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. 

ITCZ Cause and Effect

I recently had a lecture about Black Carbon (BC), a component of fine particulate matter which is produced from the incomplete combustion of organic matter. As well as climate change, BC is responsible for detrimental impacts on human health, transporting pollution, and damaging stone buildings. Figure 1 provides a summary of the global climate system effects of BC.

Figure 1: A summary of the climatic impacts of black carbon. (Source: Bond et al., 2013).

Of particular interest to me was the effect of BC in shifting the Intertropical Convergence Zone (ITCZ) to the north. Studies have shown that this happens as a result of BC strengthening the Hadley cell in the northern hemisphere but weakening the Hadley cell in the southern hemisphere (Wang, 2007; Jones et al., 2007). 

Just a few days ago, a study led by Dr Anthony Jones of the UK Met Office was published in Nature, examining how stratospheric aerosol injection (SAI), a type of SRM, could increase the frequency of hurricanes by shifting the ITCZ (Jones et al., 2017). Figure 2 illustrates the modelled impact of SAI on hurricane / tropical cyclone frequency, which has a large dependency on the hemisphere which SAI is undertaken. 

Figure 2: Modelled hurricane / tropical cyclone frequency in response to stratospheric aerosol injection (SAI) for years of geoengineering indicated by black lines between 2020-2070. Including no geoengineering (purple), annual SAI in southern hemisphere (red), annual SAI in northern hemisphere (blue), and annual global SAI (turquoise). (Source: Jones et al., 2017).

Essentially, preferential SAI in a single hemisphere alters sea-surface temperature gradients and shifts the ITCZ towards the opposite hemisphere. So, solar geoengineering in the south causes an ITCZ shift to the north, providing optimal conditions for hurricane formation near the United States from African easterly waves in an area in the North Atlantic known as the hurricane main development region (MDR) but would have the benefit of enhancing precipitation over the Sahel. On the other hand, solar geoengineering in the north would cause the ITCZ to shift to the south, which would increase wind shear over the MDR and reduce the number of hurricanes in the north, but would reduce precipitation over the Sahel and could cause droughts. 

Speaking with Carbon Brief, Dr Anthony Jones notes his concerns that positive regional impacts could motivate nations with greater influence to deploy solar geoengineering in a single hemisphere at the expense of nations in the other hemisphere. Both the BC and SAI studies highight the global impacts of regional actions and stress that global cooperation is crucial in tackling climate change, especially in a geoengineered world.

Geostorm (spoiler alert)

I recently succumbed to the pressure and went to watch Geostorm despite reading multitudes of bad reviews. The film itself was admittedly not great but was quite fun to watch. A satellite system known as Dutch Boy is responsible for controlling the world's climate and preventing natural disasters. During the process of handing over control of the system from the United States to an international committee, it begins freezing villages and setting towns ablaze. Later, it is found out to be the work of the US Secretary of State set on a path for world domination. If you can ignore the scientific mistakes and the installation of laser-powered death rays on Dutch Boy, the film does raise some interesting questions. What is the line between SRM research and deployment? Who should have power over SRM techniques and how should countries be represented? Should the public be consulted about the nature of geoengineering research currently being undertaken?

BECCS: The saviour of carbon geoengineering?

I recently read this article which tracks the development of Bio-energy with carbon capture and storage (BECCS) from its origins as a proposal within a doctoral thesis by Kenneth Möllersten for Swedish paper mills to benefit financially through capturing its carbon emissions and receiving credits. As mentioned in my previous post, BECCS is currently one of the most exciting and viable CDR technologies and is included in the majority of modelled pathways to achieve ‘the 2°C Scenario’ (2DS).

What is BECCS?

Figure 1: The carbon cycle involved with BECCS. (Source: http://www.bbc.co.uk/news/science-environment-26994746).

The concept of Carbon dioxide capture and storage (CCS) is to separate CO2 released from power plants or industrial sources and transport it by pipeline for storage deep underground in geological reservoirs or saline aquifers (Kheshgi et al., 2012). BECCS is the concept of using CCS at an electric power plant which uses biomass as a fuel and hence produces negative carbon dioxide emissions because the CO2 from the atmosphere is extracted by crops and stored permanently underground (Caldeira et al., 2013).

Due to the smaller size of BECCS plants in comparison to fossil fuel CCS plants, the costs associated with the CCS process are higher (Azar et al., 2006). However, Luckow et al. (2010) suggest that the large-scale utilisation of biomass could enable economies of scale to reduce the additional cost of applying CCS to biomass to only approximately 3% higher than coal.

It is estimated that through sustainably applying BECCS to one-hectare of a typical temperate forest, it is capable of removing approximately 2.5 tonnes of carbon per year (Kraxner et al., 2003). Modelling suggests that BECCS will deliver a significant improvement in the cost of achieving a 450 ppm concentration by 2100 (Azar et al., 2006) and may be necessary for achieving ambitious targets like 350 ppm concentration by 2100 (Azar et al., 2010).


Sounds fantastic, what's the catch?

The main issue with BECCS is the extent to which biomass needs to be commercialised to have a significant contribution towards the previously mentioned emissions targets. The IPCC estimates that to keep CO2 emissions below 450 ppm up to 100 exajoules (EJ) a year of biomass would need to be produced by 2030, with this figure rising to 325 EJ a year by 2100 (Clarke et al., 2014).

To provide some context for the scale of this undertaking, approximately 500 million hectares of land would be required to produce 100 EJ of biomass per year; this is equivalent to one-sixth of the area of global forests, or about 1.5 times the land area of India; in comparison, around 33m hectares of land is currently being used to produce biofuels (WWF, 2014).


With BECCS demanding such a large area of land to act as a feasible method of achieving emissions targets, there are an array of environmental and human concerns that arise. Firstly, a high demand for biofuels is capable of displacing land assigned for food production and hence increasing food prices and decreasing food security (Baier et al., 2009). Environmentally, there are concerns that unsustainable BECCS could increase CO2 emissions if forested areas are cleared to make space for biofuel production.

BECCS has not yet been developed and tested on a commercial scale, and like any other CCS technology, there is always a minor risk of CO2 leakages underground. So, is BECCS the 'saviour' of carbon geoengineering? Perhaps it is a premature saviour. Whilst it certainly has potential to be included alongside other carbon geoengineering methods in achieving emissions targets, there is much work to be done to increase its efficiency to reduce the land area required, as well as the need for a strict global regulatory framework to ensure that the biomass fuelling it is gathered in a sustainable manner.