Volcanoes have always had a lasting influence on geological formation and demographic change on Earth. But the impact of larger eruptions can be felt on the climate. For more than 40 years, NASA has been working to observe these little-known giants in order to anticipate their influence on the atmosphere and the disturbances they induce.
History has shown that volcanic eruptions can have a lasting effect on a regional and sometimes global scale: destruction of Pompeii and Herculaneum in 79, the eruption of Krakatoa in 1883 or that of Eyjafjöll in 2010. Since 1978, theuses some of its satellites to observe these magmatic monsters. The goal ? Monitor their impact on .
In the violent eruptions cited above, their power influenced the climate internationally. The space agency has therefore developed a procedure called(or NASA eruption monitoring plan), launched in 2018, in order to anticipate these events.
The influence of volcanoes on the atmosphere
All thedo not have the power to disrupt the climate when they erupt. The most violent, described as “explosives”, in four categories: peleans, whose explosions are to be classified in the “moderate” category, having a variable explosiveness from moderate to strong, the vesuvians whose classification goes from moderate to violent, the whose expansiveness is very violent and the krakatoens, considered “cataclysmic”.
During an eruption, the explosion of the top of theof a volcano will project a volcanic plume or column in the , at heights that can occasionally reach the . In 1815, the column following the explosion of the Tambora in Indonesia peaked at 44 kilometers above sea level. Of these explosions, a huge amount of comprising various is thrown into the air. These gases are mainly from of dioxide (SO2) and you (H2S) which, once suspended several kilometers high, do not disappear instantly. After a few weeks, they turn into sulfate, the ionic compound of (H2SO4).
The aerosol spreading effect of sulphate blocks the arrival of. The temperature will thus drop significantly by 0.5 ° C in places and for a extending from one to three years after the eruption: this is called a volcanic winter. Several examples through the ages have made it possible to observe the consequences of these eruptions. , located in Iceland, in 1783, was such that it caused a drop in temperatures throughout Europe, coupled with acid rain created by sulfuric acid present in the aerosol released by the volcano. The eruption caused historical devastation: in Iceland, 21% of the population died during the year 1784, due to the famine following the death of numerous farms of horses, cattle and sheep. Some historians believe that the eruption of Laki would even have influenced the onset of the French Revolution in 1789.
NASA, volcanic monitoring body
Since 1883, other massive eruptions have taken place: Mount Saint Helens in 1980 in the United States, the Novarupta in Alaska in 1912, the Pinatubo in the Philippines in 1991 … Faced with all these risks, various organizations andexist. Permanent observatories observe the sites at risk, using seismographs to detect the “tremors”, small caused by volcanic activity or even geodimeters useful for measuring the geological modification around the volcano.
NASA plays a major role in the observation and understanding ofvolcanic from space. The space agency relies on 38 satellites to volcanoes showing signs of activity, in order to activate if necessary its Eruption Response Plan. Probes such as the series of or Sentinel 1 have several instruments on board to collect data on the molecular composition of eruptive columns and volcanic clouds, or to study their thermal variations. To this end, other institutions such as or the (National Oceanic and Atmospheric Administration) participate in the research effort on the climatic impact of volcanic eruptions.
For now, no major eruption is expected to disturb theearthly. But faced with the climate issues highlighted by , NASA and others should continue to study these rare and exceptional phenomena of volcanic eruptions with the launch of the Landsat-9 satellite, scheduled for September 23, 2021.