Black Carbon and black carbon aerosols

Context: A recent study conducted on Tibetan plateau showed that increase in South Asian black Carbon aerosols is increasing loss of glaciers from Tibetan Plateau.

Key highlights of the study:

• Black carbon deposition in snow reduces the albedo of surfaces which accelerate melting of glaciers and snow cover and changes hydrological process and water resources in the region.
• Albedo is ability to reflect back Sun’s radiations.
• Black carbon aerosols in South Asia heat up the middle and upper atmosphere and increases North South temperature gradient.
• This increases convective activity in South Asia which causes convergence of water vapour in South Asia.
• Black carbon also increases the number of cloud condensation nuclei in the atmosphere.

About Black Carbon:

• Black carbon is the sooty black material emitted from gas and diesel engines, coal-fired power plants, and other sources that burn fossil fuel.
• It comprises a significant portion of particulate matter or PM, which is an air pollutant.

Impact of black carbon:

• Climate impacts: It has a warming impact that is 460-1,500 times stronger than CO2 on climate.
• It converts incoming solar radiation to heat.
• It influences cloud formation and impacts regional circulation and rainfall patterns.
• Health impacts- With size of 2.5 micrometres (PM2.5) or smaller, it can penetrate into lungs and facilitate transport of toxic compounds into the bloodstream.
• 5 can cause premature death and cause heart and lung disease, strokes, heart attacks, chronic respiratory disease like bronchitis, asthma and pneumonia.
• Impacts on ecosystem and vegetation- if deposited on plant leaves it will decrease its capability of photosynthesis and thus reduce food production.
• It can reduce sunlight that reaches the earth and modify rainfall patterns.

About Black Carbon aerosols:

• It is produced by the incomplete combustion of fossil fuels and biomass.
• It has strong absorption of solar radiation like- visible and infrared radiation.
• It is also called soot and is part of particulate matter above PM2.5.
• Thus, it contributes to pollution and Global warming.
• It can increase the temperature of atmosphere and darken surfaces, specifically snow and ice.
• It has short lifetime in atmosphere and gets removed in 1-2 weeks, so its impacts tend to be more regional rather than global.

Source: The Hindu

Previous Year Questions

Q.1) Among the following crops, which one is the most important anthropogenic source of both methane and nitrous oxide ? (2022)

1. Cotton
2. Rice
3. Sugarcane
4. Wheat

Q.2) In the Guidelines, statements: context of WHO consider the Air Quality following

1. The 24-hour mean of PM2.5 should not exceed 15 ug/m³ and annual mean of PM 2.5 should not exceed 5 µg/m³.
2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather.
3. PM10 can penetrate the lung barrier and enter the bloodstream.
4. Excessive ozone in the air can trigger asthma.

Which of the statements given above are correct? (2022)

1. 1, 3 and 4
2. 1 and 4 only
3. 2, 3 and 4
4. 1 and 2 only