One of the major challenges facing humankind is to provide an equitable standard of living for the current and future generations: adequate food, water and energy, safety, shelter and a healthy environment. Human-induced climate change, and increasing climate variability, as well as other global environmental issues such as land degradation, loss of biological diversity, increasing pollution of the atmosphere and fresh water and stratospheric ozone depletion, threaten our ability to meet these basic human needs. Considerable efforts have been deployed in monitoring and projecting the changes and in evolving possible options for managed systems including agriculture and forestry.

Today, there is certainty from the surface temperature data, collected by WMO's Global Observing System, that the globally averaged surface temperatures are rising. According to records maintained by members of WMO, the global surface temperature has increased since the beginning of instrumental records in 1861. Over the 20th century that increase was about 0.6 °C. The rate of change for the period since 1976 is roughly three times that of the past 100 years. Analyses of proxy data for the Northern Hemisphere indicate that the late 20th century warmth is unprecedented for at least the past millennium. Over the same period, the 1990s were the warmest decade, the year 1998 was the warmest year and the years 2002 and 2003 the second and third warmest, respectively. The projected temperature rise by the end of the century is between 1.4 and 5.8 °C.

Scientific assessments have shown that over the past several decades, human activities, especially burning of fossil fuels for energy production and transportation, are changing the natural composition of the atmosphere. Proxy records indicate that for over at least the last 400,000 years, up to about 1800 AD, the atmospheric concentration of carbon dioxide (CO2) varied only by 1-3 per cent. Since then, it has increased by more than 33 per cent, and reached 376 parts per million by volume (ppmv) at the end of 2003. WMO's Global Atmosphere Watch observing network monitoring atmospheric chemistry show that today's atmospheric CO2 concentration has not been exceeded during the past 420,000 years. More than half of that increase in CO2 concentration has occurred since 1950.

It is also possible, even likely in some cases, that human-induced climate change will affect naturally occurring climate variability such as the frequency or intensity of El Nino/Southern Oscillation (ENSO) events. A growing number of extreme weather and climate events, some of which have been of unprecedented intensity, continue to be observed with associated degradation of the environment. This requires the global community to give urgent attention and high priority to addressing key issues related to climate change through appropriate measures and policies at national and regional levels.

Climatic Change (2005) 70: 5-7

© Springer 2005

Climate variability affects all economic sectors, but agricultural and forestry sectors are perhaps two of the most vulnerable and sensitive activities to such climate fluctuations. Climate change and variability, drought and other climate-related extremes have a direct influence on the quantity and quality of agricultural production and in many cases, adversely affect it, especially in developing countries, where the pace of technology generation, innovation and adoption does not allow them to counteract the adverse effects of varying environmental conditions. For example, inappropriate management of agroecosystems, compounded by severe climatic events such as recurrent droughts in many parts of the world, have tended to make the drylands increasingly vulnerable and prone to rapid degradation and hence desertification. Even in the high rainfall areas, increased probability of extreme events can aggravate nutrient losses due to excessive runoff water logging. Projected climate change can influence pest and disease dynamics with subsequent crop losses. Improved adaptation of food production, particularly in areas where climate variability is large, holds the key to improving food security for the global population.

The range of adaptation options for managed systems such as agriculture and forestry is generally increasing because of technological advances, thus opening the way for reducing the vulnerability of these systems to climate change. However, some regions of the world, particularly developing countries, have limited access to these technologies and appropriate information on how to implement them. Here successful traditional technologies used over the centuries should be maintained. Incorporation of climate change concerns into resource-use and development decisions and plans for regularly scheduled investments in infrastructure will facilitate adaptation.

Agriculture and forestry are currently not optimally managed with respect to today's natural climate variability because of the nature of policies, practices and technologies currently in vogue. Decreasing the vulnerability of agriculture and forestry to natural climate variability through a more informed choice of policies, practices and technologies will, in many cases, reduce the long-term vulnerability of these systems to climate change. For example, the introduction of seasonal climate forecasts into management decisions can reduce the vulnerability of the agriculture to floods and droughts caused by the ENSO phenomena.

It is with this background that WMO had organized the International Workshop on Reducing Vulnerability of Agriculture and Forestry to Climate Variability and Climate Change in conjunction with the 13th session of the Commission for Agricultural Meteorology of WMO held in October 2002 in Ljubljana, Slovenia. The workshop was co-sponsored by the Asia-Pacific Network for Global Change Research (APN), the Canadian International Development Agency (CIDA), the Centre Technique de Cooperation Agricole et Rurale - Technical Centre for Agricultural and Rural Co-operation (CTA), the Environmental Agency of the Republic of Slovenia, the Ministry of Agriculture, Forestry and Food of the Republic of Slovenia, the Ministry of Environment, Spatial Planning and Energy of the Republic of Slovenia, the Food and Agriculture Organization of the United Nations (FAO), the Fondazione per la Meteorologia Applicata and the Laboratory for Meteorology & Climatology (F.M.A.-La.M.M.A.), Meteo-France, the International START Secretariat (START), the Ufficio Centrale di Ecologia Agraria (UCEA), the United Nations Environment Programme (UNEP) and the United States Department of Agriculture (USDA).

The workshop reviewed the latest assessments of the science of climate variability and climate change, and their likely impacts on agriculture and forestry in different agroecological regions during the 21st century. It also surveyed and presented a range of adaptation options for agriculture and forestry and recommended appropriate adaptation strategies required to reduce vulnerability of agriculture and forestry to the observed and projected climate variability and climate change highlighted earlier. I hope that the papers presented in this special issue will serve as a major source of information to all services, agencies and organizations at national, regional and global levels involved with designing and implementing appropriate programmes in using agrometeorological techniques to reduce vulnerability to climate variability and climate change through the course of the 21st century.

World Meteorological Organization Geneva, Switzerland E-mail: [email protected]

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