Mass Extinction re. Climate engineering: Minor potential, major risk of side-effects?

"Humans burning fossil fuels are currently emitting as much SO2 every 1.7 years measured in Greenland as one “large” volcanic eruption. Such a high level of SO2 is causing not only global warming but widespread extinction of many species. Humans are also emitting 2 to 3 orders of magnitude more CO2 than large volcanic eruptions, compounding global warming. Both CO2 and SO2 emissions must be reduced significantly to reverse global warming, but reducing SO2 should be the highest priority."
Peter L. Ward

 (OE) While reading the recent study titled "Climate engineering: Minor potential, major risk of side-effects?" please keep in mind the above quote from another study. It could be helpfull when considiring SRM geoengineering. I think this latest study should be considered from at least two different angles. The first and most obvious, as criticism and a warning about the deployment of climate geoengineering. And the second, less clear, as a warning against the reduction of sulfur aerosols of anthropogenic origin, which are already acting as ‘accidental geoengineering' by blocking some sunlight and fertilizing the ocean 'un-intentionally' as we have discussed in the past. [1] [2] [3]

Additionally, an important consideration could be made in light of the ongoing 'sixth extinction' more recently explored in the book 'The Sixth Extinction: An Unnatural History' by journalist Elizabeth Kolbert. (On my reading list!) This (in-process) extinction is attributed to human activities, primarily through fossil fuels CO2 emissions. But I think also a very important factor, that unfortunately is very seldomly discussed, is the current sulfur emissions of anthropogenic origin: from aviation, maritime shipping, transportation, etc. These sulfur emissions, may be a great accelerator of this sixth extinction. [4]

So I think it is important to also highlight the question:

What would be the consequences for biodeversity of ignoring continuous ‘accidental geoengineering’ processes resulting from anthropogenic sulfur emissions?

Links to the recent article and the original study titled "Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario" can found in the references. Also, find a few excerpts regarding the role of sulfur dioxide as a driver of mass extintions. (Oscar E)

Climate engineering: Minor potential, major risk of side-effects?[5]
ScienceDaily - Date: February 25, 2014
Source: Helmholtz Centre for Ocean Research Kiel (GEOMAR)

Summary:
Researchers have studied with computer simulations the long-term global consequences of several 'climate engineering' methods. They show that all the proposed methods would either be unable to significantly reduce global warming if CO2 emissions remain high, or they could not be stopped without causing dangerous climate disruption.




                                                                  *************


Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario
David P. Keller, Ellias Y. Feng & Andreas Oschlies  
Nature Communications 5, Article number: 3304
doi:10.1038/ncomms4304

Abstract:
The realization that mitigation efforts to reduce carbon dioxide emissions have, until now, been relatively ineffective has led to an increasing interest in climate engineering as a possible means of preventing the potentially catastrophic consequences of climate change. While many studies have addressed the potential effectiveness of individual methods there have been few attempts to compare them. Here we use an Earth system model to compare the effectiveness and side effects of afforestation, artificial ocean upwelling, ocean iron fertilization, ocean alkalinization and solar radiation management during a high carbon dioxide-emission scenario. We find that even when applied continuously and at scales as large as currently deemed possible, all methods are, individually, either relatively ineffective with limited (<8%) warming reductions, or they have potentially severe side effects and cannot be stopped without causing rapid climate change. Our simulations suggest that the potential for these types of climate engineering to make up for failed mitigation may be very limited.

                                                             **************

On mass extinctions (Emphasis mine)

Sulfur dioxide initiates global climate change in four ways[4]
Peter L. Ward
Teton Tectonics, P.O. Box 4875, Jackson, WY, USA

(Excerpt)
7. Extreme rate: Very frequent basaltic eruptions, mass extinctions

The largest known basaltic fissure eruption in the past 1000 years is Laki in southern Iceland, which produced 14.7 km 3 of basalt in 8 months beginning in June,1783 [48]. The 10 eruption episodes were not all that spectacular (VEI=4), with ash reaching altitudes of only 13 km, but this 27-km-long fissure complex emitted 122 Mt of SO2, more than 5 times that of Pinatubo, as well as 235 Mt of H2O,15 Mt of chlorine, 7 Mt of fluorine, some hydrogen sulfide and some ammonia.
Most of these gases were emitted into the troposphere but high enough to be caught in the jet stream headed for Europe. A dry fog covered the North Atlantic, Europe, north Africa and Asia with the greatest opacity between mid-June and mid-July.
   It was a very cold and harsh summer in Iceland and Siberia, but very dry and hot in western Europe, most likely from solar heating of the dry fog. Intense thunderstorms and hail were unusually frequent.
The winter of 1783–1784 was one of the most severe on record for Europe and North America with large floods in Europe in the spring.
Cold winters and crop failures in Europe lasted into 1788 helping to spawn the French Revolution in 1789[170]. Most birch trees, shrubs, and moss were killed in Iceland. Grass withered to the roots.
Throughout Europe, from England to Sweden to Italy, trees and plants were damaged by acid rain and crops failed.
   In Iceland, 50% of the cattle, 79% of the sheep, 76% of the horses and 24% of the people (10,521) perished from pollution of the air, water, and forage by the volcanic gases or from the resulting famine [171].In England there were approximately 20,000 deaths related to the
eruption[172], and more than 16,000 in France[173]. Famine and death even resulted among the Alaskan Inuit[174]. When similar mortality studies are completed throughout Europe, life loss from the eruption of Laki is likely to rival the largest known historic volcanic loss of 60,000 people during the eruption of Tambora in Indonesia in 1815 (VEI=7)[175]. In fact one million people died during the Great Tenmei Famine in Japan exacerbated by the eruption of Laki and the local small eruption of Asama[176].
   Basaltic eruptions typically emit 10 to 100 times more volatiles per cubic kilometer of magma than the “large” silicic eruptions discussed inearliersectionsofthispaper [177–179]. Given such major environmental effects from erupting less than 15 km 3 of basalt, what would be the effects of erupting more than 3,000,000 km 3 of basalt in the Siberian Traps around 249.4 Ma, he equivalent of 200,000 Laki eruptions? The Siberian Traps cover an area of 2,500,000 km2, almost as large as Washington, Oregon, California and Nevada combined.
   Courtillot and Renne [180] summarize studies of the twelve largest fissure basalt eruptions known in the past 360 m.y. and known mass extinctions and ocean anoxia events. They
find a one-to-one correspondence between basaltic eruptions and extinctions within
theprecisionof the datingforall theevents (Fig. 3). The only exceptionis the Ordovician–
Silurian mass extinction (443.7 Ma), probably the second largest, occurring in two separate prolonged events. Flood basalts of this age have not yet been recognized. Therefore there may
be another explanation for at least one major mass extinction.
   Only one mass extinction, on the other hand, clearly coincides with a meteorite impact, the Cretaceous/Tertiary boundary (65.5 Ma). Most paleontologists conclude that mass extinctions are not instantaneous; they tend to occur over at least thousands of years. While a meteorite
may have complicated the extinction around 65.5 Ma, it is now clear that radiation did not kill the dinosaurs [181] and that large percentages of animals could have survived a large impact by
sheltering [182]. Mass extinctions typically involve runaway green-house warming, major changes of acidity of air and water, dramatic increases in light carbon isotopes, and anoxia over hundreds to tens of thousands of years [183–188].
   Given that massive increases in SO2 appear to have caused mass extinctions in the past (Cardinal Rate IV, Table 1) and that there has been a significant increase in SO2 gases since 1925 (Fig.10), we should not be too surprised to discover that we are currently in the midst of a major mass extinction. In 2005, more than 1360 scientists under the auspices of the United Nations, completed the Millennium Ecosystem Assessment [189,190]. This was followed by the Global Biodiversity Outlook 2 under the Convention on Biological Diversity, a legally binding global treaty created in 1992 with nearly universal participa-tion of countries. Among their conclusions are [191]:

1.“15 out of 24 ecosystem services are in decline including the ability to provide fresh water and the ability of the atmosphere to cleanse itself of pollutants.”
2.“Trends among 3000 wild populations of species show a consistent decline in average species abundance of about 40% between 1970 and 2000.”
3.“Between 12% and 52% of species within well-studied higher taxa are threatened with extinction.”
4. “The global demand for resources exceeds the biological capacity of the Earth to renew these resources by some 20%.”
5.“Humans are currently responsible for the sixth major extinction event in the history of the earth, and the greatest since the dinosaurs disappeared, 65 million years ago.”

                                                           ************


February 8, 2009
Sulfur Dioxide Initiates Global Climate Change in Four Ways - Notes for Science Writers[7]
Peter L. Ward

(Excerpt)
Mass Extinctions
   Eruptions of basalt typically emit 10 to 100 times more sulfur dioxide per cubic kilometer of
magma than the “large” silicic eruptions discussed throughout most of the paper. Basalt is a
primitive magma that forms from the partial melt of eridotite that makes up the parts of the earth
below the crust and uppermost mantle layers called the lithosphere.
When the lithosphere cracks or is broken, basalt rises. If the lithosphere is thin, such as is typical under ocean basins, the basalt rises to the surface and is erupted forming a mid-ocean ridge or a line of volcanic islands. If the lithosphere is thick, such as is typical under continents, the basalt
is not buoyant enough to erupt. It forms magma chambers at depths such as 5 to 15 kilometers (3 to 9 miles) where it cooks with the surrounding rocks forming silicic volcanics that are lighter and can ultimately erupt with the help of the gases that separate from the magma.
   While I have not developed the concept in the scientific literature, I believe that flood basalts
tend to be erupted where mid-ocean ridge triple points approach a trench and clog the trench, ending subduction. See en.wikipedia.org/wiki/Plate_tectonics to understand this terminology. The eruption of flood basalts causes the thermal anomaly under the ridge to grow downward into the mantle thereby forming a volcanic hotspot that can continue to erupt more magma than surrounding lithosphere for millions to tens of millions of years. This may be the physical reason why massive flood basalts and mass extinctions only occur on average every 20 million years.
Many flood basalts are massive with volumes as large as 3 million cubic kilometers (720,000 cubic miles). The largest historic basaltic eruption was from the Laki fissure in southern Iceland, on the Mid-Atlantic Ridge. The damage from this eruption of less than 15 cubic kilometers (3.6 cubic miles) of basalt was prodigious. I describe these effects in some detail in the paper to help readers imagine what the effect of erupting 200,000 times as much basalt would be. This provides a way to understand what the climate might have been like during a major mass extinction. The surprise for me was the conclusion cited in the paper from 1360 scientists that
“Humans are currently responsible for the sixth major extinction event in the history of the earth.” Twentieth century concentrations of sulfur dioxide compare not only with the concentrations during the major warming phases coming out of the last ice age (Figure 2) but also with the concentrations during many mass extinctions throughout geologic time.

                                                      ----------------------

“The concentration of SO2 in the atmosphere appears to initiate global climate change in four ways:

I. Very low concentrations allow the atmosphere to cleanse itself by oxidizing most pollutants. This thins the atmospheric blanket, cooling the earth and causing drought.

II. Sporadic “large” volcanic eruptions cause cooling of the earth for approximately three years by forming a sulfuric acid aerosol in the lower stratosphere. A sequence of such eruptions can
increment the world into an ice age.

III. When “large” volcanic eruptions occur in quick succession at the rate of at least one each year for ten or more years, the oxidizing capacity of the atmosphere is severely impaired,
greenhouse gases accumulate, causing global warming.

IV. Every 20 million years or so, the eruption of millions of cubic kilometers of lood basalts overwhelms the oxidizing capacity of the atmosphere for tens of thousands of years or more,
causing mass extinctions. Humans burning fossil fuels are currently emitting as much SO2
every 1.7 years measured in Greenland as one “large” volcanic eruption. Such a high level of SO2 is causing not only global warming but widespread extinction of many species. Humans are also emitting 2 to 3 orders of magnitude more CO2 than large volcanic eruptions, compounding global warming. Both CO2 and SO2 emissions must be reduced significantly to reverse global warming, but reducing SO2 should be the highest priority.
Humans have developed many ways to reduce significantly the amount of SO2 emitted; we need to implement them widely and aggressively. It might even be possible in the future to carefully
maintain a constant ideal level of SO2 by supplementing natural releases with controlled human releases.


References for my comment:

[1] H2SO4 (SULFURIC ACID) FROM AVIATION MAY BE HIGHER TODAY THAN WHAT WOULD BE REQUIRED FOR A GEOENGINEERING REGIME IN 2020
http://geoengineeringclimateissues.blogspot.com/2013/11/h2so4-sulfuric-acid-from-aviation-may.html

[2] Shipping emissions can lead to high local ocean acidificaton
http://geoengineeringclimateissues.blogspot.com/2014/02/shipping-emissions-can-lead-to-high.html

[3] Geoengineering And Intentionality, Does Biodiversity Care?
http://geoengineeringclimateissues.blogspot.com/2014/01/geoengineering-and-intentionality-does.html

[4] Sulfur dioxide initiates global climate change in four ways
Peter L. Ward
Teton Tectonics, P.O. Box 4875, Jackson, WY, USA
http://tetontectonics.org/Climate/SO2InitiatesClimateChange.pdf
http://dx.doi.org/10.1016/j.tsf.2009.01.005

[5]Climate engineering: Minor potential, major risk of side-effects?[5]
ScienceDaily - Date: February 25, 2014
Source:
Helmholtz Centre for Ocean Research Kiel (GEOMAR)
http://www.sciencedaily.com/releases/2014/02/140225122519.htm

[6]  Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario
David P. Keller, Ellias Y. Feng & Andreas Oschlies  
Nature Communications 5, Article number: 3304
doi:10.1038/ncomms4304
http://www.nature.com/ncomms/2014/140225/ncomms4304/full/ncomms4304.html

[7]  Sulfur Dioxide Initiates Global Climate Change in Four Ways - Notes for Science Writers
http://www.tetontectonics.org/Climate/Notes%20For%20Science%20Writers.pdf

Other readings:

Mega-Eruptions Drove the Mother of Mass Extinctions
Richard A. Kerr
Science 20 December 2013:
Vol. 342 no. 6165 p. 1424
DOI: 10.1126/science.342.6165.1424
After 20 years of trying, researchers have finally convicted massive volcanic eruptions in Siberia as the culprit in the greatest of all mass extinctions, one that destroyed 90% of marine species on the planet.
http://www.sciencemag.org/content/342/6165/1424

Sun-dimming volcanoes partly explain global warming hiatus - study
By Alister Doyle, Environment Correspondent
OSLO Sun Feb 23, 2014 1:06pm EST
http://www.reuters.com/article/2014/02/23/us-climate-volcanoes-idUSBREA1M0W920140223

Volcanic contribution to decadal changes in tropospheric temperature
Benjamin D. Santer et al.
Nature Geoscience 7, 185–189 (2014)
doi:10.1038/ngeo2098
Published online 23 February 2014
http://www.nature.com/ngeo/journal/v7/n3/full/ngeo2098.html