Skeptics like to mention that Earth’s climate has always been changing and that there is thus no reason to worry about its changing today.
When the climate changed radically, millions of years ago, there were extinctions of plants and animals. It did not affect humanity because we did not exist back then.
When we did exist, as primitive hunter-gatherers, we could pick up our spears and gathering baskets and move to a different place if we did not like the weather in our local area. There were only a few million of us back then.
We are now civilized and densely populated. Our current population and civilization depend on intensive agriculture and city infrastructure. Global warming could impact our civilization with an increase in droughts and flooding. These changes in climate damages crops, raising food prices and destroying city infrastructure such as flooded houses, damage to roads, telephone and power lines.
We can no longer afford to move to a different part of our planet if our crops fail and our cities are made uninhabitable because there are billions of us. The result will be depopulation and a lower quality of life for those remaining.