Complex sentence: In 1997 and 1998 forest fires during the El Niño drought affected at least 20,000 km 2 in the Amazon leading to large smoke episodes which halted air traffic in the area and caused ships to collide at sea.
Split into simpler sentences: In 1997 and 1998 forest fires during the El Niño drought affected at least 20,000 km 2 in the Amazon. This lead to large smoke episodes which halted air traffic in the area and caused ships to collide at sea.