Geoengineering?

In my last post, I mentioned geoengineering in the form of carbon dioxide removal and solar radiation management. In this post, I will be exploring how geoengineering may impact agricultural productivity. In particular, I will be exploring solar radiation management.

Current climate change observations suggest an increase in average temperature, shown in the graph below. To combat rising mean surface temperatures, solar radiation management (SRM) has been suggested as a possible solution. SRM aims to reflect a proportion of the sun's rays away from Earth, by doing so stabilizing temperatures. This is done through methods such as space reflectors and stratospheric aerosols. It is seen as a cheap and effective method of stabilizing climate, as it can reduce mean temperatures within days, weeks, or months.

SRM has performed well in different models - for example, Govindasamy and Calderia (2000) used the Community Climate Model to show that it could reverse global annual mean warming. However, as Rach et al. (2008) have shown, SRM methods such as stratospheric sulphate aerosols, whilst effective in stabilizing temperature can also create changes in precipitation as well as 'contributing to the total global source of acid rain'.

Source: NASA

In cases like these, I wonder whether SRM may impact agricultural production leading to changes in food security. I stumbled across Pongratz et al. (2012)'s paper on this very subject, where they found that SRM under climate models showed increase crop yield. The top panels show yield increases on different crops with SRM, in comparison to unmodified climate. 

Source: Pongratz et al. (2012)

However, what I found interesting was that this effect is not uniform across the globe. The study then looks into yield and crop production by geoengineering, this time separating it by latitude. 

Source: Ibid

The second figure suggests that regions will experience changes in crop productivity to varying extents, and thus may indicate changes in food security. I do wonder whether the regions that experience loss in agricultural productivity are compensated by those experiencing gains. 

In this sense, I further question whether geoengineering will be a viable option in the future, because countries will not willingly put themselves at a loss. Additionally, SRM's impacts on agriculture in regions may create new geopolitical tensions especially if an area goes under famine. Furthermore, what happens if a region predicted to gain agricultural productivity does not deliver completely? Jamais Cascio suggests that an international body takes over to supervise geoengineering- but I am skeptical as international bodies does not guarantee tension-free food security. Therefore it does not come to me as a surprise when the UN extended the freeze on geoengineering based on the premise that we do not know its full impact on biodiveristy. 

Pongratz et al. (2012)'s study indicates that a country with a massive population such as India, will experience losses in maize yields, but have increased rice, and wheat yields. In Yang et al. (2016)'s paper on Indian groundnuts, SRM has a huge impact by decreasing its yield up to 20%. Interestingly, they also found that once SRM is switched off, the yields slowly return back to normal with no statistical difference. I wonder if this could mean we could experiment with geoengineering to understand the implications for each country. But again, I don't believe geoengineering is a viable option anytime in the future, especially since it may negatively impact certain areas' agricultural productivity which threatens a nation's food security.

What I find quite odd is that within cost-benefit analysis of geoengineering, little about health is mentioned. To rectify this, Effiong and Neitzel (2016) investigates the health impacts of stratospheric aerosol from SRM. The two found that SRM is unjustifable given the direct health impacts such as respiratory weakening. The table below summarizes the main impacts. This study was terrifying for me, as there are so many insufficient data available when it comes to potential SRM aerosol interactions. Additionally, this study only looks into the direct impacts of inhaling these aerosols and I wonder if health effects will worsen through indirect means as well. 

Source: Effiong and Neitzel (2016)

To conclude this post, as hopeful I was about geoengineering possibly being the future for climate action, I now question whether it is possible in the first place as some countries will be negatively affected, as well as whether the WHO will allow this to go fowards. Of course, there are other methods of geoengineering that I have not covered, but I hope to do so after my assessment for this module is over.

My next post will summarize my blogging journey. I hope you have a lovely Christmas and a fantastic New Year. Thank you for being here with me on my knowledge journey.