Climate normals and climate change: how to communicate these together?

Abstract

<p>Meteorological institutes all over the world are publishing new “climate normals” in 2021, as prescribed by the World Meteorological Organization. These “climate normals”, averages over the period 1991-2020, generally have higher temperatures than the previous climate normals over the period 1981-2010 or earlier 30-year periods. As a consequence, in weather forecasts from 2021 the expected temperatures for the coming days and weeks are less often “above normal”, compared to earlier years. In the Netherlands there has been already a lot of discussion about these “climate normals”. Several people, including climate researchers and weather providers, object to them, since they say that these “normals” obscure climate change. Especially the word “normals” is what bothers them, since the current state of the climate should not be considered normal. At KNMI we understand this problem, although we also see the importance of providing regular updates of the description of the “current” climate. Many aspects in society are designed and operated taking into account the averages and extremes in the current climate. Climate is an important aspect in almost any sector, from water management, agriculture to super markets and theme parks. Several visualizations (climate dashboard and weather and climate plume) are developed at the Royal Netherlands Meteorological Institute (KNMI) that combine information on “climate normals”, past and future climate change and weather forecasts.</p><p>During the presentation examples of the above described visualizations are shown and the advantages and disadvantages are described. Suggestions are presented on how to communicate about “climate normals” and climate change.</p>