Volcanic Gas

This is because sulfur emissions create aerosols that block the sun's incoming rays temporarily. While volcanoes do emit powerful greenhouse gases like carbon dioxide, they do so at a rate that is likely 100 times less than humans (Gerlach, 2011).Volcanic gases include a variety of substances given off by active volcanoes.Emitted Gases. ... During large eruptions, gaseshave actually caused global climate change. In other systems, gases are emitted continuously into the atmosphere from soils, volcanic vents, fumaroles and hydrothermal deposits. The gradual release of gasacts as an irritant and may pose long-term health-hazards.

These are some examples of gas eruptions

1.Mammoth Mountain-On August 21, 1986 in the Cameroon highlands, West Africa, Lake Nyos emitted carbon dioxide that moved like a river down-valley for 110 kilometers and suffocated 1200 people in the town of Nyos, and, in nearby villages of Subum and Cha, more than 500 died. In addition 3000 cattle died along with all preditors and insects.At the present time, carbon dioxide gas is seeping upward through Mammoth Mountain, a composite volcano on the edge of Long Valley Caldera. The carbon dioxide leaks are occurring at several places around the volcano. Long Valley and Mammoth Mountain are being watched by the U.S. Geological Survey. It is not known whether or not the CO2 leaks could be a precursor to a volcanic eruption.

2.Eyjafjallajökull Volcano-, English Island Mountain Glacier, is one of the smaller ice caps of Iceland, north of Skógar and west of Mýrdalsjökull. The ice cap covers the caldera of a volcano with a summit elevation of 1,651 metres.Wikipedia

3.Lascar is a stratovolcano within the Central Volcanic Zone of the Andes, a volcanic arc that spans the countries of Peru, Bolivia, Argentina and Chile. It is the most active volcano in the region, with records of eruptions going back to 1848