[Eruption of Mount Pinatubo pumped large quantities of sulfur dioxide into the stratosphere, effectively changing the climate]

The increasing speed that climate change is impacting our globe, coupled with slow transformations of lifestyle and policy to radically reduce GHG emissions, have prompted many climate change scientists to (re)consider Geoengineering, A.K.A planetary climate-engineering, to rapidly cool the earth.  Levels of carbon dioxide in the atmosphere have surpassed 385 parts per million, rising above the limit of 350 parts per million that many scientists consider to be the threshold for maintaining a stable ‘natural’ climate.  Despite the present interest in global warming, current studies reveal that we are still pumping more carbon dioxide into the atmosphere – approximately increasing the levels by 2 parts per million each year.  Geoengineering – an option that was seldom considered viable, is now being acknowledged as a potential solution, or Plan B to climate change.  One of the reasons for this (beyond the grim reality of carbon levels) is that geoengineering could potentially be very cheap.  Many now argue that geoengineering is an economic alternative to ‘buy us time’ to develop zero-emission technology in a cost effective manner.  While most scientists agree that the reduction of GHG emissions is the fundamental solution (Plan A), they also admit that geoengineering may one of the few options to address future climate change. Ronald Prinn, a professor of atmospheric science and the director of the Center for Global Change science at MIT, explains why climate scientists have started to change their minds about geoengineering in this video.   Put simply, we have come too far and engineering our way out of this situation may be our only choice.

[Comparison of various Geoengineering Strategies via newscientist.com]

For years, geoengineering techniques were only to be found in science-fiction novels, and not put on the table as possible options.  Now, as geoengineering is being reconsidered, we realize how little we know about the atmosphere and climatic changes.  This has already prompted research and a report on Geoengineering by the UK’s Royal Society, as well an American report, instigated in part by President Obama’s science advisor, John Holdren.  Even the IPCC’s report touches on geoengineering in section 4.7, stating what many scientists firmly believe – geoengineering focuses on the symptoms rather than the cause.  The purpose of this nascent research, however, is to wage the various options of geoengineering, understand how to implement them, and run models to gain insights on their potential side effects.  There are several schemes currently being cooked up by scientists to geoengineer our climate that fall into two basic categories: (i) Solar Radiation Management and  (ii) Mitigation techniques, such as carbon sequesterering.  While several of these initial ideas are seemingly sci-fi in nature, they are becoming increasingly plausible solutions to address climate change.  Step 1 is to understand atmospheric systems more precisely and Step 2 is to figure out how to manipulate this system.

[Cloud seeding and cloud brightening with salt water to increase solar reflection via wired.com]

Solar Radiation Management could take several forms, but the basic premise of each strategy is the same: to block or reflect solar radiation out of the atmosphere.  Proposals range from cloud seeding, to arctic ice harvesting (for its reflective quality) to large sun disks in outer space.  The first notable proposal, which is still under investigation today, was by the Soviet Scientist, Mikhail Budyko in 1974.  Budyko suggested the injection of gases into the upper reaches of the atmosphere would cool the earth.  The idea is inspired by the natural phenomenon of volcanic eruptions or massive forest fires that send sulfur dioxide into the upper atmosphere where it acts as micro-deflectors of sunlight.  Hovering 10 kilometers above the earth in the stratosphere, this sulfur not only reduces the amount of sunlight that hits the surface, it also creates a haze that diffuses the sunlight.  The most cited precedent for such an approach is the eruption of Mount Pinatubo (Philippines) in 1991, which released 15 million tons of sulfur dioxide into the stratosphere, and cooled average temperatures by half a degree Celcius.   Current predictions estimate that between one and five million tons of sulfur would need to be injected into the stratosphere each year.  From rockets filled with sulfur to hot air balloon smokestacks from coal-fired power plants, there are several options on how to actually get the sulfur into the stratosphere.  One major issue with sulfur injections is that they do not address GHG emissions.  In fact, they require a continual supply of sulfur dioxide in the atmosphere – and, as the earth is further heated - will always require more and more sulfur dioxide in future years.  The economic and resource investment would be continually past down to future generations.  Beyond the technical and unsustainable growth model of sulfur dioxide injections, scientists don’t know enough about atmospheric chemistry to predict exactly what will happen. Without percise climate models, there is little understanding on how this will affect rain, wind patterns and ocean currents.  And simultaneously, climate modeling is our only choice - as it is difficult to test several ideas without impacting climatic systems.  The unpredictable nature of the ensuing effects could be more disasterous than our current climatic crisis.  Others have noted that sulfate shields only work to block sun, and would therefore be less effective during the night and winter.  This differential climate would have several large reaching effects on the world’s ecosystems and oceans.  Oceans, in fact, would continue to acidify because the GHG’s would linger and build in the atmosphere.  Other climate models show that sulfur sunshades could also create catastrophic droughts (droughts were noticed for a year after Mount Pinatubo’s eruption).  With so many variables and little precision in climate modeling, sulfur dioxide injections may pose more problems than solutions, especially because they are cheap.

[Solar Shading - Sulfur, Clouds or Disks? via livingearth.com]

Mitigation Techniques include different forms of carbon capture and carbon sequestering.  Three of the major strands of research here involve (i) Phytoplankton Storage (ii) Artificial Trees, and (iii) Geological Storage.  Phytoplankton consume large amounts of carbon dioxide during photosynthesis. Filling the seas with iron – a favorite of phytoplankton – would encourage blooms that would absorb large amounts of carbon dioxide and transport this to the bottom of the ocean.  The dropping of massive quantities of iron into the ocean and promoting large scale phytoplankton production would have great repercussions on ocean ecosystems – repercussions that we cannot predict.

[The Ocean as a Mega-Phytoplankton Farm? via popularmechanics.com]

Other materials that can capture and store large amounts of carbon dioxide are being explored to augment natural processes.  One such trajectory of research is examining peridotite rocks, which form magnesium carbonate when they react with carbon dioxide.  Others, such as Columbia University’s Klaus Lackner, are exploring the production of ‘artificial trees’.  Lackner’s tree is able to capture a ton of carbon from the atmosphere each day.  What are these ‘trees’ made of?  For the most part, panels of an absorbent resin that react with carbon dioxide to form a solid.  Lackner’s prototypes suggest that a 10m x 10m area of panels could extract 1,000 tons of carbon dioxide each year.  Once captured, these filters can be cleaned with steam.

[Rendering of Artificial Trees developed by Lackner]

The largest issue with attempting to orchestrate a climatic transformation is that we just don’t know enough about how our atmosphere works and the repercussions of our tampering.  Further, most geoengineering schemes require future generations to maintain such measures, with little end in sight.  Geoengineering also poses a political issue, as any response would affect the entire globe.  Because certain schemes, such as sulfate shading, are quite simple and relatively cheap to implement, they could be done by most nations, creating the seeds for future conflicts. Currently, no international laws or treaties would prevent a country from unilaterally beginning a geoengineering project.  Who would monitor such projects, and who should have a say?  The political administering of geoengineering is just as complex as some of the schemes.  Another issue is a social one – the present energy on climate change initiatives may slow if there is a belief that we can always find new engineering solutions to address unsustainable practices.  As it stands, the risks of geoengineering seem to outweigh any possible benefits.  Some scientists predict that we are about 40 years away from understanding this technology.  Once we do, Plan B may be less risky than doing nothing.

A great discussion on Geoengineering took place a few weeks ago on TVO’s The Agenda.  You can watch the episode here.


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