Wednesday, December 24, 2014
PLACERVILLE, CALIFORNIA
99 CENTS

Rock doc: Medieval monks recorded Ireland’s climate

By
From page A4 | August 05, 2013 |

Ireland enjoys a mild and stable climate. But even in Ireland there are years that stand out as unusual. Recently a team of researchers led by Harvard’s Francis Ludlow announced results of a study of Ireland’s climate based on the Irish Annals, a body of writings containing more than 40,000 entries.
The Annals record events from 431 A.D. to 1649 A.D. During the Medieval period they were written by monks. From the 1200s onwards some entries were written by historians of the wealthy and aristocratic families of the period. Finally, toward the end of the Annals, entries were contributed by military historians as British colonialism took hold.
As recently reported on the Website ScienceNOW, Ludlow’s team looked through the Irish Annals for information about weather. Of particular interest were notes about cold times, such as years with ice on certain lakes or winters of heavy snowfall. In the Annals the researchers identified a total of 70 times of unusual cold. Ludlow thinks those who wrote the Annals likely recorded all the significantly cold seasons they experienced because cold has a profound effect on agricultural productivity.
Cold spells can arise for a number of reasons, including the simple natural variation that’s always at work in weather and climate. But one specific cause of cold years is volcanic eruptions. Volcanoes eject ash and lava when they erupt, but they also sometimes spew tiny drops of sulfur dioxide into the atmosphere. Those droplets drift downwind and reflect sunlight back into space, cooling the ground below. For short periods of time volcanic eruptions can drop temperatures by a couple degrees Fahrenheit — quite enough to make a real difference.
As it happens, we have a pretty good natural record of volcanic eruptions near Ireland. It’s based on variations in Greenland’s glacial ice. Scientists have drilled into the icecap and pulled up layered cores of ice. Each pair of layers denotes summer and winter snowfall in Greenland, so researchers can simply count back in time to assign dates to deeper and deeper layers.
The glacial ice is marked by sulfates when volcanic eruptions occurred. During the time spanned by the Irish Annals, scientists found 48 layers denoting significant volcanic eruptions. Many of the eruptions occurred in the Northern Hemisphere at high latitudes, but we have other evidence to think that one large eruption occurred in the year 1600 in Peru.
How does the Greenland record match up with the Irish Annals? In short, there isn’t a perfect fit but a number of the sulfate rich ice layers come from around the times the Annals report cold spells. That’s good enough for me, as I wouldn’t expect the two records to speak only with one voice. Climate is complex and volcanic eruptions are only one factor in what determines temperature. Certainly some cold spells occur simply due to natural cycles in temperature variations, not because of specific volcanic events.
But it’s nifty from my point of view to think that the records of Medieval monks could now be fed into computer simulations of climate.
Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University. 

Comments

Subscription Required

Thank you for reading the MtDemocrat.com digital edition. In order to continue reading this story please choose one of the following options.

Current Subscribers
If you are a current subscriber and wish to obtain access to MtDemocrat.com, please select the Subscriber Verification option below. If you already have a login, please select "Login" at the lower right corner of this box.

Subscriber Verification

Special Introductory Offer
For a short time we will be offering a discount to those who call us in order to obtain access to MtDemocrat.com and start your print subscription. Our customer support team will be standing by Monday through Friday, 8am to 5pm to assist you.

Call and Save! (530) 344-5000

If you are not a current subscriber and wish not to take advantage of our special introductory offer, please select the $12 monthly option below to obtain access to MtDemocrat.com and start your online subscription

Help?

E. Kirsten Peters

  • Recent Posts

  • Enter your email address to subscribe and receive notifications of new posts by email.

  • .

    News

     
    Cameron Park vet survived Battle of the Hurtgen Forest

    By Wendy Schultz | From Page: A1 | Gallery

     
    Two house fires Sunday: Girl injured

    By Cole Mayer | From Page: A1

    County employees overcome Tahoe Grinch

    By Chris Daley | From Page: A3

     
    EDSO warns of jury duty scam

    By Cole Mayer | From Page: A3

    New technology chief will join McNaughton Newspapers

    By Special to the Democrat | From Page: A3

     
    .

    Opinion

    ‘Nuts!’

    By Mountain Democrat | From Page: A4

     
    Belltower: Christmas past and present

    By Michael Raffety | From Page: A4

    My turn: My analysis of EID

    By Special to the Democrat | From Page: A4

     
    .

    Letters

    Gracie’s Christmas wish

    By Letters to the Editor | From Page: A5

     
    Placerville Webcam

    By Letters to the Editor | From Page: A5

    Altshuler advice

    By Letters to the Editor | From Page: A5

     
    Tremendous community involvement

    By Letters to the Editor | From Page: A5

    Gratitude for Supervisor Santiago

    By Letters to the Editor | From Page: A5

     
    .

    Sports

    Outside with Charlie: Cold hard facts

    By Charlie Ferris | From Page: A8

     
    The dos and don’ts of buying new skis

    By Jeffrey Weidel | From Page: A8

    Ponderosa girls get back on track

    By Jerry Heinzer | From Page: A8

     
    Trojans advance to Toss Up title game

    By Mike Bush | From Page: A8 | Gallery

    Sports scene: Dec. 23, 2014

    By Jerry Heinzer | From Page: A9

     
    Roundup: Dec. 23, 2014

    By Democrat Staff | From Page: A9 | Gallery

    .

    Prospecting

    Wood shop becomes toy shop

    By Democrat Staff | From Page: B1 | Gallery

     
    At a glance: Time to sing

    By Mimi Escabar | From Page: B2

    Quilters help piece life back together

    By Pat Lakey | From Page: B2 | Gallery

     
    Fantasy authors unveil writing secrets

    By Friends Of | From Page: B2

    Book relates story set in El Dorado County

    By Gold Trail Union School District | From Page: B3

     
    Grow For It! Gifts from the garden

    By Robin Stanley | From Page: B3

    FAN clothing drive a big success

    By Foster Awareness Network | From Page: B3

     
    A guide for thrifty fashionistas

    By Christian Women's Connection | From Page: B3

    Holiday happiness for the whole family

    By Visiting Angels | From Page: B4

     
    Mitchell wines receive top marks

    By Charles B. Mitchell Vineyards | From Page: B6

    California State Fair receives international recognition

    By California Exposition And State Fair | From Page: B7

     
    Transplant recipients and donor families to decorate float

    By Sierra Donor Services | From Page: B7

    Jean the ‘dancing machine’ turns 100

    By News Release | From Page: B12

     
    .

    Essentials

    Collision Log: Dec. 1-4

    By Cole Mayer | From Page: A2

     
    Building permits 12/15-19/2014

    By Michael Raffety | From Page: A2

    Weather stats 12-23-14

    By Michael Raffety | From Page: A2

     
    Crime Log: Nov. 23-25

    By Cole Mayer | From Page: A2

    .

    Obituaries

    .

    Real Estate

    .

    Comics

    Rubes

    By Contributor | From Page: A10

     
    New York Times Crossword

    By Contributor | From Page: A10

    Long Story Short

    By Contributor | From Page: A10

     
    Flying McCoys

    By Contributor | From Page: A10

    Speed Bump

    By Contributor | From Page: A10

     
    Tundra

    By Contributor | From Page: A10

    Horoscope, Thursday, December 25, 2014

    By Contributor | From Page: A10

     
    Horoscope, Wednesday, December 24, 2014

    By Contributor | From Page: A10

    TV Listings

    By Contributor | From Page: A10

     
    Shoe

    By Contributor | From Page: A10

    Sudoku

    By Contributor | From Page: A10