On March 23rd, World Meteorological Day is celebrated, and this year the World Meteorological Organization has chosen the theme “Observing Today, Protecting Tomorrow,” highlighting the importance of meteorological observations in forecasting extreme events and supporting civil protection. The quality of weather forecasts depends heavily on the so-called “initial state of the atmosphere,” which consists of the values of various atmospheric variables at the starting point of the forecast.
The figure below illustrates the improvement in the quality and accuracy of weather forecasts over the past 40 years. Meteorological observations are one of the main factors behind the increased reliability of forecasts, as they allow for a more precise characterization of the initial state of the atmosphere, resulting in more accurate weather predictions.
In the aftermath of recent events that caused severe impacts across the country (storms Kristin, Marta, and the “train” of depressions that hit Portugal in January and February), the central role of meteorology in forecasting such events and issuing warnings to the public and civil protection authorities has once again proven crucial. However, there has also been criticism regarding the fact that some forecasts did not accurately predict the intensity of the storms or the most affected areas. In 1961, meteorologist Edward Lorenz (MIT) discovered for the first time that weather forecasting can never be 100% accurate, as the atmosphere is a chaotic physical system, making it impossible to predict its future states with complete precision.
Weather forecasting is an extremely complex science, in which non-linear physical equations representing atmospheric dynamics are solved approximately (as they cannot be solved analytically) using mathematical models on supercomputers, assimilating hundreds of millions of global observations in the process. In recent decades, there has been significant progress in the quality and accuracy of weather forecasts; however, nearly 65 years after Lorenz’s discovery, this fundamental limitation remains unchanged: the atmosphere will always be impossible to predict with complete accuracy—at least until we achieve full knowledge of all atmospheric processes, develop new mathematical techniques capable of solving complex non-linear equations, and attain virtually infinite computational capacity to simulate the entire planet and its atmosphere (and their interactions) at microscopic or even atomic scales. Therefore, forecast error must be understood as natural and unavoidable.
At CESAM, research in this area is framed within Thematic Line 1 — Climate Change, Adaptation and Mitigation, which aims to understand climate processes, the impacts of climate change, and the vulnerability and adaptive capacity of natural and human systems, promoting mitigation and adaptation strategies grounded in scientific knowledge. This research is developed in an integrated way across different Research Clusters, namely RC1 — Deep Sea, Ocean and Transitional Ecosystems, which studies marine ecosystems and their interactions with global change; RC2 — Soil Functions, Agriculture and Forests, which analyses interactions between climate, land and terrestrial systems; and RC3 — Ocean and Atmospheric Modelling, which focuses on the simulation and prediction of climate and environmental processes.
In recent years, several CESAM projects have contributed to advancing scientific knowledge and supporting public policy in this area. The ClimACT project develops the Future Climate Atlas for Portugal, providing essential scientific information to support climate adaptation policies and risk management; the FIRESTORM project studies the influence of meteorological conditions on extreme wildfires, generating knowledge relevant for prevention, risk management and civil protection; and the A-AAGORA project develops innovative solutions to enhance climate resilience in coastal areas, promoting the integration of scientific knowledge into policy-making and sustainable management.
Article by David Carvalho, CESAM/DFIS researcher and Coordinator of CESAM Thematic Line 1: Climate Change, Adaptation and Mitigation.