Scientists weigh up stratospheric sunlight barrier to curb warming

Spraying sun-dimming chemicals high above the Earth to slow global warming could be “remarkably inexpensive”, costing about $2.25 billion a year over a 15-year period, according to a study by U.S. scientists.

This geoengineering technique known as a stratospheric aerosol injection (SAI) could limit rising temperatures that are causing climate change.

Stratospheric sulfur aerosols are sulfur-rich particles which exist in the stratosphere region of the Earth’s atmosphere. The layer of the atmosphere in which they exist is known as the Junge layer, or simply the stratospheric aerosol layer.

These particles consist of a mixture of sulfuric acid and water. They are created naturally, such as by photochemical decomposition of sulfur-containing gases, e.g. carbonyl sulfide.

Sulfur aerosols are common in the troposphere as a result of pollution with sulfur dioxide from burning coal, and from natural processes.

Volcanoes are a major source of particles in the stratosphere as the force of the volcanic eruption propels sulfur-containing gases into the stratosphere.

What is Stratospheric Aerosol Injection (SAI)?

Under SAI delivery of precursor sulfide gases such as sulfuric acid, hydrogen sulfide (H2S) or sulfur dioxide (SO2) are sprayed by artillery, aircraft, and balloons.

It would involve the use of huge hoses, cannons or specially designed aircraft to spray large quantities of sulphate particles into the upper layer of the atmosphere to act as a reflective barrier against sunlight.

Total costs estimated to launch a hypothetical SAI effort 15 years from now would be $3.5 billion and average annual operating costs would be about $2.25 billion a year over 15 years.

Discounting other methods of deployment because of cost and feasibility, the research assumes a special aircraft can be designed to fly at an altitude of about 20 km and carry a load of 25 tonnes.

This proposed method could counter most climatic changes, take effect rapidly, have very low direct implementation costs, and be reversible in its direct climatic effects.

Benefits of the SAI:

  • Mimics a natural process. It is technologically feasible. The method is economically feasible and efficient.
  • Possible side effects:
  • Tropospheric Ozone depletion.
  • Whitening of the sky.
  • Tropopause warming and the humidification of the stratosphere.
  • Involves Health effects.
  • Stratospheric temperature rise and circulation change.

Excess rainfall causing Kerala floods a result of climate change: IMD chief

The India Met Department chief KJ Ramesh said Friday that excessive rainfall that led to floods in Kerala was a result of climate change. He also spoke of a new technology that has been developed to assess the rise of water levels in rivers and reservoirs due to rain which can help state government minutely monitor the impact of rainfall.

The technique is designed to forecast the expected impact as a result of expected weather. Hazard and vulnerability are taken into consideration in this forecast approach.

The heavy downpour had led to floods in Kerala and was the result of climate change. State Government had blamed IMD for lapses in its part for wrong rain forecast. IMD had forecasted estimated 98.5 mm rain in the state between 9 and 15 August 2018 but Kerala received was 352.2 mm of rainfall resulting in severe flooding.

The pre-event scenario will help state governments authorities to minutely monitor the impact of rainfall and take real-time decisions. It will help to avoid a disastrous situation similar to Kerala floods. It can generate scenario to help take decisions to release water or not from reservoirs after a heavy downpour. It will be helpful for every state authority to take a decision. This system can be run in the pre-event scenario.

India Meteorological Department (IMD):

It is national meteorological service of the country and chief government agency dealing in everything related to meteorology, seismology and associated subjects. It was formed in 1875. It functions under the Ministry of Earth Sciences. It is headquartered in New Delhi.

Undertake meteorological observations and provide current information and forecasting information for most favorable operation of weather-dependent activities such as irrigation, agriculture, aviation, shipping etc.

Offer to warn against severe weather phenomenon such as tropical cyclones, norwesters, dust storms, heat waves, cold waves, heavy rains, heavy snow, etc.

Provide met-related statistics needed for agriculture, industries, water resources management, oil exploration, and any other strategically important activities for the country.

Engage in research in meteorology and allied subjects.

Detect and locate earthquakes and evaluate of seismicity in various parts of the country for developmental projects.

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