These questions are tackled in most basic primers that should show up in a google search such as you suggest. E.g.:
https://nap.nationalacademies.org/resource/25733/interactive...
> Climate is always changing. Why is climate change of concern now?
> All major climate changes, including natural ones, are disruptive. Past climate changes led to extinction of many species, population migrations, and pronounced changes in the land surface and ocean circulation. The speed of the current climate change is faster than most of the past events, making it more difficult for human societies and the natural world to adapt.
https://www.epa.gov/climatechange-science/frequently-asked-q...
> Why be concerned about a degree or two change in the average global temperature?
> A degree or two change in average global temperature might not sound like much to worry about, but relatively small changes in the earth’s average temperature can mean big changes in local and regional climate, creating risks to public health and safety, water resources, agriculture, infrastructure, and ecosystems. Among the many examples cited by the 2018 National Climate Assessment are an increase in heat waves and days with temperatures above 90°F; more extreme weather events such as storms, droughts, and floods; and a projected sea level rise of 1 to 4 feet by the end of this century, which could put certain areas of the country underwater.