The phrase "warming effect" refers to an increase in temperature. It describes when something causes the surroundings to become warmer. Full definition
Otherwise an excellent review of the global warming effect of human contributions. (realclimate.org)
Read more about global warming effects on rain and snow. (climatehotmap.org)
When you consider even the most extreme claim for the global warming effect of human CO2, it is within the error of the estimate of almost every single variable. (drtimball.com)