Heatwaves have become more frequent, more intense and longer-lasting because of human-induced climate change. The world has already warmed by about 1.1C since the industrial era began and temperatures will keep rising unless governments around the world make steep cuts to emissions.
Where does the 1.1C figure come from? It’s about 1.5C for the past years and 1.3-1.4C for the multi-year average.
The only page where I found something starting with 1.1C is here (https://science.nasa.gov/earth/explore/earth-indicators/global-temperature/)
But 1951-1980 is obviously not “since the industrial era began”.
Global warming has been a serious issue since the early 1800s when industrialisation started based on coal. It got a major turbocharge after the 2 world war when oil was added to coal. There has been 200 years of fossil fuel delivered climate change and global warming. I think when looking at the totality, things will look worse.