1. 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

2. Plan Introduction Case study of a sub-aerial eruption
Case study of a submarine/sub- aerial eruption
(4) Conclusions

3. 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

4. Volcanic Explosivity Index (VEI)
Above VEI 2
regional impacts
on weather/climate
may already be detectable
Estimation of explosiveness of
sub-aerial volcanic
eruptions
(Newhall and Self 1982)
Acidic magma
most explosive 8

5. 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

6. Hong Kong’s rainfall record during the 3 volcanic eruptions
Agung 1963 VEI 4
Driest year
on record
Comparison
Pinatubo
1991 VEI 6
11th driest
on record
El Chichón
1982 VEI 4
2nd wettest
on record
VEI – Volcanic explosivity index

7. 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).

8. ↑ → ← Sub-aerial model Thermal plume Eruption changes normal air
circulation /
creats clouds
/ destroys O3 ↑
Ash & aerosols
reduces solar
radiation
leading to
cooling
SO2, HCl
& H2O
Warm air
stores more
moisture –
water vapour
redistribution
Air pressure
changes (low)
Cool air
stores less
moisture → ←
Cooler air
Impact longer
lasting if
major
El Chichón, Mexico 1982
USGS

9. June 15, 1991 Pinatubo eruption VEI 6

10. Track of Yunya (Oswalt et al. 1999) Day of eruption Two days before

11. ↓ Why 1991 was a global drought year?
Pinatubo eruption cloud
Typhoon Yunya
Why 1991 was a global
drought year?
Water vapour transfer into the stratosphere creating
atmospheric rivers

12. Pinatubo eruption cloud maximum elevation 55 km
Oswalt et al. (1999)

13. 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

14. 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

15. 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

16. Sea-surface temperature anomalies showing the North Pacific Blob on January 2, 2014
Nishinoshima eruption 11/2013-8/2015
Blob

17. Observations connecting Nishinoshima with the Blob __________________________________________________________________________________________________________
Date Eruption activity Northern Pacific Blob
__________________________________________________________________________________________________________
November Submarine eruption created new island Initial Blob 800 km wide and 91 m deep
2013
December Island area reached 5.6 km2 and ~25 m -
2013 above sea level
February - Temperature was ~2.5oC above normal
2014
June 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 Island now ~2.3 km in diameter and ~110 m Year without winter in western North America coast
2014 above sea level and first mass bleaching of Hawaiian coral reefs
January- Episodic eruption with lava flows -
August
2015
Early - Blob persisted and ended
2016
Source: Wikipedia
Date

18. The Blob separated into three parts on September 1, 2014
Warm water build up in slack
areas of gyres 2 3
Ocean circulation

19. Contraction of Arctic sea ice Expansion of Antarctic sea ice
Impact of the Blob on September 1, nature’s way of neutralizing hot and cold
Contraction of Arctic sea ice 1 2 3
Expansion of Antarctic sea ice

20. Sea-surface temperature anomalies on June 29, 2015 after the Wolf eruption ended
5-6/2015 with
lava flow entering
the ocean

21. Establishment of the strong 2015 El Niño August 31, 2015

22. 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.

23. Thank you Volcanic eruptions – A natural experiment to learn from
NASA
May 23, 2006 Cleveland, Aleutian islands
Thank you