Understanding geo-engineering …

Before I sink my teeth into the debate at hand, perhaps I should first clarify what is meant by the ambiguous term “geo-engineering” …

The experts offer the definition “the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change" (The Royal Society, 2009); for me this definition offers very little clarification as to what geo-engineering actually involves, to do so requires a bit of background knowledge about the Earth’s energy balance:

Much of the solar radiation that reaches the Earth’s surface is absorbed (but not all – this becomes important later!) and re-emitted as warming infrared radiation.  Although, not all the re-emitted infrared continues on its path beyond the Earth’s atmosphere, a proportion is retained in the atmosphere by greenhouse gases, a natural and necessary occurrence (else the earth would be pretty cold right now!).   However, burning of fossil fuels for example has increased the concentration of greenhouse gases, thus the atmosphere is retaining more infrared radiation and the world is getting warmer!

So what do we do about it?  

Well, if your rooms getting too hot what do you do? You have two options:

·      Turn down the thermostat and reduce the heat energy going in

·      Crack open a window and allow more heat to escape. 

…It’s simple.

These basic ideas exemplify how geo-engineering aims to re-adjust the Earth’s energy balance such that less infrared radiation is retained within the atmosphere.  Thus geo-engineering concepts fall into one of two categories: solar radiation management (SRM) which reduces the energy going into the climate system and carbon dioxide removal (CDR) which allows more heat to escape.

Solar Radiation Management (SRM)

SRM alters the energy balance of the planet by increasing its albedo, directly reducing the amount of solar radiation absorbed by the Earth’s surface and the consequential amount of warming infrared radiation emitted into the atmosphere. Such manipulations span from proposals intent on increasing the proportion solar radiation that is reflected from the Earths surface, to reducing the amount of solar radiation penetrating the atmosphere entirely.  SRM is very much the centre of the geo-engineering debate, with pro geo-engineering scientists (such as Ken Caldeira, David Keith and Paul Crutzen) portraying such technology as a quick fix in the event of a climate emergency, due to its potential for maximum efficiency and effectiveness (supposedly its cheap and easy as well!).  Conversely, the geo-engineering sceptics are up in arms about such manipulations that don’t alleviate the high concentration of atmospheric C02 and pose the threat of further distorting our climate system.  So should we put on our ‘seatbelt’ in anticipation of a climate crash as posed by Caldeira? As tempting as this might be, would we simply be relieving the symptoms instead of finding a cure? – These are kinds of discussions I’m keen to explore!

 Cardon Dioxide removal (CDR).

CDR, of the two, is regarded as the more sustainable option, working directly to correct the excessive concentration of C02 in the atmosphere.  It stands to reason that this would reduce the greenhouse effect, inducing cooler temperatures by enabling more infrared radiation to escape.  This option looks far more appealing as it directly addresses the primary cause of climate change and has fewer climatic uncertainties.  The downside, however, is that this option can be costly and by no means a quick fix, delays in climatic response mean that this type of approach needs to be implemented fairly quickly if we are to continue burning fossil fuels at the current rate!

So the debate thickens … do we develop and implement geo-engineering technology? If so, do we implement CDR and/or SRM? I warn you, don’t hedge your bets too soon, as I’m going to delve further into some of the utterly bizarre and brilliant techniques that have been proposed.