Tuesday, 8 April 2014

G3E4O Geoengineering and the Engineers of Gaia

Earthrise seen by the Apollo 8 crew, 1968. Credit: NASA
Blog by Nils Roenner and Guillermo Rein, Department of Mechanical Engineering at Imperial College London.


Because of global concerns on climate change, engineers are called to have a leading role in tackling the problem, and a new discipline is being proposed: Geoengineering (G3E4O(IN)2R).
The realisation that man has an impact on Earth has led to the idea of the Anthropocene which signifies the current geological epoch, ‘the recent age of man’. Humans are being viewed as a factor and intricate part of nature. This is in agreement with Dr Lovelock’s Gaia hypothesis, introduced in 1979, a revolutionary view of the Earth not as a simple accumulation of systems but as one self-regulating system encompassing everything, including life.
Sketch of the Earth as system of systems with interdependencies and feedback lines outlined. Adopted from Rial et al. 2004 (10.1023/B:CLIM.0000037493.89489.3f).
In an article we wrote in 2013, The Engineers of Gaia, by using the concept of Gaia and the Anthropocene as starting points, we argue that the control system view of Earth is a vital part of geoengineering. It is not about one mechanism, it is about the self-regulating system as a whole. But if geoengineering was to apply a forcing too large or at the wrong place, such that positive feedback loops overtake, the results could be drastic and unpredictable. Careful and robust control is required when engineering something as vital as the system Earth, and this argument is often invoked to stop geoengineering proposals. Paraphrasing Prof Henry Petroski, for us, the premise would be that geoengineers welcome all the relevant science they can muster, but cannot wait for complete scientific understanding before acting to save life or create a new planet-saving technology. We also maintain that up until the moment when adequate understanding and models of the system are found only reversible and well controlled geoengineering interventions should be applied on a large scale, in order to prevent uncontrollable feedback being set off or reaching tipping points by accident.

The term geoeneering has only recently gained traction in the public debate, and its definition still varies according to the source. We think this can be defined as the large-scale anthropogenic intervention into the system Earth in order to adjust planetary mass and heat transfer processes, such that global catastrophes can be mitigated. Geoengineering opens up a broad range of measures with which global climate change can be tackled. No geoengineering approach should be viewed as a single solution to all of the problems associated with climate change. Most likely a combination of approaches will yield long term success. 

Our article briefly evaluates four promising applications of geoengineering using a set of criteria by which geoengineering proposals can be evaluated in term of feasibility, effectiveness, safety, geointervention, and costs.  These are summarized here:

Carbon Capture and Storage is a good option for rich countries aiming at reducing its CO2 emissions from power plants. Apart from its high cost, this method is very feasible and effective with low levels of geointervention and risks.

Biomass Burial is a good option for countries that have suitable and extended land. It is a lower cost approach and can be scaled up to have a larger impact. Low cost, feasibility, effectiveness and low levels of geointervention speak in favour despite some risks, like fire, which need to be managed.

Iron Fertilisation of oceans is an option for countries with coastal access. The low cost involved and the proven feasibility make this method appealing. But concerns about low effectiveness, high level of geointervention and high risks question the validity of the approach.

Cool Roofing of Building is a good approach for densely populated areas or countries with high annual level of sunshine. The low cost, risks and level of geointervention of this feasible option are attractive but on the other hand, it has a weak effectiveness and cannot control secondary effects.

Illustration of the strengths and weaknesses of the proposals under study.
It can be said for all geoengineering proposals, that due to our incomplete understanding of all feedback and threshold points in the global system of the Earth, the topic has to be approached with great caution. But its potential in helping to solve the great problem of climate change, make the efforts put into research and experiments worthwhile.