winters have induced an altered agricultural regime,”
3.6 Putting the present into context with the geologic past.
See also this article by Ian Plimer The Past is Key to the Present: Greenhouse and Icehouse Over Time.
3.7 Many papers and books have been written about some of the extreme winters of the past and the famous Thames Frost fairs. As Mann and Jones mention when quoting Lamb 1977 in their own 2004 paper ‘Climate over the past millennia’ there were only 22 frost fairs on the Thames recorded between 1408 and 1814. Whilst not definitive, as river conditions prior to and post this date may have precluded some frost fairs even if the weather was suitable, it can be seen that the actual number recorded over some 400 years was relatively small
The following is an account of the frozen Thames and great frosts: [link]
Below is the Met office data showing the status of mean CET years from 1659 in a ranking from coldest to warmest, that would be reflected in FIgure 1 above [link].
3.8 Does CET have wider relevance to other parts of the world?
My article ‘The Long Slow thaw’ explored this in Section 6 entitled “Can CET represent a wider geographic area and establish the existence of a Hemispheric ally significant cooling period?” [link]
The Met office, KNMI, Mike Hulme, Hubert Lamb and Mike Lockwood were amongst those believing CET had a wider significance as a reasonable (but not infallible) temperature proxy that might reflect European Wide, Northern Hemisphere or even some sort of Global proxy. However, it is not the intention of this paper to claim that its findings and observations are relevant to any region other than Britain, although this is obviously a topic that warrants further examination at some point.
3.9 How the phrase ‘Little Ice Age’ came about
In 1940 Francis Matthes wrote in a report of a Committee on glaciers that; ‘glacier oscillation of the last few centuries have been among the greatest that have occurred during the last 4000 years perhaps…the greatest since the end of the Pleistocene ice age.’ The previous year Matthes had written in a survey on behalf of a Committee on Glaciers for the American Geophysical Union ‘we are living in an epoch of renewed but moderate glaciation ‘a little ice age’ that already has lasted about 4000 years’. Both quotes are from the book, ‘The Little Ice Age’ by Brian Fagan.
3.9 Volcanos The dates, names and VEI of the most active Volcanos used in figure 9 are shown here in tabular form;
Name VEI Year
Pinatubo 6 1991
Mt ST Helens 5 1980
Novarupta 6 1912
Santa Maria 6 1902
Mt Tarawera 5 1886
Krakatoa 6 1883
Consiguina 5 1835
Tambora 7 1815
Source Unknown 6? 1809
Grimsvota 6 1783-85
Long Island- PNGuinea 6 1660
Kolumbo (Santorini) 6 1650
Huaynaputina 6 1600
Billy Mitchell 6 1580
3.10 The references used in this article were detailed in Section 4 onwards from [link] and [link].
A number of very hot summers interrupt the multi-century period often termed the LIA, but some scientists note that an average approximate 96-year cycle characterized much of the period. This was in contrast to the shorter cycles that dominated the preceding MWP and subsequent modern warm period. Tree-ring proxies and marine deposits of g. bulloides note that cyclic behavior in the North Atlantic and there appears to be some similarity between the CET record extension and proxy data from the same basin (N Atlantic). This is explored in Gray et al 2004. “A tree-ring based reconstruction of the Atlantic Multidecadal Oscillation since 1567 A.D.”
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