What gas is thought to be responsible for the changes shown in the image below? attachment

The gas responsible for the raising temperature during last decades is greenhouse gases, which is majoritarly composed by carbon dioxide. Its production increases during last years because of the increasing number of industries and polluting cars, despite the increasing taxes on them.

Greenhouse gas can absorb more energy (more heat) than normal gases like oxygen and azote, that is why the increase of CO2 increases the global temperature, and that's why it's called "greenhouse" gas.