At the beginning of 2022, the undersea volcano of Hong Aha Apai Island in the South Pacific island nation of Tonga erupted violently, becoming the largest volcanic eruption of the 21st century so far. A large amount of sulfur dioxide (SO2), hydrogen sulfide with the volcanic eruption into the atmosphere, some netizens are worried, this eruption will be like the 1815 Tambora Volcano caused by the "summerless year"?
Regarding the possible climatic impact of the volcanic eruption, the surging news reporter interviewed Gao Chaochao, associate professor of the School of Environment and Resources of Zhejiang University, whose research direction is global climate change and low-carbon economy. "Based on the amount of SO2 gas (about 400,000 tons) that the Tonga volcano erupted into the stratosphere this month, she said, there will be no significant impact on the global climate." According to overseas research, as of January 17, the eruption of The Tonga volcano produced about 400,000 tons of sulfur dioxide into the stratosphere.
Gao's research focuses on global and regional climatic effects of aerosols, low-carbon pathways for energy use and urbanization processes, and stratospheric climate engineering mechanisms and influences. She is in J. Geophys. Res. and other international academic journals have published nearly 20 SCI papers, one of which was named a scientific highlight by the journal Nature (Research Highlight in Nature, 2006); the other was selected as a scientific highlight by the American Geophysical Society (Research Spotlight in AGU, 2014).
Gao Chaochao believes that the potential future climate impact of Tonga volcano depends first and foremost on the presence of a follow-up eruption, followed by the spread range of the sulfate aerosol, and the potential interaction of the radiative forcing it produces with other processes in the current climate system, such as the El Niño-South Oscillation.
According to the United Nations Intergovernmental Panel on Climate Change (IPCC), radiative forcing is a measure of the extent to which a factor affects the energy balance of the Earth-atmosphere system, as well as an index that reflects the importance of that factor in potential climate change mechanisms. Positive forcing warms the Earth's surface, while negative forcing cools it down.
Pre-compilation image from USGS
On January 14 and 15, local time, an undersea volcano erupted in Tonga. On January 17, the volcano was once again monitored for a major eruption that erupted for several days and even triggered a tsunami thousands of kilometers away. The Tonga government issued its first disaster notification on the 18th, saying that the eruption of submarine volcanoes triggered a tsunami of up to 15 meters, causing "unprecedented disasters" to the country.
"Volcanic activity is one of the important natural factors in the construction of the Earth's climate system, having had varying degrees of influence on the regional or global climate at different times." Gao Chaochao told the surging news reporter, "The climatic effect of volcanic eruptions mainly depends on the amount of SO2 and H2S gases that enter the stratosphere during the eruption process, which will form aerosols and cause surface cooling by reflecting solar radiation." Eruption seasons and geographic locations affect the climatic effects of volcanic eruptions on reflected solar radiation, coupled with the associated dynamics and feedback processes of the climate system. ”
For the measurement of volcanic eruptions, Gao Chaochao mentioned three criteria: volcanic dust curtain index (DVI), volcanic eruption index (VEI), and atmospheric optical thickness (AOD) sequence. She wrote in a paper: "Lamb was the first to establish the Volcanic Dust Curtain Index (DVI) using data such as historical records, radiation observations, temperature, and eruption volume. Newhall et al. and Self et al. established the Eruptive Index (VEI) based on 11 characteristic parameters such as the intensity, diffusion degree and destructiveness of volcanic eruptions. Sato et al. reconstructed the atmospheric optical thickness (AOD) sequence of volcanic activity over the past 150 years using different generations of data such as volcanic dust curtain volume, optical characteristics, and satellite observations from 1850-1882, 1882-1979, and 1979-1990, respectively. ”
At the same time, the paper also pointed out that due to the use of different proxy data for the DVI and Sato sequences, there is a lack of consistency in the time series. The VEI, on the other hand, mainly characterizes geological features such as volcanic eruption intensity and has a low direct correlation with climatic effects (such as sulfur content in eruptions).
"VEI is currently seen in the news more used, generally VEI level 4 or above will attract attention to climate observation and research." Gao Explains, "The eruption level of The Tonga volcano in January 2022 is probably below VEI5. ”
As an undersea volcano, how will the eruptions and effects of The Tonga Volcano differ from the eruptions and effects of the above-ground volcanoes?
Hyper said that submarine volcanoes usually trigger tsunamis, so they have an instantaneous impact on the surrounding sea or islands (if they exist), while above-ground volcanoes, especially mountain volcanoes, are relatively easy to spew gases such as volcanic ash and SO2 into the atmosphere at higher altitudes. In the same volume and composition of matter, the climate effects of the latter may be significant.
The land of Tonka is covered in volcanic ash. Image courtesy of CNN on January 17, 2022
According to Gao Chao, the active volcanic regions of the world are mainly distributed in three belts.
First, the Pacific Rim volcanic belt has more than 300 active volcanoes, accounting for more than 60% of the global active volcanoes. Of these, there are about 10 in South America, the west coast of Central America and the West Indies, 39 in Alaska and Aleutian, and about 200 in the western and southwestern Pacific Oceans.
Second, the Mediterranean Sea and the Indonesian volcanic belt, with a total of more than 70 active volcanoes. Among them, there are 13 along the Mediterranean Sea and more than 60 in Indonesia.
Third, the ridge volcanic belt, which is mainly distributed in the Atlantic, Pacific and Indian Ocean ridges. Of these, there are 22 in the Atlantic Ocean and 22 in Iceland and Jan Mayen.
In this regard, the surging news reporter noted that there have been several famous volcanic eruptions in history that have had a significant or even sustained impact on the global climate. For example, famous scientific magazines such as Live Science and Australian Geography have combed through the more serious volcanic eruptions in human history.
Among them, the 1815 Eruption of Tambora in Indonesia was the most violent in 500 years, and the Volcanic Eruption Index (VEI) reached a rare level of 7 in human history. Due to the massive emissions of sulfur dioxide, the world has experienced a sustained and severe temperature drop, leading to crop failures around the world and the spread of typhus in Europe. 1816, so it is known as the "year without summer" in history.
A crater formed by the eruption of Mount Tambora in 1815. Image from The Associated Press
In 1610 BC, the volcano Thera in the Aegean Islands erupted with a VEI of 7. Geologists believe that the Thira volcano in the Aegean Archipela erupted in a fraction of a second, with an energy equivalent to hundreds of atomic bombs. While there is no written record of the eruption, geologists believe it may have been the most intense eruption ever recorded, and there is reason to speculate that the large amounts of sulfur dioxide emitted by the volcano into the atmosphere altered the climate, triggering tsunamis and temperature drops.
However, the impact of some volcanic eruptions with VEI of about magnitude 6 in history on the global climate should not be underestimated.
In 450 AD, the Ilopango volcano erupted for the first time, and vei was above level 6. The eruption killed 100,000 people and displaced more than 400,000 people. It is thought to have been responsible for the cooling of global temperatures between 535 and 536 AD and caused crop failures from Rome to China.
In 1600, the volcano Huaynaputina erupted, the largest volcanic eruption ever recorded in South America, with a VEI6 rating. Volcanic ash from the eruption buried an area of more than 50 square kilometers west of the mountain and is still covered to this day. The summer after the eruption of the volcano in 1600 was the coldest in 500 years.
In 1783, the volcano Laki in Iceland erupted and lasted about 8 months, releasing about 14.7 cubic kilometers of lava, VEI6. Toxic gases not only poison crops, but also 60% of Iceland's grazing livestock. Sulfur dioxide released by the volcano caused acid rain and falling global temperatures, causing famine that killed more than 10,000 Icelanders, or about a quarter of Iceland's population at the time.
In 1991, The Pinatubo volcano in the Philippines erupted, the second largest eruption of the 20th century, with a VEI6 rating. The volcano has ejected nearly 20 million tons of sulfur dioxide into the stratosphere, causing global temperatures to plummet.
Source: The Paper