Complex sentence: The effects of El Niño are believed to be contributing to the drought, which may be exacerbated by global warming, as some areas in Yunnan have recorded record high temperatures during the winter since record-keeping began in 1950.
Split into simpler sentences: The effects of El Niño are believed to be contributing to the drought. Some areas in Yunnan have recorded record high temperatures during the winter since record-keeping began in 1950.