Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Paintings, sunspots and frost fairs: Rethinking the Little Ice Age

04.04.2017

The whole concept of the 'Little Ice Age' is 'misleading', as the changes were small-scale, seasonal and insignificant compared with present-day global warming, a group of solar and climate scientists argue.

Explanations for the cooling to Earth's climate, thought to have occurred between the 16th and 19th centuries, include low solar activity, volcanic eruptions, human changes to land use and natural climatological change.


Analysis of extreme temperatures in the Central England Temperature (CET) thermometer record.

Part (b) shows the lowest monthly average in each winter whereas part (c) shows the hottest monthly average in each summer. In both cases blue shows lower temperatures, and red shows higher temperatures than the long-term average.

The cold winter months match up very well with the years in which frost fairs were held (vertical mauve lines) or years when the Thames was reported as frozen solid (vertical orange lines). However these years are not usually also associated with colder summers, unless there was a large volcanic eruption (measured from the sulphates that it deposited in polar ice sheets) such as Tambora in 1815.

The top panel (a) shows the level of solar activity as seen in sunspot numbers (from telescopic observations and deduced from Carbon-14 stored in tree rings). It can be seen that, contrary to common claims, the Thames did not freeze more often during the Maunder minimum (c.1660-1710). Thames freezing events ceased after the demolition of the old London bridge in 1825 and the installation of the embankments, completed in 1870 (both dates marked with black lines): the faster flow meant that the river no longer froze, even when temperatures fell to values that had previously caused freezing.

Credit: M. Lockwood

But in a new paper in Astronomy & Geophysics, the house journal of the Royal Astronomical Society, Professor Mike Lockwood, of the University of Reading, and his collaborators, note that the temperature shift was smaller than that seen in recent decades resulting from the emission of greenhouse gases, and that although low solar activity may have been one driving factor, it certainly was not the only one.

Professor Lockwood said: "Commentators frequently refer to the Little Ice Age in discussions on climate change. We wanted to carry out a comprehensive study to see just how reliable the evidence is for a cooler climate, how big an impact it really had and how strong the evidence for a solar cause really was.

"On the whole the Little Ice Age was a manageable downturn in climate concentrated in particular regions, even though places like the UK had a larger fraction of cold winters. Our research suggests that there is no single explanation for this, that warm summers continued much as they do today and that not all winters were cold."

Researchers scrutinised historical records, such as the accounts of 'frost fairs' when the River Thames froze solid, and looked at the paintings from the era, such as the landscapes of Pieter Bruegel the Elder, with 'Hunters in the Snow' depicting a cold winter scene. Both of these are cited in support of the Little Ice Age concept.

From around 1650-1710, and to a lesser extent from 1790-1825, periods respectively known as the Maunder and Dalton Minima, sunspot numbers were unusually low, an indication that the surface of the Sun was slightly cooler. This external influence is often suggested as an explanation for the colder conditions.

The Reading-led team looked at the various pieces of evidence in more detail. They compared direct temperature records and proxy data such as ice records, with the years when the Thames was frozen over (whether or not a frost fair took place), and with the indications of solar activity.

Historical climate change is assessed through a variety of means. The Central England Temperature (CET) dataset tracks temperature from 1659, making it the oldest and longest running meteorological instrumental data sequence in the world. This direct record is supplemented by studies of biological proxies such as tree rings, corals, insect numbers and molluscs, all sensitive to climate change.

The authors draw comparisons with the ice ages proper. Cores taken from Antarctic ice allow global temperatures to be inferred, by measuring the proportions of deuterium (2H), a heavier atom of hydrogen, and of the heavier oxygen atom 18O, compared with their lighter 'normal' counterparts. It takes more energy to evaporate water with a higher proportion of these atoms, and they are more easily lost from rainfall, before they are deposited in ice found nearer the poles. The changing proportion of these atoms then allows researchers to assess how the temperature has changed over millions of years.

From these comparisons, the scientists argue that the description of the period as an Ice Age is misleading, as temperatures in that period fell far less than in a glaciation. During the Little Ice Age (LIA), the average temperature in the northern hemisphere fell by around 0.5 degrees. In contrast, in the most recent major glaciation that came to an end around 12,000 years ago, global temperatures were typically 8 degrees Celsius colder than today.

Frost fairs also seem to be a poor indication of overall climate, as they often did not take place despite the Thames freezing, partly for many reasons including puritanical authorities or safety as lives were lost when the ice melted. The ending of the frost fairs had nothing to do with climate change or solar activity, instead being due to the increased river flow when the original London Bridge was demolished in 1825, and the first Victoria embankment opened in 1870. Both of these prevented the river from freezing completely, despite many subsequent cold winters.

Selective use of art historical evidence appears to reinforce the illusion of a prolonged cold spell. Yet 'Hunters in the Snow', depicting a January scene, is part of a series by Bruegel known as 'The Twelve Months'. Seven of these paintings may have been lost, but 'The Gloomy Day' (February), 'Haymaking' (July), and 'The Return of the Herd' (November) all give no indication of unusually cold conditions. Consistent with this, Lockwood and his team note that even at the height of the LIA period, colder European winters were still accompanied by many warm summers.

For example, 1701 is close to the lowest point of the Little Ice Age, yet in both Paris and London the summer was reported as being unbearably hot and the CET for July that year is the 10th hottest on record, with average temperatures for the month reaching 18.3°C. The year 1676 is the second hottest June on record at 18.0°C, yet it too was in the middle of a run of cold winters. Such high summer temperatures do not fit at all with the name "Little Ice Age".

Much more dramatic variations can result from large volcanic eruptions. Samalas, a volcano which erupted in 1257 in what is now Indonesia, ejected large amounts of dust into the atmosphere, causing a temporary cooling effect. The years between 1570 and 1730, corresponding to the coldest part of the LIA, also saw continuous lower level volcanic activity that may have suppressed temperatures. Volcanic eruptions undoubtedly cause both cold winters and cold summers. One of the clearest examples was the Tambora eruption of July 1815, which caused the next year to be called "the year without a summer".

Professor Lockwood said: "This study provides little solace for the future, as we face the challenge of global warming. Solar activity appears to be declining at present, but any cooling effect that results will be more than offset by the effect of rising carbon dioxide emissions, and provides us with no excuse for inaction."

###

Media contacts

Dr Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7292 3979
Mob: +44 (0)7802 877699
rm@ras.org.uk

Dr Morgan Hollis
Royal Astronomical Society
Tel: +44 (0)20 7292 3977
mh@ras.org.uk

Pete Bryant
University of Reading
+44 (0)118 378 4912
p.g.bryant@reading.ac.uk

Science contact

Prof Mike Lockwood
University of Reading
Tel: +44 (0)118 378 5572
m.lockwood@reading.ac.uk

Images and captions

https://www.ras.org.uk/images/stories/press/Little_Ice_Age/paleo_dTplot_new_33.png

Analysis of extreme temperatures in the Central England Temperature (CET) thermometer record.

Part (b) shows the lowest monthly average in each winter whereas part (c) shows the hottest monthly average in each summer. In both cases blue shows lower temperatures, and red shows higher temperatures than the long-term average.

The cold winter months match up very well with the years in which frost fairs were held (vertical mauve lines) or years when the Thames was reported as frozen solid (vertical orange lines). However these years are not usually also associated with colder summers, unless there was a large volcanic eruption (measured from the sulphates that it deposited in polar ice sheets) such as Tambora in 1815.

The top panel (a) shows the level of solar activity as seen in sunspot numbers (from telescopic observations and deduced from Carbon-14 stored in tree rings). It can be seen that, contrary to common claims, the Thames did not freeze more often during the Maunder minimum (c.1660-1710). Thames freezing events ceased after the demolition of the old London bridge in 1825 and the installation of the embankments, completed in 1870 (both dates marked with black lines): the faster flow meant that the river no longer froze, even when temperatures fell to values that had previously caused freezing. Credit: M. Lockwood

https://www.ras.org.uk/images/stories/press/Little_Ice_Age/Pieter_Bruegel_the_Elder_-_Hunters_in_the_Snow_Winter_-_Google_Art_Project.jpeg

"The Hunters in the Snow", Pieter Bruegel the Elder, 1565. Credit: Kunsthistorisches Museum, Vienna, Austria

https://www.ras.org.uk/images/stories/press/Little_Ice_Age/Die_Heuernte.jpeg

"Haymaking", Pieter Bruegel the Elder, 1565. Credit: Kunsthistorisches Museum, Vienna, Austria

Further information

The new work appears in "Frost fairs, sunspots and the Little Ice Age", Mike Lockwood, Mat Owens, Ed Hawkins, Gareth S. Jones and Ilya Usoskin, A&G, published by Oxford University Press, in press. A copy of the paper is available from https://www.ras.org.uk/images/stories/press/Little_Ice_Age/343_AandG_MMandLIA_preprint1.pdf

Notes for editors

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

The RAS accepts papers for its journals based on the principle of peer review, in which fellow experts on the editorial boards accept the paper as worth considering. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

T: https://twitter.com/royalastrosoc
F: https://www.facebook.com/RoyalAstroSoc/

The University of Reading's meteorology department is one of the world's leading centres in the atmospheric and climate sciences. It was awarded a Regius Professorship in Meteorology and Climate Science by the Queen in 2013, recognising the exceptionally high quality of its teaching and research.

T: https://twitter.com/UniOfReading
F: https://facebook.com/TheUniversityOfReading

Media Contact

Robert Massey
rm@ras.org.uk
44-207-292-3979

http://www.ras.org.uk/ras 

Robert Massey | EurekAlert!

More articles from Earth Sciences:

nachricht Tiny microenvironments in the ocean hold clues to global nitrogen cycle
23.04.2018 | University of Rochester

nachricht Clear as mud: Desiccation cracks help reveal the shape of water on Mars
20.04.2018 | Geological Society of America

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>