During the 1980, 2 large volcanic eruptions occured, the first at Mt St Helens, in the US, and the second, at El Chichon, in Mexico, the last one being more important. Minor climatic effects were detected on a time scale of weeks and monthes, all over the Globe. They were mostly due to the aerosols injected in the high troposphere and the lower stratosphere. Through the emission of SO2, later transformed in droplets of sulfuric acid, the radiative balance of the Earth was perturbed, inducing a heating of the stratosphere, which altered the global wind circulation and, consequently, the oceanic currents. It seems nevertheless that only much more powerful eruptions will be able to modify the Earth climate on a time scale of years.