Geoengineering the climate

Meeting report by Jamie Harrower
INEOS
jamieharrower@hotmail.com
ECB Bulletin July 2016

dgl article by alan robock

article by david santillo

article by mike stephenson

article by joanna haigh

This year’s Distinguished Guest Lecture and Symposium on Geoengineering the Climate took place on 22 March 2016 at Burlington House, London. Attended by about 100 delegates, the event provided a comprehensive overview of the science and policy challenges of geoengineering.

In her introductory talk, Professor Joanna Haigh (Imperial College London) outlined the challenges that humanity faces in combating climate change and summarised the main factors contributing to an increase in the Earth’s temperature.  Her talk illustrated the increase in the Earth’s temperature since 1850, the decrease in Arctic summer sea ice, the rising global average sea level, and the increase in the average ocean heat content. She emphasised that the physics of the greenhouse effect are simple and have been known since the 19th century.

There are few options to tackle climate change on the timescales required to limit the mean global temperature rise to below 2 °C, as stated in the COP 21 agreement in Paris 2015. Exceeding this level of temperature increase may cause dramatic changes in the Earth’s weather systems. The options are to adapt to the global impacts of global warming, to significantly reduce greenhouse gases emissions, and/or to use geoengineering. Geoengineering has been defined by the Royal Society as “the deliberate large scale manipulation of the planetary environment to counteract anthropogenic climate change.”

Geoengineering schemes can be divided primarily into land-, ocean-, atmosphere- and space-based approaches. Professor Haigh explained that, fundamentally, there are two different methodologies. The first aims to remove carbon dioxide (CO₂) by physical or chemical means (carbon dioxide removal, CDR).

Natural Experiment. Volcanic eruptions such as that of Mount Bromo in Indonesia shown here, help to understand the effects of stratospheric geoengineering. Credit: Wan Fahmy Redzuan/Shutterstock

The main CDR schemes are large-scale afforestation, biochar production, carbon capture and storage (CCS), and ocean fertilisation. However, CDR schemes can only sequester a small amount of CO₂ compared to anthropogenic emissions and are thus unlikely to prevent the global mean temperature from rising 2 °C by 2100. The second methodology, solar radiation management (SRM), aims to adjust the amount of sunlight reaching the Earth, thereby counterbalancing greenhouse gas forcing. The main SRM schemes are injecting sulphur into the stratosphere to block UV light, placing sun shields to reflect sunlight, and injecting sea salt into the air above the sea to increase the reflectivity of clouds. SRM can significantly decrease the solar radiation absorbed by the Earth and therefore lower the average temperature globally. However, if SRM is discontinued, temperatures could rise rapidly. SRM also does not address the effects of high atmospheric CO₂ concentrations, such as ocean acidification. The costs and benefits of geoengineering vary across the globe, with some countries gaining significantly, while others may be faced with a worse scenario than prior to geoengineering intervention.

Professor Mike Stephenson (British Geological Survey) next spoke on “Climate geoengineering―carbon capture and storage.” He started by explaining how coal layers formed around 300 million years ago when dense forest areas on Earth were buried and protected from oxidation, thus removing carbon from the active carbon cycle. By the 1700s, Britain had started to return this captured carbon back into the atmosphere, having become reliant on coal as an energy source in its expanding cities. According to Stephenson, this marked the start of the Anthropocene, a proposed geological time period in which human activities have fundamentally altered the Earth’s geological processes. Today, the use of coal is increasing in parts of the world such as China and India.  Globally, there are around 50,000 coal-burning power stations, with about 8,000 based in the U.S.

Professor Stephenson argued that CCS may be one of the few viable options for reducing CO₂ on the timescales required to limit global warming. Established technologies for capturing carbon during energy production mainly involve two steps: CO₂ is first removed from the flue gases after coal has been burnt and then injected into deep geological layers to contain the CO₂ below impermeable rock. Offshore reservoirs may allow storage of ~78 gigatons of carbon. The injection of waste materials into geological formations is not new: the U.S. has over 140,000 disposal wells currently used by the oil and gas industry. However, CCS is not yet widely used. The Sleipner CO₂ storage project in Norway is the most successful to date, having safely stored 20 million tonnes of CO₂ in subsurface sites. The Schwarze Pumpe power station in Germany, a pilot scheme for CCS, has not been in operation since 2014. Many policy makers see bioenergy and carbon capture storage (BECCS) as a credible option for reducing atmospheric CO₂ concentrations. The idea behind BECCS is to produce negative CO₂ emissions by growing energy crops, burning them for energy, and then capturing the resulting CO₂ for storage. The implementation of a global bioenergy programme will provide numerous benefits; however, suitable carbon storage locations may be physically far from a bioenergy production region. Furthermore, large-scale energy crop production would compete with food production and is likely to have negative environmental implications.

The third talk was delivered by Dr David Santillo (Greenpeace/University of Exeter), titled “How can geoengineering research be regulated?” The speaker focused on recent advances in regulating ocean fertilisation projects. Ocean fertilisation involves adding iron into the ocean environment to stimulate the growth of phytoplankton. This could potentially increase the rate of carbon sequestration and decrease the atmospheric CO₂ concentration. Adding Fe to enhance phytoplankton growth could have positive effects on overfished fish stocks, but it may also have negatives effects, such as the development of toxic algae blooms. Field and laboratory studies conducted over the past 15 years have shown that adding Fe to high nitrite and low chlorophyll (HNLC) regions can stimulate phytoplankton blooms, which has led to a better understanding of Fe role in the oceans ecosystems. This has also contributed to the better understanding of links between ocean productivity and the Earth’s climate.

​Dr Santillo described the criteria and international guidelines set out in the Ocean Fertilisation Assessment Framework (OFAF), which was designed and implemented by the international marine organisation (IMO) to determine whether proposals for ocean fertilisation constitute legitimate research. Any activities that do not meet the criteria set out in the framework cannot proceed to the next stage of assessment without further revision. Developed over the course of just six years, the Framework shows that regulation of geoengineering is possible. The Framework may be extended to other ocean-based geoengineering schemes and may also serve as a guide for geoengineering schemes based on the atmosphere or on land.

In his Distinguished Guest Lecture, Professor Alan Robock of Rutgers University spoke on “Smoke and mirrors are not the solution to global warming.” He focused on the controversial concept of injecting sulphate aerosol precursors into the stratosphere to deflect sunlight in an effort to counter global warming. As the speaker stressed, notable climate scientists have suggested that geoengineering should only be considered as an emergency response and not a long term solution to climate change.

Professor Robock outlined the risks and benefits from stratospheric geoengineering. The benefits include reducing global surface air temperatures, which could potentially reverse the negative impacts of global warming, and an increase in plant productivity that may increase the terrestrial CO₂ sink. There are, however, many more risks associated with stratospheric geoengineering, which include large-scale drought in Asia and Africa, ozone depletion, continued ocean acidification and potentially rapid global warming if suddenly stopped. There is also the question of who controls the global thermostat and who stands to benefit or suffer as a result, with the potential for conflict between nations if any one country or group of countries decides to proceed without global agreement.

Professor Robock concluded that mitigation and adaptation to climate change must come first.  Albedo (reflectivity of the Earth’s surface) modification should not be used at this time, but should be the subject of laboratory and modeling research. Studying volcanic eruptions will also be important, as these provide natural experiments on the effects of stratospheric sulphur injections. Research into governance and ethics will be crucial to ensure that any field experiments or deployments of SRM are tightly controlled.