People will ask, “Is this climate change?” Thanks to advances in climate research, scientists can find the human fingerprint on extreme weather events by comparing today's climate anomalies to the historical record. Nowhere is that fingerprint more evident than with extreme heat. The average global surface temperature has risen roughly 1.4º F since the pre-industrial era, shifting the entire distribution of temperatures. This has produced more hot days and fewer cold days.

In a stable climate, the number of record cold days and record hot days would be roughly equal. If the average global temperature were to rise, we would expect to see more record-breaking heat and less record-breaking cold. In fact, that's precisely what's happening.

Consistent with this trend, heat waves have become more frequent, lengthy and severe. The most extreme heat waves bear the strongest human fingerprint. Experts say human-caused climate change likely fueled the heat spell currently blanketing the Southwest.

Meteorologists expect temperatures up to 120º F to persist in parts of the Southwest for much of the week. The National Weather Service is advising residents to stay hydrated and avoid going outdoors.