Threats of Climate Change to Cities Recently, many Korean cities, including Seoul, have been facing the frequent occurrence of extreme weather events such as sudden torrential rains, heatwaves, and strong winds. This summer, downtown areas in Seoul's Gangnam district suffered significant damage due to heavy rainfall in just a few hours, and both average and peak summer temperatures rose to record highs, forcing citizens to directly experience the severity of climate change. The impact of climate change is no longer merely an anomaly in seasonal patterns; it is evolving into a problem that threatens the very foundation of the vast urban ecosystem. Experts diagnose that now is the time to find answers to the fundamental question: 'How can we safely protect our cities?' Climate change is no longer a distant future problem. It is an issue directly linked to urban survival, posing significant responsibilities and challenges for all of us. Where do the threats of climate change affecting cities and citizens originate? Sea-level rise, torrential rains, heavy snow, and landslides inflict severe environmental, economic, and social impacts on cities. According to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6), global sea levels are projected to rise by an average of 43 to 84 cm by 2100 under an intermediate emissions scenario, with a possibility of rising over 1 meter in the worst-case high emissions scenario. This could pose a significant threat to low-lying cities, with millions of urban residents likely to lose their physical homes. Coastal megacities in Asia, in particular, are densely populated, raising concerns about even greater damage. Furthermore, natural disasters such as floods typically destroy urban infrastructure, transportation systems, and electricity and water networks. For example, Hurricane Katrina in 2005 devastated New Orleans, USA, causing economic losses of approximately $161 billion and becoming one of the worst natural disasters in US history, claiming over 1,800 lives. More than 80% of the entire city was submerged, and full recovery took over 10 years. This reality is by no means a problem confined to foreign countries. In Korea's case, natural disasters due to extreme weather events are also intensifying. The flood damage in Seoul's Gangnam area due to torrential rains in August 2022 and the increase in heat-related deaths during the summer heatwave of 2023 demonstrate that the climate crisis is directly impacting our lives. The climate crisis is no longer merely a policy effort related to environmental protection but a complex challenge directly linked to the survival of citizens. The subsequent topic is data. MIT Technology Review analyzes that 'data' is at the heart of solving these problems. This means not just collecting data, but processing and applying it to derive meaningful solutions. Data-driven policies are becoming the new normal in numerous cities. New York City has established FloodNet, an IoT sensor network, since 2020, collecting real-time flood data from over 500 locations. This system is used to identify flood-vulnerable areas in advance, issue early warnings to residents, and improve the efficiency of drainage systems. Indeed, during the heavy rains in the summer of 2024, this system enabled approximately 50,000 residents in Brooklyn and Queens to evacuate in advance. Singapore is considered one of the most innovative city-states in water resource management. Utilizing two-thirds of its land as rainwater catchment areas, Singapore monitors all water circulation processes in real-time through the Public Utilities Board (PUB), an integrated water management agency. Their 'Four National Taps' strategy combines local catchments, imported water, NEWater (recycled water), and desalination to ensure water security. In particular, a smart sewage system utilizing sensors and AI immediately detects anomalies to prevent floods. As of 2025, Singapore's water self-sufficiency rate has exceeded 80%, with a goal of achieving complete water self-reliance by 2030. The Netherlands is another effective example. With approximately 26% of its land located below sea level, the Netherlands has historically suffered frequent flood damage. After the Great Flood of 1953, which killed over 1,800 people, the Netherlands introduced the 'Delta Works,' a national comprehensive coastal management plan. This project consisted of 13 large-scale construction projects, including dams, sluices, dikes, and storm surge barriers, until its completion in 1997, and was selected as one of the seven wonders of modern civil engineering. More recently, through the 'Room for the River' program, they have adopted a flexible approach that allows natural river overflow but guides it to controllable areas. This system uses AI, based on real-time weather data and water level sensors, to determine the optimal timing for opening and closing sluice gates, thereby preventing floods. As of 2