Climate fluctuations, demography and development: insights and opportunities for Northeast Brazil.

• Author: Chimeli, Ariaster B.

"The environmental and social problems of the Amazon are rooted in the economic trade-offs faced by a developing country seeking improved welfare, land distribution policy, labor productivity and income distribution, with only recent progress in political stabilization."

Until recently, variations in seasonal-to-annual climate were thought to be impossible to predict with any degree of certainty. Since the 1980s, however, that situation has changed significantly. The international community now has the capacity to predict shifts in seasonal rainfall and temperature for many regions of the tropics. The ability to forecast probable shifts a season to a year ahead is an important scientific breakthrough that offers the potential to help vulnerable tropical regions to cope better with natural variations that greatly affect the livelihoods of populations, especially relating to agriculture, health and water resources. Skillful climate forecasts can also help advance environmentally sustainable development over the longer haul by aiding in planning that reduces massive relocations of vulnerable populations that impose critical stresses on impacted social and ecological environments. Improved adaptation on seasonal-to-annual time scales will inform adaptation strategies for longer-term climate change as well.

Despite the significant progress to date, the routine use of climate information and forecasts to help developing countries cope with climate variability is at present more promise than reality. Climate is just one factor contributing to multifaceted socio-political problems that can lead to massive relocations of vulnerable populations. Regional climate information systems require more comprehensive and informed development to build the trust that is critical to the use of climate information to inform decision-making in challenging environments. Partnerships must build capability in affected regions, with research agendas that comprehend and address social need. (2)

Increased understanding of climate-influence may aid decision opportunities, specifically for the case of Northeast Brazil. To assess these possibilities, it is useful to review seasonal climate elements and information systems and present a historic summary of developments over the last century in Northeast Brazil. The semi-arid state of Ceara, whose development has been constrained by the limited availability of water and high variability in its supply, is a case in point.

WORKING WITH NATURAL VARIATIONS IN SEASONAL CLIMATE

For many regions of the world, seasonal climate is strongly influenced by the moderating effect of ocean surface temperature on atmospheric circulation. The best-documented and most important oceanic influence on the atmosphere is El Nino. The term El Nino was first coined more than 100 years ago to describe the unusually warm waters that would occasionally form along the coast of Ecuador and Peru. This phenomenon typically occurred late in the calendar year near Christmas, hence the name El Nino (Spanish for "the boy child," referring to the Christ child). Today the term El Nino is used to refer to a much broader-scale phenomenon associated with unusually warm water that occasionally forms across much of the tropical eastern and central Pacific. The time between successive El Nino events is irregular, but they typically tend to recur every three to seven years.

La Nina, the counterpart to El Nino, is characterized by a shift to unusually cool water across much of the equatorial eastern and central Pacific. A La Nina event often, but not always, follows an El Nino and vice versa. Once developed, both El Nino and La Nina events tend to last for roughly a year, although occasionally they may persist for 18 months or more. El Nino and La Nina (ENSO--El Nino Southern Oscillation) are both a normal part of the earth's climate; there is recorded evidence of their having occurred for thousands of years.

The evolution of a typical ENSO episode takes place over several months. The single most important type of seasonal climate information relates to understanding the current state of the equatorial Pacific Ocean. Great improvements in our understanding of the climate system have occurred because of increased attention to observations of the climate system and the enhanced ability to interpret those observations. For instance, much of the potential to prepare for ENSO-related climate impacts comes from an ability to observe and recognize its early stages. Much of our understanding of ENSO itself was made possible by observations from a system of moored buoys, called the Tropical Atmosphere Ocean array, across the equatorial Pacific, originated in the Tropical Ocean Global Atmosphere Program in the mid-1980s, (3) which has since become a mainstay of ENSO observations. Researchers are building a complementary observational array, called PIRATA, in the Tropical Atlantic with hopes that it will lead to comparable understanding of climate variability, especially in Africa and South America. (4)

The next most important information relates to understanding and interpreting the future state of this ocean basin through the latest ENSO and sea surface temperature forecasts and outlooks. Seasonal forecasts of global rainfall and temperature patterns are generated through a suite of computer models at several centers around the world. It is essential that several sources of seasonal climate forecasts be considered, as individual prediction system performance varies by region and season at different times as initial conditions vary. (5) Many computer models and statistical techniques of varying complexity have shown skill in predicting the evolution of the equatorial Pacific sea surface temperature associated with ENSO for both El Nino and La Nina. (6) However, virtually all of these studies also suggest that ENSO techniques have some difficulties in predicting the details of the onset, magnitude and demise of ENSO episodes.

No single information source is adequate for the characterization of the present and future climate state. What is required is a Climate Information System that includes the following components: (7)

1) Reliable and complete climate observations in real time,

2) Complete and error-free climate data archives to provide a basis for placing the observations into historical context,

3) Complete real-time analyses of current climate data,

4) Access to current climate forecasts from a variety of sources,

5) Easy-to-understand forecast products,

6) Complete records and analyses of past forecast performance,

7) Routine methods for disseminating climate information to user groups and sectors and

8) Active collaboration and feedback from the user community.

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The Climate Information System should include mechanisms for monitoring and evaluating the accuracy of sea surface temperature forecasts and related precipitation and temperature forecasts produced by a variety of methods. This may be as simple as having the System access the evaluations performed by various research and academic institutions. Information on forecast model accuracy is essential to safeguard against false alarms, i.e., forecasts of El Nino or La Nina based on models that have poor historical performance under certain initial conditions.

The end aim is to insure that the tailored climate information discussed above gets into the hands of appropriate users in a timely enough fashion to have some influence on practical decisions. This can only be accomplished if the spatial scales of climate modeling and forecast and those of the decision-makers are compatible and if dissemination of climate information is properly addressed. It will do society no good if the results of climate applications research remain in the academic or research arena. Considerable efforts are required to move from global to regional climate forecasts (or downscaling of climate forecasts, in the climate sciences jargon) and to develop the appropriate means for the effective dissemination of climate information. The producers of climate information generally do not have easy and direct access to the end users of that information; in practice the mechanisms for dissemination need to be developed through a range of organizations and structures. These could range from national meteorological services, who generally have a well-defined set of users, to representatives of the ministries or government organizations who advise user communities--e.g., public health, agriculture, water resources, risk/hazard management and appropriate non-governmental organizations (NGOs).

In summary, the world has been experiencing a progressive understanding of climate processes and the development of a general framework for the analysis and use of climate information. The natural step to take next is to pursue the implementation of such a framework actively in cases of relevance to society. The potential for socially meaningful applications of climate information and forecast in the state of Ceara, Northeast Brazil, is a case in point. Effective use of climate information and forecasts in Ceara can produce social benefits that surpass the local level and provide guidance to the international community on the application of climate forecasts.

THE BRAZILIAN NORTHEAST

Severe droughts in the Brazilian Northeast remain one of the major factors negatively affecting the welfare of local populations. In recent decades, the aggregate measures of economic activity of the Northeast have become less sensitive to climate variability, but the same is not true for a large portion of the population that depends on low-productivity rain-fed agriculture and is still vulnerable to extreme climate.

The human catastrophes associated with extreme droughts in the Brazilian Northeast stem from the occupation of the semiarid portions of the region. Not all the Northeast is semi-arid. In fact, agriculture near...