GEO ENGINEERING

Subject : Environment

Concept :

Geoengineering is an umbrella term for human interventions that change the earth’s climate system .
There are currently two main approaches under the geoengineering umbrella: carbon-dioxide removal (CDR) and solar radiation management (SRM).
CDR tackles the root cause of global warming by removing greenhouse gases from the atmosphere — think carbon capture and storage.
SRM, meanwhile, leaves greenhouse gases untouched, but offsets their impact by reflecting sunlight away from the earth.
Whereas CDR addresses the cause of global warming, reducing greenhouse gases, SRM only masks it or offsets it.

Geoengineering Techniques

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 fertilizationis 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.

Stratospheric aerosol injection (SAI)

SAI is the main type of solar radiation management (SRM) .
In the case of SAI, gases are pumped into the stratosphere to reflect some of the sun’s heat, mimicking an effect that happens naturally in a strong volcanic eruption.
Scale of SAI makes its governance difficult — implementing it in one country can trigger rain and extreme weather across borders. Lack of public support might be the biggest hurdle.

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.