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in ancient times, humans had limited understanding of natural phenomena. they did not understand the principles of weather phenomena such as wind and rain, nor did they understand the laws of their occurrence. in that era of lack of scientific knowledge, our ancestors used their imagination to create myths about the "dragon king", endowing the "dragon king" with the ability to control precipitation, and imagined that disasters such as floods and droughts were caused by the "power of the gods" descending on the earth. therefore, whenever a meteorological disaster occurred, people would hold a blessing ceremony to reduce the impact of the disaster on people.

frequent climate change has brought serious meteorological disasters to various regions.for example, since the beginning of summer in 2024, torrential rains have occurred in southern china and the yangtze river basin, and the dongting lake has burst its banks, which has concerned people across the country. in august, multiple mudslides also occurred in gansu and sichuan. it seems that the "dragon king" is swinging back and forth between "fishing" and "excitement". extreme precipitation occurs frequently, and many areas are experiencing drastic "dry-wet conversions" and are in dire straits.

precipitation variability refers to the fluctuation of precipitation over time.it is often measured by standard deviation.including the fluctuation range of annual precipitation, monthly precipitation and daily precipitation.

the strength of changes in precipitation variability reflects the stability or volatility of precipitation in a region.the stronger the precipitation variability, the more uneven the temporal distribution of precipitation, the more unstable the water supply, the more "wet periods become wetter and dry periods become drier", and the more drastic the "wet-dry transition".a region may experience longer or more intense extreme droughts in one period, and unusually high rainfall in a subsequent period. this variability is a reflection of increased precipitation variability.

changes in precipitation variability have a direct impact on the climate resilience of societies and ecosystems（Climate Resilience）,yesresponseclimate change is an important aspect that must be considered. for example, extreme precipitation can cause urban flooding and damage urban infrastructure.

although climate models predict that global precipitation variability will increase with future warming, there is currently no evidence that human activities have changed precipitation variability. the latest research provides a clear answer to this question.

the study used all publicly available daily precipitation observations to reveal that since 1900, precipitation variability has increased over about 75% of the world's landmass where sufficient observations are available, with a particularly strong increase over europe, australia, and eastern north america.the global average daily precipitation variability is increasing at a rate of 1.2% per decade.

linear trend of daily precipitation variability from 1900 to 2020 based on ghcn-daily observations.

image source: references

klaus hasselmann, winner of the 2021 nobel prize in physics（Klaus Hasselmann）the optimal fingerprint method was proposed. after using this method to conduct detection attribution research, it was found thatthe increase in precipitation variability can be attributed to the increase in greenhouse gas emissions from human activities since industrialization.

greenhouse gas emissions cause the atmosphere to warm. as the atmosphere warms, its water holding capacity increases, that is, the amount of water vapor contained in the atmosphere increases. this is the classic clausius-clapeyron equation.（Clausius–Clapeyron relation）.therefore,when precipitation occurs, even if the dynamic conditions of the precipitation system remain unchanged, the increase in atmospheric water vapor content will make the precipitation intensity greater, thereby increasing the precipitation variability.this process is the thermal effect of atmospheric warming.

on the other hand,changes in atmospheric circulation can also affect precipitation variability, which is called "dynamical effects".it should be emphasized that since the response of atmospheric circulation to global warming is complex and is significantly affected by the internal variability of the climate system, the impact of "dynamic effects" on precipitation variability has strong interdecadal characteristics and regional differences.

this study provides a comprehensive understanding of the observed enhancement of precipitation variability through rigorous observational analysis, physical process diagnosis, and detection attribution.it points out the impact of human activities on precipitation variability and provides important new evidence for the enhancement of the multi-scale water cycle.

the drastic and rapid transitions between extreme events confirm the new feature of "complex extreme events", which not only poses new challenges to the current climate prediction system, but also will have a series of social and ecological impacts, including water supply, climate resilience of society and infrastructure, ecosystem function, terrestrial ecosystem carbon sink, etc.

future,this change and impact of precipitation variability will continue to intensify against the background of warming, and warming is an important influencing factor of precipitation variability.my country is facing the double pressure of water resources and drought and flood. the risks brought by the future "dragon king's bad" will bring new challenges to our disaster risk management and water resources regulation. therefore, all sectors of society urgently need to strengthen risk response and disaster prevention capabilities. at the same time, the public should also raise risk awareness, attach importance to meteorological disaster forecasts and warnings, and take "precautions before they happen."