The water cycle, which is also called the hydrologic cycle, is a process that describes the continuous movement of water within the earth's system, in its solid, liquid, and vapor forms. This cycle involves various physical processes such as evaporation, transpiration, condensation, precipitation, infiltration, and runoff which helps to maintain water levels in different reservoirs, including oceans, ice sheets, and the atmosphere.  However, the effects of climate change on the water cycle, also known as water cycle intensification, have been observed since 1980 and have led to changes in water availability, freshwater sources, and land surface. The water cycle is important for global climate and ocean circulation and involves energy exchange that affects temperature and climate patterns. Human activities such as the burning of fossil fuels have been the primary driver of climate change since the 1800s, leading to long-term shifts in temperature and weather patterns due to greenhouse gas emissions.

The sun's heat causes water to evaporate from various sources, including ice, snow, plants, and soil. The water molecule is less dense than the atmosphere's nitrogen and oxygen, making it buoyant and able to rise. As the water vapor rises, it cools and condenses into tiny droplets that form clouds. These droplets collide and fall back to the ground as precipitation in various forms. The precipitation can accumulate in ice caps and glaciers, flow as surface runoff into rivers and lakes, or infiltrate the ground as groundwater. Aquifers can store freshwater for long periods, and springs can emerge from the groundwater. The water eventually returns to the ocean to complete the water cycle, which is essential for life on Earth.

Effects of climate change on the water cycle

Climate change impacts the water cycle globally due to interconnected atmospheric parameters and temperature-dependent processes. This leads to a higher risk of extreme weather events like hurricanes, droughts, and floods. The rising global temperatures accelerate the water cycle by increasing evaporation, impacting water vapor, precipitation, and stream flow. As a result, some regions experience stronger storms while others face dry air and drought. Climate change also affects precipitation, groundwater, evapotranspiration, and hydrologic hazards like floods and extreme temperatures.

We focus in particular on how climate change is affecting the hydrologic cycle before looking at linked societal issues. The interdependent nature of the hydrologic cycle makes it difficult to understand the full impact of climate change on it. However, by examining the physical changes in the hydrologic system, we can identify a hierarchy of climate change consequences. The differentiation identified could serve as a significant model for upcoming research or social assessments of climate change. The main characteristics of actual changes in the hydrologic system around the world can be outlined. Hydrologic risks such as floods and droughts impact people worldwide, with developing nations particularly vulnerable. As the primary mechanism in the ecosystem, ecology, and earth, the water cycle has become more intense as a result of climate change. It has a direct impact on all plants, animals, and marine ecosystems.