Introduction

Climate forecasting is probably one of the oldest professions in the world. A Bably-onic scroll dated to about 3000 BC may well be the oldest-known example of an attempt to predict the weather that would affect the following season's crops. Later attempts are listed in Holy Scriptures, such as in the story of Joseph in the Bible, while phenological approaches based on perceived behaviours of flora and fauna, or on the sun, moon and stars, have developed throughout the world across many succeeding centuries. Not surprisingly there are many similarities amongst these phenological approaches between countries and continents. Interest in phenology remains strong, and has prompted new investigation by the World Meteorological Organisation's Commission for Climatology, although rigorous examination does not always provide succour to the acolytes (Marriott, 1981).

Society has been exposed to the vagaries of climate variability throughout the millennia, but resilience to and protection from these variations as they affect food supplies, water availability and comfort levels has been gained only in some countries. It is hardly surprising therefore that people have long looked to phenology and to beliefs for ways of knowing the severity of the coming winter and the beneficence of the next summer well ahead in order to prepare. Phenological and belief approaches are still used in many countries, including developed ones, and it is likely that they will continue to be employed long after modern scientific approaches have matured well past their current stage.

It is not a simple task to identify the initial breakthrough that led to the current stage of development of modern scientific seasonal to inter-annual forecasts, although the work of Gilbert Walker1 is certainly recognised as one of the prime inputs, even though its import was not fully appreciated at the time. Working in

Climatic Change (2005) 70: 201-220

© Springer 2005

India in the early 20th Century, and tasked as Director-General of the Indian Meteorological Department to find a method of predicting the monsoon rain total, Walker set out to examine statistical relationships in the global atmosphere. There were already clues that climate variations in different parts of the globe may be associated and Walker examined all data available to him in an attempt to identify predictive links for the monsoon rains. His work uncovered the North Pacific Oscillation and the North Atlantic Oscillation, apparent latitudinal "seesaws" in pressure across these basins. Neither aided the monsoon problem. However it was the third seesaw, the "Southern Oscillation", which imparted the stimulus to further study, and continues to provide one input to the prediction methods used by the Indian Meteorological Department today. It was many years, however, before the importance of the Southern Oscillation was comprehended in terms of its inherent global-scale atmosphere/ocean dynamics, and its links to El Niño recognised.

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