Copied from just doing a search on Mammoth Mountain
300 Tons a Day of CO2 - thats over 90,000 Tons a Year
from just one volcano.
Invisible CO2 Gas Killing Trees at Mammoth Mountain, California
Since 1980, scientists have monitored geologic unrest in Long Valley Caldera and at adjacent Mammoth Mountain, California. After a persistent swarm of earthquakes beneath Mammoth Mountain in 1989, geologists discovered that large volumes of carbon dioxide (CO2 ) gas were seeping from beneath this volcano. This gas is killing trees on the mountain and also can be a danger to people. The U.S. Geological Survey (USGS) continues to study the CO2 emissions to help protect the public from this invisible potential hazard.
Mammoth Mountain is a young volcano on the southwest rim of Long Valley Caldera, a large volcanic depression in eastern California. The Long Valley area, well known for its superb skiing, hiking, and camping, has been volcanically active for about 4 million years. The most recent volcanic eruptions in the region occurred about 200 years ago, and earthquakes frequently shake the area. Because of this, the U.S. Geological Survey (USGS) operates an extensive network of instruments to monitor the continuing unrest in the Long Valley area.
Numerous small earthquakes occurred beneath Mammoth Mountain from May to November 1989. Data collected from monitoring instruments during those months indicated that a small body of magma (molten rock) was rising through a fissure beneath the mountain. During the next year, U.S. Forest Service rangers noticed areas of dead and dying trees on the mountain. After drought and insect infestations were eliminated as causes, a geologic explanation was suspected. USGS scientists then made measurements and discovered that the roots of the trees were being killed by exceptionally high concentrations of carbon dioxide (CO2) gas in the soil. Today, areas of dead and dying trees at Mammoth Mountain total more than 100 acres. The town of Mammoth Lakes, just east of this volcano, has not been affected.
Geologists have detected CO2 emissions, like those at Mammoth Mountain, on the flanks of other volcanoes, including Kilauea in Hawaii and Mount Etna in Sicily. Measuring the total rate of CO2 gas emissions on the flanks of volcanoes or within calderas is difficult and labor intensive and is commonly done using portable infrared CO2 detectors.
Recent measurements at Mammoth Mountain indicate that the total rate of CO2 gas emission is close to 300 tons per day. This value varies on both short (days to weeks) and long (months to years) time scales because of changes in atmospheric conditions and in the rate at which gas is being released from beneath the volcano.