The first nine months of this year have been record-breaking for heat worldwide, in another sign that dangerous global warming continues to mount, US government scientists said Wednesday.

Last month marked the "highest September temperature in the 1880-2015 record, surpassing the previous record set last year by 0.19 Fahrenheit (0.12 Celsius)," said the National Oceanic and Atmospheric Administration (NOAA).

"The first nine months of the year (January-September) were also record warm."