Climate change poses diverse risks to society: from floods and hurricanes to heat waves and droughts. One common paradigm for managing these risks can be thought of as the engineering paradigm wherein risk is managed by constructing social and physical structures that theoretically reduce the probability of disaster: think seismic structures, sea walls, levees, and so on. This week we will explore a highly contentious (and debatable) proposal for engineering our way out of climate risk: geo-engineering.

There are several proposed ways we might reduce carbon emissions via geo-engineering solutions. These include:

• Carbon Capture and Sequestration, arguably the least invasive of geo-engineering schemes with respect to the manipulation of biophysical systems. The main idea in this case is to prevent the carbon released during fossil fuel burning from ever getting into the atmosphere by capturing and sequestering carbon emissions resulting from industrial processes, such as steel and cement manufacturing, petroleum refining, and paper mills.
• Air Capture, or a “put the genie back in the bottle” solution. Unlike Carbon Capture and Storage, which targets emissions from major point sources before they escape into the atmosphere, Air Capture approaches aim to capture CO2 that has already made it into the atmosphere, scrubbing it back out of the ambient atmosphere. In other words, to build high-functioning artificial trees that can take the carbon out of the atmosphere but which, unlike real trees, would not die, decompose, or return carbon to the atmosphere.
• Sulphate Aerosol Production: A last proposition yet is that sulphate aerosols be injected into the atmosphere to create a global “dimming effect” that could offset warming by blocking solar radiation from reaching the earth’s surface (not unlike what happens, for instance, during a major volcanic eruption). The proposition here is that such aerosoles could be injected into the atmosphere by artillery, aircraft, or balloons.

As you watch the David Keith and Naomi Klein Ted talks, think about the very different ways these two individuals frame and conceptualize environmental risk, including that potentially associated with geo-engineering. Think too about how the stories we tell about nature (the ways we socially construct nature) shape the politics of risk-taking, risk-making, and risk governance. Do you believe geo-engineering is a risk worth taking given the climate stakes, or is more of a precautionary approach required? How do such debates connect to Jasanoff’s idea of technologies of humility? What would be required to make geo-engineering a “humbler” kind of technology?