A view of the main commercial district of Karachi is seen engulfed in smog February 22, 2008Karachi and twelve other mega-cities of Asia has been declared as Atmospheric Brown Cloud (ABC) ‘hotspots’ by the UN environment agency as soot levels in these cities comprise ten per cent of the total mass of all man-made particles.
A three-kilometer-thick ‘brown cloud’ of man-made pollution, which stretches from the Arabian Peninsula to China to the western Pacific Ocean, is making Asian cities darker, speeding up the melting of Himalayan glaciers and impacting human health, says the UN Environment Programme (UNEP) in a regional assessment report with focus on Asia.
The report on ‘Atmospheric Brown Clouds’ released on Thursday states over the Asian hotspots, the annual natural plus anthropogenic (AOD) exceeds 0.3 and the absorption optical depth is about 10 per cent of the AOD, indicative of the presence of strong absorbing soot accounting for about 10 per cent of the amount of aerosols.
The annual mean surface dimming and atmospheric solar heating by ABCs over some of the hotspots range from 10 to 25 per cent, such as in Karachi, Beijing, Shanghai and New Delhi, says the report.
In addition to Karachi, the UNEP’s new publication points out Bangkok, Beijing, Cairo, Dhaka, Kolkata, Lagos, Mumbai, New Delhi, Seoul, Shanghai, Shenzhen and Tehran as being ABC ‘hotspots’.
Atmospheric Brown Clouds (ABCs), resulting from the burning of fossil fuels and biomass, has resulted in the formation of particles such as black carbon and soot which absorb sunlight and heat the air, experts write in the study released today in Beijing.
The clouds also ‘mask’ the actual warming impact of climate change by anywhere between 20 and 80 per cent because they include sulfates and other chemicals which reflect sunlight and cool the surface.
The artificial lowering of temperature by ABCs is leading to sharp shifts in weather patterns, causing significant drying in northern China while increasing the risk of flooding in the Asian nation’s south. Monsoon precipitation over India and South-East Asia has dropped up to 7 per cent since the 1950s, with the summer monsoon both weakening and shrinking.
Meanwhile, the health and food security of 3 billion people in Asia are threatened by ABCs, which impacts air quality and agriculture.
The solar heating of the atmosphere by ABCs is ‘suggested to be as important as greenhouse gas warming in accounting for the anomalously large warming trend observed in the elevated regions’ such as the Himalayan-Tibetan region, the study says, leading to the retreat of glaciers.
The acceleration of the retreat of the Hindu Kush-Himalayan-Tibetan (HKHT) glaciers since the 1970s, in conjunction with the decrease in the summer monsoon rainfall in the Indo-Gangetic Plain region, is a major environmental problem facing Asia, threatening both the water and the food security of South and East Asia. Glaciers and snow packs provide the head-waters for Asia’s major river systems, including the Indus, the Ganges, the Brahmaputra, the Mekong and the Yangtze.
If the current rate of retreat continues unabated, these glaciers and snow packs are expected to shrink by as much as 75 per cent before the year 2050, posing grave danger to the region’s water security. This potential threat should be viewed in the context of the low per-capita water availability in South and East Asia, around 2000 - 3000 m3/cap/year, far less than the world average of 8549 m3/cap/year, the report says. The most serious health impacts of particles associated with the ABC include cardiovascular and pulmonary effects leading to chronic respiratory problems, hospital admissions and deaths. The clouds contain toxic aerosols, carcinogens and other harmful particles. Review of the available evidence indicates that there are likely to be very significant public health impacts from the ABC.
While the effects of the clouds on food production and farmers’ livelihood could be immense, more research must be done to determine their precise role, it acknowledges, adding that the possible impact of ABCs could include elevated levels of ground-level ozone, which could result in massive crop losses of up to 40 per cent in Asia.
Concern for a worsening situation in the future is highlighted by projections which suggest that the annual surface mean ozone concentrations in parts of South Asia will grow faster than anywhere else in the world and exceed 50 ppb by 2030.
Another important characteristic of ABC forcing in Asia is that it introduces large north-south asymmetries in the forcing and large land-sea contrasts. Since these are the driving forces for the monsoonal climate, ABCs have become major forcing terms for regional temperatures, circulation and precipitation.
There currently exist only a few unevenly distributed ozone monitoring sites across the whole of Asia, making it difficult to obtain a true picture of the current Asian ozone climate and how this varies by geographical characteristics
Global ozone projections suggest that some of the largest increases in ozone concentration will occur in South and Southeast Asia from now until 2030. Such projections would see South Asia becoming the most ozone polluted region in the world, with annual surface mean concentrations reaching 52.2 ppb (parts per billion).
A three-kilometer-thick ‘brown cloud’ of man-made pollution, which stretches from the Arabian Peninsula to China to the western Pacific Ocean, is making Asian cities darker, speeding up the melting of Himalayan glaciers and impacting human health, says the UN Environment Programme (UNEP) in a regional assessment report with focus on Asia.
The report on ‘Atmospheric Brown Clouds’ released on Thursday states over the Asian hotspots, the annual natural plus anthropogenic (AOD) exceeds 0.3 and the absorption optical depth is about 10 per cent of the AOD, indicative of the presence of strong absorbing soot accounting for about 10 per cent of the amount of aerosols.
The annual mean surface dimming and atmospheric solar heating by ABCs over some of the hotspots range from 10 to 25 per cent, such as in Karachi, Beijing, Shanghai and New Delhi, says the report.
In addition to Karachi, the UNEP’s new publication points out Bangkok, Beijing, Cairo, Dhaka, Kolkata, Lagos, Mumbai, New Delhi, Seoul, Shanghai, Shenzhen and Tehran as being ABC ‘hotspots’.
Atmospheric Brown Clouds (ABCs), resulting from the burning of fossil fuels and biomass, has resulted in the formation of particles such as black carbon and soot which absorb sunlight and heat the air, experts write in the study released today in Beijing.
The clouds also ‘mask’ the actual warming impact of climate change by anywhere between 20 and 80 per cent because they include sulfates and other chemicals which reflect sunlight and cool the surface.
The artificial lowering of temperature by ABCs is leading to sharp shifts in weather patterns, causing significant drying in northern China while increasing the risk of flooding in the Asian nation’s south. Monsoon precipitation over India and South-East Asia has dropped up to 7 per cent since the 1950s, with the summer monsoon both weakening and shrinking.
Meanwhile, the health and food security of 3 billion people in Asia are threatened by ABCs, which impacts air quality and agriculture.
The solar heating of the atmosphere by ABCs is ‘suggested to be as important as greenhouse gas warming in accounting for the anomalously large warming trend observed in the elevated regions’ such as the Himalayan-Tibetan region, the study says, leading to the retreat of glaciers.
The acceleration of the retreat of the Hindu Kush-Himalayan-Tibetan (HKHT) glaciers since the 1970s, in conjunction with the decrease in the summer monsoon rainfall in the Indo-Gangetic Plain region, is a major environmental problem facing Asia, threatening both the water and the food security of South and East Asia. Glaciers and snow packs provide the head-waters for Asia’s major river systems, including the Indus, the Ganges, the Brahmaputra, the Mekong and the Yangtze.
If the current rate of retreat continues unabated, these glaciers and snow packs are expected to shrink by as much as 75 per cent before the year 2050, posing grave danger to the region’s water security. This potential threat should be viewed in the context of the low per-capita water availability in South and East Asia, around 2000 - 3000 m3/cap/year, far less than the world average of 8549 m3/cap/year, the report says. The most serious health impacts of particles associated with the ABC include cardiovascular and pulmonary effects leading to chronic respiratory problems, hospital admissions and deaths. The clouds contain toxic aerosols, carcinogens and other harmful particles. Review of the available evidence indicates that there are likely to be very significant public health impacts from the ABC.
While the effects of the clouds on food production and farmers’ livelihood could be immense, more research must be done to determine their precise role, it acknowledges, adding that the possible impact of ABCs could include elevated levels of ground-level ozone, which could result in massive crop losses of up to 40 per cent in Asia.
Concern for a worsening situation in the future is highlighted by projections which suggest that the annual surface mean ozone concentrations in parts of South Asia will grow faster than anywhere else in the world and exceed 50 ppb by 2030.
Another important characteristic of ABC forcing in Asia is that it introduces large north-south asymmetries in the forcing and large land-sea contrasts. Since these are the driving forces for the monsoonal climate, ABCs have become major forcing terms for regional temperatures, circulation and precipitation.
There currently exist only a few unevenly distributed ozone monitoring sites across the whole of Asia, making it difficult to obtain a true picture of the current Asian ozone climate and how this varies by geographical characteristics
Global ozone projections suggest that some of the largest increases in ozone concentration will occur in South and Southeast Asia from now until 2030. Such projections would see South Asia becoming the most ozone polluted region in the world, with annual surface mean concentrations reaching 52.2 ppb (parts per billion).
1 comment:
Lovely Article I love It Please Check my Blog Too here
Post a Comment