,That suggests that there might have been some other major eruption in
1783 (or conceivably 1782) that was responsible for an effect on climate
(should one properly talk of climate or weather, when talking about a
period of a year or so?). Does anyone know of another major eruption?
Asama,Japan,1783.But prob low in sulphur.
The Highwood study is littered with understandable caveats.
The summer of !783 was v warm ,but this may not have been due to volcanic effects any way.
Also see,but I can't find it free online,-
Thorvaldur ThordarsonStephen Self
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D1, 4011, doi:10.1029/2001JD002042, 2003
Atmospheric and environmental effects of the 1783-1784 Laki eruption: A review and reassessment
The 1783-1784 Laki flood lava eruption in Iceland emitted ?122 megatons (Mt) SO2 into the atmosphere
and maintained a sulfuric aerosol veil that hung over the Northern Hemisphere for 5 months. The
eruption columns extended to 9-13 km and released ?95 Mt SO2 into the upper troposphere/lower
stratosphere (i.e., the polar jet stream), enforcing a net eastward dispersion of the plumes which
reacted with atmospheric moisture to produce ?200 Mt of H2SO4 aerosols. Away from source, the Laki
aerosols were delivered to the surface by subsiding air masses within anticyclones. We show that
?175 Mt of H2SO4 aerosols were removed as acid precipitation and caused the extreme volcanic
pollution (i.e., dry fog) that effected Europe and other regions in 1783. The remaining ?25 Mt
stayed aloft at tropopause level for 1 year. The summer of 1783 was characterized by extreme and
unusual weather, including an unusually hot July in western Europe, most likely caused by
perseverance of southerly air currents. The following winter was one of the most severe winters on
record in Europe and North America. In these regions, the annual mean surface cooling that followed
the Laki eruption was about ?1.3°C and lasted for 2-3 years. We propose that the upper
troposphere/lower stratosphere aerosols from Laki disrupted the thermal balance of the Arctic
regions for two summers and were the main mechanism for the associated climate perturbations.
Eruptions of Laki magnitude have occurred in the recent past in Iceland and will occur again. If
such an eruption were to occur today, one of the most likely immediate consequences would be
disruption to air traffic over large portions of the Northern Hemisphere.
Published 8 January 2003.
http://www.agu.org/pubs/crossref/200...JD002042.shtml
--
regards,
david
(add 17 to waghorne to reply)