Geoengineering the Climate

There has been increasing awareness of the fact that the climate is warming at a faster rate than ever – a temperature rise between 0.2-0.8(± 0.2°C) from the pre-industrial era till date which paints a bad picture of flooding for some nations, droughts or harsh winters for others, and economic problems for all.
Several proposals have been considered by various Governments who, in accordance with the Kyoto Protocol, have set up policies to mitigate gases such as sulphur hexafluoride, hydrofluorocarbons, nitrogen oxides, methane and carbon dioxide that absorb and emit infrared radiation back to the earth’s surface. Developed nations have successfully reduced every other greenhouse gas except carbon dioxide, whose level has increased by over 108 parts per million (ppm) since 1850 due to ever-increasing emissions from fossil fuel-based plants and vehicles which, left unchecked, could result in a global temperature rise of about 2-3°C by the next century- a very significant rise in temperature, considering the fact that the temperature difference between an interglacial period and an ice-age is only 6°C.

As carbon dioxide can remain in the atmosphere from 5 to 200 years, it follows that even if every nation’s government successfully implements key carbon emission reduction policies for each sector in 2010, atmospheric carbon dioxide concentrations cannot return to the pre-industrial levels of about 280ppm within 1000 years; hence the need for geo-engineering. Geo-engineering or Climate Engineering has been described as man’s deliberate, large-scale effort to counteract the effects of anthropogenic climate change, and it is essentially a supplementary solution aimed at either reducing the incoming amount of solar short-wave radiation, termed as Solar Radiation Management (SRM), or increasing the outgoing amount of long-wave radiation by transferring significant amounts of atmospheric carbon dioxide to the depths of the earth or sea, termed as Carbon Dioxide Removal (CDR).

SRM proposals include launching reflective mirrors in space, increasing cloud albedo via ocean spray, stratospheric injection of sulphates and fabricating desert reflectors or painting roofs white. CDR proposals include deploying carbon scrubbers that capture atmospheric carbon dioxide in conjunction with sequestration of the gas in magnesium-rich sedimentary rocks or saline aquifiers, ocean iron fertilization, enhanced weathering of silicate rocks amongst others. Other climate change proposals not covered in the Royal Society’s September 2009 Geo-engineering the Climate Report are also under assessment, such as the electrolytic conversion of carbon dioxide to high octane hydrocarbons, termed as ‘Carbon Dioxide Recycling'.

The feasibility of each proposal in terms of its climate cooling effectiveness, reversibility (in the event of negative side-effects to the environment), as well as the costs, and legal/ethical implications involved need to be considered. CDR geo-engineering proposals are more accepted by scientists and the general public than SRM techniques, mainly because they directly address the root cause of global warming, and also because intuitively, the public considers CDR techniques to be less invasive to the earth’s complex and integrated climate system.

This information was obtained from various texts as part of some research I completed in 2010.

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