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.