Unusually large and intense forest fires swept the tropics in 1997  The tropics were quite susceptible to fire at that time because of the widespread drought caused by an unusually strong El Nino, an occasional global weather phenomenon
Many scientists believe the strength of the El Nino was enhanced by the global warming caused by air pollution
If air pollution enhanced the strength of the El Nino in 1997, then it also contributed to the widespread drought in that year.