• The term geo-engineering or climate engineering refers to deliberate, large-scale manipulations of the Earth’s environment designed to offset some of the harmful consequences of GHG-induced climate change. Climate engineering has two categories of technologies – carbon dioxide removal and solar radiation management.
• Some of the techniques are:
a) Solar radiation management (SRM):
• These projects are a type of climate engineering which seek to reflect sunlight and thus reduce global warming. They reflect some amount of incoming solar radiation back into space, or that would more readily enable heat radiated from the earth’s surface to escape, reducing global warming.
• For example, whitening clouds, injecting particles into the stratosphere, or putting sunshades in space could increase Earth’s reflectivity, thereby reducing incoming solar radiation and offsetting some of the warming associated with increasing GHG concentrations.
• There are four main classes of SRM proposals:
a) Stratospheric or mesospheric aerosols
b) Whitening marine clouds
c) Satellites in space
d) Whitening the surface
• Solar radiation management attempts to offset effects of greenhouse gases by causing Earth to absorb less solar radiation. Its cost is lower than the cost of methods that achieve the same cooling by reducing greenhouse gas emissions.
• Geoengineering could be the affordable and fast-acting option to avoid a global catastrophe. It addresses the control of greenhouse gases and reduce the risks of climate change.
b) Carbon dioxide removal
• Carbon dioxide removal projects seek to remove carbon dioxide from the atmosphere.
• Proposed methods include those that directly remove such gases from the atmosphere, as well as indirect methods that seek to promote natural processes that draw down and sequester CO2 (e.g. tree planting).
• Techniques in this category include:
a) Creating biochar, which can be mixed with soil to create terra preta
b) Bio-energy with carbon capture and storage to sequester carbon and simultaneously provide energy
c) Carbon air capture to remove carbon dioxide from ambient air
d) Afforestation, reforestation and forest restoration to absorb carbon dioxide
e) Ocean fertilization including iron fertilisation of the oceans
Biochar: Biochar is made from biomass via pyrolysis. Biochar has the potential to help mitigate climate change via carbon sequestration. Independently, biochar can increase soil fertility of acidic soils (low pH soils), increase agricultural productivity, and provide protection against some foliar and soil-borne diseases.
Ocean fertilization or ocean nourishment is a type of climate engineering based on the purpose fill introduction of nutrients to the upper ocean to increase marine food production and to remove carbon
dioxide from the atmosphere.
Iron fertilization is the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom. This is intended to enhance biological productivity, which can benefit the marine food chain and is under investigation in hopes of increasing carbon dioxide removal from the atmosphere.