The World Meteorological Organization, as the successor of the International Meteorological Organization, d in 1873, has its fundamental mission to support the countries of the world in providing meteorological and hydrological services to protect life and property from natural disasters related to weather, climate and water, to safeguard the environment, and to contribute to sustainable development. This cannot happen without the necessary observations, research and operations that develop the understanding and knowledge of weather and climate. Since 1961, World Meteorological Day has commemorated the coming into force on 23 March 1950 of the Convention establishing the World Meteorological Organization and the essential contribution that National Meteorological and Hydrological Services make to the safety and wellbeing of society. Each year, the celebrations focus on a theme of topical interest. The theme of this year, “Climate knowledge for climate action”, could not be timelier, as the international community moves towards ambitious decisions and action to address climate change. Climate change concerns us all. It affects almost all socioeconomic sectors, from agriculture to tourism, from infrastructure to health. It impacts strategic resources like water, food, energy. It slows down and even threatens sustainable development, and of course not only in developing countries. The cost of inaction is high and will become even higher if we do not act immediately and resolutely. Information on weather and climate, and its variability and change, is so embedded in our daily life – from daily weather forecasts to seasonal climate predictions – that at times it is easy to forget the amount of observations, research, computing and analysis that lies behind weather and climate information products. Today, the average weather forecast of five days in advance is as skillful as the two-day forecast twenty-five years ago and seasonal climate forecasts have become increasingly skillful. This has been made possible thanks to advances in remote sensing, including satellites, major improvements in science and dramatic increases in computer power. Scientific progress in meteorology and climatology in the last fifty years is indeed one of the most significant one in all scientific disciplines. The climate knowledge that has been built in the last decades is an invaluable resource and a prerequisite for decision-making and for climate action. Multiple lines of evidence – from mounting temperatures to shrinking glaciers, from sea-level rise to weather extremes – give us high confidence that the climate is changing and that this is largely due to human activities, in particular the emissions of greenhouse gases that every year reach record high levels.

Science also gives us high confidence that we can still change course and mitigate climate change to a manageable level. Today, few people contest the evidence of climate change and the responsibilities we bear towards future generations. Climate knowledge can and must support this process, helping decisionmakers at all level to make the best decisions. Climate knowledge must come in a form that is easily understood and usable by those who need it. Climate products and services can assist city planners in developing policies and action plans that can strengthen urban resilience in the face of natural disasters and foster a greener economy. Public health authorities use climate forecasts to address in a proactive way the possible health consequences of extremes such as droughts, heatwaves and floods. Thanks to predictions about temperature and rain trends, farmers can make better planting, cropping and marketing decisions. Water resources managers use climate information to optimize water supply and flood management. The energy sector uses climate information to decide where and what type of power plant should be built in a particular location. The Global Framework for Climate Services, an initiative of the United Nations System led by WMO, was conceived with precisely this purpose: to enable the provision of climate services in a way that decisions can be made based on the best possible information. This is a crucial challenge for both developing and developed countries and there is a great potential benefit in learning from each other. Experiences and advances in the development and application of climate services can be shared as examples of good practices and assist other countries in accelerating their path towards climate adaption. In conclusion, I call on WMO Members, all Governments and the civil society to share and apply climate knowledge for a strong climate action, to minimize climate risks and foster sustainable development.