IPCC Climate Assessment Report released: |
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Climate change affects hundreds of years and irreversible extreme weather is more frequent |
On August 9, Geneva time, the latest assessment report issued by the Intergovernmental Panel on Climate Change (IPCC) pointed out that scientists have been observing changes in various regions of the world and the entire climate system. Unprecedented in 100,000 years, some changes that have already begun (such as continuous sea level rise) are irreversible within hundreds to thousands of years: the increasing impact of human activities, significant regional climate changes, and more frequent extreme weather events…
The IPCC Sixth Assessment Report (AR6) Working Group 1 report “Climate Change 2021: Natural Science Foundation” was originally scheduled to be released in April this year, but due to the impact of the new crown epidemic, the report was postponed for several months. The report was approved on August 6 after a two-week online meeting (starting on July 26) attended by government representatives from the 195 member states of the IPCC. This is also the first time that the IPCC has reviewed and approved the evaluation report through an online meeting.
“This report reflects everyone’s extraordinary efforts under special circumstances.” IPCC Chairman Hoesung Lee said. “The innovations in this report, and the progress in climate science it reflects, provide valuable insights for climate negotiations and decision-making. support.”
Human activities have caused the climate to warm at an unprecedented rate
Zhai Panmao, the co-chair of IPCC Working Group I and a researcher at the Chinese Academy of Meteorological Sciences, told the China Science News: “The report is based on an improved observational data set, assessing historical warming, and scientifically understanding the impact of the climate system on human activities. Progress has been made in responding to greenhouse gas emissions.”
The report puts forward that the atmosphere, ocean, cryosphere and biosphere have undergone extensive and rapid changes under the influence of human activities. For at least the past 2000 years, the global surface temperature has risen faster since 1970 than in any other 50-year period. The report also clearly stated that since about 1750, the increase in the concentration of greenhouse gases was mainly caused by human activities.
The report shows that since 1850-1900, the average global surface temperature has risen by about 1°C, and pointed out that from the average temperature change in the next 20 years, the global temperature rise is expected to reach or exceed 1.5°C.
The report also made a new estimate of the possibility of global warming above 1.5°C in the next few decades, pointing out that unless greenhouse gas emissions are reduced immediately, rapidly and on a large scale, the warming should be limited to close to 1.5°C or even 2 ℃ will be impossible to achieve.
It’s not just a matter of temperature. Climate change is bringing many different combinations of changes to different regions, and these changes will increase with further warming, including changes in dryness, wetness, wind, snow, and ice.
“Climate change is already affecting every region on the planet in many ways. The changes we experience will intensify as the temperature rises.” Zhai Panmao said that compared with previous IPCC reports, the contents of AR6 regarding regional climate change information It is richer, adding content related to regional climate change risk assessment, and fully strengthening the convergence and consistency between different AR6 working groups.
Valérie Masson-Delmotte, co-chair of the IPCC Working Group I, believes that this report is a test of reality. “We have a clearer understanding of the past, present and future climate, which is important for grasping the future direction, taking action and responding to it. The way is important”.
Extreme heat and rainfall events are more frequent
Many changes in the climate system are directly related to increasing global warming. The main manifestations include increased frequency and intensity of extreme high temperature events, ocean heat waves and heavy precipitation, agricultural and ecological drought in some areas, an increase in the proportion of severe tropical cyclones, and a decrease in Arctic sea ice, snow and permafrost.
It is worth mentioning that the report analyzes compound events for the first time. The report found that since the 1950s, human influence may have increased the probability of compound extreme weather events.
For example, heat waves and drought events occur very close or even at the same time. Zhai Panmao told the China Science Daily: “This poses a special risk because they often leave affected communities with little time to recover between two extreme weather events.”
With the continuous development of detection attribution, the report shows that North America, Europe, Australia, many regions in Latin America, the western and eastern parts of Southern Africa, Siberia, Russia and the entire Asia…Most areas on the earth are already suffering from high temperature extreme weather ( Including heat waves).
The report believes that as the global temperature rises, the intensity and frequency of extreme high temperature weather are rapidly increasing. In addition to extreme high temperatures, extreme rainfall events will also become more frequent, leading to a significant increase in rainfall.
China’s role in the IPCC
The IPCC is a United Nations agency that evaluates science related to climate change. It aims to provide policymakers with regular scientific assessments of climate change, its impacts and risks, and to propose adaptation and mitigation strategies.
The IPCC has three working groups, namely the first working group-the natural scientific basis of climate change, the second working group-impact, adaptation and vulnerability, and the third working group-climate change mitigation. The AR6 reports of the other two working groups will be completed in 2022, and the AR6 comprehensive report will be completed in the second half of 2022.
It is understood that the IPCC does not carry out its own research, does not run models, and does not make observations of climate or weather phenomena. Its role is to evaluate the scientific, technical, and economic and social literature on understanding climate change, its impacts and future risks, and adaptation and mitigation options. The author team includes a variety of authors from different regions, both developed and developing countries and regions, to ensure that the report’s views are neutral and balanced, while not ignoring issues that are considered important by specific regions.
After six evaluation cycles, the main authors of the IPCC evaluation report in China have increased significantly, from 9 in the first evaluation report (1990) to 61 in this evaluation report. In addition, the number of citations of Chinese scientists’ literature has also increased significantly. Take, for example, the citations of the literature in which the mainland author was the first author in the report of the First Working Group. There were 87 citations in the fourth evaluation report, and 257 in the fifth evaluation report.
It is worth noting that this evaluation report is that Chinese experts have served as co-chairs of the first working group for four consecutive terms: the third evaluation report is Ding Yihui, an academician of the Chinese Academy of Engineering, the fourth and fifth evaluation reports are Qin Dahe, an academician of the Chinese Academy of Sciences, and the sixth The assessment report is Zhai Panmao.
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