Anlässlich der aktuell laufenden Klimaverhandlungen in Bonn haben wir gemeinsam mit der ETC Group für die dort involvierten NGOs und zivilgesellschaftlichen Akteure ein Briefing zum Thema Geoengineering verfasst: Climate Change, Smoke and Mirrors – a civil society briefing on Geoengineering.
Warum müssen wir jetzt darüber reden?
„For the past decade, a small but growing group of governments and scientists, the majority from the most powerful and most climate-polluting countries in the world, has been pushing for political consideration of geoengineering, the deliberate large-scale technological manipulation of the climate. Geoengineering is inherently high-risk and its negative effects will likely be unequally distributed. Because of this, geoengineering has often been presented as a “Plan B” to confront the climate crisis. But after the Paris Agreement, which set the ambitious goal of keeping the temperature to well below 2°C and possibly even 1.5°C, the discourse has changed. Now, geoengineering is increasingly being advanced as an “essential” means to reach this goal, through a mix of risky technologies that would take carbon out of the atmosphere to create so-called “negative emissions” or take control of the global thermostat to directly lower the climate’s temperature.
It should be no surprise that geoengineering is gaining political currency as temperatures rise. The fossil fuel industry is desperate to protect its estimated $55 trillion of installed infrastructure and its $20-28 trillion in booked assets that can only be extracted if the corporations are allowed to overshoot GHG emissions. The theoretical assumption is that geoengineering technologies might eventually let them recapture CO2 from the atmosphere and bury it in the earth or ocean, or that injecting sulfates in the stratosphere could lower the temperature, “buying us more time” to finally agree to radically reduce our fossil fuel emissions. Either way provides the fossil fuel industry with means to avoid popping the “carbon bubble” beyond outright climate denial.
In other words, geoengineering proposals are becoming the fossil fuel industry’s main tool to undermine the political will to lower actual emissions now. Geoengineering proposals are also becoming the weapon of last resort for some desperate climate scientists unable to produce pathways that realign our growth-driven economic model with a climate-safe future. But what exactly is geoengineering and what technologies are being proposed? And what are the risks and implications associated with the respective technologies when it comes to ecological integrity, environmental and climate justice and democracy?“
Das Papier gibt einen kurzen Überblick über die diskutierten Technologien und benennt die wichtigsten Risiken und Kritikpunkte…
Proposed geoengineering techniques
Greenhouse Gas Removal
Greenhouse Gas Removal (GGR) refers to a set of proposed technologies that remove greenhouse gases from the atmosphere. A more common umbrella term is Carbon Dioxide Removal (CDR), but that excludes other gases such as methane. Below are some of the proposals:
Ocean Fertilization (OF)
Ocean fertilization refers to dumping iron or other nutrients (e.g. urea) into the ocean in areas with low biological productivity in order to stimulate phytoplankton growth. In theory, the resulting phytoplankton draw down atmospheric CO2 and then die, falling to the ocean bed and sequestering carbon. The efficacy of OF is strongly questioned, as much of the “sequestered” carbon would likely be released again through the food chain. It can also provoke marine food chain disruption and anoxia (lack of oxygen) in some of ocean layers and may cause toxic algae blooms.
Artificial upwelling
A technique to mix ocean waters by artificially bringing nutrient-rich waters from depths up to the surface ocean to stimulate phytoplankton activity. In theory, this would draw down CO2 by ocean fertilization. As with OF, its efficacy is questioned. It will also disrupt marine food chain and environment, and bring already-sequestered CO2 to the surface.
Carbon Capture and Storage (CCS)
CCS usually refers to the mechanical capture of CO2 emissions from power plants or other industrial sources. The CO2 is typically captured before the emissions leave the smokestack, generally with a sorbent chemical. The liquified CO2 is then pumped into underground aquifers for long-term storage. CCS was originally called “enhanced oil recovery/EOR” since it is a technology from the oil industry to recover residual reserves of petroleum by pumping pressurized gas into empty wells. CCS is not economically viable unless heavily subsidized, and when used as an oil recovery technique it promotes further oil exploitation. Its ability to permanently sequester carbon is broadly questioned. The captured carbon could leak out due to many reasons: faulty construction, earthquakes or other underground movements. At these concentrations, CO2 is highly toxic for animal and vegetable life. CCS associated with fossil fuels was exempted from the UN Convention on Biodiversity definition on geoengineering, but it is still included in other definitions.
Carbon Capture Use and Storage (CCUS)
The idea behind CCUS is that captured CO2 from either industry or the atmosphere can be used as a feedstock for manufacturing, theoretically resulting in the CO2 being stored in manufactured products. One hypothetical example involves feeding captured CO2 to algae which produce biofuels; another is reacting CO2 with calcifying minerals to produce concrete for building purposes. CCUS has many of the potential impacts of CCS, but with increased risk for CO2 releases in processing and from the end-products. CCUS may also have questionable energy balance once the total energy required for transport and processing is factored in, as well as end of life considerations – there may be net increase in GHG emissions.
Direct Air Capture (DAC)
DAC refers to extracting CO2 or other greenhouse gases from the atmosphere by chemical and mechanical means, generally using a chemical sorbent and large fans to move ambient air through a filter. The CO2 is then available as a stream of gas for CCS or enhanced oil recovery or other uses. DAC is a commercial proposal that appears to have very heavy energy requirements, and like CCS is being proposed for enhanced oil recovery in locations where industrial sources of CO2 may be limited. Current DAC prototypes recover ambient CO2 at low levels. To have any significant effect they may have an environmental impact on land, and to supply the necessary levels of sorbent there may be significant toxicity impacts. The storage question is unresolved, and theoretically linking in it to CCS or CCUS will not resolve it, as described above.
Bioenergy with Carbon Capture and Storage (BECCS)
BECCS describes capturing CO2 from bioenergy applications (e.g., producing ethanol or burning biomass for electricity) and subsequently sequestering that CO2 through either CCS or CCUS. The theory is that BECCS is “carbon negative” because bioenergy is theoretically “carbon neutral,” based on the idea that plants will regrow to fix the carbon that has been emitted. Bioenergy critics point out that this overlooks emissions from land use change and life cycle emissions. According to IPCC AR5, to keep the temperature under 2 degrees with a theoretically effective BECCS system would require between 500 million and 6 billion hectares of land. Current global crop production covers 1.5 billion hectares – the impact on land, water, biodiversity and livelihoods, as well as competition for land to grow food would be devastating.
Enhanced Weathering (EW)
EW techniques propose to dissolve crushed minerals (particularly silicate minerals) on land or in the sea in order to chemically react with and fix atmospheric CO2 into oceans and soils. The huge demand for minerals would have serious impacts on land and biodiversity, extending the harmful impacts of mining operations. Deliberately changing the overall chemistry of oceans is fraught with many unknowns and unpredictable factors.
Biochar
Biochar techniques propose to burn biomass and municipal waste without oxygen to create charcoal. This charcoal is then mixed into soils as a soil additive, directly burying carbon into the soil. Biochar soils are claimed to be more fertile since they have higher carbon content. The approach is inspired by (but very different from) Amazonian Terra Preta black soils where indigenous communities have used charcoal to improve fertility. Industrial biochar would demand large land areas for plantations to be burned afterwards; it could disrupt soil life, potentially increasing greenhouse emissions from soil; and depending on the source of the biomass, may create concentrations of toxic contaminants. The claimed productivity boost from biochar as a soil amendment is inconsistent across different chars.
Solar Radiation Management
Solar Radiation Management (SRM) describes a suite of proposed technologies that aim to reflect sunlight back into space before it warms the Earth’s climate. The main SRM proposals include:
Stratospheric Aerosol Injection (SAI)
This is an SRM proposal to spray large quantities of inorganic particles (e.g. sulphur dioxide) into the stratosphere (the upper layer of the atmosphere) to act as a reflective barrier against incoming sunlight. Proposals range from shooting particles from artillery guns, using large hoses to reach the sky, or emptying particles from the back of aircrafts. The design of self-levitating particles, as well as the use of particles of other reflective materials (e.g. titanium, aluminum, calcite, even diamond dust) have also been considered. SAI using sulphates, the most-studied option, would likely cause ozone layer depletion and may disrupt rain and wind patterns across the tropics and subtropics. This could cause droughts in Africa and Asia and affect monsoons, with serious environmental impacts, and endanger the source of food and water for two billion people.
Marine Cloud Brightening (MCB) or Cloud Reflectivity Enhancement
MCB proposals aim to increase the whiteness of clouds in order to reflect more sunlight back into space. As with other SRM proposals, changing solar radiation can impact weather patterns and there may be impacts on marine and coastal ecosystems as well as agriculture.
Cirrus Cloud Thinning: By thinning cirrus clouds (wispy, elongated clouds at high altitudes), some researchers have proposed that more heat could be allowed to escape into space, creating an overall cooling of the climate. This idea could have even opposite effect, as there are many unknowns about cloud formation and chemistry with potentially unpredictable effects.
High-Albedo Crops and Snow Forest Clearance
Various proposals suggest that growing crops that reflect more light (either new genetically-engineered crops, or high-albedo varieties of existing crops) could cool the atmosphere by reflecting more solar radiation back into space. Others suggest clearing forests that exist in areas that are snow-covered for a large part of the year, which would increase the amount of light reflected back into space by the flatter, brighter snow. Using genetically modified crops or trees carries all the biosafety and land use impacts of these plantations, including soil erosion and heavy use of contaminating agrochemicals. Clearing forests to create white desserts would negatively impact biodiversity and climate.
Microbubbles and Sea Foams
Proposals are being advanced to increase the reflectivity of the ocean surface (or other water bodies) by creating tiny bubbles or dispersing foaming agents on the surface of the water. Besides disrupting the flux of light for ocean life, foams may also reduce oxygen to the upper layers of the ocean, negatively affecting biodiversity.
Weather Modification
Weather modification (WM) refers to various techniques – including cloud seeding and related techniques – for changing weather and precipitation patterns without intending to change overall climate patterns. WM have caused communities to suffer droughts and/or flooding of crops, but because it is believed to have local or regional impacts only, it is often not considered geoengineering.
To learn more about the impacts of each technology, see Geoengineering Monitor http://www.geoengineeringmonitor.org/