World Meteorological Day

World Meteorological Day is celebrated every year to mark the entry into force on 23 March 1950 of the Convention of the World Meteorological Organization (WMO) and the significant contribution made by national hydrometeorological services for the safety and welfare of society. The theme proposed by WMO in this year is “Climate knowledge for climate action”. The theme for this year could not be timelier as the international community moves towards ambitious decisions and action to address climate change.
Weather forecasts have been a part of everyday life since the mid twentieth century. Before going to work or school, people check the weather in order to know how to dress and how to keep safe. Weather forecasts help farmers, emergency workers and other decision makers in weather-sensitive sectors to schedule their daily and weekly work priorities. These forecasts are becoming ever more reliable – today’s five-day weather forecast is as good as the -day forecast of 25 years ago – thanks to advances in weather and climate science and in computing power.
Researchers are using improved observations and greater computing power to study and predict natural cycles and broader patterns in the climate system. As a result, they can provide increasingly useful seasonal climate predictions. For example, they can assess the probability that the next season will be hotter or wetter than usual.
In addition to greater knowledge about natural climate variability, scientists have made enormous progress in understanding how humanity’s greenhouse gas emissions are changing the climate. Drawing on climate science and scenarios of greenhouse gas concentrations, they can project how the climate will change, and they can assess vulnerabilities and likely impacts in specific regions. This knowledge is invaluable for longer-term planning.
Observations of weather and climate parameters are an essential starting point for climate knowledge. Such data are gathered by the land, marine, aircraft and satellite observation networks of national meteorological and hydrological services. At the backbone of that network – the WMO Global Observing System – are over 11 000 land-based weather stations and 1 300 upper-air stations and radiosondes.
In addition to weather variables such as temperature and rain, climate knowledge is built on data about levels of greenhouse gases, pollutants and aerosols, which can affect the climate, air quality, human health, and natural and human systems. The monitoring of atmospheric chemistry is coordinated by the WMO Global Atmosphere Watch.
The National Meteorological and Hydrological Services of the 191 WMO Members are honing climate knowledge to permit humanity to address the benefits and threats of climate change.