Why is a small change in average global temperature a concern?

You see, daily temperatures are very different from global average temperatures.

Sure, there are locations that see daily temperature swings of over 20 degrees during day time. These happen because these are weather-driven, short term events. Because these are short term phenomena, they have negligible effect on the ecosystem.

But when measurements of the daily high and low temperatures in many thousands of locations all over the world, and over land and ocean are examined for an entire year and then averaged together, the Earth’s annual average temperatures from year to year are found to be very stable – that is when the climate is not changing rapidly.

In such a context, a 1 degree C warming of the global average, even over a span of many decades is an unusually large temperature change. For comparison, the global average temperature increased only 0.75 degree C between 1915 and 2015, and a large part of that increase happened in just the last 40 years!