Volcanoes and their influence on our climate

Mount Tarumae, Japan had an eruption in August 1739 with a volcanic explosivity index (VEI) of 5. Mount Pinatubo's eruption of June 1991 in comparison had a VEI of 6.

An earthquake occurred on August 16, followed by intermittent eruptions on August 18 to 30 (plinian eruptions), in which of 2 or 3 days the tephra fall was so heavy that the area was darkened. At the end of the eruption period, especially strong rumbling occurred. Air-fall pyroclastic material (Ta-a) was deposited over a wide area to the northeast, approximately 1m deep around the present Chitose Airport, and several cm deep in the Taisetsuzan area. Main pyroclastic flows reached the foot of the volcano 4 times, distributed over an area of up to 10km, and flowing into Lake Shikotsu at the north and northwest feet of the volcano. There were 9 pyroclastic deposit layers. The bottom layer consisted of a small amount of air-fall deposits. The topmost layer was the largest, both in terms of distribution and strata thickness, consistent with the strong rumbling at the end of the eruption period. A 1.2x1.5 km diameter somma (small caldera) was formed at the summit.

This eruption in 1739 was followed by one of the coldest years in the UK and Ireland on record. Winter 1739/40 was the second coldest on record behind only the Lorna Doone Winter of 1683/84, and was colder than 1962-63. 1740 is the year of the infamous Great Irish Frost and the forgotten Irish Famine.

A theory is that due to its more northern latitude than Mount Pinatubo, Krakatoa and Mount Tambora, it had a greater impact on the Irish climate.

Central England Temperatures (CETs) for all seasons from the UK Met Office.

Season|December|January|February|Winter
1683-84|0.5|-3.0|-1.0|-1.17
1739-40|3.2|-2.8|-1.6|-0.40
1962-63|1.8|-2.1|-0.7|-0.33


https://en.wikipedia.org/wiki/Mount_Tarumae

Fathom wrote: »

Pacific Ring of Fire. Heating up? Hawaii. Now Nicaragua volcano eruption. Atmospheric changes due to more than one volcano erupting at the same time? Local consequences? Global?

Global consequences including Ireland will depend on how much ash particles or sulfur-rich gases advect up to the troposphere and stratosphere along with of course, the exact location of the eruption. For example, an Icelandic volcano eruption is far more likely to affect us here than let's say a Hawaiian volcano.

In my original post, I should have stated how volcanic eruptions affect the climate exactly across the globe. I will do so here in this update post today before I go into other things.

When volcanic eruptions take place, they emit a mixture of gases and particles into the atmosphere. Specific gases and particles have a cooling effect on the earth because they reflect sunlight away from the globe and examples of such include ash and sulphur dioxide. Why I focus particularly on the large significant eruptions such as Mount Pinatubo of 1991 is because they blast these particles all the way to the top of the stratosphere which is the layer of the atmosphere above the troposphere. When this happens, there is less sunlight travelling to earth which leads to the cooling of the oceans and sometimes countries or continents such as in 1816 - the year without a summer.

I think the fact that we're seeing a large increase of volcanic eruptions so far in 2018 is very natural and as a result of solar activity plunging. Now, I am a skeptic of global warming and ice age theories, I think everything is natural. Nevertheless, solar minimum is just around the corner and some people are expecting this to be longer than the previous solar minimum back in 2008 and 2009 which had been the longest in over a century. Around this period is usually when you start to see volcanic eruptions becoming more frequent - not necessarily more significant (for example, Mount Pinatubo was around solar maximum). Significant volcanic eruptions can happen at any given time courtesy of other factors like large builds up of pressure in the earth's plates. Also around the solar minimum period is when you should expect to see more Greenland blocking taking place which increases the chances of a cooler Europe as such happened in 2009-10 and to some extent, 2010-11 too. We shall see how this solar minimum goes down when it happens.

Nevado del Ruiz case study

The Nevado del Ruiz eruption, known as the Armero tragedy, of 1985 killed at 23,000 people. It was the second deadliest volcanic eruption of the 20th century. The eruption produced several lahars and one reached Armero where 20,000 of 29,000 inhabitants died. The eruption is estimated to have cost $1 billion in Colombia.

In November 1984, geologists noticed an increasing level of seismic activity near Nevado del Ruiz. There was an increase of fumarole activity and deposition of sulfur on the summit. Hot magma came in contact with water resulting in explosions as the water was almost instantly turned into steam. An Italian volcanological mission analysed gas samples from fumaroles along the crater floor and proved them to be a mixture of carbon dioxide and sulfur dioxide indicating a direct release of magma onto the earth's surface. As a result, they said that the risk of lahars taking place was very high.

In November 1985, volcanic activity once again increased as magma neared the surface. The volcano began releasing increasing quantities of gases rich in sulfur dioxide and elementary sulfur. The extensive degassing of the magma caused pressure to build up which eventually caused the explosive eruption of the volcano.

In terms of the SST anomalies for the globe, here's how the oceans and seas looked like in May 1986. You can certainly see a lot of cooler than average anomalies, notably over the Pacific Ocean, Indian Ocean, the tropics and the northeast Atlantic Ocean around Ireland.

Some points to note for our weather around the time of the eruption of Nevado del Ruiz and following it:

- 1983 and 1984 were both warm years with the summers in particular being warm (July 1983 was the warmest month on record at this time in the UK and Ireland including for the CET dataset which goes back to 1659)
- 1985 to 1987 were all cold years with November 1985 (coldest November since 1925 and we have not seen a colder November than it since; 2010 wasn't as cold), February 1986 (the second coldest February of the 20th century) and August 1986 (coldest since 1956 and an August hasn't been colder than this one since) particularly standing out for being very cold.

Two reasons for the colder years of 1985 to 1987 could be blamed on the negative phase of the Atlantic Multidecadal Oscillation (AMO) and solar activity. 1986 was the year of solar minimum. However, it's also possible that the volcanic eruption caused significant colder than average months like those named above. I'd like to add that we have not been in a negative phase of the AMO since the 1980s and we're overdue for one in the 2020s. The Atlantic Meridional Overturning Circulation (AMOC) seems to be slowing down dramatically with notable persistent patterns of easterlies in 2018 so far. As a result, the Atlantic SST profile has become very strange (and somewhat similar to that of May 1986 below) with years like 1976 - the year of the notable drought and hot Summer - of a similar such profile. 1976 preceded quite a run of cold winters that took place from 1976 to 1979 and was also in solar minimum. Not to mention, it preceded the gradual turn of the AMO going negative for the 1980s. Could 2018 be a teaser that a negative AMO is down the line?

This is all just speculation but some evidence suggesting there that Ireland may have been affected somewhat by this Nevado del Ruiz eruption in 1985.

Explosive volcanic eruptions triggered by cosmic rays

https://www.sciencedirect.com/science/article/pii/S1342937X10001966

Krakatau.... the volcano of an infamous significant eruption in 1883. Average global temperatures fell by as much as 1.2 degrees Celsius in the year following the eruption. Weather patterns continued to be chaotic for years and temperatures did not return to normal until 1888.

Didn't seem to have much of an impact on Ireland and the UK though as Winter 1883/84 was rather mild and Summer 1884 was very warm.

https://twitter.com/yamkin1/status/1010292801941262337

Ok so, I have calculated the 1841-70 averages for the CET. These would have been the relevant averages to use for 1878/79 at time for comparisons. I also added the 1981-2010 averages to the table to compare and a difference between the two in row 3.

|Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec|Ann
1841-70|3.4|3.9|5.2|8.3|11.2|14.4|15.8|15.4|13.2|9.9|5.7|4.3|9.2
1981-10|4.4|4.4|6.6|8.5|11.7|14.5|16.7|16.4|14.0|10.7|7.1|4.6|10.0
Difference|+1.0|+0.5|+1.4|+0.2|+0.5|+0.1|+0.9|+1.0|+0.8|+0.8|+1.4|+0.3|+0.8


This is kind of off topic to the volcanoes discussion but I'd like to state it before I get onto 1878/79. It seems that March and November have gotten the greatest increase in average temperature using these 30-year averages as a comparison. I would agree with November being much milder in modern times as there has been a very large lack of cold Novembers (and no severely cold ones like 1919 at that) but Marches, not totally sure about that. 2010 may have ended record breakingly cold in November but much of the month was average to mild temperature wise with Atlantic depressions.

Here's the 1878-79 (and January 1880) CETs along with their anomalies from the 1841-70 averages in brackets.

November 1878: 3.5 (-2.2)
December 1878: -0.3 (-4.6)
January 1879: -0.7 (-5.1)
February 1879: 3.1 (-0.8)
March 1879: 4.7 (-0.5)
April 1879: 5.7 (-2.6)
May 1879: 8.9 (-2.3)
June 1879: 12.9 (-1.5)
July 1879: 13.6 (-2.2)
August 1879: 14.5 (-0.9)
September 1879: 12.6 (-0.6)
October 1879: 8.9 (-1.0)
November 1879: 4.1 (-1.6)
December 1879: 0.7 (-3.6)
January 1880: 0.9 (-2.5)

Even using the old 1841-70 averages, the whole period of Nov 1878 to Jan 1880 comes out colder than average. I might convert Armagh Observatory's Fahrenheit temperature observations into Celsius then make a graph of Winter 1878-79.

I'm trying to see if there were any volcanic eruptions that preceded other severe winters like 1880-81 (the Winter of Ireland's all-time official record low temperature), 1683-84 and 1739-40.