CLIMATE
ENGINEERING

For the past decade humans have been responsible for over 35 Gt of anthropogenic carbon emissions per year[1] , which trap an increasing amount of solar radiation in the atmosphere, effectively acting like the glass in a greenhouse and raising the average global temperature.

Global climate change is not a future problem. Changes to Earth’s climate driven by human emissions are already having widespread effects on the environment: glaciers are receding, the sea level is rising, plant and animal geographic ranges are shifting, and there is an increased frequency of extreme heat waves and catastrophic weather events.

Climate Engineering refers to a set of technologies and techniques that intervene in the Earth’s climate system to address climate change. These technologies fall into two groups: those intending to remove CO2 and store it in geological, terrestrial, or oceanic reservoirs (Carbon Dioxide Removal or CDR) and those aiming at reflecting sunlight to reduce its heating effect (Solar Radiation Management or SRM).

[1] Reference: IEA-EDGAR CO2, a component of the EDGAR (Emissions Database for Global Atmospheric Research) Community GHG database version 7.0 (2022) including or based on data from IEA (2021) Greenhouse Gas Emissions from Energy, www.iea.org/data-and-statistics, as modified by the Joint Research Centre)

Three types of technologies included in the CE scheme:

Nature-based Carbon Dioxide Removal (N-CDR) uses techniques such as reforestation or soil carbon sequestration to draw CO2 from the atmosphere. Some can produce co-benefits such as wildlife restoration but their long-term capacity can be questioned in light of land use changes or wildfires for instance.

Engineered Carbon Dioxide Removal (E-CDR) technologies aim at removing CO2 from the atmosphere and storing it for long periods of time under the ground (e.g. depleted oil and gas fields) or in the sea. Currently this technique is only employed on a small scale.

Solar radiation modification (SRM) refers to methods of modifying the rate at which the Earth absorbs solar radiation to low global temperatures.

SRM

Marine Cloud Brightening (MCB) involves spraying sea salt or similar particles into marine clouds, increasing their reflectivity and blocking some incoming solar radiation.

Benefits: Relatively cheap.

Ethical challenge: Risk of sudden warming if intervention stops.

E-CDR

Enhanced Weathering (EW) involves spreading small particles of silicate and carbonate rock, which naturally absorb CO2, over the land or sea.

Benefits: Rocks act as fertiliser to improve crop production.

Ethical challenge: It entails mineral mining, which can be environmentally destructive. It may worsen air quality from rock dust spread onto soil, and local water quality.

N-CDR

Soil carbon sequestration includes several land management practices that allow the soil to capture and hold more carbon. Such practices include disturbing the soil less by changing planting schedules, managing grazing of livestock and applying compost or crop residues to fields.

Benefits: Enriches soil, making farming more sustainable.

Ethical challenge: The carbon captured can be released if disturbed.

N-CDR

Afforestation refers to planting forests upon land where forests have not historically occurred, while Reforestation refers to restoring forests upon deforested land.

Benefits: Stores carbon while also restoring nature. It supports local livelihoods, provides employment, and improves the supply of renewable wood.

Ethical challenge: Planting more carbon-efficient trees may reduce biodiversity.

SRM

Stratospheric Aerosol Injection (SAI) involves the release of gases into the stratosphere, where they form aerosols, blocking a portion of the incoming solar radiation. This mimics the effects seen during volcano eruptions.

Benefits: Rapid means of lowering some climate warming.

Ethical challenge: Radical intervention that could harm people and nature, especially in poorer nations. It could change precipitation patterns and air circulation, harming agriculture and many ecosystem types.

SRM

Ground-Based Albedo Modification (GBAM) techniques aim to increase the reflectivity of land surfaces, which deflect incoming solar radiation (e.g. whitening of roofs, no-till farming, covering deserts or glaciers with reflective sheeting…).

Benefits: Easy to deploy locally, keeps cities cool.

Ethical challenge: Some communities might object to the intervention.

E-CDR

Ocean Fertilisation (OF) involves adding nutrients to the upper layers of the ocean to stimulate phytoplankton production (photosynthesis). Limited nutrients like iron help stimulate photosynthesis in phytoplankton, which then sinks to the bottom of the ocean, storing the transformed CO2 deeper.

Benefits: Speeds up the natural cycle of carbon removal.

Ethical challenge: Unpredictable impact on ocean ecosystems.

E-CDR

Direct Air Carbon Capture and Storage (DACCS) combines carbon capture and storage with chemical processes. DACCS systems capture and separate CO2 present in the air through filters or fans covered in chemical agents. Captured CO2 is then stored underground.

Benefits: Can help balance industries hard to decarbonise.

Ethical challenge: High price, access limited to the wealthy.

E-CDR

Bioenergy with Carbon Capture and Storage (BECCS) captures and stores the CO2 generated during the burning of biomass for energy (electricity and heating).

Benefits: In principle ready to use, provides energy with net negative CO2 emissions.

Ethical challenge: Producing biofuels uses scarce water stocks and land.

Some solutions look like CDR, but are not!

Carbon Capture and Storage (CCS) involves the capture of carbon emissions from industrial production or energy combustion, which is then placed in long-term storage. Here the source of carbon is fossil fuels, therefore no net CO2 is removed from the atmosphere. In case the captured CO2 is reused in commercial products, the technique is called Carbon Capture and Utilisation (CCU). CCS and CCU are not forms of CDR because neither removes CO2 from the atmosphere.

Benefits: Commercially interesting solutions on the road to carbon neutrality.

Ethical challenge: CCS and CCU do not lower the net carbon in the atmosphere.

Adam Sébire: AnthropoScene III : Hellisheiði

Video triptych, 2018 (revised 2021)
Duration: 3mins. Split screen preview

Video artist Adam Sébire is drawn to this site for its modern-day alchemy and its post-industrial Promethean overtones: an unshakeable faith in the technological mastery of Homo sapiens.

The Climeworks/CarbFix2 project at Hellisheiði, Iceland is the world’s first industrial-scale “carbon scrubbing” experiment to capture carbon dioxide (CO₂) directly from Earth’s atmosphere. This CO₂ is mixed with water and pumped through domed injection wells down into active volcanic regions, where it becomes petrified as rock.

In the video triptych, one of the three screens investigates the experiments at Hellishei∂i (the injection wells of CarbFix plus Climeworks’ white cube “carbon scrubber” DAC module, a prototype for what’s expected to be many thousands spread across the planet). In another, a core sample of the sequestered CO₂ — now mineralised as calcite within the basalt host rock — appears as a quasi-mystical object in a vitrine (in an exhibition this screen can be replaced by a real core sample). The third screen is more ambiguous: set in a future geological era where complex lifeforms seem to have disappeared, and where the planet is correcting an atmospheric imbalance. Now, geological processes reverse. After only a few hundred thousand years, homeostasis — equilibrium — will have returned.