Final thoughts and a Goodbye

This blog has focused much on the scientific and governmental feasibility of geoengineering, so I wanted to make this final post a short ethical discussion. If a method was invented which allowed humans to control the global temperature and CO2 concentration without any side effects (i.e. David Keith’s ‘box’), would this be a good thing?

Professor Clive Hamilton (2012) argues that it isn't a good idea to attain the power to regulate the Earth as a whole when it was institutional failings and greed which brought us into the Anthropocene, potentially suppressing future ice ages.  He continues to argue that by examining our past behaviour, how could any credibility be lent to the idea that SRM techniques would be undertaken in a benevolent way which keeps the rights of the vulnerable in mind?

Heidegger (1935) wrote extensively about the difficulty of humanity controlling nature, and SRM effectively sets about to achieve a controlling of the entire Earth. From a more practical modern standpoint, climate scientist Raymond Pierrehumbert (2012) has spoken about the impossibility of maintaining an SRM scheme like aerosol injection, which would need to be re-injected every two years, while CO2 will continue to influence the climate for 10,000 years. From a political standpoint, climate change has winners and losers - what is to be done if China wants the Earth a degree hotter, but America wants it a degree colder?

A word cloud of my blog. (Source: https://www.wordclouds.com/).

Inspired by the last post of Tilak's geoengineering blog, I have included a word cloud highlighting the most used words on my blog. For me, the gargantuan size of the words 'potential' and 'impacts' on the cloud help to summarise my research into geoengineering. If utilised correctly alongside a strict reduction of greenhouse gas emissions and governed under an international framework, it has the potential to do tremendous good in mitigating the impacts of climate change (e.g. saving Arctic sea ice). If used as an excuse not to cut emissions, the so-called moral hazard, or if left to countries to pursue without regulation, it has the potential to exacerbate the impacts into something much worse.

I have enjoyed learning and blogging about such a controversial topic over the last few months and hope that you have enjoyed reading it! Farewell!

Chemtrails: a not-so-distant future?

Included in the Royal Society's (2009) Geoengineering the climate: Science, governance and uncertainty report is a table and figure replicated in Figure 1 which compares the relative effectiveness, affordability, safety, and timeliness of various geoengineering methods, granting them a score between 1 and 5.

Figure 1: A comparison of the effectiveness, affordability, timeliness, and safety of various geoengineering techniques. (Source: Royal Society, 2009).

BECCS and surface albedo enhancement (urban) have been examined on this blog and they are two of the safest methods, although neither score highly for timeliness, affordability or effectiveness. Building from David Keith's TED talk in which he claimed that stratospheric aerosols could be used to plunge the Earth into an ice age extremely quickly for about 0.01% of global GDP, I wanted to explore it in depth as it appears to be the SRM method with the most research behind and most potential.

Forming the basis of the 'chemtrail' conspiracy theory, it is also one of the most controversial methods. GeoengineeringWatch.org claim that stratospheric aerosols are already being dispersed by jet aircraft alongside other harmful chemicals and indeed an international survey of 3015 people showed that 17% of respondents believe this to be true or partly true (Mercer et al., 2011). A survey of 77 atmospheric scientists found that 76 (98.7%) had not uncovered any evidence to support this theory and believed that the 'evidence' used by sites such as GeoengineeringWatch.org could be explained scientifically (Shearer et al., 2016).

The reality of developments in stratospheric aerosol injection

Although aeroplanes have been suggested as a potential method of dispersing aerosols into the stratosphere, alongside high-altitude balloons, artillery guns, towers, and space elevators (Caldeira et al., 2013), very few studies on stratospheric aerosol injection have conducted outdoor experimentation. These include:

• A Russian study which tested the refractivity of aerosols in the lower troposphere by generators aboard helicopters (Izrael et al., 2010).
• The British Stratospheric Particle Injection for Climate Engineering (SPICE) project which aimed to test the potential of a tethered balloon to disperse aerosols but the field experiment was cancelled due to issues with patents (Cressey, 2012).
• The Harvard University Stratospheric Controlled Perturbation Experiment (SCoPEx) project, previously mentioned on this blog, plans to launch a balloon to 20 km altitude and spray up to 1 kg of aerosols to create an air mass which can be tested by equipment on board the balloon (Dykema et al., 2014).

How does it work?

In 1991, Mount Pinatubo erupted and created eruption columns containing approximately 17 megatons of sulphur dioxide (SO2) reaching 40 km in altitude, with the resulting aerosol cloud attaining global coverage within a year and causing a global surface cooling in excess of 0.5°C in 1992 (Dutton and Christy, 1992; Self et al., 1993). Literature praising sulphur aerosols as a potential geoengineering technique often point to the fact that they are created naturally and their impacts have been studied.

Figure 2: The 1992 Mount Pinatubo eruption. (Source: https://pubs.usgs.gov/fs/1997/fs113-97/)

SO2 oxidises in the atmosphere to form H2SO4 (sulphuric acid) which then undergoes a process called nucleation, which is the condensation of this gaseous precursor to create aerosols; solid or liquid particles suspended in a gas. Depending on their physical properties, different aerosols possess varying scattering or absorbing properties: sulphate aerosols reflect almost all radiation they encounter whereas black carbon aerosols, the subject of an upcoming lecture, absorbs radiation and warms the atmosphere as well as reducing surface albedo.

There are two methods to instigate this nucleation to form a stratospheric sulphate aerosol cloud: the release of SO2 (the precursor gas) or the release of H2SO4 directly. H2SO4 is more costly than SO2 to release (you reading this can purchase 1 tonne of SO2 on Alibaba for as little as $350) but allows the potential for control over the size of the aerosols created and the location of the cloud formed; smaller particles are more effective at reflecting light and have longer lifespans.


What are the potential issues?

Any global SRM method is accompanied by a wealth of political and governance issues (touched upon here and explored in-depth here), but according to MIT research (2009) and Robock (2008) stratospheric sulphate aerosols have numerous direct physical impacts as well, including:

• Regional Precipitation Changes: studies suggest that the Mt Pinatubo eruption did not only cause global cooling but it also severely impacted the hydrological cycle, decreasing precipitation over land and river discharge; causing an increase of drought occurrences in 1992.
• Increased Acid Deposition: if sulphuric acid (or a precursor) is regularly injected into the stratosphere, some will inevitably pass through the troposphere and deposit on the Earth's surface through acid rain which creates a plethora of ecological and health impacts. 
• Ozone Depletion: sulphate aerosols increase the surface area available for the reactions creating the Antarctic ozone hole, which the Mount Pinatubo eruption exacerbated as well as causing mid-latitude ozone concentrations to fall to the lowest levels ever recorded in the year following the eruption (Self et al., 1993).    

David Keith TED Talk

In 2007, David Keith spoke about geoengineering at TEDSalon. I highly recommend that you watch it as he discusses a range of issues and gives a convincing argument as to why public debate about geoengineering is important. 

He presents a thought: if an alien came to Earth and gifted us with a box with two dials, one controlling global temperature and the other global CO2, wars would be fought over that box. He says that scientists are currently creating that box, and we must be ready with a treaty to act cooperatively when it is inevitably completed. I hope that none of you receive this box for Christmas though! Merry Christmas!

Geoengineering and Biodiversity

Friday marked the second part of our lectures on biodiversity (biological diversity), and I wanted to explore if geoengineering could help tackle anthropogenic threats to biodiversity, and if it could, to what extent? 

Figure 1 illustrates the number of species on the IUCN red list which are threatened by various human activities and impacts; climate change is notably much less severe than other factors like over-exploitation or agricultural activity. However, the authors of this study acknowledge that climate change will become an increasing threat in the future as temperatures continue to rise (Maxwell et al., 2016). 

Figure 1: The number of species on the IUCN red list affected by a variety of threats. (Source: Maxwell et al., 2016).

Mark Urban (2015) of the University of Connecticut combined the data of 131 extinction studies to produce a global estimate of the impacts of climate change on biodiversity. The study found that the Paris Agreement target of 2-degree warming would increase the percentage of species facing extinction risk from 2.8% (present) to 5.2%. A previous blog post discussed the difficulties of meeting this target, which should be frightening because a 4.3-degree rise could see 16% of species (or 1 in 6) facing a risk of extinction.

In 2010, news headlines heralded that the UN Convention on Biological Diversity (CBD) had 'banned geoengineering' at its 10th Conference of the Parties (COP). A more accurate statement would be that the 193 signatories had agreed to postpone large-scale projects, but allow small-scale research, until its impacts on the environment and biodiversity are fully understood. 

The Secretariat of the CBD have been leading research examining the links between geoengineering and biodiversity, with a technical report published in 2012 and an updated report in 2016. 

Regarding CDR methods, these reports suggest that the impacts depend largely on the scale and exact implementation but acknowledge that they are expected to mitigate the biodiversity impacts of climate change, and most methods would also help tackle ocean acidification. The reports note, however, that the scale at which methods such as BECCS are included in IPCC models would require land-use change on such a large scale that the impacts would partially offset or exceed the carbon sequestered as biomass. 

Regarding SRM methods, the report admits that many impacts on biodiversity are uncertain due to the immense changes in ecosystem dynamics that would occur if global dimming were combined with no changes to CO2. However, it is noted that only species threatened by rising temperatures would be protected, and not those threatened by ocean acidification or greenhouse gas emissions. The report stresses the potentially grave dangers to biodiversity and ecosystem services of any rapid termination of prolonged significant SRM techniques.

Geoengineering, particularly CDR methods, are capable of mitigating the climate change impacts on biodiversity, but nothing would be more effective than simply reducing CO2 emissions initially.

It may be better to reverse the issue though and enhance biodiversity as a means of achieving a reduction in CO2. This 'natural geoengineering', Oswald Schmitz of Yale University argues, works by preserving top predators to control herbivore populations and thus maximise the amount of CO2 an ecosystem can store.

Geoengineering news from across the pond

Today I received news from a friend at UCLA that a Californian congressman, Jerry McNerney, introduced the Geoengineering Research Evaluation Act. If it passes, the act will commission the National Academies of Science (NAS) to undertake further research and produce reports about the development of a research strategy for albedo modification methods (SRM) as well as setting a framework to govern geoengineering research. 

The NAS have previously been consulted and produced two reports which concluded that more research is required before any large-scale SRM techniques are undertaken. Personally, I welcome the proposed act and hope that it passes. Primarily so that clear governance standards can be put in place regarding research, but also to aid in better understanding the potential dangers of these techniques from a nonprofit non-governmental organisation like NAS to stop Geostorm becoming a reality!

Geoengineering: a COP out or a necessity?

Every year, the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC), an international environmental treaty with 165 signatories and 197 ratifiers, meet to discuss progress with tackling climate change and setting emission reduction targets. 

The most recent meeting was COP 23 earlier this year in Bonn, Germany, but the roleplay that our class engaged in was a re-enactment of COP 21 in Paris during 2015. This particular meeting was important, as it was the first meeting since the 1997 Kyoto Protocol (COP 3) which set a global legally binding agreement on climate with targets for each country. The Paris Agreement, signed by 195 nations, has a primary objective of keeping global warming from pre-industrial levels this century below 2 degrees Celcius as well as beginning mechanisms to review target achievement progress and provide funding for developing nations to invest in renewables. The emission reduction targets set by individual countries are, however, voluntary and not legally binding. Climate scientist James Hansen even called the entire agreement 'a fraud'.

Irrespective of the targets not being legally binding, a problem encountered during our roleplay was the struggle even to set targets which came close to achieving the 2-degree scenario (2DS). This is mirrored in reality, and it has widely been acknowledged that the targets set under the Paris Agreement would not be sufficient to achieve the 2DS. An even larger shadow has been cast over the ambitions by Donald Trump announcing a withdrawal of the United States from the agreement. A recent Bayesian probabilistic model by Raftery et al. (2017) which incorporates trends in the economy, emissions, and population growth predicts that there is just a 5% chance of remaining under 2 degrees warming by 2100, and just a 1% chance of remaining under 1.5 degrees. The study places the likely warming between 2.0 degrees and 4.9 degrees, with 3.2 degrees as the median.

The IPCC has concluded that to stay below 2 degrees warming, global greenhouse gas (GHG) emissions would need to decrease by 1.3-3.1% per year between 2010 and 2050. For perspective, the crippling 2008 recession only managed to reduce global emissions by 1% for a single year. 

Figure 1: Predicted global mean warming according to current policies in place and pledges under the Paris Agreement. Last updated 13th November 2017. (Source: Climate Action Tracker, 2017).

As discussed in a previous blog post, 2DS models often rely heavily on technologies such as BECCS to an unfeasible extent. The question now is: should other geoengineering methods be introduced as a means of making the 2DS a realistic target, despite side effects and not dealing with other impacts of emissions like ocean acidification? Alternatively, maybe the 2-degree target should be reassessed and shifted to 3-degrees or higher? Maybe, as Roger Pielke Jr. suggests, the 'degree warming' metric needs to be reframed into an easy-to-understand trackable goal like examining the proportion of carbon-free energy used. 

It is clear though that if we are serious about achieving the targets set by the Paris Agreement, it is time to talking about geoengineering.

A white roof future

In 2009, Nobel prize-winning scientist and the former US Secretary of Energy, Steven Chu, spoke in London at a meeting on climate change. His message was simple: paint your roof white.

It's a novel and intriguing idea, and in the excerpt of his talk embedded below, he claims that a worldwide whitening of roofs and roads is capable of removing as much carbon dioxide as removing every car for 11 years. A study conducted by Akbari et al. (2012) estimated that light-coloured roofs, pavements and roads could increase urban albedo by about 10%, and if undertaken globally could offset 130 - 150 billion tonnes of CO2, equivalent to removing every car for 50 years.

It shocked me that such a seemingly easy procedure like painting a roof could have such a significant impact, so I was eager to investigate the potential of this method and how suitable it was for urban areas in colder environments.

How can painting a roof white help to combat global warming?

Figure 1: Approximate albedos of various urban surfaces. (Source: https://weather.msfc.nasa.gov/urban/urban_heat_island.html).

As Figure 1 illustrates, the reflectivity of roofs varies immensely. Roofs and roads together account for roughly half of urban areas and contribute to the Urban Heat Island (UHI) effect by preventing evaporation and absorbing sunlight. The idea is simple: increase the albedo (solar reflectance) of these roofs and roads, which in turn will reflect more incoming solar radiation and hence tackle global warming (Akbari et al., 2008).

White roofs are also capable of reducing energy use through air conditioning by up to 40% in some climates and through reducing the impact of the UHI effect, could also provide better air quality and comfort as well as mitigating the UHI contribution to global warming (Akbari et al., 2008).

How effective is it?

There is currently much debate within the scientific community about the effectiveness of white roofs. Most notably, a modelling study by Jacobson and Ten Hoeve (2011) estimated that the UHI effect might contribute to 2-4% of global warming, in comparison to 79% from greenhouse gases and 18% from dark particulates. The study suggested that a worldwide conversion to white roofs could cause a net warming of the Earth due to less hot air rising resulting in fewer clouds being formed, as well as the increased surface reflectance creating an increase in sunlight absorbed by dark pollutants like black carbon. Jacobson and Ten Hoeve (2011) suggested that attaching photovoltaic panels to roofs would be a much better alternative, but their study on white roofs did not account for any reduction in electricity use for cooling.

However, later research such as the previously mentioned Akbari et al. (2012) study disagree with Jacobson, and a more recent study by Sproul et al. (2014) comparing roofs in the United States suggested that white roofs are the most economic to install and are three times more effective than green roofs (vegetated) at achieving global cooling.

What about in cold climates?

Within the research, there is a problem that the studies are often undertaken in hot climates (the bulk of research coming from the Lawrence Berkeley Laboratories) and do not assess their full environmental consequences. More recent research suggests that net negative environmental impacts can occur in colder climates due to a large heating penalty occurring from white roofs; that is, the resulting increase in heating required from high solar reflectance (Cubi et al., 2015).

The website of Steven Chu's former department, the U.S. Department of Energy, now explicitly states that cool roofs can increase energy costs in colder climates and acknowledge other potential problems such as increased susceptibility to the accumulation of moisture.

Regardless, the idea is limited in its potential impacts by the fact that less than 1% of the Earth's surface is urban. It appears to be an easy, inexpensive, effective strategy when applied to particular hot and dry climates but lacks the potential to be scaled globally as a significant geoengineering technique.