I spent my weekend researching the possible exacerbations geo-engineering may pose to our climate, riveting I know… One that seemed to erode on me was the issue of acid rain as a result of Stratospheric Sulphate Injection. Are we going to have to get down with pH to combat climate change?
Acid rain is the result of an increased presence of Sulphuric or Nitric acids having reacted with water, hydrogen and other molecules which then precipitates as rain, snow, or tiny dry sediments. The concern here is where that precipitation ends after surface processes. Aquatic environments and ecosystems are particularly vulnerable to the effects of acid rain.
The Institute for Public Affairs, an Australian think tank attempted to discuss the topic, ‘Would you swap climate change for acid rain?’ The review lacked any insight to the influence SSI would actually have on global sulphuric deposition; and instead attempted to form an almost sceptical, critical analysis on the discourse of SSI and somehow relate this to previous efforts to prevent acid rain?! I didn’t really get where they were going with it either…
Yes, what goes up, (most of the time), must come down. Whilst the IPA made a feeble attempt to discuss a valid argument, Ben Kravitz did not. A 2008 paper distinguished injection of sulphate aerosols both throughout the tropics and polar regions to study acid circulation and deposition, and as a result where would be most affected. The figure below illustrates the increased load in acid deposition with a peak concentration of 35 mEq m−2 a−1 due to solely SSI. Injection in tropical latitudes shows increased acid deposition across much of the northern hemisphere whilst this is constrained to mid – latitudes in the southern hemisphere. The regions most effected follow current patterns of areas with greater acid deposition.
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| Kravitz, B., A. Robock, L. Oman, G. Stenchikov, and A. B. Marquardt (2010), Correction to “Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols,” J. Geophys. Res., 115, D16119, doi:10.1029/2010JD014579. |
Kravitz published two papers, one – concluding the effects of acid deposition were minimal and only in ‘pristine areas’ would the environment not act as a sturdy buffer; and the second – a paper actually correcting himself. Kravitz made a little mistake with his arithmetic and one of the governing equations yet this mistake only progressed his conclusion! (I'm sure he felt very smug and since reading the IPA review I can't help empathising with him). I think one is right in saying Stratospheric Sulphate Injection will influence acid deposition, however, the concentration of Sulphur to be injected is minute compared to that produced by current industrial processes, and realistically the additional loading isn’t a real cause for concern.
I came across this interview between Alan Robock, renowned for his research in the field, and Patrick Roddie, an environmental activist. Watching I felt sorry for Alan having to answer what can only be described as a dumb question, 'What are the health effects of SSI (and in turn acid rain)?'' Personally, I feel acid rain is just a popular household phrase one can jump to when discussing harm to the environment, there are much more serious issues surrounding SSI which keep me on the fence. To ask about the 'health effects,' my advice to Roddie would be, drink it and find out.
Initially when writing this post I was curious how SSI would influence acid deposition as I had encountered many contradicting thoughts during lectures and discussions the past few weeks. However, thinking back to the idea of ‘tipping points’ in the Earth system, if SSI can prevent an irreversible moment at the cost of a little extra ‘acid rain’; my answer to the IPA would be, YES, LET’S GET DOWN WITH pH!
Love it. Idea: link to your first post when you intro SSI in the second post.
ReplyDeleteGreat read on the 'PH side' of geoengineering! What is the viability of SSI in terms of technological capacity and cost implications? How certain are scientists in terms of SSI's efficiency in reducing global warming, and within which timeline would this happen with respect to the 'conventional' ways of dealing with the problem?
ReplyDeleteHi Asha, thanks for your input! I will be discussing the economic and technological aspects in a later post - it's a big topic and the literature carries a lot of uncertainty, understandably! The idea of SSI (which some disagree with) is that it is a 'quick fix.' So to answer that question, the method is expected to act very quickly. Once injected there is no activation time, the heat flux at the top of the atmosphere would begin to fluctuate as soon as the molecules were in the atmosphere.
DeleteVery interesting and thought provoking read! I have mixed feelings about this topic as I feel the impacts of acid rain in particular on the ecology of lakes and rivers is detrimental and outweighs the benefits of geoengineering. What are your thoughts on this?
ReplyDeleteThank you very much! I would disagree since writing this post, Kravitz' report identifies prospected loading to be minute, less than 1% of acid deposition from current sources. If acid rain is of concern I would be more interested in mitigating current procedures causing sulphur dioxide emissions which act in the Troposphere. The prospect of geo-engineering is to curb rising temperatures, not prevent acid rain.
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