In the past 20 years, wildfires have destroyed 47,000 square kilometers (18,000 sq. mi) in Mexico, equivalent to five times the area of all sections of Mexico City’s Chapultepec Park, the largest urban park in Latin America. The average fire in Mexico affects 32 hectares (80 acres); this figure has not changed significantly in recent years, even though the incidence of fires has increased somewhat due to a combination of climate change and an increase in the number of people living on the margins of forested areas. The National Forestry Commission (Conafor) says that 99% of Mexico’s forest fires are caused by human error, and only 1% are due to natural causes such as lightning strikes.
It generally takes about 30 years to rehabilitate forest areas ravaged by fire, with reforestation costing up to $2400/ha.
Wildfires are not entirely bad. For example, they help regenerate grassland areas, especially, with fresh young plants. On the other hand, in addition to protecting the existing vegetation, stopping wildfires when they occur helps to preserve soil structure and prevents additional emissions of CO2 from the burning of more plant material. At a national level, it is estimated that fires result in the erosion of 86 million metric tons of soil a year.
In a 2009 study, Conafor used 17 variables to identify the areas of the county with the highest risk of wildfires. Three broad areas accounted for the 900,000 square kilometers identified as having either a “medium” or “high risk” for wildfires:
- i. Yucatán Peninsula, Chiapas, Oaxaca and Guerrero
- ii. Central Mexico – Veracruz, Tlaxcala, Puebla, México, Michoacán, Jalisco and the Federal District. This area has more fires than any other because local populations often use fire to clear fields before planting.
- iii. Baja California. This is the only area where the main fire season is in summer, from March to November. This is the rainy season in the remainder of Mexico, where the fire season corresponds with the winter dry season.
The first half of 2011 was an especially bad period for wildfires in Mexico, the worst for at least 30 years.
Coahuila wildfire, April 9, 2011 (Earth Observatory, Landsat-5)
During the first half of 2011, serious wildfires devastated several areas of northern Mexico, with the states of Coahuila and Nuevo León being hardest hit. Other states badly affected included Durango, Chihuahua, Quintana Roo, Oaxaca, Puebla and Guerrero. More than 7,800 fires occurred, severely damaging a total area of 4100 square kilometers. 30 of Mexico’s 32 states were affected; only Tabasco and Baja California Sur escaped unscathed.
Conafor’s annual fire-fighting budget for the entire country is only 650 million pesos ($50 million dollars); the average annual area damaged by wildfires is only 2600 square kilometers, of which 500 square kilometers are forest. At the height of the 2011 fire season, more than 60 new fires were being reported each day, according to Conafor.
In the state of Coahuila, fires damaged 250 square kilometers in four weeks. It is believed that 50% of these fires were due to farmers losing control of deliberate burns. Farmers are supposed to have an adequate fire-suppression plan in place before setting a deliberate burn, but in practice this requirement is not enforced.
The main locations were La Sabina and El Bonito. Authorities were very slow to respond. Diana Doan-Crider, a wildlife biologist at Texas A&M University, has spent the past 25 years studying the Mexican black bear in the Serranía del Burro in Coahuila, an ecological corridor that runs parallel to the Eastern Sierra Madre. The area includes a large population of Mexican black bears. Doan-Crider claims that authorities completely ignored the first warnings and that their eventual response (two weeks after the first fires started) lacked adequate coordination. Many mother bears and their young cubs perished in the fires.
Firefighters in Coahuila had to cope with a spectacular but terrifying fire whorl or fire tornado
In the neighboring state of Nuevo León, large swathes of ranching land were ravaged by fire. One rancher who lost more than 10,000 ha of cattleland was equally critical of the slow response time of firefighters who took more than two weeks to appear on the scene, by which time the fires had taken hold.
David Garza Lagüera had converted his 14,000 ha ranch into the Cumbres de Monterrey National Park, one of the key areas of bear habitat. The largest pines on his land were more than 150 years old. All were totally destroyed.
The worst damage was in Galeana, Montemorelos, Zaragoza, Aramberri and Mina. The area burned in Nuevo León in May 2011 was almost ten times the total area affected in the state for the whole of 2010.
Why was the 2011 fire season so bad?
To quote the Earth Observatory, “Lack of winter rain and frost left the plants dry and prone to fire. On top of that, the area has not burned for more than 20 years, during which time fuel built up. Thunderstorms and steady strong winds with gusts up to 110 km/h (70 mph) completed the formula for a dangerous, fast-moving wildfire.”
Ironically, the passage of Hurricane Alex in July 2010, which brought 1500 mm (60″) of rain to the Serranía del Burro, actually worsened the fire damage the following year. The rain from Hurricane Alex encouraged so much new growth in the final months of the rainy season that when it died back in the dry season, there was far more fuel available than usual for any wildfire that was sparked.
By the time the federal government declared a state of emergency, it was too late; the fires had already destroyed large areas of grassland, scrubland and forest. The emergency response when it finally arrived included help from the USA and Canada such as the specialist aerial Mars water-bombers stationed on Vancouver Island. The fires were only fully extinguished once the annual rainy season arrived.
As we now know, the disastrous fires of April-May 2011 were an early sign of Mexico’s worst drought for 70 years: