The sulfuric aerosols that formed from the sulfur dioxide circled the Earth within 3 weeks and remained in the atmosphere for 3 years , reflecting enough sunlight to cool the entire planet by half a degree Celsius during that time. However, during the following winter, Europe experienced surprisingly warm temperatures. What could be going on? This temperature gradient strengthened the Arctic Oscillation , a wind pattern circling the Arctic.
The shifted jet stream allowed warm winds to flow over the Northern Hemisphere during the winter, Robock said.
Because the jet stream flows like a wave, while Europe was receiving warm air from the south, the Middle East received colder air from the north, bringing to Jerusalem the worst snowstorm in 40 years.
The eruption helped scientists definitively declare that human emissions of greenhouse gases are to blame for at least the past 60—70 years of warming. Temperatures rose again once the cooling aerosols fell out of the atmosphere. Pinatubo, in a sense, served as a natural climate experiment to test and calibrate models. Scientists plugged observed volcanic emissions into climate change models with and without anthropogenic emissions of greenhouse gases. This observation helped climate scientists sharpen their models further, confirming that humans—and the unprecedented amounts of greenhouse gases they pump into the atmosphere every year—are to blame for the warming climate.
The Intergovernmental Panel on Climate Change was able to use these newly sharpened models to further support the attribution of climate change to human activities. Robock and other scientists agree that this kind of injection would have negative consequences.
To halt global warming, humans would have to inject million tons of sulfur dioxide into the atmosphere every year—that amounts to about five Pinatubo eruptions per year. Clouds of sulfuric acid particles—created when sulfur dioxide newly injected into the stratosphere meets water—provide surfaces on which ozone-destroying chemical reactions take place.
Robock said that to halt global warming, humans would have to inject million tons of sulfur dioxide into the atmosphere every year—that amounts to about five Pinatubo eruptions per year. Scientists generally agree that the consequences of geoengineering are too risky to attempt. Pinatubo almost overtook us. Mount Pinatubo, for now, stands relatively quiet, some meters shorter than it was before it exploded 25 years ago.
What might the next 25 years bring to Pinatubo? Time will tell. Wendel, J. Published on 09 June The authors. Any reuse without express permission from the copyright owner is prohibited. Iddris et al. Skip to content The 15 June eruption of Mount Pinatubo. Preeruption Mount Pinatubo on 9 June , viewed from the northeast. Credit: P. Tiltmeters measure how the ground swells during volcanic unrest.
Credit: USGS. Evacuation zones surrounding Mount Pinatubo, created by scientists before the 15 June eruption. Cars and people traverse a flooded river in June after lahars wiped out bridges.
Aerial view to the south of the 3-kilometer-wide Pinatubo caldera showing the start of a small explosion on 1 August Credit: T.
The yellow x marks the volcano. A typhoon struck the area after the eruption. The weight of the rain-saturated ash, earthquake shaking and strong winds, caused numerous roofs to collapse in the communities around the volcano , including at the two large U. The effects of the eruption were not limited to the area around Pinatubo. Pinatubo affected weather around the globe.
Huge quantities of particles from Pinatubo's tall ash cloud injected into the global wind system in the stratosphere. These particles affected the weather in two ways. Photo above courtesy of Peter Baxter, University of Cambridge. Because it had lost most of the gas contained in it on the way to the surface like a bottle of soda pop gone flat , the magma oozed out to form a lava dome but did not cause an explosive eruption.
However, on June 12 Philippine Independence Day , millions of cubic yards of gas-charged magma reached the surface and exploded in the reawakening volcano's first spectacular eruption. When even more highly gas charged magma reached Pinatubo's surface on June 15, the volcano exploded in a cataclysmic eruption that ejected more than 1 cubic mile 5 cubic kilometers of material. The ash cloud from this climactic eruption rose 22 miles 35 kilometers into the air.
At lower altitudes, the ash was blown in all directions by the intense cyclonic winds of a coincidentally occurring typhoon, and winds at higher altitudes blew the ash southwestward. A blanket of volcanic ash sand- and silt-size grains of volcanic minerals and glass and larger pumice lapilli frothy pebbles blanketed the countryside.
Fine ash fell as far away as the Indian Ocean, and satellites tracked the ash cloud several times around the globe. Huge avalanches of searing hot ash, gas, and pumice fragments pyroclastic flows roared down the flanks of Mount Pinatubo, filling once-deep valleys with fresh volcanic deposits as much as feet meters thick.
The eruption removed so much magma and rock from below the volcano that the summit collapsed to form a large volcanic depression caldera 1. Much weaker but still spectacular eruptions of ash occurred occassionally through early September From July to October , a lava dome was built in the new caldera as fresh magma rose from deep beneath Pinatubo. Continuing Hazards Even after more than 5 years, hazardous effects from the June 15,, climactic eruption of Mount Pinatubo continue.
The thick, valley-filling pyroclastic-flow deposits from the eruption insulated themselves and have kept much of their heat. When water from streams or underground seepage comes in contact with these hot deposits, they explode and spread fine ash downwind. Since the climactic eruption, ash deposits have also been remobilized by monsoon and typhoon rains to form giant mudflows of volcanic materials lahars.
The June 15, , explosive eruption of Mount Pinatubo, Philippines, was the second largest volcanic eruption of this century and by far the largest eruption to affect a densely populated area. The eruption produced high-speed avalanches of hot ash and gas pyroclastic flows , giant mudflows lahars , and a cloud of volcanic ash hundreds of miles across.
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