Some thoughts on the contributions of Tim Palmer

Peter Webster

Georgia Institute of Technology, USA

Tim Palmer is a physicist and philosopher who, after his university work on general relativity at the university of Oxford, moved to the field of weather and climate dynamics, first with the British Meteorological Office and then at the European Centre for Medium-Range Weather Forecasts. During his tenure at ECMWF, and later at Oxford, as a Royal Society Research Professor, Tim has conducted research that has lifted our understanding of chaos and nonlinear systems and how such knowledge can be used for the betterment of society.

During the 1980s, I was a member of the ICSU/WMO Joint Scientific Committee and Chair of the WCRP Tropical Ocean Global Atmosphere (TOGA) Steering group. The aim of TOGA was to explore the coupled global ocean-atmosphere system and the predictability of such phenomena as the El Niño-Southern Oscillation. But, during this period we had become aware of a number of stumbling blocks standing in the way of extended prediction. At this stage in meteorology, numerical weather prediction depended on models initialized by the “best estimate” of an initial field. A particular issue was the limitations of deterministic forecasts and the relatively rapid growth of errors as anticipated by the work of Lorenz in the 1960s that quickly grew, limiting the horizon of useful deterministic forecasts. Some members of the WCRP suggested that the thoughts of Tim Palmer might help and he was invited to join the WCRP committees. His contributions were new, exciting, revolutionary and thought provoking.

At Tim’s invitation I spent a sabbatical year with his group at ECMWF. At that stage Tim was working towards the development of a stochastic prediction system, essentially a Monte-Carlo technique system, where a model would be initialized multiple times with slightly differing initial conditions. From this ensemble of forecasts emerged the probabilities of possible future outcomes. This was particularly exciting as it allowed, based on probabilities, decisions to be made that were impossible from single deterministic forecasts. During the next couple of decades, the Ensemble Prediction System (EPS) approach was extended to a fully coupled ocean-atmosphere system with lead-times 7-14 days and at lower resolution for extended horizons for subseasonal and seasonal horizons.

Obvious applications EPS were evident, especially in the developing world where severe events (floods, droughts) would arrive unexpectedly wreaking havoc for the unprepared. The EPS allowed an agricultural community to determine the risk of a disadvantageous event occurring and decide upon mitigatory actions depending on their cost. In other words, the evolving EPS forecasts allowed a cost-benefit analysis to be made during the entire agricultural cycle. Over a decade ago, the first trans-boundary forecasting system was developed for the Brahmaputra-Ganges system with a concentration on Bangladesh and later, an equivalent model for the Pakistani Indus system. An economic analysis of the benefit of prewarning of floods in Bangladesh showed considerably reduced losses of the order of annual incomes.

The Bangladesh flood forecasting system is just one example of the benefit to society enabled by Tim Palmer and his group. His research spans a broad range of areas from the deeply theoretical to the highly practical. Most importantly, he has transformed the results of Lorenz, often thought of the death knell of extended numerical prediction, into a benefit to all of humanity! This is not an idle statement. He has promoted a system that allows all of humankind to potentially make reasoned and balanced choices in a changing world having to cope with weather variability in a variable and uncertain climate. Access to such forecasts is, of course, necessary, and Tim Palmer is an advocate of their wide dissemination.

Many of Tim’s thoughts and accomplishments are encapsulated in his recent book “The Primacy of Doubt”. It is a magnum opus that spans, and joins together, concepts of quantum physics, uncertainty, and climate change. This is a very welcome addition to a field some decades ago that may have been stricken with a “paucity of doubt”. This philosophical treatise creates a pathway for humankind through life’s nonlinearity and chaos.

Tim Palmer has received many awards from across the globe and there is not space enough here to list them all. But he is a Fellow of the Royal Society and foreign member of many academies of science as well as uppermost honors from learned societies. His gift to humanity is a gift for the ages.

Finally, I should say that I am honored to be a colleague and friend of Tim Palmer. They are important components in my own pathway through life and science.