Volcanoes and their influence on our climate

Somebody showed me this interesting chart to do with solar activity, volcanic aerosols found in ice sheets, Summer maximums and Winter minimums using the CET:

I apologise for the lack of updates, I really do. However, these IMTs are taking forever to calculate. I've now calculated back to 1965. After I have done all the calculating on them, I will start the comparing and researching for volcanic eruptions that occurred.

If you guys have any questions regarding the research project, feel free to throw them at me.

You have found some quite interesting links Fathom by the way, I appreciate you trying to help by posting them here.

I was reading up on Kieran Hickey's PDF on the historical record of cold spells in Ireland as part of Irish Geography Volume 44 Issue 2-3 and came across this part in particular which referenced volcanic eruptions and their effects on cold spells in our part of the world.

It is apparent from the descriptions of historic cold spells that there is also an important volcanic component to the record. For the year 1023 BC the Annals of the Four Masters state that ‘there was this year a huge snow with a vinious taste from which Oill-finsneachta was so called’ (Britton 1937, p. 7). Oill finsneachta has been translated as wine snow. It is likely that this unusual snow was associated with volcanic fall-out from Iceland, hence the unusual description. Similar descriptions of unusual snow are recorded for 665 BC and 538 BC. It is possible that this is just one event, but equally it could refer to two or three separate events, particularly given the fact that the information was written down long after these events took place.

The volcanic record from Iceland shows that there were eruptions in all three of these time periods, further supporting the suggestion that these eruptions are the most likely origin of these unusual snows (Hickey 2010).

Two of the historic cold spells took place as a result of major global volcanic eruptions, and it is very likely that some of the other cold spells prior to AD 1500 may also be as a result of such events. However, the record of volcanic eruptions prior to AD 1500 is very incomplete, deteriorating further as one moves back in time. The role of large scale explosive volcanic eruptions in reducing global temperature, among other effects, is well established (Eddy 1980, Dawson et al.1997, Robock 2000). Their role in previous cold periods is still under investigation (Wohletz 2000).

http://irishgeography.ie/index.php/irishgeography/article/view/48/49

As he said and like I also said in the original post of this thread, volcanic eruptions' impacts on global climate is clear and leads to cooling around the world. However, the role of volcanic eruptions on the Irish climate remains a mystery and is the reason why I decided to take out this project. I would like to present case study 1 below on the Mount Pinatubo eruption of 1991.

Here's some background information on the day of the Mount Pinatubo eruption.

The Mount Pinatubo eruption of June 15 1991 was the second largest volcanic eruption of the 20th century, only behind the Novarupta eruption of 1912. It was some ten times larger of an eruption than that of Mount St. Helens in 1980. The eruption produced high speed avalanches of hot ash and gas, massive lahar floods as well as massive clouds of superheated volcanic material across hundreds of kilometers.

The collapse of the summit and the creation of a caldera caused major earthquakes to occur. Typhoon Yuyna struck the Philippines on the same day of the eruption. The typhoon rains helped to obscure the eruption as a result. However, measurements had shown that ash was ejected to 34km high by the most violent phase of the eruption which lasted for about three hours. Pyroclastic surges poured from the summit of the volcano reaching as far as 16km away from their original point. Typhoon rains mixed with the ash deposits causing massive lahars. The volcanic column from the crater covered an area of around 125,000 km squared leaving much of Central Luzon in darkness. Tephra fell over the majority of the South China Sea and ash falls were recorded as far away as Vietnam, Cambodia, Singapore, Malaysia and Indonesia.

The eruption had led to huge damage across the board as you might have guessed including a death toll of 847 people which was not helped by the simultaneous arrival of Typhoon Yuyna.

The eruption injected significant quantities of aerosols and dust into the stratosphere. Sulfur dioxide oxidised in the atmosphere to produce a haze of sulfuric acid droplets, which gradually spread throughout the stratosphere over the year following the eruption. This was the largest injection of aerosols into the stratosphere since the eruption of Krakatoa in 1883, which I'll look at it in a later date. This very large stratospheric injection resulted in a reduction in the normal amount of sunlight reaching the Earth's surface by about 10%. This in turn led to a decrease in the temperatures of the Northern Hemisphere for a few years with a temperature drop of about 0.5 or 0.6c. This may not seem like a lot at first but it is very extreme because remember, these average drops are considering all countries in the Northern Hemisphere so should not expect a very high deviation.

NOAA even don't have monthly SST charts for 1991/92 because of volcanic aerosol contamination caused by Mount Pinatubo, see below.

http://www.ospo.noaa.gov/Products/ocean/sst/monthly_mean_anom.html

These are the Irish Mean Temperatures (IMTs) for every year from 1985 to 1996. The IMT is the Central England Temperature (CET) counterpart to Ireland basically and every figure here is calculated by me using Met Éireann's historical data and the UK Met Office's data for Northern Ireland. All IMTs are provisional though so are always open to changes and fixes. I found that including these years was the suitable thing to do in this discussion about Mount Pinatubo.

The years I decided to use specifically to see if there's any cooling going on in Ireland were 1991, 1992 and 1993. As can be seen below, these three years were the coolest since 1987 though not spectacularly cool, in fact, using the 1961-90 averages, they would have been warmer than average years. But they were still cooler than anything from 1988 to 1995. 1996 was a cool year probably because it was the year of solar minimum, same with 1986.

Summer 1991 was when the eruption occurred so I will only focus on seasons from that point on up until the end of 1993. Summer 1991 was a fairly warm Summer but June 1991 was very cool and it was one of the coldest Junes of the 20th century. September 1991 broke records for warmth at the beginning of the month. October was cooler than average whilst November was close to normal on the cool side. December was anticyclonic but mild and very dull. 1991/92 was a very unusual Winter with mild, very dry and dull conditions persisting during much of it. 1991 had a total of 5 cooler than average months in comparison to 3 months in 1990 and 2 months in 1989.

March 1992 was mild but very wet. April was cold and very wet. May though was very warm and was the warmest on record for some. June was warm and July started off warm but then went down hill with a rapid deterioration into August bringing the coldest August since 1986. The Autumn of 1992 was very cool too with one of the coldest Octobers on record, perhaps somewhat moderated by a rather mildish November. December though was cool. 1992 had a total of 5 cooler than average months just like 1991.

1993 started off very mild in January to April but May was cooler than average with a notably cold day on the 14th, a maximum of only 6c at Dublin Airport on this day. Each of the Summer months was cooler than average especially August and the daytime temperatures. These colder than average conditions continued into Autumn - for the second year in a row - with again October 1993 being one of the coldest Octobers on record just like October 1992. November 1993 had some notable early snowfalls and before 2010, they were the most notable early snowfalls for November. December was milder than average. 1993 had a total of 7 cooler than average months. 1993 to no surprise was the coolest year out of the trilogy.

It seems that after the initial volcanic eruption in June 1991, the number of cooler than average months annually in Ireland increased up to 1993. 1991 was at a time when solar maximum was a thing and just on its way out towards solar minimum in 1996 so cold would struggle to take place in the Winter, just like it did for Solar Cycle 24 with Winters 2013-14 to 2016-17.

Year|Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec|Ann
1996|6.7|4.5|6.6|8.8|8.9|13.9|15.7|15.6|13.7|11.1|6.5|4.4|9.7
1995|6.1|6.8|6.7|9.1|11.2|14.4|16.9|18.2|13.3|11.7|8.2|4.1|10.6
1994|6.2|5.0|7.7|8.1|10.6|12.9|15.5|14.7|12.3|10.2|9.8|6.7|10.0
1993|6.3|7.3|8.2|9.4|10.4|13.5|14.9|14.5|12.5|8.0|6.6|5.3|9.7
1992|6.1|6.4|7.9|8.6|12.5|14.5|15.7|14.2|12.2|8.1|7.6|4.8|9.9
1991|5.0|4.5|7.9|8.6|11.9|11.5|15.9|16.4|14.1|9.2|7.0|6.4|9.9
1990|6.9|7.0|8.5|8.3|12.4|12.9|16.1|16.7|12.8|10.5|7.0|4.8|10.3
1989|7.0|6.3|7.8|6.4|12.9|13.8|17.8|16.0|13.1|10.9|7.4|4.9|10.4
1988|5.9|5.5|7.9|8.9|11.4|14.6|13.5|14.8|12.6|9.9|6.9|7.2|10.0
1987|4.7|5.2|6.5|9.1|10.9|12.2|15.6|15.8|12.8|8.7|7.1|6.0|9.6
1986|5.0|-0.5|5.9|5.2|10.1|13.9|15.1|13.1|11.3|10.0|7.7|5.8|8.6
1985|2.3|5.4|6.7|9.0|10.8|12.6|15.3|13.8|13.9|10.5|4.5|6.4|9.3
Mean|5.5|5.3|7.1|8.5|11.3|13.7|15.4|15.4|13.0|10.1|7.2|5.6|9.8

https://twitter.com/metoffice/status/994298207629971456