Sorry, my researcher instincts demand at least one boring proof-post in this series.
Here goes: The world emits 30 billion tonnes of CO2 yearly, amounting to about 15300 km3 in volume. At roughly 10 km thickness, the atmospheric volume is 5.11 billion km3. Dividing these two numbers reveals that humans raise the CO2 concentration by roughly 2.99 ppm yearly. Actual measured CO2 rises are around 2 ppm yearly, implying that the earth manages to absorb about a third of our emissions.
CO2 is a greenhouse gas. This means that it allows short wavelength solar radiation in, but captures and randomly redistributes long wavelength infrared radiation re-emitted by the earth’s surface. Naturally, the heat captured increases with the CO2 concentration, hence global temperatures increase with CO2 concentrations.
97% of all peer-reviewed scientific literature agrees.