Given that humans are pumping 60-times more carbon dioxide
gas into the Earth’s atmosphere than all of the planet’s volcanoes combined,
would solar geoengineering be a viable method to limit global warming rise to
2-degrees Celsius?
By: Ringo Bones
Even if we manage to halt all of our production of carbon
dioxide tomorrow, it would take quite awhile for overall carbon dioxide gas
concentrations in our atmosphere to return to pre-industrial levels. In an
interview back in July 9, 2012, the 1984 Nobel Physics Prize laureate Carlo
Rubbia stated that based on what we currently know on the behavior of gaseous
carbon dioxide currently circulating in the Earth’s atmosphere, the average
lifetime that the carbon dioxide generated by human activity – as in biomass
and fossil fuel burning – stays in the atmosphere before being sequestered back
into wood and dissolved into the world’s oceans and lithosphere, is 30,000
years. Therefore most of the carbon dioxide produced when Emperor Nero burned a
section of Rome as he fiddled around 2,000 years ago is still in our
atmosphere. Given the relatively long delay time of removing excess carbon
dioxide from our atmosphere, are there other more effective ways to halt the
average global temperature rise to within 2-degrees Celsius by the year 2100?
Professor of Physics and Public Policy at Harvard David
Keith suggests a method which he calls solar geoengineering. Despite of the
risks, due to our still limited understanding of the planet Earth’s overall
climate system, there are aspects of solar geoengineering that is directly
modeled after recent climatic events and how it can be implemented for our
overall benefit. Professor Keith suggests mimicking how volcanic eruptions
trigger a global cooling effect for a number of years after the event. We could
manage to keep the inevitable temperature rise to within 2-degrees Celsius by
the year 2100.
Remember when Mt. Pinatubo erupted back in June 1991? It
manage to lower overall global temperature by 2-degrees Celsius and another
unforeseen consequence of the volcanic eruption was the resulting increased
farm and ecosystem productivity that happened two years after the event. And
according to Professor Keith, solar geoengineering could mimic such natural
phenomena by flying jet planes to the stratosphere at the near equatorial
region and spraying sulfur dioxide gas to produce sulfuric acid ice crystal
clouds in order to increase planet Earth’s albedo – i.e. the reflectivity – of the
Earth’s atmosphere reflecting excess infrared energy our planet receives from
the Sun back into space. The planet Venus’ naturally occurring sulfuric acid
ice crystal clouds is the reason why it has a higher albedo in comparison to
planet Earth and this its “brighter” appearance in comparison to its sister
planet. Although there are unforeseen risks involved due to our still limited
understanding on how our planet’s climate system works and the formidable
logistics involved of using a fleet of our current jet aircraft to produce
sulfuric acid crystal clouds of similar density of that created by the Mt.
Pinatubo eruption around the Earth’s equator, it seems that it is the only
scheme that could produce a plausibly desirable result when it comes to keeping
overall global temperature rise to within 2-degrees Celsius by the year 2100.