# Sunlight reduction in large volcanic events

1. Feb 25, 2009

### mheslep

Last night I watched the fun, if not reliable, history channel piece on volcanic eruptions large enough to significantly reduce sunlight. I'm curious. What's a rough order of magnitude of sunlight reduction expected from the various size of events? Some quick googling gives me:

• Small, Pinatubo size: blocked ~5% for some months, 1-2 per century
• Large, super volcano size: like the one in Yellowstone, blocks 90% for decades, ~ 1 per ~1,000,000 yrs, but also directly destroys all life on a majority of its continent, poisons the oceans.
• Medium, Krakatoa size: can't get a number here. Assume bounded between 5 and 90% reduction, reduced planetary temperature a few degrees for a couple years.
Sound reasonable? Anyone have some Krakatoa-scale numbers?

http://www.climate4you.com/ClimateAndVolcanoes.htm

2. Mar 10, 2009

### jwlm88

Krakatoa was said to cause a year without a summer and cause abnormally high tides, as well as huge tsunamis. I couldn't find any hard numbers.

3. Mar 10, 2009

### Xnn

Don't remember where I got the following from originally, but here is some history:

Kuawe (1452-1453) -- An underwater vulcano in the South Pacific. In Sweden, grain tithes fell to zero as crops failed; western U.S. bristlecone pines show frost damage; and the growth of European and Chinese trees was stunted in 1453–57. According to the history of the Ming Dynasty in China in the spring of 1453, "Nonstop snow damaged wheat crops." Later that year, as the dust obscured the sunlight, "Several feet of snow fell in six provinces; tens of thousands of people froze to death. "Early in 1454, "it snowed for 40 days south of the Yangtze River and countless died of cold and famine." Lakes and rivers were frozen, and the Yellow Sea was icebound out to 20 km from shore.

HUAYNAPUTINA (1600) -- A stratovolucano location in Peru. The explosion had effects on climate around the Northern Hemisphere, where 1601 was the coldest year in six centuries, leading to a famine in Russia that eventually lead to an estimated 2 million deaths. From 1600 to 1602, Switzerland, Latvia and Estonia had exceptionally cold winters. The wine harvest was late in 1601 in France, and in Peru and Germany wine production collapsed. Peach trees bloomed late in China, and Lake Suwa in Japan froze early. Sulfuric acid levels deposited in the Greenland ice cap are larger than that from Krakatau (1883).

LAKI (1783) -- The eastern U.S. recorded the lowest-ever winter average temperature in 1783-84, about 4.8 degree C below the 225-year average. Europe also experienced an abnormally severe winter. Benjamin Franklin suggested that these cold conditions resulted from the blocking out of sunlight by dust and gases created by the Iceland Laki eruption in 1783. The Laki eruption was the largest outpouring of basalt lava in historic times. Franklin's hypothesis is consistent with modern scientific theory, which suggests that large volumes of SO2 are the main culprit in haze-effect global cooling.

TAMBORA (1815) -- Thirtythree years later, in 1815, the eruption of Mt. Tambora, Indonesia, resulted in an extremely cold spring and summer in 1816, which became known as the year without a summer. The Tambora eruption is believed to be the largest of the last ten thousand years. New England and Europe were hit exceptionally hard. Snowfalls and frost occurred in June, July and August and all but the hardiest grains were destroyed. Destruction of the corn crop forced farmers to slaughter their animals. Soup kitchens were opened to feed the hungry. Sea ice migrated across Atlantic shipping lanes, and alpine glaciers advanced down mountain slopes to exceptionally low elevations.

KRAKATAU (1883) -- Eruption of the Indonesian volcano Krakatau in August 1883 generated twenty times the volume of tephra released by the 1980 eruption of Mt. St. Helens. Krakatau was the second largest eruption in history, dwarfed only by the eruption of neighboring Tambora in 1815 (see above). After the Krakatau eruption, average global temperatures fell by as much as 1.2 degrees Celsius. Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888. Brilliant sunsets and prolonged twilights were due to the spread of aerosols throughout the stratosphere.

http://www.tehrantimes.com/index_View.asp?code=185344

http://www.volcano.si.edu/world/find_eruptions.cfm

Last edited by a moderator: Apr 24, 2017
4. Mar 11, 2009

### Andre

What would be the logic for individual dust particles to settle slower when there are more?

5. Mar 11, 2009

### Gokul43201

Staff Emeritus
Fick's Law.

And I believe it's sulfur-based aerosols residing in the stratosphere (not dust particles) that are primarily involved in long-term (several months) modification of albedo following a volcanic eruption.

6. Mar 13, 2009

### Bystander

???!!!!! Aw --- please --- don't do this.

7. Mar 14, 2009

### Gokul43201

Staff Emeritus
I'm guessing you are asking me to be more clear (admittedly, my previous post was a terrible rush job).

If you model the dispersion of particles (of some chosen size range) as a 1D diffusion problem following an initial pulse (the volcanic event) that ejects $N_0$ particles into a small region, the concentration of particles at (x,t) looks something like:

$$n(x,t)=\frac{kN_0}{\sqrt{Dt}}exp(-x^2/Dt)$$

where D is the diffusivity and k is some constant that I haven't looked up.

The important thing is that the total number of particles in any region R=(-d,d) around the location of the pulse, at some time t depends on the total number of particles ejected in the initial pulse ( $\int_R n(x,t) dx \propto N_0$ ) and falls away with time like $N_0~erf(d/\sqrt{t})/\sqrt{t}$. From the form of the expression, one can guess that it is takes longer to reduce the number of particles in R to some chosen value when the $N_0$ is larger (since the time it takes to make some relative number, $N/N_0$ is a characteristic timescale of the system - and this is generally the case, even if the dispersion mechanism is not strictly diffusive).

And what determines the albedo is the total number of particles in R, not the number relative to the initial number. So to get back to Andre's question, it is actually because (for a fairly wide range of concentrations) the distribution of settling times (probability of a particle initially at height h having settled within time t) is essentially independent of the initial number of particles that the albedo at any successive time increases with the number of particles thrown up initially.

Last edited: Mar 14, 2009
8. Mar 14, 2009

### Bystander

Not Fick's Law.

9. Mar 14, 2009

### Gokul43201

Staff Emeritus
Solving Fick's Laws tells you how the concentration of stuff varies with time, distance and the amount of stuff thrown up in the first place. If you know how this stuff affects the albedo, you can then figure out how the albedo varies as a function of these things.

10. Mar 19, 2009

### Astronuc

Staff Emeritus
Some measurements from Mauna Loa.

The Mauna Loa observatory is one of ten sites that collects solar radiance data on a daily basis.
http://www.mlo.noaa.gov/livedata/mlosolar.html

Some earlier work: Volcanically Related Secular Trends in Atmospheric Transmission at Mauna Loa Observatory, Hawaii
BERNARD G. MENDONCA, KIRBY J. HANSON, and JOHN J. DELUISI
http://www.sciencemag.org/cgi/content/abstract/202/4367/513

Abstract:

Last edited: Mar 19, 2009
11. Mar 19, 2009

### Xnn

Interesting...

The level of solar energy transmitted since Mt Pintubo has not (as of ~2005) reached 100%. Levels prior to Feb 1963 were noticeably greater; nearly 100% and 100% was briefly exceeded only around 1977.

I wonder if it is from pollution?

12. Mar 19, 2009

### mheslep

13. Mar 19, 2009

### Redbelly98

Staff Emeritus
This is not at all my field. Is there a simple explanation why tides would increase from a volcanic eruption?

14. Mar 20, 2009

### granpa

15. May 21, 2009

### granpa

real tides are complicated. they are more like standing waves than anything else. I suppose that krakatoas effect on the ocean immediately surrounding it was like the effect of hitting a bell with a hammer. it set up standing waves that continued to ring for some time.

http://www.coas.oregonstate.edu/research/po/research/tide/index.html [Broken]

Last edited by a moderator: May 4, 2017
16. May 23, 2009

### Count Iblis

You are confusing supervolcanoes with flood basalts. Supervolcanoes happen quite frequently on geological time scales. Life has adapted to it, although we humans would have difficulties dealing with such an event.

http://en.wikipedia.org/wiki/Flood_basalt" [Broken] This could have led to poisoning of oceans and the atmosphere:

Last edited by a moderator: May 4, 2017
17. May 23, 2009

### TVP45

18. May 24, 2009

### mheslep

How so? I believe I just did not include flood basalts. I proposed supervolcanoes as 1/1m years which is indeed frequent by geologic time scales.

19. May 24, 2009

### Count Iblis

The statement that it
sounded a bit strong to me.

20. May 24, 2009