Distr.
GENERAL
FCCC/SBSTA/1997/8
22 September 1997
Original: ENGLISH
SUBSIDIARY BODY FOR SCIENTIFIC AND TECHNOLOGICAL ADVICE
Seventh session
Bonn, 20-29 October 1997
Item 3 of the provisional agenda
Paragraphs Page
INTRODUCTION 1 - 2 2
POSSIBLE ACTION BY THE SBSTA 3 2
The Global Atmosphere Watch 3
GE.97-
co-ordination, for example, on the monitoring of greenhouse gases
(GHGs) in the atmosphere with the World Meteorological Organization
(WMO) and to advise the SBSTA on these activities
(FCCC/SBSTA/1996/20, para. 42).
Intergovernmental Panel on Climate Change (IPCC);
- Express its appreciation to those Parties already operating stations within the existing network, as well as to the Global Environment Facility (GEF) for its support in the establishment and operation of several stations;
- Invite Parties and relevant funding organizations and programmes to provide financial and other support to strengthen and maintain the GAW; and
- Invite WMO to continue its efforts to implement the GAW and to report on progress to future sessions of the SBSTA.
Introduction
The major responsibility for monitoring global changes in the
atmospheric environment belongs to the World Meteorological
Organization (WMO). The Organization coordinates the environmental
monitoring activities and scientific assessments of its 178 Member
states and 5 territories through its Global Atmosphere Watch (GAW), a
system of networks of observing stations, related facilities, and
infrastructure encompassing the measurement and related scientific
assessment activities devoted to the investigation of the changing
chemical composition and related physical characteristics of the
global atmosphere. GAW serves as an early warning system to detect
further changes in atmospheric concentrations of greenhouse gases,
changes in the ozone layer and in the long-range transport of
pollutants, including acidity and toxicity of precipitation as well
as of atmospheric burden of aerosols (dirt and dust
particles).
Background
GAW was established by the WMO Executive Council in June 1989 to
strengthen and better co-ordinate WMO environmental data-gathering
activities that began in the 1950s. It provides framework design,
standards, intercalibrations and data collection systems for global
monitoring and data evaluation. Through GAW, state-of-the-science
measurements of a number of mostly low-concentration chemical and
physical constituents of the atmosphere at levels extending from the
surface to the stratosphere and at some of the most difficult
locations on Earth are being made. Some three hundred stations now
comprise the WMO GAW network (Figure 1). GAW has become broadly
recognized, both by governments and within the scientific community
at large, as an essential tool for monitoring the state and the
evolution of the composition of the atmosphere and for improving the
understanding of its interactions with all aspects of the
environment.
Bearing in mind heightened public awareness and concerns for
climate and environmental issues in general, activities associated
with the further development and implementation of GAW continue to be
prominent. In recent years, new stations have been added to the
network and existing ones upgraded. Complementing this overall
extension of the observing network are important supporting
activities in areas such as education and training, and quality
assurance and assessment procedures. In particular, the establishment
of Quality Assurance/Science Activity Centres (QA/SACs), a number of
World Calibration Centres (WCCs) and the increased number of WMO
World Data Centres such as the WMO World Data Centre for Greenhouse
Gases in Japan are seen as major steps forward for maintaining
consistent and known data quality in the GAW Programme.
The Measurement of Greenhouse Gases
In 1956, long-term carbon dioxide measurements were begun at Mauna
Loa Observatory in Hawaii, USA. Since that time three other gases
were recognized as important greenhouse gases: nitrous oxide
(N2O), methane (CH4), halocarbons (CFCs) and
tropospheric ozone.
Carbon Dioxide Carbon dioxide data have been
included in the WMO atmospheric monitoring programme in the 1960s and
as early as 1975 WMO issued an authoritative assessment of the
potential role of the CO2 increase for climate. In the mid
1970s, the WMO Research and Monitoring Project on Atmospheric Carbon
Dioxide was initiated whose objectives were to strengthen long-term
monitoring for better trend determination, to predict its
concentration through the next century, and to assess its possible
effects on the climate. The monitoring aspects of CO2
remain within WMO GAW whereas the other objectives have been further
developed within the WMO World Climate Programme activities. In
Figure 2, the long term record from four diverse locations show the
global CO2 increase.
To measure CO2 an instrument called a non-dispersive
infra-red analyser (NDIR) is more or less universally used. Numerous
manufacturers make this instrument. It compares the absorption of
infra-red radiation from a source in the instrument (sample) with the
absorption of a known concentration of CO2 (reference) in
a specially prepared mixture of standard gases. The CO2
concentration is determined from the relative analyser output between
the sample gas and the reference gas. CO2 concentration is
also determined by collecting air in flasks and returning the flasks
to a central laboratory where NDIR measurements are made. The network
coordinated by the US National Oceanic and Atmospheric Administration
is shown in Figure 3.
Methane CH4 is emitted into the
atmosphere from a variety of natural and anthropogenic sources such
as natural wetlands, rice patties, fermentation processes in animals,
biomass burning, natural gas production and landfills. While the
major sources of atmospheric methane have been identified, the
relative strength of each source is not yet clearly known. It can be
seen in Figure 3 that methane is also measured at the locations along
with CO2. The most common method of measurement is by gas
chromatography which can only be done at locations with high
technical skills. The global distribution of methane is shown in
Figure 4.
Nitrous Oxide N2O is also an important
greenhouse gas which has both natural and man-made sources. However
these are poorly quantified. Determination of global concentrations
is difficult since nitrous oxide, which is released mainly from
soils, is very heterogeneous. It is estimated to contribute about 6%
to the overall greenhouse effect. Trends in N2O are shown
in Figure 5.
Halocarbons The main concern with the family of
man-made halocarbons has been their impact on the destruction of the
stratospheric ozone layer. However they also act as greenhouse gases.
The restriction imposed by the Montreal Protocol show that for
selected halocarbons there has been a decrease in their growth in the
atmosphere (Figure 6).
Tropospheric Ozone Tropospheric ozone has just
been recognized as a potentially important greenhouse gas. Because it
varies both regionally and vertically, it is hard to assess its
long-term global trend. Under the GAW programme, there is a great
need to expand the measurement of this gas on a world-wide basis. A
number of ozone vertical measurements have been
proposed.
Use of the network
Recently a major effort has been to expand the GAW greenhouse gas
network through the support of the Global Environment Facility (GEF).
As project manager WMO, working closely with UNDP, has established
six new GAW stations of global importance in Algeria, Argentina,
Brazil, China, Kenya and Indonesia. These stations are already
producing data or will shortly. Furthermore, a regional GEF project
in South America which is managed by the WMO has been established to
increase the measurement of ozone (Argentina, Brazil, Chile, Paraguay
and Uruguay). These two projects have successfully demonstrated that
some of the gaps in greenhouse gas measurements can be filled.
However, similar projects are needed in other parts of the world, in
particular in Africa and Asia.
Without WMO's coordinated greenhouse gas measurement programme,
the potential problem of climate change due to the changing
atmospheric composition would not have been recognized. With this
recognition, climate modellers have used these data to predict
climate change scenarios. This has been the key to the analysis under
the activities of IPCC. Particularly, the WMO's GAW programme is
considered the atmospheric chemistry contribution to the Global
Climate Observation System (GCOS). Figure 7 shows a conceptional
design of an operational framework of observations, analysis
prediction and research underpinning climate services to
society.
Global warming of the Earth-atmosphere system is being brought
about by the greenhouse effect. The uncertainties in the predictions
relating to the timing, magnitude and regional patterns of climate
change are being addressed and here the WMO GAW greenhouse gas
network is essential in providing the basic data used to resolve
these uncertainties. These critical data are obtained from monitoring
sites located in pristine regions of the world. Siting criteria is
very specific from the standpoint of evaluating global trends. Only
accurate monitoring over long periods of time can provide the data
necessary to document trends and project potential of future
pollution loads. Relating changes in climate, or other factors of the
global environment, to concurrent trends in the background levels of
greenhouse gases may permit forecasting of future changes. The low
levels found in background conditions and the accuracy required to
document small changes require continued scientific
studies.
Infrastructure
WMO, through its earlier monitoring programmes and now GAW, has
promulgated standardization of measurements by bringing interested
scientists together at regular intervals. For example, to date five
specialized conferences discussing methods of CO2
observations and analysis have been sponsored by WMO (Bern 1981,
Interlaken 1985, Hinterzarten 1989, Carqueiranne 1993 and Cairns
1997).
As an important function of GAW, the data obtained are archived at
the WMO World Data Centre for Greenhouse Gases (WDCGG) established in
Tokyo, Japan in 1990. There, systematic collection and distribution
of data on the concentrations of greenhouse gases (CO2,
CH4, CFCs, N2O etc.) and the related gases
(e.g. CO, NOx , SO2) are made. Further, the WMO
has established three Quality Assurance Science Activity Centres in
Germany, Japan and the United States where the quality of the GAW
measurements are overseen on an international basis. For example,
under this system the World Calibration Centre for Carbon Dioxide
Measurements is at the NOAA laboratory in Boulder, USA.
Summary and future needs
To better predict climate change due to the greenhouse effect,
there is a need to sample the atmosphere much more comprehensively,
but still at reasonable cost. From the GAW monitoring perspective,
the following needs can be outlined:
- The GAW system has been successful in establishing a world-wide
network to measure greenhouse gases. However there are still many
areas where there is an urgent need to expand these measurements if
we are to understand the full implementations of climate change. GEF
should consider this as a number one priority.
- The technical aspects of maintaining a sophisticated measurement
programme require a strong infrastructure to ensure the consistent
global quality. For example, though international calibration
standards for carbon dioxide are in place, no such standards are
available for the other greenhouse gases. This is one of the flaws in
the GAW in ensuring a harmonized data set.
- A framework for the measurement of greenhouse gas concentrations
is in place but to understand their sources and sinks requires
measuring transport and flux in both the horizontal and vertical.
Aircraft measurements play an important part in this where new
automated techniques are now just being developed.
- Stronger ties between the modelling and measurement communities
must be fostered. The upcoming meeting in Cairns, Australia (8-12
September 1997) will be the forum for such discussions.
There is no question that the accurate measurement of the
concentrations and fluxes of greenhouse gases under the WMO's GAW
programme is a basic activity in understanding and forecasting
climate change.
Figure 3. The GAW network of CO2 and other greenhouse gases around the world.
Countries actively involved include: Australia, Canada, China, France,
Germany, Hungary, Italy, Japan, Korea, New Zealand, Sweden and
USA