Modelling study shows how controversial geoengineering may affect global food production

Subject: Environment

Section: Climate Change

Context:

Implementing a controversial climate intervention could likely create inequities in food production, benefitting some and harming others, a new study published in journal Nature Food warned.
The intervention proposed to counter climate change is a geoengineering technology called stratospheric aerosol intervention (SAI).

Stratospheric aerosol intervention (SAI):

SAI mimics volcanic eruptions by injecting sulphur dioxide into the stratosphere (layer of atmosphere extending from about 10 kilometres to 50 km in altitude), where it oxidizes to form sulphuric acid, which then forms reflective aerosol particles.
- Example: Mount Pinatubo in the Philippines erupted in 2001 and injected about 15 million tonnes of sulphur dioxide into the stratosphere, which then formed aerosol particles which caused a drop in the average global temperature of about 0.6 degrees Celsius over the next 15 months.
Injections would need to occur continuously to maintain decreased solar radiation and surface temperature.

Impact of SAI:

It will affect agriculture in different ways in different locations and other climate factors important to agriculture such as precipitation and solar radiation.
Cold regions will benefit from climate change so SAI will impact these regions negatively. While agricultural production in the tropics could see an increase with climatic interventions like SAI.
Under continued uncontrolled climate change, crop production is favored in cold, high-latitude areas such as Canada, Russia, the United States’ northern border states, Scandinavia and Scotland.

Other geoengineering techniques include:

Bio-energy with carbon capture and storage (BECCS)
- It is the process of extracting bioenergy from biomass and capturing and storing the carbon, thereby removing it from the atmosphere. The carbon in the biomass comes from the greenhouse gas carbon dioxide (CO2) which is extracted from the atmosphere by the biomass when it grows.
- Energy is extracted in useful forms (electricity, heat, biofuels, etc.) as the biomass is utilized through combustion, fermentation, pyrolysis or other conversion methods.

Ocean fertilization or ocean nourishment
- Ocean fertilization is a type of climate engineering based on the purposeful introduction of nutrients to the upper ocean to increase marine food production and to remove carbon dioxide from the atmosphere.
- A number of techniques, including fertilization by iron, urea and phosphorus have been proposed.

Soil carbon sequestration (SCS)
- Soils can serve as a sink for carbon dioxide since atmospheric concentrations of carbon dioxide have crossed 410 parts per million and oceans are already turning acidic.
- Carbon sequestration in soils has the potential to offset GHG emissions from fossil fuels by up to 15% annually.
- Soil organic carbon (SOC) comes from plants, animals, microbes, leaves and wood, mostly found in the first metre or so.
- There are many conditions and processes that determine changes to SOC content including temperature, rainfall, vegetation, soil management and land-use change.

Marine cloud brightening (MCB)
- MCB involves reflecting sunlight away from the earth in some way. In this case, sea salt or other particles are sprayed into marine clouds to make them thicker and more reflective.

Cirrus cloud thinning (CCT)
- CCT is almost the opposite of marine cloud brightening. High-altitude Cirrus clouds are thin and whispy, so they don’t reflect much solar radiation back into space, and instead trap long-wave radiation on earth.
- CCT proposes thinning them further through cloud seeding, letting more long-wave radiation escape.

Source: DownToEarth