How will the volcanic eruption in Tonga affect the global climate? Experts: China's summer rain belt or south

Beijing, January 19 (Reporter Chen Ruihai Huang Yuling) On January 15, a violent eruption of an island volcano occurred in the South Pacific island country of Tonga, and the volcanic ash cloud that was instantly spewed out broke through the top of the troposphere and formed an umbrella-shaped cloud with a diameter of nearly 500 kilometers. This may be the largest eruption in 30 years.

After the volcanic eruption on the island of Tonga, topics such as "volcanic eruptions will change the global climate" have aroused heated discussions. The 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, and there will be a cooling effect of about 0.3 °C. For the continent, 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.

How do volcanic eruptions affect the continental and global climate?

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), Elchjom Volcano (April 4, 1982) and Pinatubo Volcano (June 15, 1991). In the winter of the year after their eruption (December to February), temperatures were low in most parts of the mainland except the northeast and Xinjiang. 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.

According to experts, 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, thus 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 a volcanic eruption on the island of Tonga was 62 kilotons. Michael Mann, a distinguished professor of atmospheric science at Penn State University, analyzed that 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 impact of previous eruptions on temperature drops was to be achieved, 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.

Can "man-made volcanic eruptions" cool the planet?

After the volcanic eruption in Tonga, Chen Ying, a researcher at the Institute of Ecological Civilization of the Chinese Academy of Social Sciences, has been paying close attention to it. She noticed a hotly debated topic on social media: "If volcanic eruptions have a cooling effect, then don't we just artificially create this aerosol and spread it into the atmospheric stratosphere, and then we don't have to spend a lot of effort to reduce emissions?" "Without the premise of emission reduction, only relying on SRM (solar radiation intervention, that is, changing the radiation balance of the Earth system at a large scale through artificial methods to cope with global warming) will certainly not solve the problem of climate change." ”

Chen Ying added that SRM will not solve the problem of ocean acidification, and may also bring other risks and uncertainties, such as changing the temperature and precipitation distribution. What is certain is that SRM cannot be the "workhorse" of the fight against climate change. However, according to recent studies, SRM has the potential to serve as an adjunct to climate change if it is based on significant emission reductions.