Geo-engineering interlude and other SRM considerations

Over the last couple of weeks I have hopefully given you a bit of insight into key features of the main solar radiation management (SRM) approaches.  I expect that you have been able to gauge the imperfect nature of the methods proposed, that their feasibility (cost, effectiveness and risks) are flawed.  They should not go ahead without question nor further investigation. There are numerous reasons that I ask you to think beyond what I've been able relay to you, as there is so much more to consider beyond the summarised version I have so far portrayed:

• Local/regional scale impacts: Where will be subjected to the most significant climate and weather anomalies due to geo-engineering? Who will be affected? To what extent are these societies and ecosystems able to successfully adapt to these adverse conditions? What are the financial implications? These are all questions that require thorough evaluation before such measures be taken.  Take the South Asian Summer monsoon for example. I’ve referred to several studies forecasting the disruption of this monsoon system under the influence of geo-engineering (such as Bollasina et al, 2011).  The lives of 1.5 billion people in South Asia alone are intrinsically linked to this dynamic system.  The success of their water resources, agriculture, ecosystems, health and economies is shaped by the 70-80% of annual rainfall that falls in just 4 short months.  Compounded by high levels of poverty and a significant reliance on agriculture in this region, the acknowledged sensitivity of the monsoon system ensures that this region is highly vulnerable to geo-engineering.  The capabilities of such large and growing populations to adapt, and the financial implications (the cost of adaptation and the potential losses induced by declines in productivity) need to be fully appreciated.  This applies to all sensitive areas, including consideration to the impacts on the biosphere.

• Unexpected outcomes: No amount of modelling can guarantee the future outcomes of geo-engineering.  There is much progress to be made towards further understanding the non-linear and variable nature of climate and its associated feedbacks.  The knowledge that we lack is reflected within our models, as their performance is dependant on the data and parameters we put into them. We have a long history of ‘accidentally’ altering our natural environments (acidification, global warming, holes in the ozone), with many of the mechanisms driving this change becoming apparent once the negative impacts have been realised.  Hindsight is a wonderful thing, but can we afford to risk unpredictable climate changes when the stakes are so high?  Similarly, with the stakes being so high execution of the more feasible SRM techniques would be need to be meticulously executed.  As with our history of ‘unexpected’ impacts, we also have a long history of just doing things wrong – everyone makes mistakes, but can we afford to? If we consider the possibility of implementing stratospheric aerosols.  If we found ourselves in a situation whereby we were had been successfully geo-engineering our climate for an extended period of time and something went wrong (somebody forgot to do something, a system failed, or we find that the negative impacts are simply to great), that leads us to a new problem - the termination problem (Matthews and Caldeira, 2007).  If geo-engineering were to stop abruptly subsequent years would undergo a rate of climate warming 20 times greater than we are currently experiencing (with 20 times more catastrophic impacts?).  Where A2 is a scenario for continued global warming, GEO showing the effect of geo-engineering and OFF_2025/2050/2075 indicating the abrupt stopping of geo-engineering at for each of those respective years; the diagram demonstrates that the longer we employ geo-engineering, the more significant the termination would be.

Figure from Matthews and Caldeira (2007)

          ... which raises a new point, geo-engineering is a commitment – if we start we can’t 

          simply stop! We would be committing future generations to sustaining an SRM   

          program.

• High levels of CO2 are still high! A final point I’d like to raise is that of global warming not being a lone symptom of anthropogenic CO2 emissions.  Thus, to treat this one symptom with SRM geo-engineering neglects the other real threat of ocean acidification.  Integrated within the Earths biogeochemical cycle, the ocean is a key sink for C02. As we have emitted C02 in to the atmosphere, the ocean has taken up equivalent to half these emissions serving to lower the average pH by 0.1.  Already we are seeing significant impacts on ocean biota, such as coral bleaching and subsequent food web alterations.  Based on past records it has been estimated that if we continue on our current trajectory of CO2 emissions the pH of the ocean will decline by a further 0.4 by 2100 with devastating impacts on ocean biodiversity and associated food-webs including human livelihoods (Royal Society, 2009).  Ice core records indicate that in the past Earth has experienced substantially higher atmospheric C02 than at present.  However, the fastest know increase was 80ppm over 6000 years IPCC (2001). Slow changes accommodate inertia in the ocean systems, such that they can gradually alter and buffer the impacts of changing CO2 levels. After 200 short years of rapidly increased CO2 draw down into the oceans not only are we experiencing dramatic impacts, but the oceans will require tens of thousands of years to fully readjust.  Artificial means of reducing acidification are currently not an option; the only sure solution is to reduce emissions.  If we fail to remedy ocean acidification, additionally the rate of CO2 draw down will decline thus increasing the demand for geo-engineering.  For me this highlights the need to directly address CO2 emissions and not SRM!

And with that, over the next few posts I am going to move on to the remaining category of geo-engineering, CDR. These methods could be considered a form of mitigation as they address the issue of high atmospheric CO2 concentrations.  Will these prove to be viable options or by entertaining these ideas are we simply ignoring the elephant in the room?