Background

The total global surface temperature reached 1.1 °C above 1850–1900 during the 2011–2020 decade1. Continued greenhouse gas (GHG) emissions will lead to a further increase in global warming in the future, and the 1.5 °C global warming level is very likely to be exceeded in 2021–2040 under a very high GHG emissions scenario (SSP5-8.5). The pervasive issue of global warming has already profoundly impacted meteorological systems, natural environments, and human societies2,3,4. Global warming has intensified atmospheric thermodynamics while reducing atmospheric stability. The atmospheric environment is undergoing more intense changes, leading to more severe variations in precipitation and thus a higher likelihood of extreme rainfall events.

Heavy rainfall is one of the primary triggering factors for geological hazards such as landslides and debris flows, and climate change has significantly influenced the triggering conditions of geological hazards in mountainous regions with complex terrain. In addition, climate change influence geological hazards through diverse mechanisms: the extreme drought and sudden shift between drought and flood conditions, permafrost degradation, which damages the stability of rock and soil masses, and soil erosion caused by rising sea levels5,6,7,8. The increased frequency and intensity of heavy rainfall and changes in meteorological, geographical, and hydrological environments due to global warming undoubtedly exacerbate the risk of geological disasters, which is a phenomenon that has been familiar and predictable through decades of research into rainfall-triggered geological hazards9,10,11.

Governments worldwide have formulated long-term climate change adaptation action plans in response to global warming. For instance, the Chinese government has issued the “National Health Adaptation Action Plan for Climate Change (2024–2030)”, aimed at enhancing capabilities for health adaptation to climate change and risk prevention. The European Union’s “Green Deal” emphasized climate-resilient infrastructure development in geologically vulnerable regions. Additionally, UNESCO’s “Global Geoparks Network” integrated climate adaptation into geological disaster risk management strategies, highlighting transnational collaboration. These efforts, alongside renewable energy transitions and policy innovations, provide multifaceted pathways to mitigate climate impacts. Beyond developing adaptation action plans, a series of government-led measures, including renewable energy development, resilient infrastructure construction, policy innovation, and international cooperation, have also provided effective channels for addressing the impacts of climate change12,13.

To tackle the disaster effects of extreme weather, monitoring and forecasting systems for weather have gradually been established and continue to experience breakthroughs with advancements in computer technology14,15. Government departments responsible for natural hazard management in numerous countries have established early warning, response, and rescue mechanisms specifically tailored to address natural hazards triggered by extreme weather. These mechanisms guarantee rapid and effective action during extreme rainfall disasters, thereby minimizing potential losses16,17,18,19,20.

Currently, global warming has significantly intensified the risks and losses associated with rainfall-triggered geological disasters. However, existing research or relevant policies have predominantly focused on the analysis and summarization of historical cases concerning the impacts of climate change on geological hazards, while being relatively deficient in forecasting the potential future impacts and risk trends. In the face of increasingly frequent extreme rainfall and heightened risks of geological disaster, our understanding of the geological disaster risk situation under climate change still seems to be lacking. The cases of extreme rainfall and severe geological disasters in recent years prompt us to delve deeper into this issue: How will the predictability of geological disasters and their associated risks change in extreme weather conditions?

Characteristics of extreme weather and rainfall-triggered geological disasters

Since the 1950s, in most terrestrial regions where global precipitation observation data are sufficient for trend analysis (with high confidence), the frequency and intensity of extreme rainfall events have significantly increased1,6,21. Over the past four decades, the proportion of major tropical cyclones occurring globally has also risen. Numerous rare and extreme weather events, along with the cascading disasters such as floods and waterlogging, have occurred worldwide in recent years (Fig. 1), causing tremendous economic losses and casualties22. Additionally, rising temperatures have led to increased terrestrial evapotranspiration, resulting in an increase in agricultural and ecological drought in some regions (with medium confidence). In monsoon climate regions, where droughts and floods coexist, prolonged high temperatures and droughts cause the surface soil to lose moisture, become loose or hardened, and accumulate atmospheric energy. This makes the regions prone to severe convective weather and concentrated short-duration heavy rainfall, which can easily trigger flash floods and induce cascading disasters, resulting in compound disaster effects involving simultaneous hazards23,24.

Fig. 1: Statistics and distribution of extreme weather events that have caused significant losses globally in the past decade (2015–2024).
Fig. 1: Statistics and distribution of extreme weather events that have caused significant losses globally in the past decade (2015–2024).
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The data is derived from EM-DAT (https://www.emdat.be/), and the extreme weather types mainly include heavy rainfall, storms, extreme high temperatures, and droughts.

Large-scale, high-intensity rainfall is a primary trigger for geological hazards. When rainwater infiltrates into soil pores or rock crevices, it not only increases the weight of the rock-soil mass but also decreases its shear strength. Under alternating wet and dry conditions, rainfall more readily causes cracking within the rock-soil mass, further exacerbating both rainfall infiltration and slope instability25. The relationship between rainfall and geological hazards, as well as the risk patterns, varies across different terrains, landforms, or geological conditions. For instance, in the mountainous regions along the edge of the Qinghai-Tibet Plateau, the synergistic effect of intense tectonic uplift and monsoon rainfall leads to frequent shallow landslides26. In the Andean mountainous areas, the weathered layers of volcaniclastic rocks can trigger deep-seated slides under the influence of the El Nino phenomenon27. In the Alps regions, there has been a notable increase in geological hazards resulting from the coupling effects of glacial retreat, rainfall, and periglacial processes28. Additionally, the impact of global climate change on geological disaster risk is multifaceted. In addition to being induced by external rainfall conditions, changes in geological formations and landscape features or the deterioration of rock and soil due to variations in temperature and rainfall, also serve as internal factors that intensify the occurrence of geological disasters5.

Heavy rainfall usually triggers large-scale geological hazards. Typical cases include the triggering of more than 54,000 landslides by rainfall in Tianshui, Gansu Province, China, in June 201329; 2665 landslides in Sanming, Fujian Province, China, in May 201630; 2241 landslides in Luhe, Guangdong Province, China, in August 201831; 5012 landslides in the Western Ghats region of Maharashtra, India, in July 202132; 1687 landslides in the Marche-Umbria regions of central Italy, in September 202233; 648 landslides in southern Norway, in August 202334. Additionally, detailed cataloging data on geological hazards form the foundation for assessing risks and developing early warning systems for rainfall-triggered geological hazards. However, globally, there are very limited publicly available and detailed catalog databases of rainfall-triggered geological hazards. Progress in compiling historical data on rainfall-triggered geological hazards has been slow and limited. It poses significant challenges for understanding the status and trends of rainfall-triggered geological hazards, as well as for devising effective response strategies or measures.

The rainfall-triggered geological disasters have caused serious casualties

The geological disasters triggered by heavy rainfall have caused immeasurable losses worldwide. Figure 2 presents the statistical data and spatial distribution of fatalities due to geological disasters over the past decade (2015–2024). The statistics indicate that geological disasters causing casualties are widely distributed, representing a global issue. Notably, in many instances of heavy rainfall, some deaths attributed to geological disasters may instead be labeled as floods. Therefore, the actual number of fatalities caused by geological disasters is likely to be higher than currently reported. Despite this underestimation, the annual number of deaths from rainfall-triggered geological disasters still accounts for a significant proportion. Over the past decade, the average annual number of casualties from rainfall-triggered geological disasters worldwide has been at least 750. In terms of the frequency of disaster occurrences, regions such as Eastern and Southern Asia, and Eastern Africa have been more severely affected.

Fig. 2: Statistics and distribution of fatalities caused by geological disasters in the past decade.
Fig. 2: Statistics and distribution of fatalities caused by geological disasters in the past decade.
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The dashed line in the subgraphs represents the linear fitting line, and the shaded area represents the confidence interval. The data is derived from EM-DAT (https://www.emdat.be/), and the types of disasters included in the statistics is geological disasters triggered by rainfall, including landslides and debris flows.

We analyzed the trends in fatalities caused by rainfall-triggered geological disasters across Europe, Asia, the Americas, Africa, and Oceania over the past decade (as depicted in the subgraphs in Fig. 2). It is noteworthy that the increasing trend in geological disaster risk under the influence of climate change is indisputable. However, incidents of casualties caused by geological disasters still exhibit a high degree of contingency and unpredictability. This is the primary reason for the often-fluctuating inter-annual characteristics in the number of casualties resulting from geological disasters. Nevertheless, despite this, the statistical results indicate that there is a marked upward trend in the number of deaths due to rainfall-triggered geological disasters globally, and on most continents. Although the Americas exhibit a fluctuating downward trend, the amplitude of these fluctuations indicates a lack of stability or predictability in the downward trend. In other words, due to the extreme and sudden nature of weather conditions, the risk of significant losses from rainfall-triggered geological disasters remains high under the trend of global warming.

The number of global deaths caused by such disasters has continued to increase, showing a rapid upward trend since the year 2021. Extremely severe rainfall-triggered geological disaster events in 2024 were particularly frequent and devastating. The intensification of that trend is inextricably linked to the ongoing impact of global climate change. It is foreseeable that, against the backdrop of continued global climate change and warming temperatures, the risk of casualties and property losses from rainfall-triggered geological disasters will further intensify for an extended period in the future. In natural hazards assessment, the risk situation is typically represented through indicators related to both external drivers and internal stability. When external climatic forcing and the internal vulnerability simultaneously surpass critical thresholds, the disaster environment transitions from a state of discrete, sporadic disasters to one characterized by chained and clustered occurrences. However, does the anomalously high death toll from geological disasters in 2024 reflect a climate-induced tipping point, or is it an isolated outlier? It is a topic worthy of attention. Against the backdrop of rising global temperatures, increasing precipitation variability, shortened return periods of heavy rainfall, and heightened probabilities of extreme rainfall events, we are compelled to consider the possibility of a shift in geological disaster patterns from “linear gradual change” to “nonlinear surge”.

Strategies and key issues for dealing with the risk of rainfall-triggered geological disasters

Currently, the frequent occurrence of extreme weather events poses a severe threat to human health and life, and the globe is confronting this challenge. Against the threat, governments worldwide have formulated long-term climate change adaptation action plans and a series of policy measures. Weather monitoring systems, natural hazard warning systems, and response and rescue mechanisms, which are based on AI, large models, and other new technologies, are continuously being improved and developed14,19,35. In urban planning and construction, climate carrying capacity and disaster risks associated with extreme weather are being considered to enhance urban climate adaptability and the resilience of disaster prevention and mitigation. However, facts and data indicate that the risks and losses from extreme rainfall-triggered geological disasters have not decreased but may instead become increasingly severe. This implies that the current policies and measures to respond to climate change and extreme weather have limited effectiveness in preventing such disasters. This necessitates that we consider whether, in an environment where the extremity, suddenness, and frequency of heavy rainfall are intensifying, we truly understand the risks and threats posed by rainfall-triggered geological disasters. This is an issue that cannot be ignored by government departments and disaster prevention and mitigation agencies worldwide.

The reasons for this issue are many. Firstly, the issue stems from disaster chain thinking. Current policies, strategies, and measures for dealing with extreme weather and disaster effects, whether in monitoring, warning, response, or rescue, still largely follow the traditional mode. On the one hand, due to inadequate research and understanding of the complex relationship between rainfall and geological hazards, it is difficult to predict and assess the triggering conditions and evolution of disaster chains. On the other hand, in disaster response and rescue efforts, more attention is paid to individual disasters themselves, often neglecting the chain effects of disasters. A typical example is that government departments and disaster reduction agencies in many countries habitually categorize casualties caused by rainfall-triggered geological hazards into the category of concurrent torrential rain or flood disasters. In recent years, there has been a notable shift in the global paradigm for disaster prevention and mitigation policies, with its core feature manifesting as a transition from responding to individual disaster types to a paradigm focused on the systematic prevention and control of disaster chains. It marks a promising beginning for disaster governance to enter the phase of “full-chain” risk management.

Secondly, it lies in technological capabilities. Enhancing the technological capabilities in monitoring, assessing, early warning, and response to rainfall-triggered geological hazards and their associated disaster risk exerts a direct and multilevel causal impact on reducing disaster risk. For instance, it involves implementing high-precision monitoring of potential hazards, issuing early warnings for impending disasters, or conducting precise zoning of risk-prone areas. Currently, the disaster prevention and mitigation technology system faces challenges in dealing with geological hazards caused by heavy rainfall. Although geological hazards monitoring and warning systems are continually emerging and developing, the effective range, accuracy, timeliness, and adaptability of related technologies and equipment to complex scenarios still need to be improved and developed. It is worth noting that this is not an issue that can be simply solved by integrating emerging technologies such as artificial intelligence into existing technologies for rainfall-triggered geological disaster risk assessment and emergency rescue. Instead, it is a systematic engineering problem that involves comprehensive policy systems, scientific theories, and technological systems.

Lastly, and most easily overlooked, is public awareness. On the one hand, the public lacks sufficient knowledge of early warning and prevention of rainfall-triggered geological hazards. The lack of understanding of early warning signals, escape routes, and self-rescue and mutual-rescue skills for geological disasters hinders people’s ability to make correct responses and take appropriate actions during and even after disasters. On the other hand, the public does not prioritize rainfall-triggered geological disasters enough. Generally, people could think that geological disasters are far from them or that once a disaster occurs, it is unavoidable, leading to a lack of motivation for prevention and response. In environments prone to extreme weather and disasters, the lack of awareness may exacerbate disaster losses and impacts.

Summary

In recent years, extreme weather events such as heavy rainfall, extreme heat waves, and superstorms have occurred frequently. Following that are frequent rainfall-triggered geological hazards, which pose a global issue. Unlike disaster risks associated with torrential rain and floods, rainfall-triggered geological hazards are characterized by clustering, suddenness, and high destructiveness, posing severe challenges for governments worldwide in their disaster prevention and mitigation efforts. Statistical analyses of disaster cases and loss data over the past decade indicate a noticeable upward fluctuating trend globally in casualties caused by rainfall-triggered geological disasters. This provides new evidence for understanding and attaching importance to the risks associated with rainfall-triggered geological hazards, as well as their prevention and response measures. While focusing on the processes of torrential rain and flood disasters and related rescue operations, attention should also be paid to the cascading geological disasters and their potentially significant risks.

The unusually high number of deaths attributed to geological disasters over the past year, which serves as a warning, indicates that we need to consider the potential transition in geological disaster patterns from predictable “linear gradual change” to unpredictable “nonlinear surge”. Therefore, to effectively deal with the substantial risks and uncertainty in the future that are posed by rainfall-triggered geological disasters and minimize disaster losses, governments should actively promote in-depth research and theoretical development on the meteorological-geological disaster chain, fostering a disaster chain mindset. On this basis, in the areas of identifying and monitoring potential geological hazards, risk assessment and precise quantitative zoning, short-term or medium-to-long-term early warning, emergency response, and rescue, we advocate deepening research in algorithms, models, technological systems, data openness and sharing, and international cooperation mechanisms. Targeted advancements in science, technology, and education systems for disaster prevention and mitigation should be pursued. Ultimately, it is hoped that a government-led and socially co-managed working mechanism for the prevention and mitigation of rainfall-triggered geological disasters can be established.