Weather, climate and the air we breathe - WMO

In this issue
The theme of World Meteorological
Day this year is “Weather, climate
and the air we breathe”. This issue
of the Bulletin is conceived around
the same theme, with articles on air
quality and its manifestation in urban
and surrounding regions, couplings
with weather and climate change and
the impact of pollutant deposition,
including nitrogen, on the upper
ocean. It opens with a message from
the Secretary-General on the occasion
of World Meteorological Day, as is
customary in the January Bulletin.
Between 1800 and 2007, the fraction
of the global population living in
cities has risen from about 3 per cent
to 50 per cent. As a consequence,
megacities and regional hot spots
have developed with anthropogenic
pollutant emissions and changes in
land use that have large environmental
implications both in the regional
hot spots themselves and on a
larger scale. Air pollution in densely
populated areas affects human
health in important ways throughout
the world. The forecasting of air
pollution in urban areas is a service
required to allow the population to
take precautions on a daily basis
and to identify policy measures to
reduce emissions so that pollution
target levels can be met. Through
the Global Atmosphere Watch (GAW)
programme and its Urban Research
and Meteorology Experiment (GURME)
project and the World Weather
Research Programme (WWRP)
| WMO Bulletin 58 (1) - January 2009
WMO enhances the capabilities of
Member countries to provide airquality
forecasting, illustrating the
linkages between meteorology and
air quality.
Atmospheric chemical composition,
weather and climate are strongly
interconnected. There is pollutant
emission growth in the Far East; and
in South America, while emissions
in Europe and North America are
levelling off or being reduced. The
economy is globalized with important
consequences for intercontinental
transport of air pollution; aircraft
emissions (International Civil Aviation
Organization); and shipping emissions
(International Maritime Organization).
Changes in farmland practices and
in physical climate give rise to more
biomass burning and forest fires.
The transport of air pollution across
national, regional and continental
boundaries is an important aspect
of the global cycling of air pollution,
including the impact in the Arctic and
on adjacent seas.
Air pollution and climate change
interact both ways. The United Nations
Framework Convention on Climate
Change focuses on the climate change
effect of long-lived greenhouse gases.
Aerosols (directly and indirectly) and
tropospheric ozone, exert regional
radiative forcing on climate which is
expected to modify the distribution
of synoptic weather patterns and
the distribution of weather elements
such as precipitation and wind on
a regional basis. The extent of the
modification and its societal impact
is not well known, but is likely to be
important.
Climate variability and change have
consequences for atmospheric
composition through the
modification of factors that affect
the life cycle (sources, transport,
chemical/physical transformation
and removal) of a pollutant in
the atmosphere; for example,
temperature, surface properties
(drought and plant cover), cloud
cover, precipitation (including length
of dry periods) and boundary layer
mixing properties. The adaptation
of societies to climate change has
consequences for atmospheric
composition; for example, through
changes in the emissions from
energy consumption as the
energy production system moves
towards more extensive inclusion
of renewable energies, including
biofuels. WMO has a particular
responsibility and proven ability to
lead in the technical analysis of how
climate variability and change and
air pollution interact both ways on
a regional basis and in combination
on a global basis, as these are issues
of immediate concern affecting
societies throughout the world to
an extent that is not well known but
could be significant (air pollution
events, floods, droughts, water
supply, food supply, etc).