What is geoengineering?

Scary, exciting, mad, amazing, never, or why not now? These are some of the initial reactions which people have to the idea of geoengineering. Geoengineering has the potential to leave a deep mark on the 21st century. This is the first in a series of blogs in which I will explore geoengineering and ethical issues associated with it. In this post I will try to give you a sense of what geoengineering is.

 Geoengineering is the idea that technology can be used to control the climate. How? This seems a natural question to ask, how could we control the climate? How could we control this intangible background condition of life? The answer is quite simple, crudely put our climate is the product of sunlight (solar radiation as a source of heat), passing through the stratosphere, and the quantity of greenhouse gases in the atmosphere, which determine how much sunlight is trapped. Therefore we can geoengineer by altering the amount of sunlight that passes through the stratosphere or altering the quantity of greenhouse gases in the atmosphere.

Ok, that may well make sense in theory, but is it actually possible? We can hardly stop the sun from shining; can we really reduce the amount of sunlight that passes through the stratosphere? Or can we remove greenhouse gases from the atmosphere? If this sounds like an idea that belongs in the realm of science fiction… you have a point, insofar as the idea of the climate being controlled exists in seminal science fiction stories such as Doctor Who and Hitchhikers Guide to the Galaxy. In a further blog, I will provide a fuller account of the history of the idea of geoengineering which is not only futuristic but exists in the pages of history as well.

Despite sounding like something from science-fiction, geoengineering does not require a time-lord esque level of technology. Think of removing greenhouses gases from the atmosphere; this already happens naturally when plants absorb carbon dioxide from the atmosphere to photosynthesise. There is a set of geoengineering response which propose using or enhancing this natural process on a scale to alter the earth climate. Alternatively, we can consider more science fiction like carbon capture technologies, where we have an image of a black box that absorbs carbon.

Let’s consider the other variable in the climate equation, solar radiation; how can we prevent it from reaching the earth’s surface? It might seem that answers to this question will be science-fiction-like and many are, but there are natural ways of doing this. Simply put, light coloured surfaces reflect sunlight. So simply painting our house white would reflect sunlight, as do clouds. These inspire a set of proposals that try to increase how reflective the earth’s surface is to counter climate change. Now we reach the science fiction examples, there a set of proposals that consider how to stop sunlight passing the stratosphere. For example, we could put mirrors in space to reflect sunlight prior to it reaching the stratosphere. Or we could increase the reflective properties of the stratosphere by increasing the quantity of sulphur in the stratosphere.

So there are loads of different ways in which geoengineering could happen. Your reaction to the idea of geoengineering may be strong; it is a thought and emotion-provoking proposal. Often people have a response of concern about humans seeking to engineer the climate when we frequently fail to handle much simpler problems. In a few of the following blog posts, I shall present some different reasons for being interested in geoengineering, ranging from the fear of untrustworthy politicians having control over geoengineering to geoengineering being an insurance policy against a climate emergency. Once we have this clear idea of why we might be interested in geoengineering (and the bad reason for being interested in it), we can start to explore the maze of tough and interesting questions that relate to geoengineering.

This is just meant to provide a sense of what geoengineering is, this should not be understood as a comprehensive account of geoengineering science, for further information on the science of geoengineering I recommend reading:

An overview of the Earth system science of solar geoengineering: https://onlinelibrary.wiley.com/doi/full/10.1002/wcc.423

Royal Society report on Geoenigneereign (2009). Geoengineering the Climate. Relevant chapters 1-3: https://royalsociety.org/~/media/Royal_Society_Content/policy/publications/2009/8693.pdf