Will the volcanic eruption in Tonga change the global climate? Expert: There is a cooling effect of about 0.3 °C

Cover news reporter Teng Han

After the volcanic eruption on the island of Tonga, there was a heated discussion about "volcanic eruptions will change the global climate" and even "benefiting from volcanic eruptions can offset the impact of global warming and reduce the pressure to reduce emissions".

On January 19, the cover news reporter learned from the China Meteorological Administration that some experts believe that volcanic eruptions will generally have a sustained impact on the global and East Asian climate in the next 1 to 2 years, with a cooling effect of about 0.3 °C. For the mainland, volcanic eruptions can weaken the intensity of the East Asian summer winds the following year, which in turn leads to the southward summer rain band of the continent.

It is reported that the volcanic eruption on the island of Tonga may be the largest volcanic eruption in 30 years. As can be seen from the 1000-meter resolution multi-channel true-color composite map produced by the Fengyun-4 B star data on January 15, the volcanic ash cloud that erupted instantaneously broke through the top of the tropopause and formed an umbrella-shaped cloud with a diameter of nearly 500 kilometers, and the huge shock wave around it was clearly visible.

Some experts believe that volcanic eruptions will generally have a sustained impact on the global and East Asian climate in the next 1 to 2 years, with a cooling effect of about 0.3°C. For the mainland, volcanic eruptions can weaken the intensity of the following year's East Asian summer winds, which in turn leads to the southward summer rain band of the continent. Some experts also said that without the premise of emission reduction, only through artificial methods to change the radiation balance of the Earth system at a large scale, the problem of climate change cannot be solved.

Historically, a number of volcanic eruptions have demonstrated that volcanic eruptions do correlate with falling global temperatures. Tonga island volcano is located in a low-latitude region, and Zhu Congwen, deputy director and researcher of the Institute of Climate and Climate Change of the Chinese Academy of Meteorological Sciences, said that in the past 100 years, there have been three large-scale low-latitude volcanic eruptions, namely Agung Volcano (March 17, 1963), Elchijom Volcano (April 4, 1982) and Pinatubo Volcano (June 15, 1991), which were low in the winter of the year after their eruptions (December to February), and most parts of the mainland except northeast China and Xinjiang were cold. In addition, the occurrence of La Niña also played a cooling role in the winter temperature of the mainland except the Qinghai-Tibet Plateau that year.

The main reason why volcanic eruptions cause cooling is that it injects sulfur-containing aerosols into the atmosphere, which enter the stratosphere and help the Earth reflect more sunlight, creating a cooling effect in the atmosphere. However, it should be noted that if this causal relationship is true, an important factor must also be considered - "magnitude".

Monitoring maps from NASA's Aura (Breezy in Latin) Earth observation satellite show that the release of sulfur dioxide on the first day of the volcanic eruption on the island of Tonga was 62 kilotons. According to MikeL Mann, a distinguished professor of atmospheric science at Penn State University, the eruption of Mount Pinatubo, which caused a 0.5°C drop in global average temperatures, eventually released 20,000 kilotons of sulfur dioxide, so if the previous eruption had a temperature drop, the Tonga Island volcano would need to emit more sulfur dioxide.

Zhu Congwen said that a series of studies have shown that volcanic eruptions generally have a sustained impact on the global and East Asian climate in the next 1 to 2 years, with a cooling effect of about 0.3 °C. For the mainland, volcanic eruptions can weaken the intensity of the following year's East Asian summer winds, which in turn leads to the southward summer rain band of the continent. Therefore, it is recommended that the continuing effects of volcanic eruptions be taken into account in flood precipitation forecasters.

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