The research came up with ‘relatively modest temperature changes’. One NASA atmospheric scientist commented: “To me, this is another example of why geoengineering via stratospheric aerosol injection is a long, long way from being a viable option.” (Here’s another one). Climate alarmists can imagine doing some things, but so can Hollywood scriptwriters.
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New research suggests that sunlight-blocking particles from an extreme eruption would not cool surface temperatures on Earth as severely as previously estimated, says Phys.org.
Some 74,000 years ago, the Toba volcano in Indonesia exploded with a force 1,000 times more powerful than the 1980 eruption of Mount St. Helens. The mystery is what happened after that—namely, to what degree that extreme explosion might have cooled global temperatures.
When it comes to the most powerful volcanoes, researchers have long speculated how post-eruption global cooling—sometimes called volcanic winter—could potentially pose a threat to humanity.
Previous studies agreed that some planet-wide cooling would occur but diverged on how much. Estimates have ranged from 3.6°F to 14°F (2°C to 8°C).
In a new study published in the Journal of Climate, a team from NASA’s Goddard Institute for Space Studies (GISS) and Columbia University in New York used advanced computer modeling to simulate super-eruptions like the Toba event. They found that post-eruption cooling would probably not exceed 2.7°F (1.5°C) for even the most powerful blasts.
“The relatively modest temperature changes we found most compatible with the evidence could explain why no single super-eruption has produced firm evidence of global-scale catastrophe for humans or ecosystems,” said lead author Zachary McGraw, a researcher at NASA GISS and Columbia University.
To qualify as a super eruption, a volcano must release more than 240 cubic miles (1,000 cubic kilometers) of magma. These eruptions are extremely powerful—and rare. The most recent super-eruption occurred more than 22,000 years ago in New Zealand.
The best-known example may be the eruption that blasted Yellowstone Crater in Wyoming about 2 million years ago.
Full article here.
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Image: Volcanic eruption.
Tallbloke's Talkshop 
I like scientific speculation, the purer the better.
If super eruptions only have a limited effect, humans squirting substances into the atmosphere to alter temperatures isn’t even worth discussing.
oldbrew says: March 4, 2024 at 9:00 pm
Nuf said! No reason to discuss this OB.
suricat.
These two “climate scientists” thought otherwise.
ATMOSPHERIC CARBON DIOXIDE AND AEROSOLS:
Effects of Large Increases on Global Climate.
Abstract.
Effects on the global temperature of large increases in carbon dioxide and aerosol densities in the atmosphere of Earth have been computed.
It is found that, although the addition of carbon dioxide in the atmosphere does increase the surface temperature, the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere.
For aerosols, however, the net effect of increase in density is to reduce the surface temperature of Earth.
Because of the exponential dependence of the backscattering, the rate of temperature decrease is augmented with increasing aerosol content. An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5 deg.K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age.
The rate at which human activities may be inadvertently modifying the climate of Earth has become a problem of serious concern . In the last few decades the concentration of CO2 in the atmosphere appears to have increased by 7 percent . During the same period, the aerosol content of the lower atmosphere may have been augmented by as much as 100 percent .
How have these changes in the composition of the atmosphere affected the climate of the globe? More importantly, is it possible that a continued increase in the CO2 and dust content of the atmosphere at the present rate will produce such large-scale effects on the global temperature that the process may run away, with the planet Earth eventually becoming as hot as Venus (700 deg. K.) or as cold as Mars (230 deg. K.)?
We report here on the first results of a calculation in which separate estimates were made of the effects on global temperature of large increases in the amount of CO2 and dust in the atmosphere.
It is found that even an increase by a factor of 8 in the amount of CO2, which is highly unlikely in the next several thousand years, will produce an increase in the surface temperature of less than 2 deg. K.
However, the effect on surface temperature of an increase in the aerosol content of the atmosphere is found to be quite significant. An increase by a factor of 4 in the equilibrium dust concentration in the global atmosphere, which cannot be ruled out as a possibility within the next century, could decrease the mean surface temperature by as much as 3.5 deg. K. If sustained over a period of several years, such a temperature decrease could be sufficient to trigger an ice age!
Schneider S. & Rasool S., “Atmospheric Carbon Dioxide and Aerosols – Effects of Large Increases on Global Climate”, Science, vol.173, 9 July 1971, p.138-141
Those results were based on a climate model developed by none other than James Hansen, incidentally.
Rog, why do I and my posts linger in ‘moderation’ here?
RSPV. suricat.
Because, Ray, you were exceptionally rude to my co-blogger Oldbrew recently and I won’t be allowing the publication of your further comments until they are vetted. ~TB
If we have a thing we don’t understand and want to know how it will affect a thing we don’t understand, all we need to do is build a model!
Seriously, it’s going to affect stuff somewhere between a bit and a lot. No matter how pretty your model.
An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5 deg.K
Factor of 4 increase for the whole planet – how would that be done? Sounds implausible.
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Geoengineering: What, how, and for whom? – Kevin E. Trenberth
The cost and viability of any such proposals are other major issues, but in my view, they are overwhelmed by the ethical considerations.
https://pubs.aip.org/physicstoday/article/62/2/10/399196/Geoengineering-What-how-and-for-whom
That depends if it’s a continuous super eruption which I think most are not. Planet will go flat.
If you accept the net negative feedback number from all causes of 7.1W/m^2, then a covering of volcanic ash or whatever aerosoly thingies in the atmosphere quickly causes a reduction in surface temperature by lowering stops surface heat loss at the rate of 7 W/m²deg K ‘ ish. So just a few degrees cooling should do it. It may there has been a burn off of all carbon based species on land, and a few billion fish from near the surface as phytoplankton temporarilly reduces. Earth, but hey, that’s the natural World. We do it all the time. Why are these obvious things so hard? IMO of course.
What about “The Year Without A Summer” after the Mount Tambora eruption?
https://en.wikipedia.org/wiki/Year_Without_a_Summer
jeremy — the effects were large but temporary.
Models, models models – come on guys at 82 +VAT I’m too old to be interested in models.
To qualify as a super eruption, a volcano must release more than 240 cubic miles (1,000 cubic kilometers) of magma.
Beat that, earthlings.