Transcript day-1-paper-9-yim

Sub-aerial and submarine
volcanic eruptions and
climatic variability
Wyss Yim
Department of Earth Sciences, The University of Hong Kong /
Institute of Space and Earth Information Science,
Chinese University of Hong Kong /
Association for Geoconservation, Hong Kong
Presentation at the London Climate Change Conference, Conway Hall on September 8-9, 2016
Plan
(1) Introduction
(2) Case study of a sub-aerial
eruption
(3) Case study of a submarine/subaerial eruption
(4) Conclusions
Why study present day volcanic eruptions?
Eyjafjallajökull (E-15)
April 14, 2010 eruption
Effect – Slovakia wettest
year since 1881
Most reliable record –
Information age
Applications –
Farming/climatic variability
( Meteorological observations
( Satellite observations since ~1980
( Weather disaster media reports
( Aviation safety
Volcanic Explosivity Index (VEI)
Estimation of
explosiveness of
sub-aerial volcanic
eruptions
Above VEI 2
regional impacts
on weather/climate
may already be
detectable
(Newhall and Self
1982)
Acidic magma
most explosive
8
1958-1994 solar radiation record from Mauna Loa
Why I am interested in volcanic eruptions?
Agung 1963 VEI 4
Comparison
Pinatubo
1991 VEI 6
El Chichón
1982 VEI 4
VEI – Volcanic explosivity index
Hong Kong’s rainfall record
during the 3 volcanic eruptions
Agung 1963 VEI 4
Driest year
on record
Comparison
11th driest
on record
Pinatubo
1991 VEI 6
El Chichón
1982 VEI 4
VEI – Volcanic explosivity index
2nd wettest
on record
Classification of volcanic eruptions –
(1) Sub-aerial / land
- switches on hot air followed by cooling (atmospheric warming,
injection of ash, gases and aerosols, blockage of shortwave
radiation, pressure changes, moisture redistribution, continental
cooling, ozone depletion, circulation changes, severe weather)
(2) Submarine / sea floor
- switches on hot seawater (cause of sea-surface temperature
anomalies, pressure changes, ocean and air circulation
changes, moisture redistribution, continental warming, severe
weather events including cyclones)
(3) Mixed
- initially submarine later sub-aerial (combination of 1 and 2).
Sub-aerial
Thermal plume
↑
model
Ash & aerosols
reduces solar
radiation
leading to
cooling
Warm air
stores more
moisture –
water vapour
redistribution
Air pressure
changes (low)
Eruption
changes
normal air
circulation /
creats clouds
/ destroys O3
SO2, HCl
& H 2O
→
←
El Chichón, Mexico 1982
USGS
Cool air
stores less
moisture
Cooler air
Impact
longer
lasting if
major
June 15, 1991 Pinatubo eruption VEI 6
Track of
Yunya
(Oswalt et al.
1999)
Day of
eruption
Two days
before
eruption
Pinatubo eruption cloud
Typhoon Yunya
Why 1991 was a global
drought year?
Water vapour transfer into
the stratosphere creating
atmospheric rivers
Pinatubo eruption cloud
maximum elevation 55 km
Oswalt et al. (1999)
Space shuttle photo over South America taken on August 8, 1991,
showing double layer of Pinatubo aerosol cloud (dark streaks)
above high cumulonimbus tops
Global temperature drop
of ~0.5o C
NASA
Submarine model*
* Initially submarine later sub-aerial, basaltic magma hotter
Examples studied –
El Hierro, Canary Islands
10/2011-3/2012
Hunga, Tonga*
12/2014-1/2015
Nishinoshima, Japan*
11/2013-8/2015
Action –
Switching on of hot
seawater causing ocean and
air circulation changes
El Hierro
NASA
Nishinoshima submarine/sub-aerial eruption
940 km south of Tokyo
November 2013 to August 2015 (Wikipedia)
Image on November 13, 2013: Japan Coast Guard
Image on December 8, 2013: NASA
Sea-surface temperature anomalies showing
the North Pacific Blob on January 2, 2014
Blob
Nishinoshima eruption
11/2013-8/2015
Blob
Observations connecting Nishinoshima with the Blob
__________________________________________________________________________________________________________
Date
Eruption activity
Northern Pacific Blob
__________________________________________________________________________________________________________
November
2013
Submarine eruption created new island
Initial Blob 800 km wide and 91 m deep
December
2013
Island area reached 5.6 km2 and ~25 m
above sea level
-
February
2014
-
Temperature was ~2.5oC above normal
June 2014
-
Name Blob was coined by Nicholas Bond
Size reached 1600 km x 1600 km and 91 m deep
Spread to the coast of North America with patches
off Alaska, Victoria/California and Mexico
December
2014
Island now ~2.3 km in diameter and ~110 m
above sea level
Year without winter in western North America coast
and first mass bleaching of Hawaiian coral reefs
JanuaryAugust
2015
Episodic eruption with lava flows
-
Early
Blob persisted and ended
2016
__________________________________________________________________________________________________________
Source: Wikipedia
The Blob separated into three parts
on September 1, 2014
1
Warm water
build up in slack
areas of gyres
2
3
Ocean circulation
Impact of the Blob on September 1, 2014
- nature’s way of neutralizing hot and cold
Contraction of Arctic sea ice
1
2
3
Expansion of Antarctic sea ice
Sea-surface temperature anomalies on
June 29, 2015 after the Wolf eruption ended
Wolf eruption
5-6/2015 with
lava flow entering
the ocean
Establishment of the strong 2015 El Niño
August 31, 2015
Main conclusions
(1) Sub-aerial and submarine volcanic eruptions are underestimated natural
causes of climatic variability.
(2) Volcanic eruptions may be the cause of air and ocean circulation changes,
extreme weather events, and polar sea ice changes.
(3) The release of volcanic aerosols including water vapour into the atmosphere
is important in regional/global climatic variability.
(4) Possible contributors to the strong 2015 El Niño year include the
Nishinoshima eruption during November 2013 to August 2015, the Hunga
eruption during December 2014 to January 2015 and the Wolf eruption during
May to June 2015.
(5) Volcanic eruptions are a timely reminder of Earth systems science geoethics.
Acknowledgements
Thanks are due to the records available including NASA, NOAA and Wikipedia.
Volcanic eruptions –
A natural experiment
to learn from
NASA
May 23, 2006 Cleveland, Aleutian islands
Thank you