It is possible to disturb the biological balance so much, that agriculture would become impossible in large parts of the world. Large parts of earth would be too hot for humans to live there. This would include most of South America and even the south of the USA and it could happen in several decades.
Natural climate change takes thousands of years. Humanity could cause worse
in a mere hundred years.

I hope to stick around on earth for several decades. I'm lucky to live in a country with a mild climate. The hottest it has ever been in The Netherlands is 40.7°C/105.3°F on the 25th of July 2019. The record was 35.7°C/96.3°F in 2018. We could see temperatures around 40°C/104°F being the norm, with new records around 50°C/122°F, within a few decades. This is because the global temperature rises much slower than temperature records do, because the extremes are getting more frequent and more severe. I will most likely get to experience what people in the north of the US and Canada have been through.

In hotter climates, new record temperatures could soon reach 60°C/140°F.
Do I have to paint a picture of how that would feel and what would happen to agriculture and forests?

These are just the current events:
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“Hundreds of North Americans have died of heat-related illness over the past week. Wildfires exploded in the record-hot air over southern British Columbia on Wednesday, June 30, producing several massive fire-generated thunderstorms. The intense heat flash-dried the rugged, forested landscape, and wildfires mushroomed across the area. Most homes in the town of Lytton have been destroyed, according to provincial authorities.”
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