Víctor Riera
Project technician at the Pau Costa Foundation
The article analyzes and highlights a specific episode in August, linking it to the episode of major forest fires in the northwest of the peninsula.
It is true that there are no records of such a large area being burned in such a short time (since 1961 according to the EGIF; I do not know how old the Portuguese record is, but it is not that old). In 2022, there was already talk of an unprecedented summer, but the area burned by it was spread mainly between June and July (this video clearly shows how the Saharan intrusions, purple colors on the map, predisposed the vegetation to large fires in the middle of each month). In addition, the number of fires in 2022 was higher (EFFIS).
On the other hand, it is compared with 2017, as it was particularly virulent in this area. However, the most notable episode of that campaign was the arrival of Ophelia, causing very strong winds and an unprecedented wave of fires, especially on October 15. Therefore, it should be considered an anomaly.
Regarding the episode of high temperatures, AEMet has reiterated throughout the month the unusual nature of the conditions (for example, as referenced in the article). However, it has not yet issued any official report, nor have I seen any analysis of the episode of high temperatures or heat waves, although it is likely to do so later this month (they usually publish an operational report on their official blog, in addition to issuing a monthly climate summary).
The article analyzes the episode using the DSR index, a variation of the Fire Weather Index. I was not familiar with this index, and its references are recent (Calheiros et al., 2020; Silva et al., 2023). As it is based on the FWI, I understand that it also takes into account the accumulated drought, which, in this case, coincides with the accumulation over three months, although the analysis focuses more on abnormal temperature values.
In summary, I find the article very interesting in terms of the statistical analysis of an extreme event such as the one we have experienced, as it conveys a very clear and strong message. Also in the use of the DSR, as it is a variation of the FWI applied to the area in question (the articles are Portuguese and focus on their territory), but it fails to link the fire episode using only this indicator and, above all, by focusing solely on maximum temperatures. I understand that they themselves correct this by adding other reasons:
"Across parts of Portugal and Spain, there has been a trend of rural depopulation (e.g. due to livelihood opportunities in urban areas), combined with an aging population, contributing to plots of unmanaged forest land and dense fuel loads (Canadas and Novais, 2019). This trend has reduced traditional agricultural practices such as extensive livestock grazing that once acted as a mechanism of vegetation clearance to reduce fuel loads."
To give it robustness, and simply looking at fire statistics, the areas that have burned are those that tend to have the highest number of fires every year, and the people who live there coexist with fire (a clear example is Castromil, on the border between Zamora and Ourense). This year, the usual areas have burned, but this time, the fire has not stopped. When we analyze a fire, we need to compare it with other years, see what the fire has done to understand why it has done so. I am convinced of the high availability of fuel and the effect of these heat waves, but to know that this event has been so unusual, we need more comparison than just total hectares.
You could also mention the effect of soil overheating on the vertical profile (formation of thermal lows, causing instability in the local atmosphere and favoring extreme fire behavior). I also do not understand the references to the fire season being extended, although this is mentioned and explained in one of the reference articles.
Finally, implications for public policy. Those we are seeing and have already mentioned: extraordinary mobilization of firefighting resources with a direct increase in costs. In the medium term, the development of common protocols and investment in more infrastructure that has been lacking or has failed during this episode, and in the medium to long term, greater investment in prevention in order to mitigate these extraordinary costs.
In short, and as I mentioned earlier, I believe it conveys a simple and powerful message: this extreme episode of high temperatures has a ‘return period’ shorter than we thought.
The rest is known to us, either by those who experienced it firsthand or by experts who understand the implications of such an extensive heat wave on vegetation.
And finally, a reference to a closely related article.