Abstract

How might we cool the planet if we fail to meet our CO2 emissions targets? This is a question that perhaps we shouldn’t even ask because it will distract us from our primary goal of reducing CO2 emissions. But seriously, what if our CO2 reduction efforts don’t work? Do we just accept the climate consequences of the CO2 we generate (35 billion tonnes we emit annually) – sea level rise, desertification, ocean acidification, loss of habitat – or do we try to fix the damage that we are causing?

There are several viable technologies for controlling the climate – known as “geoengineering”. Carbon Dioxide Removal (CDR) by sequestering CO2 is one, or Solar Radiation Management (SRM) using space reflectors is another. The SPICE project (Stratospheric Particle Injection for Climate Engineering) investigates the benefits, risks, costs and feasibility of SRM by injecting reflective aerosols in the atmosphere. If particles can be pumped into the stratosphere at an altitude of 20km, emulating the effects of a large volcanic eruption, then global cooling of about 2 degC can be achieved. The particles would be pumped through a number of high-pressure pipes suspended by balloons. SPICE presents many novel engineering challenges, especially the design of the pipe and pumping systems to withstand pressures up to 4000 bar and tensions up to 500 tonnes. In this non-technical introductory presentation a number of these challenges will be discussed. The important questions of ethics and governance will also be addressed.

The answer to the question is “No, we should not engineer the climate”. In that case we should stop burning fossil fuels