Marissa HughesWater and a Changing World
Water is essential for life, but around the world, it’s becoming increasingly difficult to manage and predict. Across continents, scientists are gathering evidence of a rapidly changing hydroclimate. Hydroclimate refers to the interaction of precipitation, evaporation, runoff, and storage in the global water cycle. Today’s climate is marked by more frequent and intense storms, melting ice caps, shrinking reservoirs, ecosystem stress, and accelerating biodiversity loss. While Earth’s climate has changed in the past, these more recent shifts are not simply seasonal or meteorological—they indicate a deeper reorganization of the global climate and hydrologic systems that regulate water quality and quantity.
Observing a Changing Hydroclimate
Since the early industrial period, human activity has altered the Earth’s energy balance in measurable and profound ways. The widespread use of fossil fuels releasing greenhouse gases into the atmosphere, deforestation reducing carbon sinks in forests, and the formation of heat islands in cities have contributed to a warmer atmosphere and more chaotic weather patterns. These shifts have intensified the global water cycle, leading wet regions to become wetter, and dry regions to become dryer.
Communities and Water Extremes
This new hydroclimate doesn’t only affect ecosystems—it creates significant challenges for people. Reduced water availability, degraded water quality, and more volatile weather patterns are already affecting community food production, public health, and the stability of vulnerable communities. These effects are not evenly distributed. The most severe impacts often occur in regions already facing environmental stress, conflict, or limited access to resources, underscoring how water scarcity, climate vulnerability, and inequality are closely intertwined.
At the center of all these issues is a fundamental question of where water is, how it moves, and who can access it. The United Nations reports that only a small fraction of Earth’s water is suitable and accessible for human use, and this supply is increasingly threatened by climate extremes and competing demands. Simultaneously, warming oceans are driving stronger tropical cyclones and more intense coastal flooding, posing new risks to densely populated lowland regions.
Looking Forward
Thanks to recent advances in Earth observation systems, including hourly climate observations and the SWOT satellite mission, we now have unprecedented capacity to monitor changes in water storage and availability. These tools allow us to quantify patterns in rainfall and river discharge, as well as lake and reservoir storage, with frequent and near-global coverage.
Climate change is not a distant threat. It is a present-day reality, with water as both a driver and a signal of change. But this also means water is part of the solution. With better forecasting tools, increased observational capacity, and sustained investment in sustainable water management, we can develop strategies to mitigate these changes. Strengthening the resilience of water systems—both natural and human-managed—will be critical to adapting to this new climate reality.
Artificial Intelligence Statement
I would like to acknowledge the contribution of HydroGPT -4o(By Aaron Nichols), a language model developed using OpenAI (https://openai.com/) specifically for hydrologic studies, in providing direction for this article and its guiding questions. I would also like to acknowledge the contribution of Gemini for Workspace developed by Google (https://gemini.google.com/) in creating this article’s featured image. These models were accessed in April 2025.