CDR: Negative Emissions For A Positive Future

Since the United Nations Framework Convention on Climate Change in 1992, there has been a growing urgency in the scientific community for stabilising atmospheric greenhouse gas levels. However, stabilising greenhouse gas levels, as shown by modelling (Matthews, 2006) is not enough to stabilise the global climate. His model (as well as others) illustrated that despite stabilisation, we have committed ourself to future warming. Management should not simply focus on stabilising current emission levels but should work to reduce them, cutting anthropogenic emissions to an all time low. It is here where Carbon Dioxide Removal (CDR) methods of geoengineering are most valuable.

Mathews & Calledeira (2007) suggested a need for 0 carbon emissions from anthropogenic sources to reduce further future warming. However, cutting emissions to nothing overnight is next to impossible. The same could be said for the next decade or even next few decades. However, if we invest in some of the carbon capture schemes mentioned in the second blog post, we can attempt to offset our emissions through finding a balance between carbon emissions and carbon capture. Such a strategy will prolong the use of fossil fuels in sectors where decarbonisation will require more time and technology (e.g the transport sector).

The main challenge currently faced is the need to make CDR technologies universally economically viable. Authors such as David Keith (2009) argue that the cost of large scale air capture schemes will decrease and enter competitive markets in the near future. However, this has recently been fiercely opposed by authors suggesting previous cost suggestions for CDR are gross underestimates.

I personally take a more optimistic view on this topic. When faced with the issue of carbon emissions from vehicles it was not long until electric cars were introduced, with pioneering designs such as the Tesla Model S making their way into markets at a competitive $30,000 price. Such innovations make me hopeful about future technology at economically viable prices. We are already seeing new start ups (e.g Climeworks, Global Engineering & Global Thermostat) entering the markets, attempting to provide innovative and affordable methods of CDR, with more research this could be an upcoming field. For example, the company Carbon Engineering has already produced an effective mechanism for air capture of carbon. Summed up in the cutting-edge video below (give it a watch!), the air capture system filters CO2 from the air and stores it as a liquid form. Most interesting, however, is where the video discusses the potential for a globally sustainable carbon supply. Here carbon is absorbed from the atmosphere, converted into hydrocarbons and placed back into the atmosphere in a self-sustaining system (Figure 1).

Furthermore, with greater environmental governance such as the recent COP21 negotiations, nations will be inclined to invest in CDR strategies to meet agreed targets. Where targets are unrealistic, wide scale CDR schemes will provide effective assurance.

Figure 1: Potential for a global self sustaining system of carbon capture, conversion, use and capture again (Source: http://carbonengineering.com).

However, the environmental viability of CDR schemes is also a matter which is commonly contested. A recent article in Nature by Williamson (2016) it was suggested 600 gigatonnes of CO2 must be removed from the atmosphere to limit global temperature rise to 2°C. Using Bio-Energy with Carbon Capture and Storage (BECCS), this would require the equivalent of half the land area of the United States to be planted with crops solely for the purpose of carbon removal. Therefore, he indicated that the land requirements required for BECCS to work would accelerate the loss of grasslands and primary forests. The biodiversity losses of this would be catastrophic, potentially even worse than a business as usual scenario. The paper then highlights issues with other CDR methods such as iron fertilisation, biochar application and enhanced weathering. However, the author gave appraisal to the direct air capture (DAC) method of carbon removal but highlights similar concerns for land space and potential carbon leakages.

In conclusion, I still believe CDR remains a valid potential mitigation strategy. Williamson's study does not make reference to BECCS being used alongside innovative CDR schemes which together can offset carbon. I follow Keith's argument and take example from our ability to develop solutions when a problem is pertinent. Despite concerns, CDR shows innovative potential and although it is not going to be the silver bullet, stand alone cure to our climate conundrum, it is a bullet in itself and a strong one nonetheless.