Earth sweltered to a record hot September last month, with U.S. climate officials saying there's nearly a two-to-one chance that 2020 will end up as the globe's hottest year on record.

Boosted by human-caused climate change, global temperatures averaged 60.75 degrees (15.97 Celsius) last month, edging out 2015 and 2016 for the hottest September in 141 years of recordkeeping, the National Oceanic and Atmospheric Administration said Wednesday. That's 1.75 degrees (0.97 degrees Celsius) above the 20th century average.

This record was driven by high heat in Europe, Northern Asia, Russia and much o...