Recently,   Based on the updated version of MST 2.0, a global surface temperature data set,   an evaluation pointed out that 2023 is the third hottest first half of the year since the observation record was recorded, only slightly lower than the hottest first half of 2016 and 2020. Further analysis also shows that if the surface temperature in the second half of 2023 reaches the average level of nearly 5 years, the global average surface temperature in 2023 (1.26℃ higher than that in the pre-industrial period, replaced by the average value from 1850 to 1900, the same below) will be close to or even break the record of the highest surface temperature in 2016 (1.25℃ higher). Judging from the fact that the global average surface temperature has been significantly broken in July 2023, this record-breaking situation is very likely to become a reality.

Global Annual and First Half Year Average Temperature Series Based on the China MST2.0 Dataset

(The orange line represents the average temperature in the first half of the year; the blue line represents the annual average temperature, and the red column refers to the average forecast for the past 5 years)

The Sixth Scientific Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR 6) released in August 2021 pointed out that in the past 40 years, since the instrumental observation period, it has been warmer every 10 years than the previous 10 years. From 2011 to 2020, the average temperature increased by 1.09℃ compared to that before industrialization (replaced by the averages of 1850-1900). This conclusion is based on five widely recognized global benchmark surface temperature data sets (HadCRUTemp 5 in Britain, NOAAGlobalT 5 in the United States, GISTemp 4, Berkeley Earth and China-MST-Interim in China) and several derived data sets.

On the basis of collecting global land temperature data from 1850 to 2023, the China -MST data set integrates relevant frontier research achievements of many countries and regions over the past decade, cooperates with expert groups from Britain, the United States, Canada and Australia, innovates data set reconstruction methods and parameters, reconstructs uncertainty evaluation model, and obtains the latest research achievements.

Earlier, on July 27th local time, United Nations Secretary-General Guterres issued a statement regarding global surface temperatures reaching a new high in July. Guterres said that it was a cruel summer for parts of North America, Asia, Africa and Europe, but it was a disaster for the whole planet. "This is just the beginning. The era of global warming has ended and the era of global boiling has arrived. Global warming mainly emphasizes the dynamic process of temperature rise. With the obvious increase in extremely high-temperature events recently," global boiling "means that global temperatures have reached a very high level, emphasizing the current state. Based on the temperature in the pre-industrial period, it can be seen that global warming has entered an accelerated period since the late 1970s.

There are many factors that cause this phenomenon. Human activities (including the emission of greenhouse gases such as carbon dioxide and methane) lead to long-term warming, especially in the time scale of 50 to 100 years. In about 10 years or less, fluctuations within the climate system, such as El Niñ o and Pacific interdecadal oscillations, will have a significant impact on short-term warming trends. On the one hand, accelerating global warming will increase the probability of extreme weather events and even disasters.

Global warming can result in extreme temperature changes. For example, research shows that the highest temperature rises in summer and the lowest temperature drops in winter, which indicates that the range of extreme temperature fluctuations is expanding. On the other hand, the aggravation of global warming has also had a great impact on human comfort. In addition, the changes in human comfort are obviously faster than the changes in temperature itself. When temperature accelerates, people's sense of discomfort will increase obviously, and the low latitude areas are more prominent than the high latitude areas, which deserve further attention.

References：

Sun W, LiQ*, Huang B, Dong W, Wang X, Zhai P and Phil Jones, 2021. Theassessment of global surface temperature change from 1850s: the C-LSAT2.0ensemble and the CMST-Interim datasets, Adv. Atmos.Sci., 38, 875-888, https://doi.org/10.1007/s00376-021-1012-3

Sun W., Yang Y.,Chao L., Dong W., Huang B., Jones P., and Li Q.*, 2022, Description ofthe China global Merged Surface Temperature version 2.0, Earth Syst. Sci.Data, 14, 1677-1693, https://doi.org/10.5194/essd-14-1677-2022.

HuangJ, Li Q*, Song Z., 2022, Historical Global Land Surface Air ApparentTemperature and its Future Changes Based on CMIP6 Projections, Sci.Total. Enviorn., 816, 151656. https://doi.org/10.1016/j.scitotenv.2021.151656

Li Z., Sun W.,Liang C., Xing X., Li Q*. Arctic warming trends andtheir uncertainties based on surface temperature reconstruction under differentsea ice extent scenarios. Adv. Clim. Change Res.,14(3): 335-346, https://doi.org/10.1016/j.accre.2023.06.003.