Air
pollution and climate change tackling
both problems in tandem
Geneva, 31 January
2003 - Scientists and policy makers
should no longer treat air pollution
and climate change as distinct problems,
because the two are very closely related.
The recent Workshop on Linkages and
Synergies of Regional and Global Emission
Control, organized under the UNECE Convention
on Long-range Transboundary Air Pollution
by the International Institute for Applied
Systems Analysis (IIASA), looked at
the numerous links between these two
policy areas. It concluded that these
links are so important that they merit
close cooperation.
Air pollution affects
the regional and global climate both
directly and indirectly. Ozone in the
lower layers of the atmosphere contributes
to global warming even more than some
greenhouse gases included in the Kyoto
Protocol, and particulate matter in
the atmosphere also has important climate
impacts. However, although black carbon,
or soot particles, has a warming effect,
other particles, for instance sulphates
and nitrates, may cool the climate.
The current high levels of sulphates
and nitrates mask the effects of climate
change to some degree. Through cuts
in sulphur and nitrogen emissions necessary
to protect human health and the environment
the climate impacts of the greenhouse
gases may actually show more quickly.
On the other hand, measures to cut black
carbon emissions, for instance from
diesel combustion, will have double
benefits, protecting both human health
locally and also the climate regionally
and worldwide.
Methane has a direct
negative impact on climate (it is one
of the Kyoto Protocol greenhouse gases)
and it contributes to ground-level ozone
levels. Methane emissions (mainly from
agriculture, energy and waste management)
have grown very rapidly since pre-industrial
times. Cutting these emissions will
reduce health- and ecosystem-damaging
ozone levels and reduce the extent of
climate change.
While indications of
the climate impacts of increasing greenhouse
gas concentrations can already be seen
in the rise of mean temperatures and
the increase in the numbers of extreme
climate events (floods and droughts),
most impacts are likely to happen over
the next 50-100 years. Some gases, like
carbon dioxide, stay in the atmosphere
for a very long time, so measures to
reduce emissions only start to show
an effect after a few decades. In contrast,
ozone, black carbon and methane can
be controlled to show effects much sooner
(10-20 years). Cutting these pollutants
could help reduce some climate impacts
while waiting for longer-term measures
to pay off.
Besides such links
between atmospheric effects, there is
also a strong link between the sources
of emissions. Energy production and
transport are responsible for most CO2
emissions and much of the air pollution.
Cutting energy consumption and car use
will therefore have double benefits.
Synergies can also be found in agriculture:
cutting ammonia emissions could lead
to an increase of some greenhouse gas
emissions, but the same reduction levels
can also be achieved by an integrated
strategy that will even cut some of
the greenhouse gases.
The UNECE Conventions
Centre for Integrated Assessment Modelling,
run by IIASA, estimates that the cost
of reaching the 2010 air pollution objectives
in the Conventions Gothenburg Protocol
could be reduced by at least 5 billion
if European countries cut CO2 emissions
in line with the Kyoto Protocol (without
CO2 trading). Similar results have been
found for China or Mexico.
While closely related,
air pollution and climate change have
mostly been treated as separate problems.
At the international level, efforts
under the UNECE Convention on Long-range
Transboundary Air Pollution have helped
cut air pollution levels in Europe.
Sulphur emissions are 60% lower than
in 1980, nitrogen oxides are down by
25% compared to 1990 and other pollutants
are also starting to decline. At the
global scale the United Nations Framework
Convention on Climate Change has brought
together more than 180 countries to
agree on measures to combat climate
change. More needs to be done, both
to bring air pollution down to safe
levels and to cut greenhouse gas emissions
to halt climate change.
Taking certain climate
change measures will yield additional
benefits through improved local and
regional air quality. Certain air pollution
abatement measures will also help protect
the regional and global climate. Much,
though not all, is known about such
links, but systematic studies are lacking.
The UNECE Conventions Cooperative Programme
for Monitoring and Evaluation of the
Long-range Transmission of Air Pollutants
in Europe (EMEP) has begun to integrate
these links into its assessment so that
measures to further cut air pollution
will lead to win-win situations. It
is also seeking cooperation with scientists
of the Intergovernmental Panel on Climate
Change to move this work forward.
For more information, please contact:
Henning Wuester
Environment and Human Settlements
Division
United Nations Economic Commission
for Europe (UNECE)
Palais des Nations, office 323
CH - 1211 Geneva 10, Switzerland
Phone: +41(0)22 917 23 63
Fax: +41(0)22 907 06 21
E-mail: [email protected]
Web site: http://www.unece.org/env/lrtap/
Ref: ECE/ENV/03/P02