Environmental Engineering Reference
In-Depth Information
after a future super-eruption would be poor across a vast area, due to windblown
ash. This would compound the many challenges of mounting search-and-rescue
operations. Meanwhile, many roads and railways would be impassable due to
ash fallout, and aviation would be hazardous. Valleys would be inundated by
mud ows.
Farming and agriculture would be severely affected where ash has accumulated
to depths of more than a few centimetres. As noted above, past eruptions of
Yellowstone blanketed much of North America in tephra. In such a scenario, safe
food and water resources would become increasingly scarce, and the potential
for severe social unrest would likely be very high. Hospitals would be crippled by
power cuts and shortages of medicines. In arid regions, water could become scarce.
Surface water could be contaminated by
fluoride and other chemicals leached from
the ash. Pumped water supplies would dwindle due to power shortages. A colossal
effort would be required to respond to such a disaster and mitigate loss of life in
the most affected regions, especially to stem outbreaks of infectious disease.
For a super-eruption outside the tropics, the human impacts would likely be
in
a winter-time scenario might prove deadlier
as freezing temperatures would compound the exposure of millions of people.
On the other hand a summer eruption would probably result in a deeper hemi-
spheric climate response (Timmreck and Graf,
2006
) and immediate impacts on
crops and livestock, presenting a greater threat to food security. Agriculture in the
zone affected by ash fallout would likely be curtailed for years, and potentially
decades, due to de
uenced by the season of eruption
-
cits in rainfall that can be expected after a super-eruption.
This would perturb regional climate for much longer than the
'
'
residence
of sulfuric acid aerosol in the stratosphere typical of lesser eruptions. Silicic ash is
comparably bright as snow and hence reflects sunlight that would otherwise be
absorbed by vegetation and soils. One climate model for the effects of ash cover
from an eruption of Yellowstone predicted surface cooling of around 5
C through-
out the year for North America (Jones
et al
.,
2007
; see also
Chapter 17
).
The most extreme scenarios for super-eruptions include the demise of techno-
logical civilization, and led Mike Rampino to suggest that volcanism might
represent a universal constraint on the number of extra-terrestrial civilizations
(Rampino,
2002
). He argues that the impacts of such a large eruption on worldwide
climate would severely reduce global agricultural yields potentially leading to
'
few years
widespread starvation, famine, disease, social unrest,
financial collapse, and
severe damage to the underpinnings of civilization
.
Some idea of the potential political and economic instability that could arise
from worldwide reductions in grain supply can be gauged from the impacts of the
2007
'
2011 global food crises (e.g. Rosset,
2008
), which some
implicate in increased civil unrest such as manifested during the Arab Spring
-
2008 and 2010
-
