Geoengineering May Be Necessary, Despite Its Perils
A Royal Society study sorts through the potential of technologies aimed at offsetting climate change.
Geoengineering might be a terrible idea, but it could also be the
only option if efforts to slow carbon dioxide emissions continue to fail,
according to a new report by the Royal Society
in London.
Broadly defined, geoengineering is any
attempt to counteract climate change on a massive scale. It includes two main
approaches: pulling carbon dioxide out of the atmosphere (such as by increasing
the growth of algae that take up carbon dioxide) or somehow decreasing the rate
at which the sun heats the earth (such as by shading the planet or increasing the reflectivity of clouds).
In both cases, scientists don’t know what
might go wrong with the proposed schemes–their scale is unprecedented.
According to John Shepherd, who chaired the Royal Society’s study, “used
irresponsibly or without regard for possible side effects, geoengineering could
have catastrophic consequences similar to those of climate change itself.”
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Yet if climate change starts to get out of
control, we may be left with no alternatives. “Geoengineering and its
consequences are the price we may have to pay for failure to act on climate
change,” Shepherd adds.
The study analyzed the proposed
geoengineering alternatives to decide which are most likely to work without
disastrous consequences. Notably, one approach advocated publicly by U.S. Energy
Secretary Steven Chu–painting roofs white to reflect sunlight–didn’t come out
well.
Here’s a summary of what the Royal Society
study found.
Regarding carbon capture methods:
· CO2 capture from ambient air: This would be
the preferred method of geoengineering, as it effectively reverses the cause of
climate change. At this stage no cost-effective methods have yet been
demonstrated and much more research and development is needed.
· Enhanced weathering:
This technique, which utilizes naturally occurring reactions of CO2 from the
air with rocks and minerals, was identified as a prospective longer-term
option. However, more research is needed to find cost-effective methods and to
understand the wider environmental implications.
· Land use and afforestation: The report
found that land-use management could and should play a small but significant
role in reducing the growth of atmospheric CO2 concentrations. However, the
scope for applying this technique would be limited by land-use conflicts, and
all the competing demands for land must be considered when assessing the
potential for afforestation and reforestation.
Should temperatures rise to such a level that
more rapid action needs to be taken, the following solar radiation management
techniques were considered to have most potential:
· Stratospheric aerosols: These were found to
be feasible, and previous volcanic eruptions have effectively provided
short-term preliminary case studies of the potential effectiveness of this
method. The cost was assessed as likely to be relatively low and the timescale
of action short. However, there are some serious questions over adverse
effects, particularly the depletion of stratospheric ozone.
· Space-based methods: These were considered
to have potential for long-term use, if the major problems of implementation
and maintenance could be solved. At present the techniques remain prohibitively
expensive and complex and would be slow to implement.
· Cloud albedo approaches (e.g., cloud
ships): The effects would be localized and the impacts on regional weather
patterns and ocean currents are of considerable concern but are not well
understood. The feasibility and effectiveness of the technique is uncertain. A
great deal more research would be needed before this technique could be
seriously considered.
The following techniques were considered to
have lower potential:
· Biochar (carbon
dioxide reduction technique): The report identified significant doubts relating
to the potential scope, effectiveness, and safety of this technique and
recommended that substantial research would be required before it could be
considered for eligibility for U.N. carbon credits.
· Ocean fertilization (carbon dioxide
reduction technique): The report found that this technique had not been proved
to be effective and had high potential for unintended and undesirable
ecological side effects.
· Surface albedo approaches (solar radiation
management technique, including white-roof methods, reflective crops, and desert
reflectors): These were found to be ineffective, expensive, and, in some cases,
likely to have serious impacts on local and regional weather patterns.
