|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).|
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.|