TY - JOUR
T1 - Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks
AU - Miller, Gifford H.
AU - Geirsdottir, Aslaug
AU - Zhong, Yafang
AU - Larsen, Darren J.
AU - Otto-Bliesner, Bette L.
AU - Holland, Marika M.
AU - Bailey, David A.
AU - Refsnider, Kurt A.
AU - Lehman, Scott J.
AU - Southon, John R.
AU - Anderson, Chance
AU - Bjornsson, Helgi
AU - Thordarson, Thorvaldur
PY - 2012/1/1
Y1 - 2012/1/1
N2 - Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century-scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 14301455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required. Citation: Miller, G. H., et al. (2012), Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophys. Res. Lett., 39, L02708, doi: 10.1029/2011GL050168.
AB - Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century-scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 14301455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required. Citation: Miller, G. H., et al. (2012), Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophys. Res. Lett., 39, L02708, doi: 10.1029/2011GL050168.
KW - LAST MILLENNIUM
KW - CLIMATE-CHANGE
KW - RECONSTRUCTIONS
KW - TEMPERATURE
KW - ICELAND
KW - CCSM3
KW - SHEET
UR - http://www.scopus.com/inward/record.url?scp=84856492442&partnerID=8YFLogxK
U2 - 10.1029/2011GL050168
DO - 10.1029/2011GL050168
M3 - Article
SN - 0094-8276
VL - 39
SP - 1
EP - 5
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 2
M1 - L02708
ER -