Environmental Engineering Reference
In-Depth Information
detailed proxy records of the environmental changes. However, extensive further
work is required to develop a mechanistic understanding of the links between
CFB volcanism and environmental changes. Earth system modelling likely has an
important role to play to quantify these linkages.
As a minimum, information on the volcanic volatile flux, the altitude of
emissions, and the eruption duration is needed as inputs for atmospheric
Roza lava
eld is the only individual CFB eruption where it has been possible
to constrain eruptive vent conditions based on the geological record (Brown
et al
.,
2014
). Uncertainties in such parameters for the majority of CFB provinces hamper
a full assessment of the length and severity of the potential environmental effects
and Earth system feedbacks. One such key uncertainty is hiatus length: if these
periods of quiet between eruptions outlasted the duration of the volcanic forcing
of climate, then the Earth system would have had time to recover after an eruptive
phase, weakening the feedback chain through to mass extinctions in
Figure 11.4
.
For the assessment of the environmental effects of CFB volcanism, the Laki
eruption is seen as the best historical analogue, but this was much shorter-lived
(8 months) compared with the possible length of a CFB eruption (a decade or
more based on the Roza case). Modelling studies suggest that Laki
'
s gas and
aerosol clouds dispersed widely across the northern hemisphere (e.g. Chenet
et al
.,
2005
; Stevenson
et al
.,
2003
; Oman
et al
.,
2006a
; Schmidt
et al
.,
2010
). The winter
of 1783
ow-
0.5
C colder than average in central Europe
(e.g. Thordarson and Self,
2003
; Oman
et al
.,
2006b
; Schmidt
et al
.,
2012
).
However, the differences in eruptive volume, duration and eruption style mean
that scaling the climatic effects of historical and present-day volcanic activity to
CFB eruption scale may be
-
1784 was up to
-
flawed. Evidence from both observations and model-
ling of short-lived explosive eruptions has also suggested that a simple scaling
between eruption magnitude and climatic impact has limited validity (Rampino
and Self,
1982
; see also
Chapter 13
).
To date there have only been a few modelling studies directly tailored to CFB
volcanism. Black
et al
.(
2014
) used a three-dimensional chemistry
climate model
to suggest that pulsed episodes of Siberian Traps volcanism resulted in global-scale
ozone depletion and intense episodes of acid rain (Black
et al
.,
2014
), which could
have contributed to the end-Permian mass extinction. Schmidt
et al
. (unpublished)
used a global aerosol
-
climate model to quantify the climatic and environmental
effects of sulfur released during a decade-long Roza
-
flow eruption (emitting
1,200 Mt of SO
2
per year into 9
13 km altitude) and a Deccan-scale eruption
(emitting 2,400 Mt of SO
2
per year into 9
-
13 km altitude). They concluded that
when the buffering capacities of soils is taken into account, a decade-long episode
of acid rain from sulfur alone is too short-lived to signi
-
cantly acidify soils or
