Release News| How does the volcanic eruption in Tonga affect the weather and climate in China and even the world?

The Paper's reporter Diao Fanchao

On 14 and 15 January, an undersea volcano in the South Pacific island nation of Tonga erupted violently for two consecutive times and triggered a tsunami. According to the Tonga Meteorological Service, the entire territory of Tonga is threatened by tsunamis, torrential rains, floods and strong winds as a result of this violent eruption of submarine volcanoes. The incident affected the entire Pan Pacific Rim region, and many Countries in the Pacific Rim such as Fiji, Samoa, New Zealand, Australia, Japan, the United States, Canada, and Chile issued tsunami warnings.

From the 1000-meter resolution multi-channel true color composite map produced by fengyun-4 B star data on January 15, it can be seen that the volcanic ash cloud that erupted instantaneously broke through the tropospheric roof and formed an umbrella-shaped cloud with a diameter of nearly 500 kilometers, and the huge shock wave around it was clearly visible.

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". In this regard, a number of experts said in an interview with the surging news (www.thepaper.cn) that volcanic eruptions will generally have a continuous impact on the global and East Asian climate in the next 1 to 2 years, and the cooling effect will probably appear about 0.3 °C. For mainland china, volcanic eruptions can weaken the intensity of East Asian summer winds the following year, which in turn leads to the southerly summer rain band on the continent, and experts recommend that the continued effects of volcanic eruptions be considered in flood precipitation forecasters.

In response to the claim that volcanic eruptions offset the effects of global warming, experts pointed out that without the premise of emission reduction, only artificial methods can change the radiation balance of the Earth system at a large scale, and the problem of climate change cannot be solved.

Volcanic eruptions generally have an impact on the global and East Asian climate over the next 1 to 2 years

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). ”

Zhu Congwen said that the main reason why the eruption of the volcano causes cooling is that it injects sulfur-containing aerosols into the atmosphere, which enter the stratosphere and help the earth reflect more sunlight out, thus creating a cooling effect in the atmosphere. However, it should be noted that if this causal relationship is true, the important factor of "magnitude" must also be considered. The eruption of Pinatubo, which caused a 0.5°C drop in global average temperatures, eventually released 20,000 kilotons of sulfur dioxide, and according to the monitoring map of NASA's Aurora (Latin Breeze) Earth observation satellite, the first day of the tonga island volcano eruption released 62 kilotons of sulfur dioxide, "so if the impact of the previous eruption on the temperature drop is to be reached, the Tonga island volcano needs 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, the topic of "artificial volcanic eruptions cooling the earth" has aroused heated discussion.

In this regard, Chen Ying, a researcher at the Institute of Ecological Civilization of the Chinese Academy of Social Sciences and the main author of the third working group of the fifth and sixth assessment reports of the IPCC, said: "If there is no premise of emission reduction, only 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, and may also bring other risks and uncertainties, such as changing the temperature and precipitation distribution." ”

"What is certain is that SRM cannot serve as a 'workhorse' in 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. Chen Ying added.

Cao Long, professor of the Department of Atmospheric Sciences at the School of Earth Sciences of Zhejiang University and the lead author of the first working group of the sixth assessment report of the IPCC, pointed out that the currently proposed SRM method mainly includes injecting aerosols into the stratosphere, low cloud lighting of the ocean, and increasing the albedo of the ocean and land surface. The basic starting point of these methods is to increase the albedo of the earth-gas system, reduce the solar radiation reaching the atmosphere and the ground, and counteract the warming effect caused by the increase in greenhouse gases through short-wave radiation intervention.

Cao Long said that since the ipcc's fifth evaluation report, the research on SRM has made great progress. The IPCC Sixth Assessment Report assesses the impact of SRM on the climate system and the carbon cycle, with key conclusions including that SRM can offset climate change from some of the increases in greenhouse gases at global and regional scales, but not completely offset climate change caused by increases in greenhouse gases at global and regional scales, and that SRM cannot mitigate ocean acidification.

Cao Long admits that due to the current limited understanding of the interaction and microphysical processes of cloud-aerosol radiation processes, there is still great uncertainty about the cooling potential of aerosol-based SRM, and the assessment of SRM climate effects in the first working group of the IPCC's sixth assessment report is mainly concentrated on the global scale, and there is a lack of assessment of the climate impact of SRM on different regions. In the next step of the research work, it is necessary to use high-resolution models including more complete cloud-aerosol-radiation processes to simulate SRM methods to further understand the cooling potential of different SRM methods and their impact on the climate system. Research on the global and regional climate impacts of different SRM approaches implemented at different locations and times will also be significantly enhanced.

Responsible editor: Jiang Chenrui Photo editor: Jin Jie