The dynamic interplay between atmosphere
and ocean in the boundless dimensions of time and space causes variability
of different magnitudes in climate patterns around the globe. The extreme
events in this continuous variability greatly impact society and the ennironment.
The devastating impacts of El Nino 1982-83 and 1997-98 are well documented.
For several decades the prevalent view was that it is not possible to predict
weather and its variations beyond the intrinsic limit of two to three weeks.
However, unprecedented developments in climate science over the last two
decades have now made it possible to predict climate variability with a
significant lead time, in some cases up to one year. Although it is unlikely
that any two weather maps will ever be exactly alike, the climate does exhibit
a pattern of broader repetitiveness (Rasmussan, 1984).
El Nino Southern Oscillation (ENSO) associated climate variables that
are larger in amplitude and global in scale exhibit one such pattern.
Taking advantage of this feature, significant achievements have been made
in probabilistic forecasting of seasonal and inter-annual variations in
climatic conditions associated with ENSO. Acquisition of this capability
in recent years has potential value to decision making for the benefit
of affected regions. As the tropical atmosphere responds directly to changes
in oceanic variations, seasonal mean climate is highly predictable in
tropical regions in general, and Southeast Asia in particular. This article
focuses on some of the issues connected with ENSO forecasting and its
applications in Southeast Asia.
El Nino and La Nina Impacts in Southeast Asia
Extreme climate events such as El Nino and La Nina affect the society
and the environment in Southeast Asian countries in a significant way.
During an El Nino year, rainfall in most parts of the region tends to
be below average leading to droughts, and tropical cyclone occurrences
and associated flood incidences tend to be less. The most dramatic and
disastrous effects El Nino 1982-83 and 1997-98 in Indonesia were manifested
in the large-scale forest fires. On the other hand, during a La Nina year,
the rainfall is above average with increased frequency of tropical cyclones
and more incidence of floods. A La Nina year, however, also provides opportunities
in agriculture sector for advancing the planting season, leading to an
early increased harvest as well as possibilities for harvesting one additional
crop.
Potential application of improved climate forecasts
The existing early warning system in most countries is based on monitoring
rainfall, water levels in reservoirs and the vegetation index, which can
give a one-month lead time before harvest, to enable government institutions
to implement contingency plans for food security in case of an impending
drought. In case of floods, the lead time available is a couple of days
to enable agencies to plan for emergency operations.
The advancements in climate science have now made it possible to indicate
expected behavior of weather parameters such as rainfall, temperature
and tropical cyclone occurrence in probabilistic terms with a considerable
lead time. Climate forecasts can enable individual stakeholders and critical
resource sector institutions to make appropriate adjustments to minimize
negative consequences and capitalize on potential benefits of extreme
climate events. These adjustments may include restructuring the cropping
pattern, reorienting or modifying water resource management, and undertaking
disaster preparedness and mitigation activities.
Experiences of using probabilistic forecasts
The experiences of managing the consequences of the 199798 El Nino and
19981999 La Nina events have underlined the fact that the maximum benefits
of the applications of forecast products cannot be realized without a
thorough understanding of the human, social and economic systems within
which climate forecasts will be applied. Clearly, there is a critical
gap between the climate forecasts and their application for decision-making.
There is a need for developing methods for impact pre-assessment (or consequence
analysis) based on empirical analysis of past disaster events which would
indicate the existing vulnerabilities on a geographical scale at which
the counter-measures would be most effective. Physical climate variability
and application of forecast products need to be integrated as a comprehensive
climate forecasting and application system to take full advantage of the
lead time for adopting effective disaster and resource management practices.
The direct application of global ENSO forecasts by decision makers without
adequate understanding of their implications at the local level may sometimes
lead to inappropriate policies and decisions as was evident during the
199798 El Nino and 199899 La Nina events.
The Philippine experience during the 199798 El Nino event shows that
direct application of climate forecast without an adequate impact pre-assessment
led to the initial declaration of 29 provinces as drought-affected, yet
only six of these provinces actually experienced drought. An increased
likelihood of below average rainfall was interpreted as leading to devastating
drought but in reality, the monsoon paddy crop in some parts of the country
performed even better due to the decreased number of tropical cyclones
with optimum rainfall conducive for crop growth (Flor, 1998).
The Vietnam experiences during the 1997-98 El Nino and 199899 La Nina
events show that there was inadequate appreciation of linkages between
global ENSO parameters and local weather variables. For instance, a prolonged
drought during 1997-98 caused a crop loss of as much as VND 5 trillion
(US$ 385 million). Most of the intervention was centered on providing
immediate relief to affected farmers, despite the fact that enough lead
time was available to plan and undertake proactive measures (DMU, 1998).
In Indonesia, La Nina was perceived largely as a flood inducing agent,
and excessive imports of rice were planned. However, the rice production
during wet- season 1998-99 increased due to favorable weather provided
by La NiÒa resulting in crash of paddy prices to the disadvantage of farmers
(ADPC, 1998).
These experiences indicate that there is a need to better understand
the linkages between regional climate forecasts, their implications for
local weather parameters and specific local impacts on critical resource
sectors.
Towards a better integration of climate forecasts and
their applications
An effective integration between physical climate prediction and its
application would require significant work in three distinct but inter-related
areas - Physical Climate Prediction; Consequence Analysis or Impact "Pre-assessment";
and Institutional Response to Extreme Climate Events.
Physical climate prediction
Global ENSO parameters impact the strength of regional monsoon pattern
in Southeast Asia. The behavior of monsoon in turn impinges on local weather
variables such as typhoon incidence, rainfall distribution, temperature
and humidity. These weather parameters influence the climate sensitive
sectors like agriculture, water resources and public health. The direct
application of global ENSO parameters into local decision-making poses
serious difficulties. Policy planners and end users are not able to utilize
the information like the sea surface temperature (SST) index and thermoclime
depth in the tropical Pacific for making resource management decisions.
Clearly, the local decision makers' specific interest is to know what
are the specific impacts attributable to the precursor, growth and decay
phases of ENSO on local weather variables such as onset and strength of
southeast and northwest monsoons.
Hence, there is a need to downscale and desegregate the specific impact
of ENSO parameters on monsoon patterns and the impact of monsoon patterns
on local weather variables. There is a need to establish linkages of global,
regional and local climate/weather variables and their impact on a given
socio-economic system in a particular area. The disaggregation of ENSO
associated potential impacts on temporal and spatial basis would provide
better resolution to climate forecast products that will enable end users
to undertake proactive response measures. The following specific issues
need to be addressed:
- What is the suitability of current climate and weather forecast products
for consequence analysis (impact pre-assessment) and decision-making
in various user departments?
- What are the opportunities and constraints in producing and disseminating
end user friendly climate forecast products?
- What are the opportunities for institutionalizing climate forecasts
through greater involvement of experts form other disciplines such as
agro-climatology, natural resource management, public health and water
resource management?
Impact "Pre-assessment" or Consequences Analysis
The existing methods used by different departments and agencies rely
on monitoring of concurrent indicators during the course of the monsoon
season like rainfall, crop condition, water level position in reservoirs,
etc. This system gives a relatively small lead time to make resource management
and disaster preparedness decisions. The ENSO climate forecasts now available
can potentially provide information on possible onset of monsoon and its
behavior during the entire season with enough lead time so as to facilitate
the pre-assessment of the potential impacts on critical resource sectors.
Few methods for such impact pre-assessment exist now and constitute a
critical gap between climate forecasts and their application for decision
making. In the wake of 199899 La Nina event, the Asian Disaster Preparedness
Center (ADPC) in collaboration with the National Disaster Management Coordination
Board of Indonesia and the National Oceanic and Atmospheric Administration
(NOAA) took the initiative to undertake a rapid pre-assessment of the
affects of La Nina on Indonesia.
The main focus was on the agriculture sector. This was a successful experience
and indicated that documentation and empirical analysis of past sectoral
impacts and their management experience in a given area can pave the way
for establishing and institutionalizing consequence analysis or impact
pre-assessment system in different sectors. The following specific issues
need to be addressed:
- What kind of consequences can be anticipated (pre-assessed)? Natural
disasters, floods, droughts, fires, reservoir levels, crop production,
public health problems, etc.
- Where are the opportunities (within the existing institutional context)
to establish systems for impact pre-assessment? What is the kind of
interagency coordination required for doing this most effectively?
Institutional Response to Extreme Climate Events
The possibility of establishing an impact pre-assessment system enlarges
the scope of better institutional responses to extreme climate events.
However, there is a need to assess the status of the current institutional
network to climate sensitive sectors such as agriculture, forestry, public
health, water resources, etc. to institutionalize pre-assessment and proactive
response efforts. The following specific issues need to be addressed:
- How, and to what extent, is probabilistic forecasting information
used by resource managers in national, provincial and local governments?
- What are the kinds of risk management and/ or contingency plans adopted
by various institutions to deal with forecasted extreme climate events
(El Nino or La Nina) and their anticipated consequences?
- Does the increased use of probabilistic forecast information on weather
variables and its pre-assessed potential impacts actually lead to decisions,
which have superior outcomes from an overall societal perspective?
Conclusion
Over the last two decades, regional and global climate forecasting capabilities
have reached an unprecedented level. However, a lot remains to be done
for the application of these new capabilities to the maximum benefit of
society. This will require a significant dialogue between, and amongst,
the climate science community and the existing and potential end users
of climate information. Following the 1997-98 El Nino and 199899 La Nina
events, a number of sector-specific and cross-sectoral initiatives have
come up at the national and regional levels to address this need.
At the regional level, one such initiative is the Program on Understanding
Extreme Climate Events (ECE) in Southeast Asia managed by ADPC in collaboration
with NOAA and supported by the United States Office of Foreign Disaster
Assistance. In its pilot phase, the program works in Indonesia, the Philippines
and Vietnam and aims at improving the understanding of extreme climate
events and their affects on the society and environment in these countries.
The program endeavors to provide an interface between the scientific and
research community, generating information on extreme climate events,
and the users of this information, such as national governments, NGOs,
national and regional press bureaus, etc.
There are other initiatives in the Southeast Asian region that focus
on specific sectors such as forestry, agriculture, etc. Each of these
initiatives constitutes small steps towards improved understanding of
extreme climate events and will offer benefits to a wide range of stakeholders.
However, it will require multi-dimensional and innovative institutional
arrangements to take full advantage of improved climate forecasting.
