As the climate changes, are weather forecasts still reliable?

The extreme weather events that occurred this summer have raised questions about the role of climate change and the reliability of weather warnings. From the beginning of the school year, Lisabeth Borne will launch the development of a new national adaptation plan.

Record heat waves, unprecedented droughts and devastating storms… With the increasing number of extreme weather events France has experienced this summer, can we still rely on weather forecasts? The idea that climate change is progressing faster than the forecasts established by scientists is however disputed by many meteorologists and climatologists, who prove News-Environment Fabio D’Andrea, researcher at the Dynamic Meteorology Laboratory of the École Normale Supérieure in Paris. The scientist first emphasized the importance of understanding the difference between weather and climate, different, not only in terms of the timing of the forecast, but also in the nature of the forecast itself. .

Meteorology describes the weather at a particular moment and predicts the weather for a short period of time (days, weeks, maximum three months). The weather forecast is determined such a place, such a time to estimate such as temperature, such as rainfall, such as atmospheric pressure, etc., he looked back. On the other hand, climate forecasting, a type of statistic, is concerned with the average probabilities of events being studied over long periods of time. Climate models provide possible scenarios of the sequence of meteorological conditions over several decades, particularly depending on the evolution of greenhouse gas levels.

Weather models incorporate climate change data, but

One can imagine that climate change may change, in a regular and permanent way, some atmospheric parameters, and some parts of forecasting models may not adapt well to the new distribution of these parameters due to climate change. However, in fact, there is no (current) study that shows whether, on the one hand, the forecasts of the models are less good because of climate change. There is no evidence of this or any clues. And on the other hand, there are no studies that I know of that say that the very predictability of the atmosphere is being altered by climate change, explained Fabio D’Andrea.

There are no studies that I know of that say that the very predictability of the atmosphere is being altered by climate change.

Fabio D’Andrea, researcher at the Dynamic Meteorological Laboratory

Climate change won’t complicate the weather forecast any more than thatsure too, release, Jean-Pierre Chaboureau, researcher at the Laboratory of Arology of the University of Toulouse-CNRS. Since weather models are based on physics equations, which do not change, they are universal. What changes are atmospheric conditions, temperature or humidity. However, the models incorporate this new reality of climate change and its consequences.

storms stay hard to predict

Fabio D’Andrea also highlights the improvement in the quality of weather forecasts since the 1980s, thanks to progress in observation (with satellite data), more accurate forecast models and increased computing power. Faced with the extreme climatic episodes that France has experienced in t2022, pressure has increased on Mto-France and its alerts. Since mid-June, the organization has predicted four heat waves to affect France, including again this week. But after the deadly storms and violent winds that hit Corsica on August 18, the public meteorological establishment was selective. The forecasters explained that they had been surprised at the extraordinary amount of gusts, which had never been observed before, and they caused a meteorological phenomenon hard to predict. Storms is the result of complex processes affecting a very limited geographical area. So it is difficult to predict this kind of phenomenon., explains Mto-France. Climatologists and geographers interviewed by the media also acknowledge the difficulties in forecasting hurricanes, such as specialist Fabio D’Andrea. Hurricanes are more difficult to predict and strike at a scale of several tens of kilometers. Potential storm conditions and intensity can be predicted, but statistical uncertainties must always be considered when dealing with this type of event.said the researcher.

However, the higher resolution of numerical weather forecasting models, allows progress in forecasting hazardous phenomena, including thunderstorms. Thanks to a 1.3 km mesh, one of the models used by Mto-France, called Arome, can describe more precisely the physical processes responsible for triggering storms. However, if, in Corsica, the simulations made by Arome suggested a hurricane close to observed, other simulations which seems more likely to have placed it in the seasaid forecaster Franois Gourand, Mto-France, according to AFP.

Better to expect extreme events

After two consecutive rainy-storm episodes passed through Corsica on August 18 and 19, the Council of Ministers confirmed, on August 24, the recognition of the state of natural disaster for the island. The judgment was published, this August 25, Official gazette. In order to better predict these phenomena, the acquisition of five meteorological muds will also be carried out on the island of Beaut.

With climate change, there will therefore be more extreme climatic events, especially extreme rainfall and heat, warns Meteo-France. Therefore, there are more issues around weather warnings, to improve the response to emergency situations and the protection of populations.

As announced in the Council of Ministers, at the beginning of the school year, Prime Minister Elisabeth Borne will launch the preparation of the third national plan for adaptation to climate change (PNACC). This PNACC should emphasize work on improving the observation and forecasting of phenomena, information on monitoring and alerting populations. Christophe Bchu, Minister for Ecological Transition and Territorial Cohesion, will oversee its preparation, in consultation with all the actors concerned and with all the ministers concerned. This necessary work on adapting to the effects of environmental regulations will be accompanied by efforts to mitigate climate change by doubling the rate of reduction in our greenhouse gas emissions.added the government.

Article published on August 25, 2022

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