GLOBAL IMPACT OF ASIA’s POLLUTION

[Anonymous]

Global impact of Asia’s pollution
Industrial
pollution coming from Asia is having a wider effect on global weather
and climate than previously realised, research suggests.The “Asian
haze” of soot is boosting storms in the Pacific, scientists find.It is
also enhancing the growth of large clouds, which play a key role in
regulating climate globally.Writing in the journal Proceedings of the
National Academy of Sciences (PNAS), the researchers say impacts may be
felt as far away as the Arctic.”It’s a complex picture,” observed study
leader Renyi Zhang from Texas A&M University in College Station,
US.”But the bottom line is that the aerosols actually enhance
convection and increase precipitation over a large domain,” he told the
BBC News website

Hot water
While
clean air legislation has reduced production of industrial aerosols –
fine particles of dust, soot and sulphur – in Europe and North America,
the opposite trend is seen in Asia.Here, rapid industrialisation has
led to the formation of a pollution haze which is especially marked in
winter as coal burning increases.Sulphur emissions have increased by
more than one-third over the last decade.These aerosols drive cloud
formation, as water droplets coalesce around the tiny particles.When
aerosols are abundant, the droplets stay too small to form rain. Under
these conditions, clouds may grow bigger and last for longer.When the
clouds are of the type known as deep convective clouds, this means they
also transmit more heat from the Earth’s surface into the higher
atmosphere.Deep convective clouds play a key role in regulating the
global climate; and the role of aerosols in cloud development remains
the major uncertainty in forecasting climate change.

Clouding up
In
the latest research, Professor Zhang and his colleagues used satellite
records to show that the amount of deep convective clouds over the
north Pacific has increased.Coverage for the period 1994-2005 was
between 20% and 50% higher than in the preceding decade.With increased
clouds and increased convection came a growth in storminess – the
“storm track” – over the ocean.Computer models suggest that the trends
are being driven by Asian aerosol production, rather than by other
factors such as changes in ocean temperature.”The storm track regulates
the jet stream,” commented Professor Zhang. “And if more heat is being
transported from lower to higher latitudes, that is going to have a
large effect on the global circulation.”But the link between clouds and
aerosols works in the opposite direction too. Clouds transport the tiny
particles, and more abundant and persistent clouds will transport them
further – even to polar regions, Professor Zhang suggests.Some studies
have suggested that accumulation of these particles is changing the
properties of Arctic ice, making it absorb more of the Sun’s
energy.This would mean the ice is more prone to melting, as well as
reducing the Earth’s capacity to reflect solar energy back into space.

[Author]

March 6, 2007 at 10:26 AM