In 1998 Mexico suffered its worst fire season on record. Caught in the oscillations of an unusually heavy ENSO, the fires began early and continued late (Fig.1). Hurricanes twice slammed into the Pacific side of the southern states, encouraging fuels; then seasonal rains failed to arrive, either from the south (Pacific) or later from the north (Gulf of Mexico). Drought, temperatures, and winds reached historic proportions in many regions. Traditional burning – fundamental to Mexican agriculture and pastoralism – soon escalated out of control. Complicating factors included drug traffickers in some areas and rebellion in Chiapas.
Fig. 1. Comparative burned area by years
While all the Mexican states experienced wildfire, the heaviest zones were along the Sierra Madre Occidental, the central Highlands, and the tropical mountains of Oaxaca and Chiapas (Fig.2). Officially, 14,302 fires covered over 583,664 ha. The area burned was roughly twice the average.
Fig. 2. Map of burned area by Mexican states (1 January – 15 July 1998)
Fig. 2. Fire causes in Mexico1998
An estimated 26% of the burned landscapes were forested, 32% were grasslands, and 42% brushlands. Some 97% of the fires had human origins.
Environmental damage was extensive. Apart from the often severe burns, following drought, a number of national parks and nature reserves suffered, resulting in a declaration of environmental emergency in Oaxaca and Chiapas. Grave concerns centered especially on the fires that threatened Los Chimalapas, a preserve of spectacular biodiversity in a cloud forest for which natural fire is rare. Thousands of rural Mexicans had to evacuate their homes. Subsequent heavy rains have further worsened the aftereffects, particularly in the Federal District and Chiapas.
Smoke caused a major deterioration of air quality in Mexico City and submerged many cities, from Villahermosa to Veracruz, in chronic haze.
Then the pall spiraled into the southern United States, causing a pronounced decay in air quality in Texas and Louisiana, in particular.
Recent research also implicates the smoke in a higher proportion of positive lightning in those regions (see Lyons et al ).
Control costs were high. Mexico mounted a massive response, moving beyond the normal interinstitutional group headed by the Secretaria de Medio Ambiente, Recursos Naturales y Pesca (SEMARNAP) and creating an emergency intersecretarial group at the federal level. An estimated 823,971 manhours of firefighting – national and state employees, army personnel, campesinos, volunteers – all supported the suppression effort. A total of 60 firefighters died. Aircraft involvement provides a useful index of this extraordinary year. For 1995-97, SEMARNAP deployed three planes and six helicopters. During the 1998 season it fielded 57 planes, 25 helicopters, three Skycranes, and a CL-415. The United States assisted with over 50 advisors, firefighting materiel, and an infrared-mapping aircraft. Expenses raced ahead of the 40 million pesos (US$4 million) budgeted to exceed 290 million pesos (US$29 million).
The response to the fires within Mexico has been immediate and widespread, a gamut of political alarm that has extended from villages to the presidency. The press offered unprecedented, daily converage. Scientists, institutes, and universities are all committing research to understand the particular consequences of these fires, and what might be done to ameliorate their damages, but also the larger question of Mexico’s fire ecology.
Accordingly, a review of the national fire protection system is underway. SEMARNAP has outlined a massive restoration program aimed primarily at timber salvage, soil stabilization, and reforestation. The Comision Nacional Para el Conocimiento y Uso de la Biodiversidad (CONABIO) has reviewed the consequences of the fires relative to Mexico’s efforts at nature conservation, especially their impact on biodiversity. The United States is extending assistance through its Forest Service (Office of Foreign Disaster Assistance) and Agency for International Development for training, personnel exchanges, and advice on landscape restoration.
The relevant Mexican agencies have posted an excellent statistical summary of the season and their response on a comprehensive internet site. Consult:
Lyons, Walter A. et al, “Enhanced Positive Cloud-to-Ground Lightning in Thunderstorms Ingesting Smoke from Fires,” Science 282 (2 Oct 1998), pp. 77- 80.
Rodriguez Trejo, Dante Arturo. Incendios Forestales (Universidad Autonoma Chapingo and Mundi-prensi Mexico, 1996)
Dante A. Rodriguez Trejo and Stephen J. Pyne School of Forest Resources and Conservation University of Florida 226 Newins-Zeigler Hall PO Box 110410 Gainesville, FL 32611-0410 USA Email: firstname.lastname@example.org Department of History Arizona State University PO Box 872501 Tempe, AZ 85287-2501 USA Email: email@example.com