Image by Red Cross Chile.
Extreme wildfires in coastal-central Chile have been fuelled by intense and persistent fire-conducive weather conditions in the region since the beginning of the year favouring the spread of severe fires in Viña del Mar (33°S, 71°W) in early February.
During the early days of February 2024, a low-pressure system formed along the coast of central Chile, a well-known phenomenon affecting the western coast of subtropical South America, known as the coastal low.
It leads to clear skies and high temperatures as well as strong winds due to an inverted pressure gradient between an intense subtropical high extending well into midlatitudes and the coastal low farther north. These conditions are highly conducive to wildfires i.e favour spread, especially during summer when conditions are warmer and drier. On February 2, 2024, wildfires ignited in the mountainous forested areas east of, forested areas east of the city Viña del Mar and around Lake Peñuelas.
The flames rapidly advanced into densely populated city outskirts despite authorities’ efforts to curb their spread. The humanitarian impact continues to worsen, with over 29,000 hectares burnt since February 4, resulting in 132 deaths, 300 missing, 7,200 houses destroyed and 40,000 people affected.
Figure 1: Burned area of the 2-Feb-2024 fire in central Chile’s Viña del Mar – Valparaíso sector. The background image is the Shortwave Infrared, Bands 7-5-4 from Landsat 8/9 OLI acquired on 5 February 2024. The burned area stands out in red against the non-burned vegetation in green. The yellow dots are active fires detected from MODIS Terra/Aqua on 2 February 2024. Also shown are the urban limits and main roads, plus the meteorological conditions (Max wind and Max Temperature) during 2 February 2024 from from DMC + SERVIMET
Researchers from Chile, Brazil, Colombia, the Netherlands, Germany, Sweden and the United Kingdom collaborated to assess to what extent human-induced climate change altered the likelihood and intensity of the weather conditions at the time of the fires, and how the conditions will be affected with further warming.
Fire weather is defined by a combination of elevated temperatures, reduced humidity, minimal rainfall, and heightened winds persisting over a period. To capture the characteristics of this event, we use a fire weather index (HDWI) based on high wind speeds, high temperatures and low humidity. While not taking the build-up of fuel into account like other, more complex indices, it is an effective hazard metric for estimating threat to communities and difficulty of containment. We focussed on a coastal region affected by the wildfires that include Valparaíso and Viña del Mar.
Figure 2 shows the index values for the four days of highest fire intensity, when most impacts occurred.
Figure 2: Maximum of average 4-day Hot-Dry-Windy-Index (HDWI) that occurred between January 31 to February 4, 2024 over central Chile (from ERA5-Land dataset).
Main findings
- There is significant interaction between extreme climate conditions and land management policies, leading to particularly devastating impacts in informal settlements.