25 Years of Science Serving Society
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World Climate Research Programme: 25 years of science serving society WMO © 2005, World Meteorological Organization NOTE The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Meteorological Organization concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. 2 Foreword Understanding climate and its change represents one of the most difficult challenges to modern science because of the complexity of physical, chemical and biological interactions occurring on the Earth — in its atmosphere, oceans and on land — at the widest range of space and timescales. Through the World Climate Research Programme (WCRP), the World Meteorological Organization (WMO), the International Council for Science (ICSU) and the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO) have joined efforts to support and coordinate the activities of the global meteorological and oceanographic communities and the wider academic community to address this challenge. The WCRP, in the 25 years since it was established, has made enormous contributions to advancing climate science. As a result of WCRP efforts, it is now possible for climate science to monitor, simulate and project global climate with unprecedented accuracy so that climate information can be used for governance, in decision-making and for support of a wide range of practical applications. At the same time, there are still many gaps in our knowledge, and much better and more detailed climate system observations, models, assessments and services are required. The Joint Scientific Committee for the WCRP, in collaboration with the WCRP projects and the larger scientific community, is developing a strategy for the next decade which will ensure that WCRP works efficiently and effectively towards strengthening our knowledge and increasing our capabilities with regard to climate variability and change and their prediction. This strategy, known as Coordinated Observation and Prediction of the Earth System (COPES), will facilitate the analysis and prediction of the Earth system variability and change for use in an increasing range of applications of direct relevance, benefit and value to society. I am confident that in this way the WCRP will continue to make a significant contribution to the understanding and governance of the Earth. P. Lemke Chairperson Joint Scientific Committee for the WCRP 3 WCRP — at the forefront of climate science since 1980 The main objectives, set for WCRP at its inception and still valid, are to determine the predictability of climate and to determine the effect of human activities on climate. To achieve these objectives, WCRP adopts a multidisciplinary approach and organizes large-scale, observational and modelling projects, each of which focuses on aspects of climate too large and complex to be addressed by any one nation or individual scientific discipline. Three major WCRP projects have been successfully completed in the last decade. The Tropical Ocean and Global Atmosphere (TOGA) project (1985–1994) established the physical basis for the understanding and prediction of El Niño temperature signals and associated changes in global climate. This led to a major breakthrough in operational seasonal climate forecasting. The World Ocean Circulation Experiment (WOCE) (1982–2002), the biggest and most successful global ocean research programme to date, collected observations of the world’s oceans of unprecedented quality and coverage and led to the development of important new ocean observing techniques and improved understanding of physical processes in the ocean. The Arctic Climate System Study (ACSYS) (1994–2003) examined the complex and interrelated pieces of the Arctic climate system to ascertain its role in the global climate system. WCRP research over the years has greatly improved our understanding of key climate processes and a vigorous modelling programme has resulted in significantly improved climate models, as well as better operational weather and ocean forecasting models. Improved modelling of the climate system has provided increasingly accurate simulation and predictions of natural climate variations, giving more confidence in projections of human-induced climate change. WCRP research has provided the scientific underpinning for each of the assessments of the Intergovernmental Panel on Climate Change (IPCC) that, in turn, contribute to the political process related to climate change. Ocean sections occupied during WOCE. Comprehensive field measurements and the provision of essential global and regional climatological data sets are major components of all WCRP projects. Some of these, such as the observing system in the Pacific established by TOGA and the global array of subsurface floats implemented during WOCE, have led to operational climate observing activities which are crucial to monitoring and predicting climate. 4 Climate models with only °C “natural” forcings (volcanic and solar) do not reproduce observed late twentieth century warming. When increases in anthropogenic greenhouse gases and sulphate aerosols are included, models are able to reproduce the observed warming. G.A. Meehl Today the WCRP consists of four major core projects: • The Climate Variability and Predictability (CLIVAR) project; • The Global Energy and Water Cycle Experiment (GEWEX); • The Stratospheric Processes and their Role in Climate (SPARC) project; • The Climate and Cryosphere (CliC) project and the co-sponsored Surface Ocean-Lower Atmosphere Study (SOLAS). WCRP — building awareness of climate “Climate change … change and related risks may well be the greatest challenge that your generation It was the international community of physical climate scientists that alerted will have to face. … the world to the reality of global warming, the prospect of anthropogenic This is not some climate change and its consequences. It is this same community that has distant, worst-case determined the most likely causes of the recent global climate change and scenario. It is which has the capability to provide increasingly reliable climate-change tomorrow’s forecast. scenarios, which are crucial for many aspects related to planning for Nor is this science sustainable development. WCRP has helped bring such climate-related issues fiction. It is sober to centre-stage by carrying out policy-relevant science and by raising the prediction, based on level of scientific, governmental and public appreciation to the importance of the best available climate issues. This has been done through fostering much greater science.” cooperation between hitherto distinct scientific disciplines in understanding the whole climate system. Kofi Annan, Secretary-General of the United Nations Keynote address at Tufts University Fletcher School of Law and Diplomacy, 20 May 2001. 5 Enabling more useful climate predictions Climate predictions seasons in advance — now a reality The WCRP TOGA project established the physical basis for predicting El Niño temperature signals and associated changes in the global atmospheric circulation from a season up to a year in advance. This was a major breakthrough in the ability to make skilful forecasts of seasonal climate signals. The current WCRP activities are aimed at increasing the reliability of El Niño/Southern Oscillation (ENSO) event predictions and also extending predictive potential towards mid- and polar latitudes. The objective is to reveal all predictable features at the global and regional scales. Three-dimensional output from a coupled Cold Warm atmosphere-ocean simulation of conditions over the equatorial Pacific region. Cloud water Ocean temperature (Colour) Ocean current (Arrows) Earth Simulator Center/JAMSTEC Monsoon rains — a source of life — can we predict them? Over half of the world’s population lives within the influence of the Asian monsoon and a further large fraction lives within the monsoon areas of Africa and the Americas. Forecasting monsoons, their onsets, breaks and duration, remains a very difficult scientific problem due to the complexities of the interactions involved. Advances in simulation of clouds and radiation, progress in assimilation of humidity and temperature data sets, better cloud- resolving schemes and several other factors have set the stage for WCRP to concentrate efforts on improving the monsoon prediction capabilities. 6 Long-term climate variability — can it be predicted? In the North Atlantic, the changes to the patterns and intensity of the storm tracks associated with changes in the strength of the so-called North Atlantic Oscillation can result in periods of severe winter storminess with potential damage to property and loss of life. The changes in annual rainfall in the African Sahel on decadal and longer timescales and the dust bowl years of the 1930s in the United States are other examples of how longer term variations of climate affect the life support systems. On much longer timescales, the cycles of glacial (ice age) and interglacial periods (such as we are in now) demonstrate the very long-term variability of climate. Recent WCRP studies have indicated that there is some potential predictability on longer timescales; this avenue of research is being vigorously pursued. Contributing to risk assessment There are inherent limits to weather and