Scientists are wondering if global warming and El Nino have an accomplice in fueling this summer’s record-shattering heat. …Scientists agree that by far the biggest cause of the recent extreme warming is climate change from the burning of coal, oil and natural gas [and] El Nino, a temporary warming of parts of the Pacific. But some researchers say another factor must be present. …One surprising source of added warmth could be cleaner air resulting from new shipping rules. Another possible cause is 165 million tons of water spewed into the atmosphere by a volcano. Both ideas are under investigation….Florida State University climate scientist Michael Diamond says Maritime shipping has for decades used dirty fuel that gives off particles that reflect sunlight in a process that actually cools the climate. In 2020, international shipping rules took effect that cut as much as 80% of those cooling particles,” said Tianle Yuan of NASA.