The Curious Case of Geoengineering.

In considering if we can reverse the effects of climate change, considering geoengineering is imperative. This is because by implementing geoengineering techniques, in some cases, would result in the direct removal of GHG’s -  which is the very causation of climate change as determined in previous posts. Geo-engineering is the purposeful modification of the earth’s climate. Only this time, instead of emitting greenhouse gases (GHG’s), modification would aim to remove GHG’s from the atmosphere.

How Would Geo-Engineering Work?

The two main forms of geoengineering are solar radiation management (SRM) and carbon dioxide removal (CDR). SRM reduces the effect of climate change without reducing the level of greenhouse gases. CDR, on the other hand, actively effects climate change through the removal of one of highest emitted GHG’s: Carbon Dioxide.

Solar Radiation Management (SRM):

SRM effectively reduces the amount of sunlight absorbed by the earth’s surface and so effectively reduces the subsequent warming effect. The manual addition of reflective aerosols, like sulphate, in the atmosphere is one of the main SRM techniques proposed amongst many other techniques (whitening of roofs, rearing more reflective agriculture and placing reflective mirrors in space – all to reflect solar radiation). If successful, SRM can modify the climate in an aspect which could allow the mitigation of many centuries of harmful emissions. Planet Earth has another chance.

The premise of reflective aerosols can be understood by considering volcanic eruptions and the ejection of sulphates in the atmosphere that trigger cooling through enhancement of radiation reflection (Timmreck 2012).

There are multiple risks attached to the SRM technique: reflective aerosol addition to the atmosphere. Adding aerosols into the atmosphere would bring about a rapid change in the atmosphere, driving cooling immediately – however, this is based on the premise that aerosols will be replenished continually. Where there is a failure, the climate would rapidly warm, at rates greater than current. Further, the control of aerosols once released is out of the question, meaning that global distribution could be uneven – resulting in uneven modification of climate across the globe (Caldeira et al 2013). This is hardly ethical, nor is it moral. Feasibility and the uncertainty are the main drawbacks attached SRM geo-engineering.

Carbon Dioxide Removal (CDR):

 There are multiple CDR techniques. Concerns surrounding CDR techniques are mainly around the scale of application. Further, will the projects be initiated due to costs and risks attached? In seeking to understand whether global scale reversal of climate change can be attained, I will focus on carbon capture and storage geo-engineering technique.

Carbon Capture and Storage (CCS) is a technology that can capture prior and current emitted carbon dioxide and store it in a suitable place (this can be in depleted oil fields or deep saline aquifers) – effectively removing the driving causation of climate change. CCS is important to initiate change in carbon dioxide levels, particularly where residence time is persistent for thousands of years. CCS allows the possibility of climate change reversal. The science behind CCS is briefly outlined in the video below (Figure 1):

(Figure 1: ZEP - Safe Storage: Closing the carbon loop - CO2 Capture and Storage)

Currently there are 22 projects, either under construction or operational CCS projects. The risks behind CCS needs to be understood to derive viability. Health risks are raised where the input of high concentrations of carbon dioxide may contaminate surrounding areas–thus effecting animals and humans alike. High concentrations can lead to sink lesions, memory loss and death as seen in the release of carbon dioxide at Lake Nyos, Cameroon in 1986 where 100 000 tons approx. of carbon was released (Fogarty 2010). Concerns also include whether CCS can reverse some of the damage borne through anthropogenic emissions (Caldeira et al 2013).

Geo-engineering has multiple risks attached to initiating the schemes. CDR schemes are more appealing to me, tackling the situation at the source. Further, unlike reflective aerosols that involve tampering with the atmospheric climate – I believe we have done enough of that. Of course, there are multiple other SRM techniques like raising plant reflectivity and placing large mirrors in space – but these lack finesse in their ability to affect global temperatures and viability, respectively. I believe that geo-engineering schemes are valuable in line with renewable energies – seeking an alternative away from carbon dioxide is vital whilst managing the current anthropogenic emissions is the way forward to reversing climate change.