Through a series of workshops with members of the public, Australia’s Natural Environment Research Council (NERC) conducted a public dialog to assess public opinion on howgeoengineering research should be directed, conducted and communicated. The research effort explored people’s attitudes towards various potential geoengineeringmethods. At the workshops, participants came together for up to threedays to discuss the ethical, moral and social issues associated with the possible use of geoengineering methods to alter our environment.
What is geoengineering?
Geoengineering is “the deliberate large-scale intervention in the Earth’s climate system, in order tomoderate global warming,” according to the Royal Society’s report Geoengineering the climate. It includes technologies which could either remove CO2 from theatmosphere or reduce global temperatures by reflecting sunlight backinto space.
This public dialogue focused on nine geoengineering technologies. The technologies chosen for discussion broadly reflected those discussed in the Royal Society’s report. The dialogue did not provide exhaustivecoverage of all geoengineering techniques. For practical reasons, mostnotably the time available to discuss the technologies with participants and to avoid information overload, a selective list was necessary. Thetechnologies can be divided into two main categories, Carbon DioxideRemoval (CDR) and Solar Radiation Management (SRM). Both sets oftechniques have the ultimate aim of lowering global temperatures, butapproach the task in different ways. The dialogue project included aselection of both CDR and SRM techniques.
CDR techniques address the root cause of climate change by removingCO2 from the atmosphere. During the dialog, the following techniqueswere discussed:
Biochar: Vegetation, which uses CO2 from theatmosphere for growth, is heated and starved of oxygen to lock thecarbon into biochar (finely grained charcoal) rather than releasing thestored CO2 back into the atmosphere when the vegetation decays. Thebiochar is then buried and can store away carbon for thousands of years.
Liming the Ocean: ‘Lime’ (Ca(OH)2) would be createdfrom limestone carbonate rocks and added to the oceans to make them more alkaline, which makes them absorb more CO2 from the air.
Iron Fertilization: Adding nutrients such as iron to certain areas of the ocean to promote ‘blooms’ of algae. As the algaegrow they soak up carbon dioxide from the atmosphere. When they die they sink out of the upper ocean, taking the carbon with them potentiallyfor hundreds of years.
Air Capture: ‘Artificial trees’ would be made thatremove carbon dioxide from the air. The air passes through chemicalsolutions or compounds that absorb and collect CO2, which can then beremoved, transported and stored.
Afforestation: Planting more trees and managing land use would help reduce CO2 levels as the newly-planted trees wouldabsorb more from the atmosphere as they grow.
SRM technologies attempt to offset effects of increased greenhousegas concentrations by reflecting a small percentage of the sun’s lightand heat back into space. The following were included in the dialoguediscussions:
Sulphate Particles: These would mimic what happenswhen large volcanoes erupt, sending sulphate particles up into the air.Sulphate particles scatter the sun’s rays back into space, preventingthem from reaching Earth and so cooling the Earth. Military planes orhot air balloons would disperse sulphate particles in the upperatmosphere.
Mirrors in Space: Many small mirrors or reflectivemesh put high up in space, acting as a sunshade to reflect some sunlight away from the Earth, and preventing it from warming the atmosphere.White Roofs: Painting surfaces white or making them more reflectivemeans that less heat from sunlight is absorbed by the Earth, so lowering temperatures.
Cloud Whitening: Some clouds cool the Earth byreflecting sunlight back into space. By spraying small seawater droplets into the air over the sea, it is possible to increase the reflectivityand (possibly) longevity of existing clouds. The seawater could bedeployed using normal ships, radio controlled vessels or airplanes.
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