Scientists look beyond climate change and El Nino for other factors that heat up Earth

Scientists are wondering if global warming and El Nino have an accomplice in fueling this summer’s record-shattering heat. The European climate agency Copernicus reported that July was one-third of a degree Celsius hotter than the old record. That’s a bump in heat that is so recent and so big, especially in the oceans, that scientists are split on whether something else could be at work. Researchers say by far the biggest cause of the recent extreme heat is human-caused climate change, with a smaller contribution from a natural El Nino. But some scientists are searching for an additional factor.