VOLCANO VS MAN - Myth vs Reality

"The 1991 eruption of Mt Pinatubo in the Philippines was one of the largest in the past 100 years. The injection into the stratosphere of 14-26 million tonnes of sulfur dioxide led to a global surface cooling of 0.5°C a year after the eruption. The climatic impact of the Pinatubo aerosol was stronger than the warming effects of either El Niņo or human-induced greenhouse gas changes during 1991-93."
http://www.dar.csiro.au/publications/greenhouse_2000e.htm

"The volcanic pollution results in a substantial reduction in the direct solar beam, largely through scattering by the highly reflective sulphuric acid aerosols. This can amount to tens of percent. The reduction, is however, compensated for by an increase in diffuse radiation and by the absorption of outgoing terrestrial radiation (the greenhouse effect). Overall, there is a net reduction of 5 to 10% in energy received at the Earth's surface."

1. From article at http://volcano.und.nodak.edu/vwdocs/Gases/man.html Carbon Dioxide

"Present-day carbon dioxide (CO2) emissions from subaerial and submarine volcanoes are uncertain at the present time. Gerlach (1991) estimated a total global release of 3-4 x 10E12 mol/yr from volcanoes. This is a conservative estimate. Man-made (anthropogenic) CO2 emissions overwhelm this estimate by at least 150 times."...... read more

2. Facts and Myths about Global Warming:
A Conservative Perspective

From article at http://rep.org/news/ge5_globalwarming.htm

by John R. E. Bliese, Ph.D.

"Global warming is one of our most critical environmental problems, but it is surely the most misunderstood. There is a lot of misinformation out there, and there has also been a disinformation campaign by some special interests who want to protect their short-term profits by preventing us from solving the problem."....... read more

3. http://info-pollution.com/warming.htm GREAT LINKS TO INFO ABOUT MYTHS AND GLOBAL WARMING

4. IN GENERAL, VOLCANOS CAUSE GLOBAL COOLING
From article at http://www.defra.gov.uk/environment/climatechange/index.htm

Explosive eruptions can inject large quantities of dust and gaseous
material (such as sulphur dioxide) into the upper atmosphere (the
stratosphere - see Figure 1.1, section 1.2.2), where sulphur dioxide is
rapidly converted into sulphuric acid aerosols. Whereas volcanic pollution
of the lower atmosphere is removed within days by the effects of rainfall
and gravity, stratospheric pollution may remain there for several years,
gradually spreading to cover much of the globe.

The volcanic pollution results in a substantial reduction in the
direct solar beam, largely through scattering by the highly reflective
sulphuric acid aerosols. This can amount to tens of percent. The reduction,
is however, compensated for by an increase in diffuse radiation and by the
absorption of outgoing terrestrial radiation (the greenhouse effect).
Overall, there is a net reduction of 5 to 10% in energy received at the
Earth's surface.

Clearly, this volcanic pollution affects the energy balance of the
atmosphere whilst the dust and aerosols remain in the stratosphere.
Observational and modelling studies (e.g. Kelly & Sear, 1984; Sear et al.,
1987) of the likely effect of recent volcanic eruptions suggest that an
individual eruption may cause a global cooling of up to 0.3°C, with the
effects lasting 1 to 2 years. Such a cooling event has been observed in the
global temperature record in the aftermath of the eruption of Mount Pinatubo
in June 1991. The climate forcing associated with individual eruptions is,
however, relatively short-lived compared to the time needed to influence the
heat storage of the oceans (Henderson-Sellers & Robinson, 1986). The
temperature anomaly due to a single volcanic event is thus unlikely to
persist or lead, through feedback effects, to significant long-term climatic
changes.

Major eruptions have been relatively infrequent this century, so the
long-term influence has been slight. The possibility that large eruptions
might, during historical and prehistorical times, have occurred with greater
frequency, generating long-term cooling, cannot, however, be dismissed. In
order to investigate this possibility, long, complete and well-dated records
of past volcanic activity are needed. One of the earliest and most
comprehensive series is the Dust Veil Index (DVI) of Lamb (1970), which
includes eruptions from 1500 to 1900. When combined with series of acidity
measurements in ice cores (due to the presence of sulphuric acid aerosols),
they can provide valuable indicators of past eruptions. Using these
indicators, a statistical association between volcanic activity and global
temperatures during the past millennia has been found (Hammer et al., 1980).
Episodes of relatively high volcanic activity (1250 to 1500 and 1550 to
1700) occur within the period known as the Little Ice Age, whilst the
Medieval Warm Period (1100 to 1250) can be linked with a period of lower
activity.

Bryson (1989) has suggested a link between longer time scale volcanic
variations and the climate fluctuations of the Holocene (last 10,000 years).
However, whilst empirical information about temperature changes and volcanic
eruptions remains limited, this, and other suggested associations discussed
above, must again remain speculative.

Volcanic activity has the ability to affect global climate on still
longer time scales. Over periods of millions or even tens of millions of
years, increased volcanic activity can emit enormous volumes of greenhouse
gases, with the potential of substantial global warming (Pickering & Owen,
1994; Rampino & Volk, 1988). However, the global cooling effects of sulphur
dioxide emissions (Officer & Drake, 1983) will act to counter the greenhouse
warming, and the resultant climate changes remain uncertain. Much will
depend upon the nature of volcanic activity. Basaltic outpourings release
far less sulphur dioxide and ash, proportionally, than do the more explosive
(silicic) eruptions...... read more

5. Volcanic eruptions and climate change
http://www.dar.csiro.au/publications/greenhouse_2000e.htm
CSIRO Atmospheric Research Greenhouse Information Paper

A massive volcanic eruption can blast huge clouds of ash and gases
into the atmosphere. Millions of tonnes of sulfur dioxide gas may reach the
upper atmosphere (the stratosphere). There, the sulfur dioxide transforms
into tiny particles of sulfuric acid, known as aerosol. The particles
reflect energy from the sun back into space, preventing some of the sun's
rays from heating the Earth.

This information paper examines the impact of volcanic eruptions on
climate and the make-up of the atmosphere.

Surface cooling
Volcanic eruptions that add significant quantities of sulfur dioxide
into the stratosphere lower global surface temperatures. Conversion of the
sulfur dioxide to sulfuric acid aerosol in the stratosphere takes some
months, so maximum cooling occurs up to a year after the eruption. It may
take as long as seven years before the cooling influence of the volcanic
aerosol disappears completely.

The 1991 eruption of Mt Pinatubo in the Philippines was one of the
largest in the past 100 years. The injection into the stratosphere of 14-26
million tonnes of sulfur dioxide led to a global surface cooling of 0.5°C a
year after the eruption. The climatic impact of the Pinatubo aerosol was
stronger than the warming effects of either El Niņo or human-induced
greenhouse gas changes during 1991-93. .... read more