COUNTERPOINT:
The "hockey stick" is the creation of Mann, Bradley and Hughes in 1998 and it has become the poster child of the climate alarmism movement. The graph is a presentation of temperatures that includes corrections applied to the data that removed historic warming and cooling trends. The result is indeed a relatively flat temperature chart with a large increase starting in about 1900. Coincidentally 1900 happens to be defined as the beginning of the industrial revolution and the large temperature increase then gets blamed on human emissions.

The hockey stick only proves how bad science can create any result you want.

COUNTERPOINT:
Over the past 100 years CO₂ concentration in the atmosphere has indeed increased primarily due to the increased use of fossil fuels. However, inferring that the increase in CO₂ concentration caused the earth’s warming is incorrect. The Vostok Antarctica ice core measurements have demonstrated that temperature changes precede CO₂ concentration changes by about 800 years.

COUNTERPOINT:
In 2020, CO₂ constitutes ~411ppm (parts per million) which is ~0.04% of dry air.
Water vapour is actually the most abundant greenhouse gas.

COUNTERPOINT:
Temperatures have varied over the centuries with many recorded warming and cooling trends. Specifically, since the 1860s global temperature has indeed risen as a whole. However the rate of change has not been unprecedented and demonstrates evidence of several positive and negative rate changes. These rate changes support that temperatures have not risen in an exceptional manner.

COUNTERPOINT:
Computer models are constructed to test hypothesises. In the case of climate change they test the hypothesis that CO₂ is the primary driver of warming.
Using the output of a model created to prove that CO₂ causes global warming to verify that CO₂ drives climate is circular reasoning.

COUNTERPOINT:
No scientific proof that man-made CO₂ causes significant global warming has been found by the IPCC even though they do their best to look for it.
It is important to note that the IPCC was not created to evaluate the cause of climate change but to document that it is man-made.

COUNTERPOINT:
A survey of official weather sites and the scientific literature provides strong evidence that the first half of the 20^th century had more extreme weather than the second half, when anthropogenic global warming is claimed to have been mainly responsible for observed climate change.

COUNTERPOINT:
Receding glaciers and ice shelves calving only prove that temperatures have warmed since the Little Ice Age and not that any of it is man-made.

COUNTERPOINT:
The northern hemisphere is warming while the southern is not. Consequently Arctic ice is melting while Antarctica is growing.